Patent Application
20250204934
The present disclosure relates generally to the field of medical devices and methods. More specifically, the particular embodiments described herein relate to devices and methods for controlling clot removal from a patient's vasculature by aspiration thrombectomy.
Stroke is a significant cause of disability and death, and a growing problem for global healthcare. Stroke may be caused by a blockage in a cerebral artery resulting from a thromboembolism (referred to as an “ischemic stroke”), or by a rupture of a cerebral artery (referred to as a “hemorrhagic stroke”). Hemorrhagic stroke can result in bleeding within the skull, limiting blood supply to brain cells, and placing harmful pressure on delicate brain tissue. Blood loss, swelling, herniation of brain tissue, and pooling of blood can result in formation of clot mass inside the skull, and can rapidly destroy brain tissue. Hemorrhagic stroke is a life-threatening medical emergency with limited treatment options.
Aside from cerebral stroke, thromboembolism throughout the vasculature, in both arterial and venous circulation, is characteristic of numerous common, life-threatening conditions. Examples of potentially fatal diseases resulting from thrombotic occlusion include pulmonary embolism, deep vein thrombosis, and acute limb ischemia. Acute pulmonary embolism is a significant cause of death in the United States. Pulmonary embolism may be a complication from deep vein thrombosis. The aforementioned are some non-limiting examples of conditions in which treatment may include aspiration or evacuation of clot and/or blood.
Particular embodiments described herein provide systems and methods that improve catheter aspiration by enabling a more efficient procedure, by enhancing the ingestion of occlusive material, or both. In particular embodiments, the amount of fluid flowing through an aspiration catheter under vacuum aspiration is monitored to determine whether the flow is unrestricted, restricted, or clogged. Depending on the determined flow state, particular embodiments may employ different techniques and methods to improve catheter aspiration. In particular embodiments, unrestricted flow is detected, and aspiration is automatically and temporarily restricted for blood saving purposes. Minimizing blood loss and increasing the ratio of occlusive material to healthy blood removed may thereby allow more complete removal of occlusive material. In particular embodiments, restricted flow is detected, and full vacuum aspiration is automatically applied. In yet another particular embodiment, a clogged catheter is detected, and pulsed aspiration is automatically applied. This may beneficially enhance the ingestion of large, tough, or otherwise troublesome occlusions. Alternatively, pulsed aspiration, full aspiration, or restricted aspiration may be applied on demand by a user of particular embodiments.
In particular embodiments, the systems and methods described address the problem of excessive blood loss through dynamic aspiration cycling. The nature and flowability of the material being withdrawn by the aspiration catheter is monitored so that the system may either allow continuous aspiration when in clot, or sampling of extraction rate to determine whether the tip of the catheter is in contact with clot, in order to reduce the risk of excess blood loss. While determining and monitoring of blood flow rate is disclosed in the exemplary embodiments below, other measurements of the flowability and/or structural composition of the aspiration effluent, such as monitoring the collection chamber's volume, monitoring the collection chamber's fill rate, visually monitoring the aspiration tubing (clot is darker than fresh blood), or placing a strain gauge on aspiration tubing, could also be used.
The systems and methods of particular embodiments may respond to variations in flow rate, pressure, differential pressure, or other indicators of the composition of the material inside or adjacent to an aspiration catheter in a sub-second time frame to limit the unnecessary aspiration of blood during a thrombectomy procedure. Particular embodiments may be useful with any thrombectomy, embolectomy, atherectomy, or other catheter or probe system where blood and clot are withdrawn wholly or partially by application of a vacuum to the proximal end of any reperfusion, aspiration catheter or probe for the purpose of clot extraction.
Particular embodiments may provide a vacuum aspiration control system for use with a vacuum source and an aspiration catheter. In particular embodiments, the system comprises a flexible connection tubing, an on-off valve, a sensing unit, and a controller. In particular embodiments, the connection tubing may be linear in an unconstrained configuration and is configured to connect the vacuum source to an aspiration lumen in the aspiration catheter. In particular embodiments, the on-off valve may be configured to be operatively connected to the connection tubing, and the sensing unit may be configured to determine flow rate within the connection tubing and to produce a signal representative of such flow, such as either unrestricted flow, restricted flow, or clogged flow. In particular embodiments, the controller may be connected to receive the signal representative of flow through the connection tubing and to open and close one or more on-off valve(s) in response to the signal. In particular embodiments, the controller may be configured to automatically close the on-off valve to stop flow through the connection tubing when the signal indicates unrestricted flow, for e.g., that primarily healthy blood or blood free of vessel-obstructing clot is flowing through the connection tubing, and/or that the catheter is substantially free from contact with clot or other occlusive material. In particular embodiments, the controller may be configured to initiate pulsed aspiration when the signal indicates a clog, which may be caused by some occlusive material in or adjacent to the catheter or connecting tubing.
In particular embodiments, the controller may be configured to automatically open the on-off valve at a predetermined interval to sample effluent material through the connection tubing and the valve will typically only remain open if the signal indicates a return to clot. In particular embodiments, the controller algorithm may be configured to determine differences between healthy blood and clot independent of aspiration source and the inner diameter of the attached catheter.
In particular embodiments, the sensing unit may comprise any one or more of a variety of sensors, including differential pressure sensors, acoustic (including ultrasonic) flow sensors, optical flow sensors, thermal flow sensors, magnetic flow sensors, sensors which detect circumferential expansion of the connection tubing, rotational aspiration pump torque sensors, and the like. While differential pressures are described in more detail below, it will be appreciated that any sensing unit capable of detecting when flow or extraction rate through the connection tubing is excessive and/or clogged, would be suitable for use in particular embodiments, and are contemplated herein.
In particular embodiments, the sensing unit may comprise multiple pressure sensors at spaced-apart locations along the connection tubing, such as to measure differential pressure. In particular embodiments, the controller may calculate flow based on the differential pressure, and may determine whether the calculated flow rate indicates unrestricted flow, restricted flow, or a clog.
In particular embodiments, the sensing unit may use optical sensors that measure transmission, absorption, or both of light to characterize the contents flowing through the connection tubing. In particular embodiments, visible light is used determine whether flow contains clot or is primarily clot-free. By way of example and not limitation, flow with clot can be darker, which is detectable by optical sensors. Additionally or alternatively, in particular embodiments, the optical sensors may sense infrared, ultraviolet, visible light, or a combination, such as to analyze contents within the connecting tubing.
In particular embodiments, the sensing unit may use circumferential expansion sensors to determine the contents flowing through the connection tubing. In particular embodiments, the internal pressure of the connecting tubing and/or the contents flowing through the connecting tubing may affect the circumference of the connecting tubing. By way of example and not limitation, under strong vacuum, such as during a clog, the tubing may experience relatively large contraction and/or larger decrease in circumferential extent. By way of example and not limitation, during high flow rates comprising primarily clot-free blood, the tubing may experience relatively lower contraction and/or lower decrease in circumferential extent. By way of example and not limitation, during restricted flow, clots and/or blood may cause a relative expansion of the connecting tubing.
In particular embodiments, the sensing unit may be integrated into a rotationally-driven inline aspiration pump. In particular embodiments, the consistency of the effluent in the tubing may affect the torque required to pump the effluent. By way of example and not limitation, when removing occlusive material, the torque may approach relatively large values. By way of example and not limitation, during removal of primarily clot-free blood, the torque required may be relatively low.
In particular embodiments, the on-off valve may take a variety of specific forms. In particular embodiments, the on-off valve may comprise an actuator, such as a solenoid actuator, that is powered to open the valve. In particular embodiments, a valve may take a variety of forms, such as a pinch valve, an angle valve, or any of a variety of other valves, or a combination thereof, that can provide suitable actuation. Additionally or alternatively, in particular embodiments, a manual on-off valve may be provided that allows a user to initiate and/or terminate functions and features of particular embodiments.
In particular embodiments, the controller may be configured to open the valve and hold the valve open until a flow pattern which indicates unrestricted flow is detected whereupon the controller closes the valve. In particular embodiments, the controller may be further configured to automatically re-open the on-off valve. In particular embodiments, in what may be referred to as “sampling mode”, the controller may be further configured to periodically sample, or test flow to re-characterize flow and determine if it is safe to recommence aspiration. By way of example and not limitation, in particular embodiments, the controller may periodically test flow by opening the on-off valve for a fixed time interval, such as 150 milliseconds, to establish a “test” flow. In particular embodiments, the test flow may be characterized and, if it so indicates, the on-off valve may be reopened into a “treatment” mode to allow continued aspiration treatment. In particular embodiments, if the system characterizes the flow as unrestricted, e.g. excessive, then the system may dwell in a closed configuration for a fixed time interval, for example between a quarter second and two seconds, before an additional pressure differential sample is taken.
In particular embodiments, the controller may not be configured to automatically reestablish flow when safe conditions have been reached. By way of example and not limitation, in particular embodiments, the controller may be configured to allow a user to reposition the aspiration catheter and, after repositioning, to manually open the on-off valve (typically by actuating a switch which causes the controller to open the on-off valve) to resume aspiration treatment. In such instances, the controller may immediately return to the “sampling mode,” however, and if the reestablished flow is characterized as unrestricted flow, the controller may again close the on-off valve, and the user may again reposition the aspiration catheter in order to engage clot and manually resume aspiration. In particular embodiments, some systems may provide a manual switch to allow the user to manually open the on-off valve.
In particular embodiments, the controller may be configured to control two or more valves. In particular embodiments, the controller may control a first on-off valve between an aspiration catheter and a vacuum source and a second on-off valve between an aspiration catheter and a pressure source with a pressure at least above that of the vacuum source. In particular embodiments, the controller may alternate between opening the first on-off valve and the second on-off valve to generate pressure variations within an aspiration catheter and/or tubing adjacent to such a catheter. In particular embodiments, the controller may sample flow while the first on-off valve is opened to determine whether an attached catheter is still positioned in clot or otherwise occluded. In particular embodiments, the controller may hold the first on-off valve open if occlusions or clogs are detected. In particular embodiments, the controller may hold the second on-off valve closed if no occlusions or clogs are detected. In particular embodiments, the controller may operate one or more valves to alternate between providing a low pressure, such as a vacuum, and a high pressure, such as by introducing a fluid medium, to the aspiration catheter and/or tubing. In particular embodiments, the controller may operate one or more valves to simultaneously connect the aspiration catheter and/or tubing to a low pressure source, such as a vacuum, and to a high pressure source, such as by introducing a fluid medium. By way of example and not limitation, simultaneous connection of a high pressure source and a low pressure source may be used to facilitate flushing a fluid medium through the aspiration catheter and/or tubing.
In particular embodiments, the vacuum aspiration systems comprise a base unit which incorporates at least one on-off valve and the controller. In particular embodiments, the base unit may be configured to be mounted directly on or near a vacuum pump or console, and/or may include a connecting cable in order to receive power from the vacuum console or line and optionally exchange information with the controller and the vacuum console. In particular embodiments, the connection tubing may have a proximal end configured to connect the vacuum source and distal end configured to connect to the aspiration catheter. In such instances, the vacuum aspiration system may further comprise an external unit configured to be secured to the connection tubing at a location between the distal end and the proximal end thereof. In particular embodiments, exemplary external units may comprise at least a portion of the sensing unit. By way of example and not limitation, in particular embodiments, the sensing unit may comprise a first pressure sensor in the base unit and a second pressure sensor in the external unit. In particular embodiments, the controller may be configured to determine if a differential pressure exists based on the signals from the first and the second pressure sensor.
