Disclosed herein are implementations of an occlusion device and systems for measuring blood pressure using the occlusion device. In an aspect, an occlusion device includes a catheter and a toroidal balloon. The catheter may include a lumen. The toroidal balloon may be coupled to the catheter. The toroidal balloon may include an outer surface that has a first diameter. The outer surface may be configured to seal against an inner portion of a vessel wall. The toroidal balloon may include an inner lumen that has a second diameter. The inner lumen may be configured to allow blood to flow through the toroidal balloon.
In one or more aspects, the toroidal balloon may be inflatable via the lumen to dynamically decrease the second diameter to decrease the blood flow through the toroidal balloon. In one or more aspects, the toroidal balloon may be deflatable via the lumen to dynamically increase the second diameter to increase the blood flow through the toroidal balloon. In one or more aspects, the outer surface may include one or more traction elements to reduce migration of the occlusion device. In one or more aspects, the catheter may be coupled to the toroidal balloon such that the catheter passes through a body of the toroidal balloon. In one or more aspects, the catheter may be coupled to the toroidal balloon such that the catheter runs tangent to the inner lumen. In one or more aspects, the toroidal balloon may be comprised of at least one of a silicone material, a polyurethane material, a latex material, a polyether block amide (PEBA) material, a nylon material, a polyethylene terephthalate (PET) material, or any suitable material.
In one or more aspects, the occlusion device may include a second toroidal balloon coupled to the catheter. In one or more aspects, the catheter may comprise a second lumen that is configured to inflate and deflate the second toroidal balloon. In one or more aspects, the second toroidal balloon may be comprised of at least a silicone material, a polyurethane material, a latex material, a PEBA material, a nylon material, or a PET material.
In one or more aspects, the occlusion device may include a third toroidal balloon coupled to the catheter. In one or more aspects, the catheter may comprise a third lumen that is configured to inflate and deflate the third toroidal balloon. In one or more aspects, the third toroidal balloon may be comprised of at least a silicone material, a polyurethane material, a latex material, a PEBA material, a nylon material, or a PET material. In one or more aspects, the third toroidal balloon may be configured to provide rigidity to the occlusion device.
In one or more aspects, the catheter may include a port and a flexible membrane. The flexible membrane may be coupled to the port. The flexible membrane may be configured to act as a barrier to translate the pressure from the vessel into the fluid filled lumen, which may be measured by a pressure sensor to determine the blood pressure. In one or more aspects, the port may be disposed on a proximal side of the toroidal balloon and the flexible membrane may be configured to measure blood pressure on the proximal side of the toroidal balloon. In one or more aspects, the catheter may include a second port and a second flexible membrane. The second flexible membrane may be coupled to the second port. The second flexible membrane may be configured to measure blood pressure. In one or more aspects, the second port may be disposed on a distal side of the toroidal balloon and the second flexible membrane may be configured to measure blood pressure on the distal side of the toroidal balloon.
In one or more aspects, the catheter may include a micro electro-mechanical system (MEMS) blood pressure sensor configured to measure blood pressure. In one or more aspects, the MEMS blood pressure sensor may be disposed on a proximal side of the toroidal balloon and configured to measure blood pressure on the proximal side of the toroidal balloon. In one or more aspects, the catheter may include a second MEMS blood pressure sensor disposed on a distal side of the toroidal balloon and configured to measure blood pressure on the distal side of the toroidal balloon.
The disclosure is best understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, according to common practice, the various features of the drawings are not to-scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity.
Non-compressible torso hemorrhage (NCTH) has been identified as a leading cause of potentially survivable death from trauma in both battlefield and civilian settings. A standard therapeutic option to increase systolic blood pressure and maintain cardiac and cerebral perfusion in these patients is aortic occlusion. Traditionally performed through open surgical aortic cross-clamping, the less invasive method of REBOA has been developed, to minimize subsequent surgical trauma and related complications. However, an undesired side effect of full aortic occlusion is rapid and permanent ischemic damage to downstream organs and tissue. Recent studies have shown that by performing a partial occlusion, proximal systemic blood pressure can be maintained, while providing partial blood flow to the organs and tissue below the balloon, reducing risk for temporary or permanent ischemic damage. Current REBOA solutions with spherical balloons to titrate blood flow around the partial occlusion have proven challenging to maintain, requiring constant monitoring and careful manipulation.
