Patent Application
20220265509
The vast majority of patients treated with conventional (C) cardiopulmonary resuscitation (CPR) never wake up after cardiac arrest. Traditional closed-chest CPR involves repetitively compressing the chest in the med-sternal region with a patient supine and in the horizontal plane in an effort to propel blood out of the non-beating heart to the brain and other vital organs. This method is not very efficient, in part because refilling of the heart is dependent upon the generation of an intrathoracic vacuum during the decompression phase that draws blood back to the heart. Conventional (C) closed chest manual CPR (C-CPR) typically provides only 15-30% of normal blood flow to the brain and heart. In addition, with each chest compression, the arterial pressure increases immediately. Similarly, with each chest compression, right-side heart and venous pressures rise to levels nearly identical to those observed on the arterial side. The high right-sided pressures are in turn transmitted to the brain via the paravertebral venous plexus and jugular veins. The simultaneous rise of arterial and venous pressure with each C-CPR compression generates contemporaneous bi-directional (venous and arterial) high pressure compression waves that bombard the brain within the closed-space of the skull. This increase in blood volume and pressure in the brain with each chest compression in the setting of impaired cerebral perfusion further increases intracranial pressure (ICP), thereby reducing cerebral perfusion. These mechanisms have the potential to further reduce brain perfusion and cause additional damage to the already ischemic brain tissue during C-CPR.
To address these limitations, newer methods of CPR have been developed that significantly augment cerebral and cardiac perfusion, lower intracranial pressure during the decompression phase of CPR, and improve short and long-term outcomes. These methods may include the use of a load-distributing band, active compression decompression (ACD)+CPR, an impedance threshold device (ITD), active intrathoracic pressure regulation devices, and/or combinations thereof. However, despite these advances, most patients still do not wake up after out-of-hospital cardiac arrest.
Embodiments of the invention are directed toward systems, devices, and methods of administering CPR to a patient in a head and thorax up position. Such techniques result in lower right-atrial pressures and intracranial pressure while increasing cerebral perfusion pressure, cerebral output, and systolic blood pressure (SBP) compared with CPR administered to an individual in the supine position. The configuration may also preserve a central blood volume and lower pulmonary vascular resistance. This provides a more effective and safe method of performing CPR for extended periods of time. The head and thorax up configuration may also preserve the patient in the sniffing position to optimize airway management and reduce complications associated with endotracheal intubation.
In one aspect, an elevation device used in the performance of cardiopulmonary resuscitation (CPR) and after resuscitation is provided. The elevation device may include a base and an upper support operably coupled to the base. The upper support may be configured to elevate an individual's upper back, shoulders and head. The elevation device also may include a chest compression device coupled with the base. The chest compression device may be configured to compress the chest and to actively decompress the chest.
In another aspect, an elevation device used in the performance of cardiopulmonary resuscitation (CPR) and after resuscitation may include a base and an upper support operably coupled to the base. The upper support may be configured to elevate an individual's upper back, shoulders and head. The elevation device may also include a chest compression device coupled with the base that is configured to repeatedly compress the chest. The elevation device may further include a means for repeatedly raising the chest compression device away from the individual's chest, whereby a patient's chest may be compressed and decompressed in an alternating manner.
One aspect of the invention involves CPR techniques where the entire body, and in some cases at least the head, shoulders, and heart, of a patient is tilted upward. This improves cerebral perfusion and cerebral perfusion pressures after cardiac arrest. In some cases, CPR with the head and heart elevated may be performed using any one of a variety of manual or automated conventional CPR devices (e.g. active compression-decompression CPR, load-distributing band, or the like) alone or in combination with any one of a variety of systems for regulating intrathoracic pressure, such as a threshold valve that interfaces with a patient's airway (e.g., an ITD), the combination of an ITD and a Positive End Expiratory Pressure valve (see Voelckel et al “The effects of positive end-expiratory pressure during active compression decompression cardiopulmonary resuscitation with the inspiratory threshold valve.” Anesthesia and Analgesia. 2001 April: 92(4): 967-74, the entire contents of which is hereby incorporated by reference). or a Bousignac tube alone or coupled with an ITD (see U.S. Pat. No. 5,538,002, the entire contents of which is hereby incorporated by reference). In some cases, the systems for regulating intrathoracic pressure may be used without any type of chest compression. When CPR is performed with the head and heart elevated, gravity drains venous blood from the brain to the heart, resulting in refilling of the heart after each compression and a substantial decrease in ICP, thereby reducing resistance to forward brain flow. This maneuver also reduces the likelihood of simultaneous high pressure waveform simultaneously compressing the brain during the compression phase. While this may represent a potential significant advance, tilting the entire body upward, or at least the head, shoulders, and heart, has the potential to reduce coronary and cerebral perfusion during a prolonged resuscitation effort since over time gravity will cause the redistribution of blood to the abdomen and lower extremities.