In particular embodiments, a vacuum aspiration method may be provided. In particular embodiments, the vacuum aspiration method may comprise engaging a distal end of an aspiration catheter against an occlusion in the blood vessel. In particular embodiments, a vacuum may be applied through an aspiration lumen of the aspiration catheter using a vacuum source coupled to a proximal end of the aspiration lumen by a connection tubing. In this way, portions of clot and other occlusive material may be drawn into the aspiration lumen, through the connection tubing, and into a collection receptacle by the vacuum source. In particular embodiments, flow through the connection tubing may be sensed, and a valve may be automatically closed to stop flow through the connection tubing when the sensed flow exceeds a determined value while the vacuum source remains on. In particular embodiments, flow through the connection tubing may be later reestablished by opening the valve, and the steps may be repeated until a desired amount of clot has been aspirated.
In particular embodiments, an assembly for generating pressure differentials may be provided that may result in pressure pulses to execute an extraction cycle. In particular embodiments, the assembly may include a fluid injection apparatus, a mechanical displacement apparatus, gravity induced pressure head, or a combination thereof. In particular embodiments, a fluid injection apparatus may provide a source of relative positive pressure for a catheter currently or previously under vacuum aspiration. By way of example and not limitation, the fluid may be at a pressure above that of the vacuum aspiration system, between full vacuum pressure and ambient pressure, at ambient pressure, between ambient pressure and systolic pressure, at systolic pressure, or above systolic pressure. In particular embodiments, the fluid injection apparatus may utilize an aperture, a valve, a pump, a pressure chamber, or a suitable combination. In particular embodiments, a mechanical displacement apparatus may physically displace the volume of a catheter system to provide relative increases and decreases of pressure depending on the direction of displacement. In particular embodiments, a mechanical displacement assembly may assist vacuum recovery after a catheter has had its pressure increased above the pressure of the vacuum source.
In particular embodiments, the controller may include an algorithm that is used to interpret pressure sensor signals to determine whether the contents flowing through a catheter should be characterized as unrestricted, restricted, or clogged. In particular embodiments, unrestricted flow can be a high flow that may be characterized as excessive, and/or may be primarily or completely comprised of healthy blood, clot-free blood, or blood free of vessel-obstructing clot, and/or blood that is not helpful to aspirate. In particular embodiments, restricted flow may be comprised of a mix of healthy blood and clot or other occlusive material. In particular embodiments, a clog may be caused by a clot or other occlusive material within an aspiration catheter, such as partially within an aspiration catheter, adjacent to an aspiration catheter, and/or in other connecting tubing attached to the aspiration catheter. By way of example and not limitation, healthy blood may be blood with a low enough proportion of cross-linked fibrin such that it is not sufficiently integrated to cause ischemia or other similar vessel occlusions. In particular embodiments, when the algorithm detects unrestricted flow, it may cause the system to initiate a sampling mode. In particular embodiments, when the algorithm detects restricted flow, it may cause the system to enable full vacuum aspiration. In particular embodiments, when the algorithm detects a clog, it may cause the system to generate a variety of pressure pulses with an extraction cycle. In particular embodiments, the algorithm may be responsive and adaptable to changing circumstances, such as changing to a catheter of a different size mid-procedure. In particular embodiments, the algorithm may adjust sampling modes and pressure pulse magnitudes if the catheter state remains static, changes too quickly, changes to slowly, or improves as expected.
In particular aspects of methods disclosed herein, particular embodiments may remove clot and other occlusive material from a blood vessel that comprises a vein or an artery. In particular embodiments, sensing of flow may comprise one or more of differential pressure measurement, acoustic flow measurement, optical flow measurement, thermal flow measurement, measurement of circumferential expansion of the connection tubing, rotational aspiration pump torque sensors, and/or other suitable sensing devices and methods.
In particular aspects of the method, sensing flow may comprise measuring the differential pressure using a first sensor located proximate the vacuum source and a second sensor located on or adjacent the connection tubing between the vacuum source and the aspiration catheter.
In particular embodiments of the method, resuming flow through the connection tubing may comprise opening the valve for an interval, such as a sub-second interval, detecting when the sensed flow is characterized as acceptable, and automatically resuming flow. In particular embodiments, automatically resuming flow may comprise automatically detecting when the sensed flow may be characterized as acceptable, and/or holding the valve open as long as the flow is so characterized. In particular embodiments, resuming flow may comprise manually opening an on-off valve.
In particular embodiments of methods disclosed herein, pressure differentials may be generated by closing a valve to a vacuum pump, and/or opening a valve to a source of pressure, wherein the pressure of the source is at least above that of the vacuum, followed by re-opening the valve to the vacuum pump. Alternatively, or in combination, in particular embodiments, pressure differentials may be generated by mechanical displacement, wherein a volume of a chamber may be reduced to increase pressure within a catheter, and/or a volume of the chamber may be increased to decreases pressure within a catheter, whereby the actuation of the mechanical displacement chamber may result in pressure differentials. In particular embodiments, the pressure differentials may be tailored to have a specific or dynamic amplitude and frequency, so as to facilitate the removal of clot or other occlusive materials.
In particular embodiments, which may include aspects of the above embodiments, with respect to tube and system flushing, the apparatus may include connection tubing configured to act as a fluid conduit between an aspiration catheter, a fluid source, and a vacuum source; a first pressure sensor associated with a distal portion of the connection tubing; a second pressure sensor associated with a proximal portion of the connection tubing; a first controllable valve configured to control a level of vacuum in the connection tubing provided by the vacuum source; a second controllable valve configured to control an introduction of a fluid medium into the connection tubing from the fluid source; and a controller.
In particular embodiments, a third pressure sensor associated with a pressure of the fluid source may be included. In particular embodiments, a fourth pressure sensor may be used to compare pressure sensors to a reference atmospheric pressure. In particular embodiments, a fifth pressure sensor proximal to the first controllable valve and/or in the same static or contiguous fluid path as the second sensor may be included.
In particular embodiments, which may include aspects of the above embodiments, the controller may be configured to detect, via one or more of the first pressure sensor and the second pressure sensor, one or more pressure levels associated with the connection tubing; and determine, based on the one or more pressure levels detected, whether the connection tubing is occluded, wherein, based on determining that the connection tubing is occluded, the controller is further configured to determine, based on the one or more pressure levels detected, a location of an occlusion; and operate, based on determining the location of the occlusion, one or more of the first valve and the second valve to introduce the fluid medium into the connection tubing during one or more time intervals.
In particular embodiments, which may include aspects of the above embodiments, prior to the detecting of the one or more pressure levels, the controller may be configured to operate the first valve to provide fluid communication between the distal portion of the connection tubing and the vacuum source.
In particular embodiments, which may include aspects of the above embodiments, the controller may be configured to determine whether the connection tubing is occluded based on one or more differences between the one or more pressure levels detected, respectively, via the first pressure sensor and the second pressure sensor.
In particular embodiments, which may include aspects of the above embodiments, the controller may be configured to determine, based on the one or more differences between the one or more pressure levels detected, respectively, via the first pressure sensor and the second pressure sensor, that the connection tubing is occluded between the first pressure sensor and the second sensor.
In particular embodiments, which may include aspects of the above embodiments, the controller may be configured to operate, based on the determination that the connection tubing is occluded between the first pressure sensor and the vacuum source, the first valve and the second valve to introduce the fluid medium into the connection tubing during a first time interval.
In particular embodiments, which may include aspects of the above embodiments, the first time interval is a predetermined time interval. In particular embodiments, which may include aspects of the above embodiments, the predetermined time interval is between 200 ms and 800 ms. In particular embodiments, which may include aspects of the above embodiments, the predetermined time interval is between 15 ms and 900 ms.
In particular embodiments, which may include aspects of the above embodiments, the controller may be configured to determine whether the connection tubing is occluded based on one or more of the pressure levels detected via the second pressure sensor exceeding a threshold value.
In particular embodiments, which may include aspects of the above embodiments, the controller may be configured to determine, based on one or more of the pressure levels detected via the second pressure sensor exceeding a threshold value, that the connection tubing is occluded between the second pressure sensor and the vacuum source.
In particular embodiments, which may include aspects of the above embodiments, the controller may be configured to operate, based on the determination that the connection tubing is occluded between the second pressure sensor and the vacuum source, the first valve and the second valve to introduce the fluid medium into the connection tubing during a second time interval. In particular embodiments, the second time interval is a predetermined time interval. In particular embodiments, the second time interval is between 70 ms and 300 ms. In particular embodiments, the second time interval is between 150 ms and 200 ms. In particular embodiments, the second time interval is between 15 ms and 800 ms.
In particular embodiments, which may include aspects of the above embodiments, the controller may be configured, during the one or more time intervals, to selectively open or close one or more of the first valve and the second valve.
In particular embodiments, which may include aspects of the above embodiments, the controller may be configured to hold open the first valve during at least a portion of the one or more time intervals. In particular embodiments, which may include aspects of the above embodiments, the controller may be configured to repeatedly open and close the second valve during at least a portion of the one or more time intervals.
In particular embodiments, which may include aspects of the above embodiments, the aspiration thrombectomy system may further include a controllable bypass valve, wherein opening the bypass valve when the first valve is closed concurrently introduces the fluid medium into the connection tubing and disconnects fluid communication between the aspiration catheter from the vacuum source.
In particular embodiments, which may include aspects of the above embodiments, the aspiration thrombectomy system may further include a third controllable valve configured to control an introduction of the fluid medium into the aspiration catheter.
In particular embodiments, which may include aspects of the above embodiments, the aspiration thrombectomy system may comprise a fluid medium including one or more of air and saline.
In particular embodiments, which may include aspects of the above embodiments, the aspiration thrombectomy system may comprise a third pressure sensor associated with the fluid source. In particular embodiments, which may include aspects of the above embodiments, the aspiration thrombectomy system may comprise a fourth pressure sensor configured to compare one or more detected pressure levels to a reference atmospheric pressure level.
In particular embodiments, which may include aspects of the above embodiments, the aspiration thrombectomy system may comprise a fifth pressure sensor provided proximal to the first controllable valve. In particular embodiments, which may include aspects of the above embodiments, the controller is configured to determine whether the connection tubing is occluded based on one or more differences between one or more pressure levels detected, respectively, via the second pressure sensor and the fifth pressure sensor.
In particular embodiments, the techniques described herein relate to a method for aspiration thrombectomy, including: detecting, by a controller, via one or more of a first pressure sensor and a second pressure sensor, one or more pressure levels associated with a connection tubing, wherein the connection tubing acts as a fluid conduit between an aspiration catheter, a fluid source, and a vacuum source, wherein the first pressure sensor is associated with a distal portion of the connection tubing, and wherein the second pressure sensor is associated with a proximal portion of the connection tubing; determining, based on the one or more pressure levels detected, whether the connection tubing is occluded; determining, based on a determination that the connection tubing is occluded and on the one or more pressure levels detected, a location of an occlusion; and operating, based on the determination of the location of the occlusion, one or more of a first controllable valve and a second controllable valve to introduce a fluid medium into the connection tubing during one or more time intervals, wherein the first valve is configured to control a level of vacuum in the connection tubing provided by the vacuum source, and the second valve is configured to control introduction of the fluid medium into the connection tubing from the fluid source.
In particular embodiments, the techniques described herein relate to a method, further including, prior to the detecting of the one or more pressure levels, operating the first valve to enable fluid communication between the distal portion of the connection tubing and the vacuum source.
The embodiments disclosed herein are only examples, and the scope of this disclosure is not limited to them. Particular embodiments may include all, some, or none of the components, elements, features, functions, operations, or steps of the embodiments disclosed herein. Embodiments according to the invention are in particular disclosed in the attached claims directed to a method and a system, wherein any feature mentioned in one claim category, e.g. method, can be claimed in another claim category, e.g. system, as well. The dependencies or references back in the attached claims are chosen for formal reasons only. However any subject matter resulting from a deliberate reference back to any previous claims (in particular multiple dependencies) can be claimed as well, so that any combination of claims and the features thereof are disclosed and can be claimed regardless of the dependencies chosen in the attached claims. The subject-matter which can be claimed comprises not only the combinations of features as set out in the attached claims but also any other combination of features in the claims, wherein each feature mentioned in the claims can be combined with any other feature or combination of other features in the claims. Furthermore, any of the embodiments and features described or depicted herein can be claimed in a separate claim and/or in any combination with any embodiment or feature described or depicted herein or with any of the features of the attached claims.