It is critical that flow rates be consistent and smooth, as abrupt changes to flow or pressure increase the chance of rupturing any therapeutic clots that may have formed below the balloon. In conventional methods such as the example shown in
By way of contrast to conventional REBOA and p-REBOA solutions, the embodiments disclosed herein allow blood to pass through the balloon, instead of around the balloon. By allowing the blood to pass through the balloon, constant traction against the vessel wall may be achieved, regardless of flow rate, thereby mitigating distal migration. The embodiments disclosed herein include an orifice to allow blood flow through the balloon. The orifice is independent of the diameter of the vessel, therefore the effect of the diameter of the vessel changing during the procedure will not affect the flow rate of blood, in contrast with the conventional REBOA and p-REBOA solutions. The embodiments disclosed herein enable easier titration of blood flow by varying the size of the orifice when compared to conventional REBOA and p-REBOA solutions. The embodiments disclosed herein enable tight control of optimal distal flow and pressure, which minimizes rebleeding and distal ischemia while mitigating distal migration.
In the embodiments disclosed herein, a toroidal balloon, when inflated with either a gas or a sterile fluid, is configured to inflate and stretch its outer diameter to seal against a vessel wall, leaving an inner lumen (e.g., an orifice) for blood to pass through. The toroidal balloon may be constructed of a compliant material, a non-compliant material, a semi-compliant material, or a hybrid material that includes at least one compliant portion and at least one non-compliant portion. These materials may include, but are not limited to silicone, polyurethane, latex, polyether block amide (PEBA), nylon, and polyethylene terephthalate (PET).
Since flow at a static pressure differential is linearly proportional to a cross-sectional area, relocating the locus of the flow path to the center of the balloon provides finer and more predictable control of blood flow, as area changes less for a given increment at smaller radii. The following example contrasts the radius changes required to establish a flow rate of 0.48 L/min with a pressure of 90 mmHg proximal to the balloon and a pressure of 40 mmHg distal to the balloon.
The mass flow rate qm across the inner lumen 220 may be calculated as follows:
where Cd is the coefficient of discharge, β is a diameter ratio of inner lumen diameter d to vessel diameter D, ϵ is an expansibility factor (1 for incompressible gases and most liquids, and decreasing with pressure ratio across the inner lumen), d is the inner lumen diameter under operating conditions, ρ1 is a fluid density in plane of upstream tapping, and Δp is a differential pressure measured across the inner lumen 220.
Referring to
The catheter 310 may be a single or multi-lumen catheter. In an example, the catheter size may be 3Fr-12Fr (1 mm-4 mm outer diameter). The catheter 310 may have a single lumen 330 to support inflation of the single toroidal balloon 300 as shown in
The catheter 410 may be a single or multi-lumen catheter. In an example, the catheter size may be 3Fr-12Fr (1 mm-4 mm outer diameter). The catheter 410 may have a single lumen 430 to support inflation of the single toroidal balloon 400 as shown in
In some embodiments, the two concentric toroidal balloon catheter 800 may be configured as a fixed flow device. In one example, the first toroidal balloon 810 may be replaced with a balloon that when inflated, will provide a reliable and predictable shape with a known lumen diameter. The balloon may be configured for a variety of fixed inner lumen sizes. The fixed inner lumen sizes may range from 1 mm to 4 mm. In particular, some example fixed inner lumen sizes may be 2 mm, 2.5 mm, or 3 mm.
Each of the first balloon 920, the second balloon 930, and the third balloon 940 may be toroidal balloons. The first balloon 920 may be a compliant balloon such that it is in contact with the vessel wall when inflated to provide a seal against the vessel wall. Due to varying human anatomy, the first balloon 920 is configured to stretch to seal against a wide variety of vessel sizes. The second balloon 930 may be a non-compliant balloon that has an outer perimeter that is attached to a surface of an inner lumen 950 of the first balloon 920. The second balloon 930 is configured to act as a spine to provide some rigidity to the multi-staged toroidal balloon 900. The third balloon 940 may be a compliant balloon that has an outer perimeter that is attached to a surface of an inner lumen 960 of the second balloon 930. The third balloon 940, when inflated, is configured to press against the surface of the inner lumen 960 of the second balloon 930 to inflate and decrease the diameter D of the inner lumen of the third balloon 940, thereby allowing for variable orifice sizes. The variable orifice sizes enable variable and controllable restrictions to blood flow in a blood vessel. Such flow rates may vary from 0 L/min to 4 L/min. The first balloon 920, the second balloon 930, and the third balloon 940 may be connected to a multi-lumen catheter, such as the catheter 910, that provides independent control of each balloon volume. In this example, the catheter 910 includes blood pressure sensors 970 on either sides of the multi-staged toroidal balloon to monitor pressures and transmit alerts when a flow control balloon (e.g., the third balloon) requires an adjustment.