It is known that the average duration of CPR is over 20 minutes for many patients with out-of-hospital cardiac arrest. To prolong the elevation of the cerebral and coronary perfusion pressures sufficiently for longer resuscitation efforts, in some cases, the head may be elevated at between about 10 cm and 30 cm (typically about 20 cm) while the thorax, specifically the heart and/or lungs, is elevated at between about 3 cm and 8 cm (typically about 5 cm) relative to a supporting surface and/or the lower body of the individual. Typically, this involves providing a thorax support and a head support that are configured to elevate the respective portions of the body at different angles and/or heights to achieve the desired elevation with the head raised higher than the thorax and the thorax raised higher than the lower body of the individual being treated. Such a configuration may result in lower right-atrial pressures while increasing cerebral perfusion pressure, cerebral output, and systolic blood pressure SBP compared to CPR administered to an individual in the supine position. The configuration may also preserve a central blood volume and lower pulmonary vascular resistance.
The head up devices (HUD) described herein mechanically elevate the thorax and the head, maintain the head and thorax in the correct position for CPR when head up and supine using an expandable and retractable thoracic back plate and a neck support, and allow a thoracic plate to angulate during head elevation so the piston of a CPR assist device always compresses the sternum in the same place and a desired angle (such as, for example, a right angle) is maintained between the piston and the sternum during each chest compression. Embodiments were developed to provide each of these functions simultaneously, thereby enabling maintenance of the compression point at the anatomically correct place when the patient is flat (supine) or their head and chest are elevated.
Turning now to
As one example, the lower body 306 may define a substantially horizontal plane. A first angled plane may be defined by a line formed from the patient's chest 304 (heart and lungs) to his shoulder blades. A second angled plane may be defined by a line from the shoulder blades to the head 302. The first plane may be angled about between 5° and 15° above the substantially horizontal plane and the second plane may be at an angle of between about 15° and 45° above the substantially horizontal plane. In some embodiments, the first angled plane may be elevated such that the heart is at a height of about 4-8 cm above the horizontal plane and the head is at a height of about 10-30 cm above the horizontal plane.
The type of CPR being performed on the elevated patient may vary. Examples of CPR techniques that may be used include manual chest compression, chest compressions using an assist device such as assist device 312, either automated or manually, ACD CPR, a load-distributing band, standard CPR, stutter CPR, and the like. Such processes and techniques are described in U.S. Pat. Pub. No. 2011/0201979 and U.S. Pat. Nos. 5,454,779 and 5,645,522, all incorporated herein by reference. Further various sensors may be used in combination with one or more controllers to sense physiological parameters as well as the manner in which CPR is being performed. The controller may be used to vary the manner of CPR performance, adjust the angle of inclination, provide feedback to the rescuer, and the like. Further, a compression device could be simultaneously applied to the lower extremities to squeeze venous blood back into the upper body, thereby augmenting blood flow back to the heart. Further, a rigid or semi-rigid cushion could be simultaneously inserted under the thorax at the level of the hart to elevate the heart and provide greater back support during each compression.
Additionally, a number of other procedures may be performed while CPR is being performed on the patient in the torso-elevated state. One such procedure is to periodically prevent or impede the flow in respiratory gases into the lungs. This may be done by using a threshold valve, sometimes also referred to as an impedance threshold device (ITD) that is configured to open once a certain negative intrathoracic pressure is reached. The invention may utilize any of the threshold valves or procedures using such valves that are described in U.S. Pat. Nos. 5,551,420; 5,692,498; 5,730,122; 6,029,667; 6,062,219; 6,155,257; 6,234,916; 6,224,562; 6,526,973; 6,604,523; 6,986,349; and 7,204,251, the complete disclosures of which are herein incorporated by reference.
Another such procedure is to manipulate the intrathoracic pressure in other ways, such as by using a ventilator or other device to actively withdraw gases from the lungs. Such techniques as well as equipment and devices for regulating respirator gases are described in U.S. Pat. Pub. No. 2010/0031961, incorporated herein by reference. Such techniques as well as equipment and devices are also described in U.S. patent application Ser. Nos. 11/034,996 and 10/796,875, and also U.S. Pat. Nos. 5,730,122; 6,029,667; 7,082,945; 7,185,649; 7,195,012; and 7,195,013, the complete disclosures of which are herein incorporated by reference.