Particular embodiments are described below. For clarity, not all features of each actual implementation are described in this specification. In the development of an actual device, some modifications may be made that result in an embodiment that still falls within the scope of this disclosure.
In particular embodiments, the blood and clot may be drawn into the collection canister by a partial vacuum, which may be provided by a vacuum connector 28 on the base unit 12 which is connected to the vacuum pump (not illustrated). The vacuum from vacuum connector 28 may be applied to a vacuum port 24 on a removable lid 25. The vacuum connector 28 may be connected to the vacuum port 24 by an external vacuum tube 30.
In particular embodiments, clot aspiration using a mechanical thrombectomy apparatus or other a vacuum-assisted thrombectomy systems must sometimes be terminated due to the risk of excessive blood loss by the patient. By way of example and not limitation, terminating clot aspiration due to risk of excessive blood loss may be high when using large aspiration catheters. During aspiration thrombectomy, if the catheter tip falls out of contact with the thrombus or other occlusive material, the tip may be exposed to healthy blood and full flow can ensue. Under such conditions, the blood loss rate may be excessive, and in some cases, may result in premature termination of the procedure. By way of example and not limitation, if the catheter enters healthy blood and full flow ensues during an aspiration procedure, a blood loss rate in the range of 20-25 cc per second may occur, such as with an 8 French size catheter. By way of example and not limitation, assuming a maximum tolerable blood loss of 300-1000 mL for a patient, the catheter may not run in unrestricted mode for more than approximately 20 to 50 seconds. When a physician operates the system manually, the aggregate blood loss may reach an unacceptable level before sufficient clot is removed during an aspiration procedure. In particular embodiments, reliably identifying whether the tip of the catheter is in contact with clot and/or is undesirably aspirating healthy, clot-free blood can be a significant problem, and manual control may not be optimum.
In particular embodiments, during other procedures such as, for example, neurovascular procedures for treatment of ischemic stroke, excessive removal of blood may be less of a risk, and the primary focus of the procedure may be maximization of removal of occlusive material. Optimizing both technique and aspiration control may be of high importance for successful removal of occlusive material.
In particular embodiments, it can be desirable to provide improved methods and apparatus for controlling the aspiration of thrombus and clot using aspiration catheters in combination with pumping consoles. By way of example and not limitation, it can be particularly useful to provide systems and methods which limit blood loss during such aspiration procedures, such as by automatically stopping aspiration while the aspiration catheter is not in contact with clot or thrombus. Separately or additionally, in particular embodiments, it can be desirable to provide systems and methods which optimize system performance and procedures for removal of occlusive material. Particular embodiments, as will be further described herein, may be designed to meet these requirements and provide corresponding benefits.
Referring to
In particular embodiments, the vacuum system 40 may include a vacuum console 42 and a blood/clot collection canister 44 having the lid 26 discussed below in relation to
Referring to the figures,
In particular embodiments, a post 50, which may form a contiguous portion of the outer surface or wall of the enclosure 46, may be formed within the recess 48 and/or may extend upwardly from a bottom plate 56, which can act as a support for the collection canister 44 when it is received within the recess. In particular embodiments, a vacuum connector 52 and a pressure sensing connector 54 may be formed in or on an upper surface of the post 50, and may be located so that they may align with a pressure sensing port 104 and a vacuum port 102 (e.g.,
In particular embodiments, the functions of the pump may be controlled by the microprocessor controller 74. In particular embodiments, the pressure output from sensor 64 may separately or additionally be controlled and/or processed by the microprocessor controller 74. In particular embodiments, one or more of the light 58, switch 60, and/or display 62 may be connected to the microprocessor controller 74, which may be powered by the power supply 72. In particular embodiments, power supply 72 may be powered through line current connector 72A. In particular embodiments, USB connector 72B may be powered by microprocessor controller 74. By way of example and not limitation, the pump may be plugged into an outlet via a power cord that is supplied with the pump. By way of example and not limitation, the power supply may convert the AC current from the wall outlet to DC current, which the microprocessor controller may use to power one or more of the pump, switch, lights, USB connector, etc.
In particular embodiments, pressure sensor 64 may be connected to the microprocessor controller 74, and may measure vacuum pressure in the canister through the pressure sensing connector 54. In particular embodiments, another pressure sensor (e.g., a second pressure sensor, not illustrated) may be connected to the microprocessor controller 74 to measure ambient pressure outside of the pump enclosure through an internal tube, which may be routed to a vent in the base of the pump. By way of example and not limitation, the microprocessor controller may take the vacuum pressure readings from the pressure sensor 64 and divide it by the ambient pressure reading from the second pressure sensor to calculate the vacuum pressure in the canister as a percent of ambient pressure. Referring now to
In particular embodiments, main body 78 may have a bottom 98 and an open upper end 76, which may be covered by a removable clear plastic lid 80. By way of example and not limitation, the clear plastic lid 80 may be attached by a bayonet connector 82, and/or a form or other gasket 84 may seal the lid to the open end of the main body 78.
In particular embodiments, a groove 94 may be formed in one side of the main body 78. By way of example and not limitation, groove 94 may be shaped so that it may be placed over the post 50 in the recess 48 of the enclosure 46 of the vacuum console 42. As illustrated in
In particular embodiments, the pressure sensing port 104 may be connected to a tube or lumen, which may extend upwardly in the main body 48 of the canister 44 and/or may terminate in an upper opening or aperture 106. In particular embodiments, the vacuum port 102 may extend upwardly through a much larger lumen or tube, and/or may terminate in an open aperture 108 at its upper end. By way of example and not limitation, the apertures 106 and 108 may be located near the top of the interior of the main body 78, but may be below the bottom of the lid 80 when the lid is in place on the canister 44. Thus, in particular embodiments, both of the apertures 106 and 108 may be exposed to the interior of the canister 44, but may be maintained well above the mid-section and bottom where the clot and blood are collecting. In particular embodiments, the risk of contamination from blood and clot may be minimized based on this arrangement.
In particular embodiments, a filter plate 86, illustrated herein as a perforated screen but which may also be a woven screen or other separating member, may be held in the mid-section of the interior of the main body 78 of the canister 44. By way of example and not limitation, clot or occlusive material may be drawn into the interior of the canister through a connector 110, which may be attached to a proximal end of the catheter or other tubing. In particular embodiments, clot and blood may be drawn into the interior of the main body 78 by the vacuum which is drawn through the vacuum port 102 by the vacuum console 42, as previously described. By way of example and not limitation, as clot and blood may fall downward from connector 110 into the canister 44, the clot may collect on the upper surface of the filter plate 86 while the blood may flow through the perforations in the plate and collect in the bottom of the canister. As the plate may be inclined downward from a sleeve 88, which may be mounted on a post 90 in the interior of the canister in particular embodiments, excess blood may flow over an open bypass region 100 (
In particular embodiments, filter body 92 may occupy the interior of post 90 and aperture 108, and may prevent extracted material from contaminating the interior of enclosure 46. By way of example and not limitation, filter body 92 may occupy the interior of post 90, and/or extend to aperture 108. In particular embodiments, the filter body may therefore prevent extracted material from contaminating the interior of enclosure 46.
In particular embodiments, a groove 94 may be formed on a side of the main body 78 of the canister 44, and may be received over the post 50 in the recess 48 of the enclosure 46 in order to align the vacuum and pressure sensing connectors and vacuum ports. In particular embodiments, a gasket 96 may be provided at the seal between the vacuum ports and the vacuum connectors.
While particular embodiments of apparatus and methods for controlled clot aspiration for particular embodiments may be used with the vacuum system 40, it will be appreciated that the particular embodiments described and claimed herein are not limited to use with any particular vacuum console, and instead may be useful with any clot or other vascular thrombectomy or aspiration system, such as a thrombectomy or other vascular aspiration catheter in combination with a vacuum pump or other source where there may be a risk of excess blood aspiration, clogging, or both.
In particular embodiments, an exemplary system 200 for performing controlled clot aspiration may comprise a base unit 210 and an external unit 204. A proximal end of a connection tubing 206 may be connected to the base unit 210, and the external unit may be secured on or to the connection tubing at a location spaced apart from the proximal end. By way of example and not limitation, a spacing may be by some distance sufficient to make conclusions about flow. In particular embodiments, external unit 204 may be configured to connect directly to a hub and/or other proximal end of an aspiration catheter, or may be configured to be connected in the middle of the connection tubing. In particular embodiments, the connection tubing may be linear in an unconstrained configuration and/or flexible along its length.
In particular embodiments, the base unit 210 may be configured to sit directly atop the lid 26 on the collection canister 44 of a vacuum console 40. By way of example and not limitation, a communication cable 208 may extend from the base unit 210 through a portion of connecting tubing 206 to a connection receptacle on the vacuum console 40, so that the base unit may be powered by the vacuum console and may optionally communicate data with the controller within the vacuum console.
As illustrated in
In particular embodiments, an exemplary base unit 200b may comprise a base unit enclosure 216 having an open interior cavity 218, which may receive a number of components. By way of example and not limitation, a controller 220, which may include a microprocessor on a printed circuit board 248, may be mounted within the cavity 218 together with a pressure sensor 224 secured between a tube segment 232 and a proximal end on the connection tubing 206 by a pressure fitting 226. By way of example and not limitation, tube segment 232 may be collapsible and positioned in a pinch valve 228 which is driven by a solenoid 230. In particular embodiments, pinch valve 228 may be biased into a closed position by a compressive spring (not visible), unless it is opened by solenoid 230. In particular embodiments, base unit 200b may include a connecting fitting 222, which may be configured to be removably secured to a vacuum fitting (not illustrated) on the lid 26 of the canister 44. In particular embodiments, controller 220 may be configured to open and close the pinch valve 228, such as to allow and prevent, respectively, the flow of clot and blood through the tubing segment 232 from the aspiration catheter into the collection canister. In particular embodiments, base unit 200b may optionally include a button (not pictured) in electronic communication with printed circuit board 248 (for e.g., of controller 220), such as for advanced user control of various parameters of the system. In particular embodiments, a base unit may house or be in communication with a pressure chamber, a fluid source, additional on-off valves, and/or a combination thereof.
In particular embodiments, an on-off valve and a controller of the type suitable for use in aspiration control systems may be used to apply mechanical forces on a clot, thrombus, or other occlusive material. In particular embodiments, during a maceration cycle, mechanical action by the on-off valve on the occlusive material may be used for cutting, shearing, chopping, dividing, softening, macerating, or otherwise modifying the form, consistency, and/or deformability of the occlusive material. By way of example and not limitation, modifying the form or consistency of clots, thrombi, or other occlusive material by mechanical action may beneficially enable more effective aspiration of occlusive material through the aspiration catheter. For example, a large thrombus may be divided into smaller pieces for more effective aspiration. For example, a hard or dense thrombus may be mechanically softened or made more pliable by mechanical action to enable more effective aspiration. In particular embodiments, the pinch valve 228 may be used for applying mechanical forces and action on clots, thrombi, and/or other occlusive material. In particular embodiments, other types of valves, including but not limited to valves specifically designed for improved mechanical action on occlusive material, may be used. In particular embodiments, parameters for selective operation of the valve by the controller, including but not limited to timing, frequency, duty cycle parameters, and/or signal amplitude (which may correspond in particular embodiments to a valve closing-related parameter such as force), may be optimized to provide improved mechanical action by the valve on occlusive material.