The system 1000 allows the pressure sensing mechanism to be fully sealed and avoids the need to prime the lumens before use, thereby enabling easier deployment in the field, as well as reducing the risk of clot formation in the catheter 1010, These lumens may be primed during manufacture, and the sensors may be built directly into the disposable catheter. In some embodiments, the membrane separation layer may be excluded to enable a user to manually prime the lumens. In some embodiments, the fluid filled lumens may be replaced with micro electro-mechanical system (MEMS) blood pressure sensors embedded in the catheter 1010 to measure the blood pressure directly.
The catheter 1105 includes a proximal pressure port 1115, one or more occlusion balloons 1120, and a distal pressure port 1125. The one or more occlusion balloons 1120 may include any of the balloons described above. The proximal pressure port 1115, the distal pressure port 1125, or both, may be configured with a flexible membrane, such as the flexible membrane 1050 shown in
The controller 1110 includes a graphical user interface (GUI) 1130, a display 1135, a radio frequency (RF) communications unit 1140, a distal pressure sensor 1145, a proximal pressure sensor 1150, a balloon flow meter 1155, a fluid supply 1160, a balloon pressure sensor 1165, and a microcontroller unit (MCU) 1170. The GUI 1130, the display 1135, the RF communications unit 1140, the distal pressure sensor 1145, the proximal pressure sensor 1150, the balloon flow meter 1155, the fluid supply 1160, and the balloon pressure sensor 1165 may be in communication with the MCU 1170 via a bus 1175. The controller 1110 may be designed for fixed or portable use.
The GUI 1130 may be configured to obtain user inputs and may be controlled by software performing real-time analysis of sensor inputs and system response. The GUI 1130 may display, on the display 1135, real-time blood pressure readings above and below the occlusion, as well as maintain a desired flow rate.
The RF communications unit 1140 may be configured to securely communicate with an external device for remote patient monitoring. The RF communications unit 1140 may be configured to communicate using any suitable wireless technology, such as, for example, Bluetooth, near-field communications (NFC), ultra-wideband communications (UWC), WiFi, or any cellular communications such as Long Term Evolution (LTE) or 5G.
The distal pressure sensor 1145 is configured to measure blood pressure above the occlusion (e.g., distal to the balloon where blood is flowing away from the balloon) and the proximal pressure sensor 1150 is configured to measure blood pressure below the occlusion (e.g., proximal to the balloon where blood is flowing towards the balloon).
The balloon flow meter 1155 is configured to measure the flow of fluid to and from the catheter 1105. The fluid supply 1160 may include a tank that contains fluid that is used to supply the catheter 1105 during inflation of the one or more occlusion balloons 1120. In some examples, the flow meter 1155 or the fluid supply 1160 may include a pump. During deflation of the one or more occlusion balloons 1120, the fluid supply is configured to store fluid from the one or more occlusion balloons 1120.
The balloon pressure sensor 1165 is configured to detect a pressure of an occlusion balloon against a vessel wall. The system 1100 may determine that the one or more occlusion balloons 1120 are properly secured within the vessel based on the data obtained from the balloon pressure sensor 1165.
The MCU 1170 is configured to dynamically adjust the one or more occlusion balloons 1120 to maintain the target blood flow in response to varying proximal and distal hemodynamics. For example, when the proximal pressure sensor 1150 detects a blood pressure above a threshold, the MCU 1170 may determine that one or more of the occlusion balloons 1120 should be deflated to increase the size of the respective inner lumen to increase blood flow and thereby reduce the blood pressure. In this example, the MCU 1170 may deflate the one or more occlusion balloons 1120 using the balloon flow meter 1155 to control the flow of fluid from the one or more occlusion balloons 1120 to the fluid supply 1160. When the MCU 1170 determines that the desired blood pressure is achieved, for example, based on the detected blood pressure from the distal pressure sensor 1145, the proximal pressure sensor 1150, or both, the MCU 1170 will stop deflation of the one or more occlusion balloons 1120 by stopping the flow of the fluid to the fluid supply 1160. The system 1100 may include a manual operation mode that allows a user to bypass automated controls and set the one or more occlusion balloons 1120 to a fixed size.
While the disclosure has been described in connection with certain embodiments, it is to be understood that the disclosure is not to be limited to the disclosed embodiments but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law.
Filing Document | Filing Date | Country | Kind |
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PCT/US2022/016298 | 2/14/2022 | WO |
Number | Date | Country | |
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20240130731 A1 | Apr 2024 | US |
Number | Date | Country | |
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63149522 | Feb 2021 | US | |
63149523 | Feb 2021 | US |