In some embodiments, the angle and/or height of the head and/or heart may be dependent on a type of CPR performed and/or a type of intrathoracic pressure regulation performed. For example, when CPR is performed with a device or device combination capable of providing more circulation during CPR, the head may be elevated higher, for example 10-30 cm above the horizontal plane (10-45 degrees) such as with ACD+ITD CPR. When CPR is performed with less efficient means, such as manual conventional standard CPR, then the head will be elevated less, for example 5-20 cm or 10 to 20 degrees.
A variety of equipment or devices may be coupled to or associated with the structure used to elevate the head and torso to facilitate the performance of CPR and/or intrathoracic pressure regulation. For example, a coupling mechanism, connector, or the like may be used to removably couple a CPR assist device to the structure. This could be as simple as a snap fit connector to enable a CPR assist device to be positioned over the patient's chest. Examples of CPR assist devices that could be used with the support structure (either in the current state or a modified state) include the Lucas device, sold by Physio-Control, Inc. and described in U.S. Pat. No. 7,569,021, the entire contents of which is hereby incorporated by reference, the Defibtech Lifeline ARM—Hands-Free CPR Device, sold by Defibtech, the Thumper mechanical CPR device, sold by Michigan Instruments, automated CPR devices by Zoll, such as the AutoPulse, as also described in U.S. Pat. No. 7,056,296, the entire contents of which is hereby incorporated by reference, and the like.
Similarly, various commercially available intrathoracic pressure devices could be removably coupled to the support structure. Examples of such devices include the Lucas device (Physio-control) such as is described in U.S. Pat. No. 7,569,021, the Weil Mini Chest Compressor Device, such as described in U.S. Pat. No. 7,060,041 (Weil Institute), the entire contents of which are hereby incorporated by reference, the Zoll AutoPulse, and the like.
As an individual's head is elevated using a support structure or other elevation device, the individual's thorax is forced to constrict and compress, which causes a more magnified thorax migration during the elevation process. This thorax migration may cause the misalignment of a chest compression device, which leads to ineffective, and in some cases, harmful, chest compressions. It can also cause the head to bend forward thereby potentially restricting the airway. Thus, maintaining the individual in a proper position throughout elevation, without the compression and contraction of the thorax, is vital to ensure that safe and effective CPR can be performed. Embodiments of the following support structures provide upper supports that may expand and contract, such as by sliding along a support frame to permit the thorax to move freely upward and remain elongate, rather than contract, during the elevation process. For example, the upper support may be supported on rollers with minimal friction. As the head, neck, and/or shoulders are lifted, the upper support may slide away from the thoracic compression, which relieves a buildup of pressure on the thorax and minimizes thoracic compression and migration. Additionally, such support structures are designed to maintain optimal airway management of the individual, such as by supporting the individual in the sniffing position throughout elevation.
In traditional CPR the patient is supine on an underlying flat surface while manual or automated CPR is implemented. During automated CPR, the chest compression device may migrate due to limited stabilization to the underlying flat surface, and may often require adjustment due to the migration of the device and/or body migration. This may be further exaggerated when the head and shoulders are raised. The support structures described herein offer a more substantial platform to support and cradle the chest compression device, such as, for example, a LUCAS device, providing stabilization assistance and preventing unwanted migratory motion, even when the upper torso is elevated. The support structures described herein provide the ability to immediately commence CPR in the lowered/supine position, continuing CPR during the gradual, controlled rise to the “Head-Up/Elevated” position. Such support structures provide ease of patient positioning and alignment for automated CPR devices. Correct positioning of the patient is important and readily accomplished with guides and alignment features, such as a shaped shoulder profile, a neck/shoulder support, a contoured thoracic plate, as well as other guidelines and graphics. The support structures may incorporate features that enable micro adjustments to the position of an automated CPR device position, providing control and enabling accurate placement of the automated CPR device during the lift process. In some embodiments, the support structures may establish the sniffing position for intubation when required, in both the supine position and during the lifting process. Features such as stationary pads and adjustable cradles may allow the reduction of neck extension as required while allowing ready access to the head for manipulation during intubation.