In particular embodiments, an exemplary external unit 204 may include an external unit enclosure 240 having a flow fitting 242 in an interior cavity thereof. By way of example and not limitation, the flow fitting 242 may be connected to portions 206a and 206b of the connecting tubing 206, such as illustrated for particular embodiments in
In particular embodiments, by providing a first pressure sensor 224 in the base unit and a second, axially separated pressure sensor 246 in the external unit enclosure 240, the material flow rate through the connection tubing may be calculated. By way of example and not limitation, the material flow rate calculation may be based upon measured differential pressure(s) by the controller. In particular embodiments, the controller may analyze the pressure differentials and flow rate to determine the contents flowing through the aspiration catheter, connective tubing, or both.
In particular embodiments, the controller may characterize the state of a catheter's contents as unrestricted flow, restricted flow, clogged, and/or particular intermediate states. In particular embodiments, a high pressure differential between spaced-apart pressure sensors may indicate unrestricted flow. By way of example and not limitation, unrestricted flow may be comprised of primarily healthy, clot-free blood, or blood free of vessel-obstructing clot. In some examples, healthy blood may be blood with a low enough proportion of cross-linked fibrin such that it is not sufficiently integrated to cause ischemia or other similar vessel occlusions. By way of example and not limitation, aspirating such healthy blood with full aspiration may result in excessive blood loss, which may in particular embodiments require premature termination of the aspiration procedure.
In particular embodiments, a variable and intermediate or low pressure differential may indicate restricted flow. By way of example and not limitation, restricted flow may be comprised of clot, occlusive material, and/or blood. In particular embodiments, restricted flow may benefit from full aspiration. In particular embodiments, a small pressure differential or a pressure differential approaching zero may indicate a clog. In particular embodiments, such flow, or lack thereof, may benefit from an extraction cycle. It will be appreciated that the use of differential pressure for detecting increased flow and occlusions is provided by way of example and not limitation; other flow measurement and/or material property measurement techniques are fully contemplated, and are within the scope of this disclosure.
In particular embodiments, the controller 220 may implement an algorithm that may receive and/or analyze pressure sensor data. By way of example and not limitation, such data may be used by controller 220 to open and close one or more valves, such as an on-off valve. By way of example and not limitation, a valve may be a pinch valve 228 (e.g.,
In particular embodiments, the controller 220 may implement an algorithm that may use pressure sensor data to analyze the contents flowing through an aspiration catheter, and/or characterizes it as unrestricted flow, restricted flow, or clogged, and/or particular intermediate states. By way of example and not limitation, a catheter with unrestricted flow may be aspirating primarily healthy, clot-free blood, or blood free of vessel-obstructing clot. By way of example and not limitation, a catheter with mixed flow may be aspirating a combination of clot, occlusive material, and blood. By way of example and not limitation, a catheter with little to no flow may be clogged or occluded.
In particular embodiments, if an algorithm determines that an excessive amount of blood may be in the process of being aspirated, as may be the case for a catheter with unrestricted flow, it may restrict aspiration to reduce blood loss. In particular embodiments, if an algorithm determines that a catheter may have restricted flow, it may allow full aspiration. In particular embodiments, if an algorithm determines that a catheter may have little to no flow, it may initiate an extraction cycle, such as to help remove any clogs or occlusions. By way of example and not limitation, as used herein, the term “clot” may be understood to encompass any occlusive material found in vasculature, such as thrombus, embolus, plaque, occlusive material, vessel blockage, or any other obstructive material. “Clot” may be used to reference any combination of such occlusive material in particular instances described here, for brevity's sake.
In particular embodiments, a first step 1310 may be to measure maximum and minimum pressure differential windows over some assessment time period and, after the assessment period, take an instantaneous pressure differential and compare it to such maximum and minimum pressure differential windows. In particular embodiments, the maximum and/or minimum pressure differential windows may be incrementally updated. In particular embodiments, at a step 1320, if the instantaneous pressure differential is determined to be lower than a minimum pressure differential of the assessment period, the algorithm may determine at a step 1330 that the system is in clot, and/or may instruct the system to continue full aspiration, such as by keeping one or more valves (e.g., on-off valves) open until the next sample, at step 1340. On the other hand, according to particular embodiments, if the instantaneous pressure differential is determined to be above the minimum pressure differential, the algorithm may determine at step 1350 whether the instantaneous pressure differential is above a threshold pressure differential. By way of example and not limitation, a threshold pressure differential may be a product of the maximum pressure differential multiplied by a confidence multiplier ‘X’. In particular embodiments, ‘X’ may separately or additionally correspond to or include a correction factor and/or a factor of safety.
In particular embodiments, if the instantaneous pressure differential is not determined to be above the threshold pressure differential at step 1350, the algorithm may determine at step 1360 that the system is in clot, and/or may allow full aspiration. In particular embodiments, if the instantaneous pressure differential is instead determined to be above the threshold pressure differential at step 1350, the algorithm may determine open flow conditions at step 1370, and/or may restrict aspiration to limit blood loss at step 1380, such as by entering a sampling state where aspiration is limited to brief surges to make new instantaneous pressure differential readings. In either case, in particular embodiments, whenever aspiration is allowed, the algorithm may continually take instantaneous pressure differential readings, and/or compare them to the maximum and minimum pressure differentials which may be collected throughout the procedure. In particular embodiments, when unrestricted flow (e.g. open flow) is detected, the algorithm may trigger a sampling state. In particular embodiments, when a clot is detected, the algorithm may initiate full aspiration, or initiate an extraction cycle with pulsed aspiration.
In particular embodiments, a correlation algorithm is utilized that determines whether a catheter has unrestricted flow, restricted flow, or is clogged, e.g. the catheter's state, based on a correlation between flow rate and such states. In particular embodiments, a windowing algorithm may be utilized that may analyze discrete portions of pressure sensor data, such as to establish local minimum and/or local maximum pressure sensor readings. These windowed minima and maxima may be compared to global minima and global maxima across the data set. By way of example and not limitation, for a sudden large change (delta) in pressure readings, the system may preferentially make determinations of a catheter's state according to local minima and/or local maxima. In particular embodiments, pressure readings below minima and above maxima may signify a change in catheter state, e.g. below a minimum may indicate a clogged catheter, and/or above a maximum may indicate an unrestricted flow state.
In particular embodiments, an algorithm may be utilized emphasizing an analysis of standard deviations across a discrete window of data points. In particular embodiments, an ongoing flow rate signal may be compared to a mean flow rate, e.g., a running average. By way of example and not limitation, a small standard deviation may indicate that a catheter is clogged or unrestricted, while a large standard deviation may indicate that a catheter has restricted flow.
In particular embodiments, a learning algorithm may be used to determine the contents flowing through an aspiration catheter. By way of example and not limitation, training data may be formed by collecting pressure readings along the length of catheter in a variety of states, e.g. unrestricted flow, restricted flow, or clogged. Numerous pressure readings may be recorded for each catheter state, and the algorithm may then reference such data sets to interpret never-seen pressure readings, and/or to predict the state of the catheter and/or its flow.
In particular embodiments, an artificial neural network (ANN) may be utilized that may employ a multinomial logistic regression algorithm. In particular embodiments, the ANN may be trained to predict answers by considering numerous training data sets. By way of example and not limitation, the training data may include both observed data as inputs and the actual outputs. In particular embodiments, the inputs may be propagated across the ANN, which may be comprised of layered nodes that may each represent a linear transformation within the solution space. In particular embodiments, the ANN may then “learn” by analyzing differences between the ANN's calculated output and the actual output (e.g., ground truth). In particular embodiments, this difference may be translated into an error function, and/or may be backpropagated across the ANN, whereby the weight of each node may be modified according to its contribution to the error function. Weighting is a process of mathematical optimization that may establish which nodes may optimally map inputs to their correct outputs.
In particular embodiments, numerous sets of training data may be propagated across the ANN iteratively until the error function reaches convergence, i.e. an acceptable and/or predetermined level of tolerance. In particular embodiments, once the nodes have been properly weighted, in that the error function has reached convergence, the ANN may accurately predict the output of previously unseen input. By way of example and not limitation, this may mean that the trained or learned ANN may take novel pressure sensor data inputs and accurately predict catheter size, and/or whether a catheter's contents may be classified as unrestricted, restricted, clogged, and/or particular intermediate states.
In particular embodiments, an algorithm may employ semi-supervised and unsupervised learning to continually update node weights. In particular embodiments, an algorithm may employ clustering, dimensionality reduction, and/or reinforcement learning to improve prediction accuracy. In particular embodiments, an algorithm may accurately interpret pressure fluctuations associated with switching between catheters of different diameters, and/or may filter out pressure fluctuations generated by manual movements of a separator within the aspiration catheter, such as by determining and accounting for the cadence of the movement. Particular embodiments may employ one or more algorithms that may use a combination of the above algorithmic flow analysis techniques.
In particular embodiments, an algorithm may initiate a sampling mode when unrestricted flow is detected. In particular embodiments, an algorithm may detect a change in flow, such as indicating unrestricted flow, within a short period of time. By way of example and not limitation, such a short time interval may span milliseconds. In particular embodiments of the sampling mode, the algorithm may cycle off aspiration, and/or may open and close the on-off valve at a predetermined frequency. In particular embodiments, a sampling state may conduct an aspiration surge when the valve is briefly opened, and/or may make an assessment of the pressure sensor readings. By way of example and not limitation, based on such an aspiration surge, an algorithm may determine whether the system should revert to full aspiration, such as with an on-off valve in the open position, or remain in the sampling state. By way of example and not limitation, such sampling surges may occur over a millisecond order of magnitude, and/or may ensure that full aspiration occurs only when the system is engaging clot, and may thereby minimize blood loss.
In particular embodiments, upon being powered on, the system may have a brief delay before the algorithm assesses flow in the aspiration tubing. By way of example and not limitation, if the sensors indicate an unrestricted flow, then an appropriate delay of time may be calculated for which one or more valves, such as an on-off valve, may remain closed. In particular embodiments, after a brief delay, one or more valves, such as an on-off valve, may be opened to briefly allow aspiration, and/or to sample pressure readings in the aspiration tubing. By way of example and not limitation, by doing so, the system may assess whether the system may still have unrestricted flow, or if it may have been positioned into clot, and/or other occlusive material. In particular embodiments, if the sampling detects unrestricted flow, a new delay may be calculated. In particular embodiments, such a new delay may be determined to be incrementally longer for each consecutive reading, up to a threshold. In particular embodiments, if the sampling detects a restricted flow, for example, due to a clog, an appropriate delay of time may be calculated for which one or more valves, such as an on-off valve, may remain open. While open, in particular embodiments, the system may assess pressure sensors readings, such as at a regular frequency, to determine whether the system may have been positioned such to cause unrestricted flow. In particular embodiments, some, all, or a combination of these processes may repeat until the procedure is finished.
In particular embodiments, an extraction cycle may be useful to clear occlusions in an aspiration catheter, and/or to facilitate aspiration of clot that may be too large, or otherwise difficult to aspirate. In particular embodiments, an extraction cycle may establish pressure differentials between the aspiration catheter and the vacuum source. In particular embodiments, pressure differentials may be alternated or cycled in time, such as to generate pressure pulses. In particular embodiments, pressure pulses may employ multiple mechanisms to facilitate thrombus ingestion into an aspiration catheter. By way of example and not limitation, according to a mechanism, a pressure pulse may introduce an acceleration component, which may facilitate the extraction of occlusive material. By way of example and not limitation, according to a mechanism, a pressure pulse may create a force impulse, which may break static friction momentarily, which may in turn allow a lower dynamic friction to ingest thrombus. By way of example and not limitation, according to a mechanism, a pressure pulse may move a thrombus away from the distal tip of the catheter, and/or subsequently rapidly force contact between the thrombus and the catheter, which may macerate the thrombus.
In particular embodiments, an extraction cycle may alternate between providing vacuum aspiration and relative positive pressure. In particular embodiments, an extraction cycle may be initiated when an aspiration catheter is already under full vacuum. In particular embodiments, when an extraction cycle is initiated, a vacuum on-off valve between the catheter and the aspiration source may be closed, and the pressure in the aspiration catheter may be increased. By way of example and not limitation, this may cause a positive pressure pulse and establish a pressure differential between the vacuum source and the catheter. In particular embodiments, when the on-off valve is opened, the contents and the distal tip of the aspiration catheter may experience the pressure differential as a negative pressure pulse. By way of example and not limitation, a negative pressure pulse may negatively impact the structural integrity of any occlusions, such as to a degree that a static force may only achieve with a greater supply of energy. In particular embodiments, an amplitude, or magnitude, of pressure pulses may be directly correlated to a pressure differential between an evacuated catheter and a pressure source (e.g., for positive pressure pulses), and a pressurized catheter and a vacuum source (e.g., for negative pressure pulses). In particular embodiments, a frequency or timing with which one or more valves, such as an on-off valve, may open and/or close may be predetermined, or responsive to pressure sensor data, or any combination thereof. By way of example and not limitation, an extraction cycle's pressure pulses may have an amplitude, frequency, and/or other parameters optimized to extract thrombus and/or other occlusive material from vasculature.
Pressure differentials in a catheter may be generated in a number of ways. By way of example and not limitation, in particular embodiments, pressure, pressure waves, and/or pressure differentials may be generated by closing off a catheter's access to a vacuum source. In particular embodiments, pressure, pressure waves, and/or pressure differentials may be generated by introducing a fluid medium into the catheter (e.g.,
In particular embodiments, an extraction cycle may be automatically initiated when an algorithm of the controller 220 detects a clogged catheter, an occluded catheter, or a catheter positioned in clot. By way of example and not limitation, a catheter may be identified as being in a clogged state when the pressure differentials approach zero. In particular embodiments, the controller may automatically initiate an extraction cycle after the system has detected a clog lasting for more than a predetermined time interval. By way of example and not limitation, such as 5 seconds. Alternatively, an extraction cycle may be initiated, and/or terminated, on demand by a user. In particular embodiments, an extraction cycle may provide pressure pulses for a predetermined time period. Additionally or alternatively, in particular embodiments, an extraction cycle may assess pressure sensor data each time one or more valves, such as an on-off valve, open to assess or sample flow, and/or to determine whether the extraction cycle should continue or end. By way of example and not limitation, if an extraction cycle is initially unsuccessful at clearing a clog, it may vary the amplitude, frequency, and/or other parameters of pressure pulses. In particular embodiments, an algorithm on the controller 220 may consult a library of different pressure pulses, and may select one or more pressure pulses or pulse parameters from among the contents of a library. In particular embodiments, if specific parameters, such as a specific amplitude and/or frequency, starts to clear a clog, the algorithm may continue to generate pressure pulses of those parameters, such as that frequency and/or amplitude, until the clog is cleared.
In particular embodiments, three-point junction 492 may be provided with one or more valves, for example, to control one or both of vacuum forces and positive pressure pulses. By way of example and not limitation, such a configuration may allow three-point junction 492 to alternate between applying vacuum aspiration and pressure pulses, wherein a pressure of a pressure pulse may be above that of the vacuum source. In particular embodiments, aspiration valve 499 and pressure valve 496 may be opened alternatively, simultaneously, with a delay, in some overlapping sequence, or in a combination thereof. By way of example and not limitation, in an overlapping sequence, one valve may start to open when another valve is starting to close, whereby there may be a brief period wherein both valves may be at least partially open. By way of example and not limitation, in an overlapping sequence, sometimes multiple (e.g., two) valves may be open, and/or multiple (e.g. two) valves may be closed for at least short periods of time.
In particular embodiments, an aspiration valve 499 may be positioned between a catheter and an aspiration source to modulate aspiration. In particular embodiments, a pressure valve 496 may be positioned between the catheter and fluid source, for example, to modulate fluid injection. In particular embodiments, both aspiration valve 499 and pressure valve 496 may be selectively opened and closed, for example, to create pressure differentials within the catheter and/or aspiration tubing. By way of example and not limitation, selective opening and closing of both aspiration valve 499 and pressure valve 496 may be tailored to provide pressure pulses of a desired amplitude and frequency.
Alternatively, in particular embodiments, an opening of vacuum valve 799 and a closing of pressure valve 796 may result in a relative decrease in pressure at the distal tip of the aspiration catheter 750. In particular embodiments, these changes in pressure may be transmitted along a length of the aspiration catheter as a pressure pulse. In particular embodiments, a controller may close vacuum valve 799 and open pressure valve 796 for a small period of time. By way of example and not limitation, this may allow a minimal volume of fluid from the pressure source 790 to be introduced into a proximal end of aspiration catheter 750, such as to increase the relative pressure at a distal end of the aspiration catheter 750, before reverting to vacuum by re-opening vacuum valve 799 and closing pressure valve 796.
In particular embodiments, a controller may close vacuum valve 799 and open pressure valve 796 for a longer period of time, for example, allowing a larger volume of fluid from the pressure source 790 to be introduced into the aspiration catheter 750. By way of example and not limitation, this may facilitate a movement of obstructive material away from the distal end of aspiration catheter, before reverting to vacuum by re-opening vacuum valve 799 and closing pressure valve 796. In particular embodiments, connecting tubing 706 may have a dual lumen along a portion of its length, whereby one lumen, for example, may accommodate fluid, and a second lumen may accommodate connection wiring, which may enable the controller to modulate both the vacuum valve 799 and the pressure valve 796.
In particular embodiments, fluid injection may not occur at a three-point juncture, but may rather occur at a more distal region closer the catheter tip. By way of example and not limitation, a location of relative pressure injection may be used to optimize a pressure pulse variation, in order to facilitate clot removal. In particular embodiments, a distal region of an aspiration catheter may include a valve that may be opened and closed, for example, a distal valve. In particular embodiments, an aspiration valve may be closed, and the distal valve may be opened to allow blood to enter the catheter, which may increase pressure in the catheter and/or amplify a pressure differential between the catheter lumen and the vacuum source. By way of example and not limitation, the distal valve may be then closed, and the aspiration valve may be opened, wherein the pressure differential between the vacuum source and the catheter may result in a pressure pulse. In particular embodiments, fluid may be transferred into an aspiration catheter from another adjacent catheter. By way of example and not limitation, an inner catheter may deliver fluid to an outer aspiration catheter. In particular embodiments, an outer catheter may deliver fluid to an inner aspiration catheter through a valve structure. In either case, for example, a fluid medium may be delivered along the length of the aspiration catheter, rather than through a proximal end. In particular embodiments, an adjacent catheter may offer an alternative or additional connection to a vacuum source.
In particular embodiments, high frequency pressure pulses may be enabled by a mechanical method, such as that illustrated in
Pressure in a catheter may be manipulated by a variety of methods. By way of example and not limitation, vacuum aspiration may be used to reduce pressure within the catheter. In particular embodiments, removal of vacuum suction and/or the introduction of fluid may be used to increase pressure within the catheter. In particular embodiments, a mechanically actuating device may alternate between increasing and decreasing pressure within a catheter. In particular embodiments, such as illustrated by
In particular embodiments, a pulsation protocol, such as illustrated in
In particular embodiments, high amplitude (or high magnitude) pressure pulses may be generated by generating large pressure differentials. By way of example and not limitation,
In particular embodiments, an extraction cycle may use a predetermined series of pressure pulses, for example, with near full vacuum aspiration before the extraction cycle, between individual pulses of relative positive pressure, and/or after the extraction cycle. In particular embodiments, pressure pulses may be selected from a library of pressure pulses having parameters, for example amplitudes and/or frequencies, that may facilitate the extraction of clot and/or other occlusive material. In particular embodiments, a series of pressure pulses may vary from one another in terms of frequency, amplitude, or both. By way of example and not limitation, a pulsation protocol may use a series of pressure pulses with a trend wherein one or more pressure parameters, such as amplitude and/or frequency, may rise while another diminishes. By way of example and not limitation, a pulsation protocol may comprise a series of pressure pulses where both the amplitude and frequency rise or diminish, or where one of the amplitude or frequency rises or diminishes while the other remains constant.
In particular embodiments, an extraction cycle may provide specific pressure pulses, for example, based on pressure sensor readings. By way of example and not limitation, a responsive extraction cycle may measure pressure within the catheter, and then may select one or more pressure pulses optimized for a catheter with those pressure readings. By way of example and not limitation, in another responsive extraction cycle, the system may cycle through a library of pressure pulse protocols, such as with time periods of static or full aspiration and occlusion detection after each individual pressure pulse. In particular embodiments, after the library has been cycled, the system may repeat the pressure pulses that were measured or otherwise determined to be most successful. By way of example and not limitation, a degree of success of a specific pressure pulse may be commensurate with an amount of increased flow rate after the pressure pulse. In particular embodiments, the system may continue to cycle down until only a few pressure pulse protocols remain in the loop. In particular embodiments, if the efficacy of a loop begins to diminish, the system may return to the full library and initiate a fresh cycle.
In particular embodiments, a responsive extraction cycle may have three modes: cycling up, wherein successive pressure pulses may be stronger in terms of amplitude and/or frequency; cycling down, wherein successive pressure pulses may be weaker in terms of amplitude and/or frequency; and maintenance pressure pulses, wherein pressure pulses may have a consistent frequency and/or amplitude. In particular embodiments, when the system detects a clogged state, it may enter a cycling up mode. In particular embodiments, when the system detects a restricted flow state, it may enter a maintenance mode. In particular embodiments, when the system detects an unrestricted flow state, it may enter a cycling down mode.
In particular embodiments, in situations where maximizing the removal of occlusive material may be more important in particular cases than concerns of blood loss, such as particular cases during neurovascular stroke procedures, an alternative embodiment may be useful. Under such circumstances, in particular embodiments, an optimal technique may include positioning the distal end of a catheter in clot, applying full vacuum, and waiting a predetermined period of time before advancing to a next step. In particular embodiments, an objective may be complete, or nearly complete, catheter tip engagement of a mass of occlusive material. By way of example and not limitation, such engagement may essentially clog the distal end of the catheter, and is sometimes referred to as “corking the catheter.” By way of example and not limitation, if a clinician has successfully “corked the catheter” in particular situations, the catheter system may be removed from the vessel, thereby withdrawing the mass of clot or occlusion with it. Alternatively, in particular embodiments, an extraction cycle may be used to draw an occlusion through the catheter lumen, and/or cause the clot to become deeply latched, or corked, within the catheter. After completion of an extraction cycle, in particular embodiments, the clot may be removed, or corked, in the attached catheter, so that the catheter together with the clot may safely be removed from the patient.
In particular embodiments, an extraction cycle may automatically stop, and/or be manually stopped, when a clot or other occlusive material clogs a catheter, and corks it. By way of example and not limitation, the clot or occlusive substance may be too large and/or too tough to traverse an aspiration catheter, but nonetheless may become partially entrained in the aspiration catheter. In particular embodiments, the system may transition to full aspiration to allow the user to remove the corked catheter while dragging the clot or other occlusive material out with the catheter. In some instances, once an extraction cycle is initiated, the clot or occlusive material may still clog the catheter. In particular embodiments, the controller may then revert to full aspiration, and/or notify the user of the corking event, whereby the system may prompt the user to remove the catheter. In particular embodiments, the user may manually turn off an extraction cycle, and/or otherwise cause the system to return to full vacuum, and then remove the catheter.
In particular embodiments, the system may transition to a maceration cycle to allow a valve, such as a pinch valve or a different type of valve, to apply mechanical forces on a clot or other occlusive material. By way of example and not limitation, such mechanical action may be applied to sufficiently modify the form and/or consistency of a clot or other occlusive material, such as to enable more effective aspiration.
In particular embodiments, to indicate a status or operation of work to remove clots or other occlusive material, visual and/or auditory signals may be included that indicate the progress of a given extraction cycle. In particular embodiments, the start of an extraction cycle may be signaled by a flashing light, such as a flashing blue light, which may flash until the cycle is completed. In particular embodiments, at completion, the light may turn to a different color to indicate completion, such as green. In particular embodiments, base unit 200b or base unit enclosure 216 may include a light bar. By way of example and not limitation, the light bar may fill or light up incrementally, whereby the light bar may progressively “fill up” with light in proportion to a cycle's progress. Additionally or alternatively, base unit 200b or base unit enclosure 216 may include a screen for displaying images. In particular embodiments, a small screen may display an animation indicative of loading. By way of example and not limitation, loading animations may execute a repetitive pattern (for example, a spinning circular object), and/or may execute a single cycle of a prolonged animation (for example, a slowly filling circle). In particular embodiments, either in conjunction with visual progress indication or as an alternative to visual progress indication, the system may use auditory cues in particular embodiments to signify the extraction cycle's initiation, pulsating phase, and/or completion. By way of example and not limitation, auditory cues may include musical notes, beeps, and/or speech. In particular embodiments, auditory cues may include updates (e.g., “extracting”), and/or suggestions (e.g., “advance/retract the catheter”).
In particular embodiments, an algorithm may also control a lighting mechanism, e.g., an indicator light, to convey to the user whether the system is in a full aspiration state, an unrestricted flow state, a restricted flow state, a clogged state, a sampling state, and/or an extracting state. In particular embodiments, specific lights may be illuminated to indicate bubbles, and/or that the override switch has been triggered. In particular embodiments, the algorithm may control an acoustic chip, such as a piezo acoustic chip. By way of example and not limitation, the acoustic chip may convey audible information to the physician, such as regarding the state of the effluent and override switch. In particular embodiments, the piezo acoustic chip may be surface mounted. By way of example and not limitation, the piezo acoustic chip may selectively produce a 4 kHz single tone, for example, at 65 dB at 10 cm. By way of example and not limitation, the signals may include sounds and/or phrases such as tone/pitch changes, beeping patterns, “clogged,” “occluded,” “clot,” “blood,” “open flow,” etc. Particular embodiments may utilize a dynamic beeping cadence. By way of example and not limitation, a beeping pattern may steadily increase when an unrestricted flow state is increasing in duration. In particular embodiments, a speed of the beeps may indicate a length of time the system has been in a particular state, such as unrestricted flow, and/or may alert the physician to the increasingly problematic nature of the system's positioning or status. In particular embodiments, the system may additionally or alternatively include a multi-position switch or button, for example, to specifically activate different algorithms, mute audio cues, and/or to prime the system with fluid. By way of example and not limitation, such a feature may be activated by inserting a pin in the base unit 210, which may activate this customizable feature.
In particular embodiments, the system may be manually powered on and conduct aspiration for a predetermined period of time. By way of example and not limitation, if the system detects unrestricted flow, one or more valves, such as an on-off valve, may be turned off to stop flow. The attending physician may then reposition the catheter tip into clot, and/or manually trigger a mechanism (such as a foot pedal or manual switch) to initiate further aspiration. By way of example and not limitation, such a manual trigger may override the algorithm, and may allow aspiration to continue. In particular embodiments, once a manual trigger is released, the algorithm may again monitor flow to allow aspiration, for example, as long as the flow is acceptable and/or within particular parameters. In particular embodiments, if and when the system may again detect unrestricted flow, one or more valves, as such an on-off valve, may again be closed, for example, until a physician repositions the aspiration catheter and/or manually overrides the controller. In particular embodiments, such a protocol may be repeated until the physician completes the procedure.
In particular embodiments, before an aspiration catheter can be used to remove clot and other occlusive material, it may need to be primed with an incompressible fluid. In particular embodiments, a catheter may be filled with a suitable fluid, such as a saline fluid, to remove all the air from the lumen of the catheter. In particular embodiments, a catheter may be automatically primed, whereby the catheter may be filled with a suitable fluid to expel all compressible fluids (e.g., air). In particular embodiments, one or more sensors may monitor catheter contents during use. By way of example and not limitation, if compressible fluids are detected (e.g., air or bubbles or other gases), the system may alert the user. In particular embodiments, the system may indicate that the procedure needs to stop, for example, so that the catheter may be again primed to remove air bubbles.
As has been previously disclosed herein, occlusive material may be associated with partial or total blockage related to the catheter's operation, such as a clogged catheter tip, an occluded catheter, or a catheter positioned in clot, during operation of the aspiration thrombectomy system. Separately or additionally, occlusive material may partially or completely block, coat, deposit, or otherwise impede fluid communication, fluid flow, and/or vacuum transfer between a vacuum source and the catheter tip. By way of example and not limitation, occlusive material may deposit or accumulate in the lumen and/or along the walls of fluid flow passages in the system. By way of example and not limitation, such fluid flow passages may comprise the aspiration catheter and the connection tubing, which acts as a fluid conduit between the aspiration catheter and the vacuum source, as well as any other fluid medium sources in the system. Such occlusive material deposits or accumulation along the walls of the aspiration catheter and/or connection tubing may, by way of example and not limitation, decrease available flow area, increase flow passage wall friction, increase pressure drops, reduce flow rates, and/or reduce the ability and efficiency of transferring vacuum to the catheter tip.
In particular embodiments, the aspiration thrombectomy system may be configured to detect, locate, dislodge, and/or operate to displace or remove occlusive material from the tubing and system, such as by flushing with a fluid medium. It will be appreciated that while terms such as “flush” and “flushing” may be used herein to describe related aspects for brevity, this disclosure fully contemplates any and all of the aspects and/or operations described above, and other related aspects and operations. By way of example and not limitation, a flushing fluid medium may comprise air and/or saline.
In particular embodiments, an external unit, such as a unit previously described and illustrated in
In particular embodiments, the system may be provided with one or more pressure sensors, and one or more controllable valves. By way of example and not limitation, as illustrated in the embodiment of
In particular embodiments, a fluid source 2162 of a flushing fluid medium may be provided. As a non-limiting example, fluid source 2162 may comprise a saline solution. In particular embodiments, fluid source 2162 may be elevated, or otherwise pressurized, which may permit the fluid medium to flow into the connection tubing. In particular embodiments, a pressure level of fluid source 2162 may exceed a vacuum pressure level of vacuum source 2120. In particular embodiments, a pressure level of fluid source 2162 may be more than an external pressure level, such as an ambient or atmospheric pressure level. In particular embodiments, a pressure level of fluid source 2162 may be more than an external pressure level, such as a systolic blood pressure level of a patient. In particular embodiments, fluid flow from fluid source 2162 may be controlled by selectively opening a controllable valve, such as fluid medium valve 2164. In particular embodiments, fluid source 2162 may be configured to provide one or more different fluid media other than saline, such as air.
According to particular embodiments, fluid medium tubing 2168 may be used to connect fluid source 2162 with connection tubing 2110, such as at a T-junction or Y-junction (e.g., T-junction 2174). A fluid medium pressure sensor 2166, such as a saline pressure sensor, may be optionally provided. In particular embodiments, a fluid medium valve 2164, such as a saline valve, may be used to control introduction of a fluid medium from fluid source 2162 into the connection tubing 2110.
In particular embodiments, a controller 2180 may be configured to detect system quantities of interest, such as one or more pressure levels associated with connection tubing 2110 via one or more of distal pressure sensor 2170, vacuum sensor 2122, and/or fluid medium pressure sensor 2166. As will be further discussed, in particular embodiments, based on detecting pressure levels, controller 2180 may be configured to determine whether connection tubing 2110 is occluded. If connection tubing 2110 is determined to be occluded, in particular embodiments, controller 2180 may determine a location of the occlusion. In particular embodiments, based on determining that connection tubing 2110 is occluded and/or determining a location of the occlusion, controller 2180 may selectively operate one or more valves, such as vacuum valve 2160 and/or fluid medium valve 2164, to selectively introduce a fluid medium from fluid source 2162 into connection tubing 2110. In particular embodiments, controller 2180 may selectively operate one or more valves during one or more time intervals to flush occlusive material located in the connection tubing 2110. In particular embodiments, controller 2180 may selectively introduce a fluid medium during one or more time intervals.
It will be appreciated that while particular arrangements, numbers, locations, types, and/or connectivity of sensors and valves are disclosed for illustrating detection and control methods for tube and system flushing, any suitable arrangements, numbers, locations, types, and/or connectivity of sensors, actuators, and/or valves for appropriate detection and control is fully contemplated.
By way of example and not limitation, detection may include, but is not limited to, detection of the presence and/or location of occlusive material in the aspiration catheter, connection tubing, and/or other relevant portions of the aspiration thrombectomy system. By way of example and not limitation, control may include, but is not limited to, controlling levels, degrees, and/or locations, of selectively permitting fluid communication, corresponding isolation, introduction, change, and/or maintenance of vacuum and/or fluid flow of one or more media in particular portions of the tubing and system. Based on the parameters used for operating actuators or valves, such as the number, sequence, frequencies, and/or duty cycles of triggering open/closed states, many operational states of operating one or more actuators or valves are possible.
In a first step 2210 of the illustrated algorithm, the controller may detect one or more system quantities associated with the aspiration catheter or connection tubing via one or more sensors. By way of example and not limitation, one or more of a first pressure sensor and a second pressure sensor associated with the connection may be used for such detection, whereby one or more pressure levels are detected.
In a second step 2220 of the illustrated algorithm, the controller may determine, based on the one or more detected associated system quantities, whether parts of the system, such as the aspiration catheter or the connection tubing, are occluded. By way of example and not limitation, the controller may determine whether the connection tubing is occluded based on the one or more pressure levels detected via one or more of the first pressure sensor and the second pressure sensor.
In a third step 2230 of the illustrated algorithm, based on determining that the aspiration catheter or connection tubing is occluded, the controller may determine a location of the occlusion based on the one or more detected system quantities. By way of example and not limitation, based on the one or more pressure levels detected via one or more of the first pressure sensor and the second pressure sensor, the controller may determine that the connection tubing is occluded, and further, that the occlusion is located between the first and second pressure sensors.
In a fourth step 2240 of the illustrated algorithm, the controller may operate one or more actuators or valves of the system to flush particular parts of the aspiration catheter or connection tubing. By way of example and not limitation, the controller may operate one or more of the first valve and the second valve to introduce the fluid medium into the connection tubing during one or more time intervals, based on the determined location of the occlusion.
By way of example and not limitation, these figures include a distal pressure profile 2310 based on the time-varying pressure detected by a distal pressure sensor, such as distal pressure sensor 2170. A vacuum valve profile 2320 indicates the time-varying state of a vacuum valve, such as vacuum valve 2160. An open state of the vacuum valve is indicated herein as a relatively elevated level along the y-axis, such as 2320a, and a closed state of the vacuum valve is indicated herein as a relatively lowered level, such as in 2320b.
The illustrated pressure profile marked 2330 is an exemplary vacuum pressure profile 2330 based on the time-varying pressure detected by a pressure sensor associated with a proximal portion of the connection tubing, such as vacuum sensor 2122. The illustrated pressure profile marked 2340 is an exemplary saline pressure profile 2340 based on the time-varying pressure detected by a pressure sensor associated with a fluid medium or pressure source, such as fluid medium pressure sensor 2166.
The illustrated valve profile marked 2350 is an exemplary saline valve profile 2350 indicating the time-varying state of a saline valve as a control valve for a fluid medium, such as fluid medium valve 2164. As with the vacuum valve states described above, the open or closed states of the saline valve profile 2350 in illustrations herein may also be indicated by the relative elevated (e.g., 2350a) or lowered (e.g., 2350b) levels of the respective valve profiles along the y-axis.
In particular embodiments, as illustrated in
As illustrated in approximately the first half of the time window depicted in
As also illustrated, by way of example and not limitation, vacuum valve profile 2320 and saline valve profile 2350 in the early part of the window (such as prior to the approximate point in time indicated by 23-A) indicate that the corresponding vacuum and saline valves are not simultaneously held open. Accordingly, and as previously disclosed in detail herein, saline released or introduced by the fluid medium source during this early portion of the time window (prior to 23-A) may be solely directed toward the aspiration catheter to provide modulated aspiration, rather than toward the vacuum source.
Beyond about the approximate point in time indicated by 23-B illustrated in
Separately or additionally, based on one or more of the respective locations of corresponding sensors, particular detected pressure profile characteristics, and/or input from other sensors, the controller may be configured to localize a location of a detected occlusion. By way of example and not limitation, in the example of
In particular embodiments, based on determining the presence and/or location of an occlusion in the connection tubing or aspiration catheter, controller 2180 may be configured to take action to reduce, displace, and/or remove the occlusion. In particular embodiments, as further illustrated in
In particular embodiments, a fluid medium introduced into the connection tubing and/or aspiration catheter may provide flushing based on flowing due to a pressure gradient produced by one or more pressure sources and/or vacuum sources. In particular embodiments, a pressure source may comprise a fluid medium source, a pump, and/or a pressurized reservoir. In particular embodiments, one or more of the pressure sources and/or vacuum sources may be controllable, such as via a controller operating one or more controllable valves, actuators, and/or pumps.
By way of example and not limitation, as illustrated, both of the vacuum and fluid medium valves may be simultaneously opened, as indicated by the corresponding open vacuum valve profile 2320 and saline valve profile 2350, such that fluid medium, such as saline or air, that is released or introduced from the fluid medium source may now be directed through the connection tubing or aspiration catheter toward the vacuum source. In particular embodiments, the occlusive material present in the connection tubing may be flushed or dislodged based on an introduction of a fluid medium.
In particular embodiments, instead of simultaneously holding both of the vacuum and fluid medium valves open for flushing, other combinations of valve operation may be used. As a non-limiting example, during a flushing operation, one of the valves may be held open while cycling or fluttering another valve. By way of example and not limitation, vacuum valve 2160 may be held open while flushing is underway, along with fluttering fluid medium valve 2164, i.e., repeatedly opening and closing fluid medium valve 2164.
In particular embodiments, the controller may be configured to determine, based on detecting a pressure level spike, that an occlusion has been cleared. By way of example and not limitation, a pressure level spike may comprise a rapid increase in detected pressure, followed by a rapid decrease in detected pressure, such as illustrated by 23-E in
While this disclosure discusses particular ways of operating or interoperating valves during the steps of tube and system flushing, it will be appreciated that any suitable ways of operating or interoperating one or more valves and/or actuators are fully contemplated in this disclosure. Particular examples disclosed herein are included merely to provide a better understanding of configurational and operational principles. This disclosure is not limited to any specific types, configurations, or number of valves or actuators disclosed herein.
In particular embodiments, a fluid medium may be introduced or flushed into the connection tubing during one or more time intervals. In particular embodiments, a time interval for introducing a fluid medium into the connection tubing may be a predetermined time interval, such as 200 ms.
In particular embodiments, a time interval for introducing a fluid medium into the connection tubing may be based on determining that an occlusion has been reduced or eliminated. By way of example and not limitation, the controller 2180 may be configured to determine that the occlusion has cleared, such as based on a decrease (e.g., at 23-F) of vacuum pressure profile 2330 below a threshold value, and accordingly cease flushing of the connection tubing with the fluid medium by operating one or more of the corresponding valves.
In particular embodiments, the one or more time intervals may be separately or additionally based on determining a location of the occlusion. For instance, a localization of occlusion position may permit valve or actuator operation for introduction of the fluid medium based on a priori knowledge and/or empirical determination of additional relevant parameters, such as effective tubing length, diameter, type and number of bends, and/or other geometric and configurational aspects. Such an optimized flushing operation may enable more efficient and/or effective operation of the aspiration thrombectomy system, such as by limiting fluid medium waste, reducing fluid medium replenishment cycles, decreasing procedure time, and/or system power and size requirements.
By way of example and not limitation, for an occlusion determined to be present between vacuum sensor 2122 and vacuum source 2120, an interval for introducing the fluid medium into the connection tube may be between 70 and 300 ms. In some embodiments, an interval for introducing the fluid medium into the connection tube may be between 150 and 200 ms. In some embodiments, an interval for introducing the fluid medium into the connection tube may be in the range of 15-800 ms. In particular embodiments, an interval for introducing a fluid medium into the connection tube may be empirically determined.
It should be appreciated that such aspects of determination of time interval may be predetermined, and/or be determined or modified based on processing empirical input from other sensor(s), such as pressure sensors. In particular embodiments, pressure detected by, or in combination with, other sensors may be used to estimate fluid, occlusion, geometric and/or other relevant parameters. In particular embodiments, pressure detection may be combined with other known or detected system quantities to establish operation of one or more valves or actuators to flush the connection tubing, aspiration catheter, or other parts of the system.
The controller may be configured to determine the presence of an occlusion in the connection tubing. In particular embodiments, the controller may sample the pressure levels in the connection tubing based on one or more available pressure sensors. Separately or additionally, in particular embodiments, the controller may generate changes of pressure in the connection tubing for determining the presence of an occlusion, such as by operating one or more valves.
In particular embodiments, one or more controllable valves may be operated (e.g., opened and/or closed) for controller 2180 to sample the conditions in the connection tubing 2110 and/or aspiration catheter 2130 based on detecting pressure levels from one or more pressure sensors. By way of example and not limitation, as depicted at time marker 24-A, vacuum valve 2160 may be cycled for sampling the pressure levels and conditions in connection tubing 2110. Separately or additionally, exposing the aspiration catheter and/or connection tubing to the vacuum sensor 2122 based on cycling vacuum valve 2160 may generate pressure changes in the aspiration catheter and/or connection tubing, and the detection of correlated pressure levels may permit determination of the presence of an occlusion.
By way of example and not limitation, pressure values at the start and end of valve cycling, peak, minimum, and/or average pressure values within a temporal window of valve cycling, as well as dynamic aspects of pressure change and recovery based on valve cycling may be detected and used by the controller to determine the presence of an occlusion. By way of example and not limitation, one or more parameters used in determining a state of flow based on detected pressure profiles may be predetermined, and/or empirically determined based on operational data, and/or determined based on training and using machine learning algorithms, or any combination thereof.
In particular embodiments, controller 2180 may determine that an occlusion is present based on one or more pressure levels, and/or changes in pressure levels, detected by a pressure sensor. In the non-limiting example illustrated at the approximate point in time indicated by 24-A of
In particular embodiments, the controller may simultaneously or sequentially detect pressure profiles from more than one pressure sensor to determine a location of an occlusion.
By way of example and not limitation, controller 2180 may compute a difference, such as instantaneous or weighted difference, between the respective pressure levels corresponding to distal pressure profile 2310 and vacuum pressure profile 2330, to localize the occlusion.
By way of example and not limitation, the controller may localize the occlusion by sequentially checking if an occlusion is proximal to particular sensors, or sets of sensors. In the depicted non-limiting example, vacuum pressure profile 2330 remains steady at a relatively low value, such as may be established to be within particular limits or threshold values, throughout the illustrated time window. Accordingly, the controller may determine, following the example of
In particular embodiments, based on determining that the occlusion is located between distal pressure sensor 2170 and vacuum sensor 2122, controller 2180 may be configured to operate one or more valves, such as vacuum valve 2160 and/or fluid medium valve 2164, to introduce a fluid medium into connection tubing 2110 during one or more time intervals.
Accordingly, continuing to follow the non-limiting example of
In particular embodiments, such as illustrated by way of non-limiting example in
As previously disclosed as non-limiting examples, a flushing operation may cease based on completion of pre-determined time interval, and/or based on detection and determination of change in a status of occlusion, such as a reduction or elimination of occlusion detected via one or more pressure sensors and determined based on their corresponding pressure profiles and/or fluid flow characteristics.
In particular embodiments, as depicted at 24-D, controller 2180 may be configured to re-sample and/or otherwise determine if the occlusion is still present. In particular embodiments, controller 2180 may trigger one or more additional flushing operations and/or sequences, each flushing operation having identical or modified parameters. By way of example and not limitation, controller 2180 may trigger additional or separate actions based on continued detection of occlusion over time, such as longer flushing sequences, different valve operation patterns (e.g., duration, frequency, interleaving, and/or duty cycle of opening and closing) involving one or more valves, and/or providing an alerts and information to the user regarding the occluded status and/or known occlusion parameters of the system.
In particular embodiments, as depicted by way of non-limiting example at the approximate point in time indicated by 24-E, controller 2180 may determine, such as by sampling one or more pressure sensors, that the occlusion has cleared. As previously discussed, and as further detailed by incorporation by reference, a state of flow comprising non-occluded flow may be determined by controller 2180, such as based on the detected pressure profiles. Accordingly, in particular embodiments, normal operation of the aspiration thrombectomy system may be subsequently restored. In the non-limiting example of
In particular embodiments or cases, based on the system state inferred to exist in the aspiration catheter or connection tubing based on the detected pressure profile, the controller may determine that no additional vacuum valve operation is immediately required. For instance, the controller may generate a pressure level change in the connection tubing by opening, and then closing, the vacuum valve. In particular embodiments, if the controller were to subsequently determine that presence of unrestricted or open flow in the aspiration catheter, it may continue to keep the vacuum valve closed, until the next action step is required.
System states may comprise qualitative and/or quantitative descriptions of flow states within the aspiration catheter and/or connection tubing. In particular embodiments, the flow state may be an unrestricted or open flow state, wherein the distal end or tip of the aspiration catheter may be in contact with healthy blood, and there may be little or no occlusive material in the catheter and/or connection tubing. In particular embodiments, an occluded flow state may exist in the aspiration catheter, such as due to a clot and/or other occlusive material. In particular embodiments, flow states may also include “in-between” states, such as partially occluded flow.
Particular embodiments of system state detection may separately or additionally use sensors other than the distal pressure sensor described above. In particular embodiments, a vacuum pressure sensor monitoring the level of vacuum at the canister may be used. In particular embodiments, a saline pressure sensor monitoring the pressure level of the saline fluid may be used. Furthermore, sensors used in particular embodiments of this methodology may not be limited to pressure sensors. In particular embodiments, data may be sourced from a variety of sensors, including, for instance, sensors for detecting pressures, sonic energy, ultrasonic energy, and flow rates. In particular embodiments, one or more system scores may be determined for determining system states, wherein each system score, independently or in combination with other system scores, may indicate a likelihood of specific system states in the aspiration catheter or the connection tubing. In this respect, system scores may function as metrics for quantifying the corresponding likelihood of specific system states.
System scores may be directly or indirectly derived from sensor data, such as the detected pressure profiles discussed above. In particular embodiments, system score determination may be based on automatically identifying specific features from the detected pressure profiles, extracting pressure parameters based on values and trends derived from those specific features, and calculating one or more system scores based on the pressure parameters of those features. In particular embodiments, system scores may be determined as summations of specific parameter indicators, such as pressure parameters. By way of example and not limitation, one or more pressure parameters indicating a system state of open flow may return a system score of 1, or 2, or 3, for instance, depending upon the specific pressure parameter(s) and specific threshold values used in the system combination, application, and/or embodiment, which may be directly summed for computing quantitative values of one or more system scores, such as an open flow score. In particular embodiments, determining system scores may involve further processing. In particular embodiments, determining system scores based on pressure parameters may further comprise appropriate weighting of the parameters, and/or use of correction factors. By way of example and not limitation, weighting of pressure parameters may be determined empirically. Maximum and minimum values, thresholds, and other characteristics relevant to system scores may be determined and/or adjusted based on specific system combinations and/or applications. For instance, specific thresholds of system scores may be varied based on specific combinations of catheter and aspiration systems. Several examples and particular embodiments with specific features involving detected pressure profiles and corresponding system scores will be further discussed. It should be appreciated that derivation of system scores from sensor data may vary across embodiments, and may be tailored for the specific configuration and application.
In particular embodiments, system scores may be determined based on machine learning. In particular embodiments, intermediate quantities used toward determining system scores may be determined based on machine learning. By way of example and not limitation, intermediate quantities of interest may include thresholds and/or weighting factors. In particular embodiments, training data sets may be assembled from detected pressure profile data taken over a broad range of scenarios, incorporating statistical variations, and corresponding to system states of interest. Trained machine learning models may be then used to make predictions of system state for novel situations. In particular embodiments, machine learning algorithms may employ semi-supervised and/or unsupervised learning. The algorithms may employ clustering, dimensionality reduction, and/or reinforcement learning to further improve prediction accuracy. Additionally, an algorithm that uses a combination of the above algorithmic flow analysis techniques may be employed in particular embodiments.
It is noted that particular sensor parameters and profiles, such as pressure profiles, choices of parameters, thresholds, and other criteria, and/or all other quantities such as valve states that are illustrated in this document are exemplary, and not limiting. For example, illustrations in
For example, a value of the distal pressure corresponding to its starting value prior to the sudden distal pressure decrease may be identified as a Start (or Starting) Distal Pressure, as illustrated. For instance, in particular embodiments, a Starting Distal Pressure may be indicative of a patient's blood pressure, as well as of time history of the system state. Further, in particular embodiments, rates of change of Starting Distal Pressure may be correlated with blood viscosity, and/or the presence of clots in the catheter. Following the subsequent closing of the vacuum valve, the contents of the connection tubing and aspiration catheter may experience an abrupt deceleration, and an eventual return to the new pressure equilibrium in the system disengaged from the vacuum source.
One or more peak pressure levels may be pressure parameters of interest for determining system scores, and/or system states. In particular embodiments, the recorded maximum value of the large overshoot of distal pressure corresponding to the vacuum valve closing in this scenario may be identified as the Maximum Absolute Rebound pressure, as illustrated in
In particular embodiments, one or more pressure levels and/or time intervals corresponding to restoration of pressure level equilibria following a pressure change generation event, such as vacuum valve cycling, may be pressure parameters of interest for determining system scores, and/or system states. For instance, a time window may be established based on pressure and/or time metrics that corresponds to the cessation of effects of a pressure disturbance related to an opening and closing sequence of the vacuum valve. In particular embodiments, the value of the distal pressure at such a time instant may be identified as an Ending Distal Pressure, as illustrated. For instance, in particular embodiments, an Ending Distal Pressure may correspond to the distal pressure value at a predetermined time interval, such as 80 ms, after vacuum valve closing, or may also be based on a time interval determined based on other parameters.
It should be appreciated that specific definitions and thresholds for sensor parameters may vary across embodiments, based on the requirements of specific configurations and applications. The following disclosed pressure parameters and related features are intended to be exemplary, and not limiting.
In particular embodiments, measures of pressure variance may be further extracted as pressure parameters. For instance, the pressure variance between the time instants marking Start and Ending Distal Pressure may be considered for such extraction. In particular embodiments, a Mean Absolute Deviation (“MAD”) of pressure about the Median (“Med”) pressure, as illustrated, may be identified as a measure of pressure variation between closing of the vacuum valve and the time instant of Ending Distal Pressure. Mean Absolute Deviation of pressure about the Median pressure (“MAD/med”) may also be correlated with blood viscosity.
In particular embodiments, differential pressure levels may be pressure parameters of interest for determining system scores, and/or system states. In particular embodiments, for two consecutive vacuum valve cycling sequences, the difference of the second Start Distal Pressure relative to the first Start Distal Pressure may be identified as a differential pressure level of interest, as illustrated in
As previously discussed, system scores may be determined based on detected pressure parameters. In particular embodiments, an Open Score may be determined based on detected pressure parameters. As an example and not by way of limitation, the value of the Open Score may vary between 0 and 7, and may indicate the likelihood of at least an open flow state. Similarly, in particular embodiments, an Occlusion Score may be determined based on detected pressure parameters. As another example and not by way of limitation, the value of the Occlusion Score may vary between 0 and 7, and may indicate the likelihood of at least an occluded flow state. Furthermore, in particular embodiments, various combinations of an Open Score and an Occlusion Score may indicate the likelihood of one or more additional system states of interest, for instance, a partially occluded flow state.
In particular embodiments, thresholds may be established for determining system states based on system scores. As some examples and not by way of limitation, in particular embodiments, the system may be determined to be in an occluded state if the Occlusion Score equals or exceeds 3 (out of a maximum possible score of 7). In particular embodiments, the system may be determined to be in an open flow state if the Open Score equals or exceeds 3 (again, out of a maximum possible score of 7). In particular embodiments, if the Open Score and Occluded Score are both less than 3, the system may be determined to be in a partially occluded state. Such a partially occluded state may, in particular embodiments, suggest the presence of a clot or thrombus that is pliable or deformable enough to be extracted by continuous aspiration, and not necessarily require pulsed or modulated aspiration.
Although this disclosure describes establishing specific thresholds for determining system states based on particular system scores in a particular manner, this disclosure contemplates providing any suitable thresholds for determining system states based on any system scores in any suitable manner.
For instance,
As another example,
As another example,
It will be appreciated that particular aspects and features illustrated in
In particular embodiments, a control valve 3010 may be separately or additionally provided to permit selective isolation of the distal portion of the connection tubing and/or aspiration catheter 2130, such as from vacuum source 2120. By way of example and not limitation, closing control valve 3010 while flushing connection tubing 2110, such as while having vacuum valve 2160 and fluid medium valve 2164 simultaneously open as an illustrative example without limitation, may reduce the risk of unintentionally exposing a tip of aspiration catheter 2130 to a vacuum. By way of example and not limitation, such a control valve 3010 may be beneficial when the catheter tip encounters unoccluded or free flow of blood.
In particular embodiments, a bypass valve 3020 may be separately or additionally provided to permit selective isolation of the distal portion of the connection tubing and/or aspiration catheter 2130, such as from vacuum source 2120. By way of example and not limitation, bypass valve 3020 may permit concurrent introduction of the fluid medium into the connection tubing and fluid disconnection of the aspiration catheter from the vacuum source. For example, closing vacuum valve 2160 while opening fluid medium valve 2164 and bypass valve 3020 may reduce the risk of unintentionally exposing a tip of aspiration catheter 2130 to a vacuum.
In particular embodiments, aspects of the disclosure described relative to connection tubing 2110 may be extended to include aspiration catheter 2130. By way of example and not limitation, one or more control valves and/or pressure sensors associated with the aspiration catheter 2130 may be provided. In particular embodiments, a catheter valve 3030 may be separately or additionally provided to permit selective introduction of a fluid medium into the aspiration catheter. By way of example and not limitation, such upstream introduction (relative to flow directed toward vacuum source 2120) may provide benefits of flushing longer extents of aspiration catheter 2130 and/or connection tubing 2110.
In particular embodiments, based on methods previously discussed in detail herein, controller 2180 may be configured to determine the presence of an occlusion within or proximal to aspiration catheter 2130, and/or determine a location of the occlusion, and/or provide flushing operation. By way of example and not limitation, an occlusion may be detected between the distal tip of aspiration catheter 2130 and a pressure sensor associated with aspiration catheter 2130. As another non-limiting example, an occlusion may be detected between a pressure sensor associated with aspiration catheter 2130 and a pressure sensor associated with connection tubing 2110.
By way of example and not limitation, a flushing operation may include introduction or release of a fluid medium into aspiration catheter 2130, such as by operating catheter valve 3030, wherein the introduced fluid medium is flushed in a direction away from the distal tip of aspiration catheter 2130.
In particular embodiments, one or more pressure sensors disclosed herein may be configured to provide differential pressure sensing relative to a reference atmospheric and/or ambient pressure. In particular embodiments, one or more additional or alternative pressure sensors may be provided to compare pressure sensors to a reference atmospheric and/or ambient pressure.
In particular embodiments, one or more additional pressure sensors may be provided in the fluid path of vacuum sensor 2122. In particular embodiments, pressure sensor 3040 may be provided proximate to vacuum valve 2160, i.e., near vacuum valve 2160. In particular embodiments, pressure sensor 3040 may be disposed proximal to vacuum valve 2160. In particular embodiments, pressure sensor 3040 may be provided in the same static and/or contiguous fluid path as a vacuum sensor 2122, which may be provided in proximity to vacuum source 2120. By way of example and not limitation, pressure sensor 3040 may sense the same, or a substantially similar, value of static fluid pressure as sensed by vacuum sensor 2122 when there is no flow through the portion of connection tubing 2110 connecting them, such as by closing one or more valves distal to pressure sensor 3040. In particular embodiments, pressure sensor 3040 may be additional or alternative to vacuum sensor 2122.
In particular embodiments, the presence of an occlusion located between vacuum valve 2160 and vacuum sensor 2122 may be detected based on using pressure sensor 3040. Separately or additionally, in particular embodiments, the presence of an occlusion located between vacuum valve 2160 and vacuum source 2120 may be detected using pressure sensor 3040. By way of example and not limitation, pressure sensor 3040 may be used to detect one or more occlusions, such as described above, without requiring vacuum valve 2160 to be opened.
Herein, “or” is inclusive and not exclusive, unless expressly indicated otherwise or indicated otherwise by context. Therefore, herein, “A or B” means “A, B, or both,” unless expressly indicated otherwise or indicated otherwise by context. Moreover, “and” is both joint and several, unless expressly indicated otherwise or indicated otherwise by context. Therefore, herein, “A and B” means “A and B, jointly or severally,” unless expressly indicated otherwise or indicated otherwise by context.
The scope of this disclosure encompasses all changes, substitutions, variations, alterations, and modifications to the example embodiments described or illustrated herein that a person having ordinary skill in the art would comprehend. The scope of this disclosure is not limited to the example embodiments described or illustrated herein. Moreover, although this disclosure describes and illustrates respective embodiments herein as including particular components, elements, feature, functions, operations, or steps, any of these embodiments may include any combination or permutation of any of the components, elements, features, functions, operations, or steps described or illustrated anywhere herein that a person having ordinary skill in the art would comprehend. Furthermore, reference in the appended claims to an apparatus or system or a component of an apparatus or system being adapted to, arranged to, capable of, configured to, enabled to, operable to, or operative to perform a particular function encompasses that apparatus, system, component, whether or not it or that particular function is activated, turned on, or unlocked, as long as that apparatus, system, or component is so adapted, arranged, capable, configured, enabled, operable, or operative. Additionally, although this disclosure describes or illustrates particular embodiments as providing particular advantages, particular embodiments may provide none, some, or all of these advantages.
Figures provided herein may be illustrated schematically rather than literally or precisely; components and aspects of the figures may not necessarily be to scale. Moreover, while like reference numerals may designate corresponding parts throughout the different views in many cases, like parts may not always be provided with like reference numerals in each view.