Turning to
The thoracic plate 406 may be contoured to match a contour of the patient's back and may include one or more couplings 418. Couplings 418 may be configured to connect a chest compression device to support structure 400. For example, couplings 418 may include one or more mating features that may engage corresponding mating features of a chest compression device. As one example, a chest compression device may snap onto or otherwise receive the couplings 418 to secure the chest compression device to the support structure 400. Any one of the devices described above could be coupled in this manner. The couplings 418 may be angled to match an angle of elevation of the thoracic plate 406 such that the chest compression is secured at an angle to deliver chest compressions at an angle substantially orthogonal to the patient's sternum, or other desired angle. In some embodiments, the couplings 418 may extend beyond an outer periphery of the thoracic plate 406 such that the chest compression device may be connected beyond the sides of the patient's body. In some embodiments, mounting 406 may be removable. In such embodiments, thoracic plate 406 may include one or more mounting features (not shown) to receive and secure the mounting 406 to the support structure 400.
Typically, thoracic plate 406 may be positioned at an angle of between about 0° and 15° relative to a horizontal plane and at a height of between about 3 cm and 8 cm above the horizontal plane at a point of the thoracic plate 406 disposed beneath the patient's heart. Upper support 404 is often within about 15° and 45° relative to the horizontal plane and between about 10 cm and 40 cm above the horizontal plane, typically measured from the tragus of the ear as a guide point. In some embodiments, when in a stowed position thoracic plate 406 and upper support 404 are at a same or similar angle, with the upper support 404 being elevated above the thoracic plate 406, although other support structures may have the first portion and second portion at different angles in the stowed position. In the stowed position, thoracic plate 406 and/or upper support 404 may be near the lower ends of the height and/or angle ranges.
In an elevated position, upper support 404 may be positioned at angles above 15° relative to the horizontal plane. Support structure 400 may include one or more elevation mechanisms 430 configured to raise and lower the thoracic plate 406 and/or upper support 404. For example, elevation mechanism 430 may include a mechanical and/or hydraulic extendable arm configured to lengthen or raise the upper support 404 to a desired height and/or angle, which may be determined based on the patient's body size, the type of CPR being performed, and/or the type of ITP regulation being performed. The elevation mechanism 430 may manipulate the support structure 400 between the storage configuration and the elevated configuration. The elevation mechanism 430 may be configured to adjust the height and/or angle of the upper support 404 throughout the entire ranges of 15° and 45° relative to the horizontal plane and between about 10 cm and 40 cm above the horizontal plane. In some embodiments, the elevation mechanism 430 may be manually manipulated, such as by a user lifting up or pushing down on the upper support 404 to raise and lower the second portion. In other embodiments, the elevation mechanism 430 may be electrically controlled such that a user may select a desired angle and/or height of the upper support 404 using a control interface. While shown here with only an adjustable upper support 404, it will be appreciated that thoracic plate 406 may also be adjustable.
The thoracic plate 406 may also include one or more mounting features 418 configured to secure a chest compression device to the support structure 404. Here, upper support 404 is shown in an initial, stored configuration. In such a configuration, the upper support 404 is at its lowest position and in a contracted state, with the upper support 404 at its nearest point relative to the thoracic plate 406.
As described in the support structures above, upper support 404 may be configured to elevate a patient's upper back, shoulders, neck, and/or head. Such elevation of the upper support 404 is shown in
Upper support 404 may be configured to be adjustable such that the upper support 404 may slide along a longitudinal axis of base 402 to accommodate patients of different sizes as well as movement of a patient associated with the elevation of the head by upper support 404. Upper support 404 may be spring loaded or biased to the front (toward the patient's body) of the support structure 400. Such a spring force assists in managing movement of the upper support 404 when loaded with a patient. Additionally, the spring force may prevent the upper support 404 from moving uncontrollably when the support structure 400 is being moved from one location to another, such as between uses. Support structure 400 may also include a lock mechanism 408. Lock mechanism 408 may be configured to set a lateral position of the upper support 404, such as when a patient is properly positioned on the support structure 400. By allowing the upper support 404 to slide relative to the base 402 (and thus lengthen the upper support), the patient may be maintained in the “sniffing position” throughout the elevation process. Additionally, less force will be transmitted to the patient during the elevation process as the upper support 404 may slide to compensate for any changes in position of the patient's body, with the spring force helping to smooth out any movements and dampen larger forces.
In some embodiments, a mechanism that enables the sliding of the upper support 404 while the upper support 404 is elevated may allow the upper support 404 to be slidably coupled with the base, while in other embodiments, the mechanism may be included as part of the upper support 404 itself. For example,
While shown with roller track 414 as being coupled with the base 402 and rollers 422 being coupled with the upper support 404, it will be appreciated that other designs may be used in accordance with the present invention. For example, a number of rollers may be positioned along a rail that is pivotally coupled with the base. The upper support may then include a track that may receive the rollers such that the upper support may be slid along the rollers to adjust a position of the upper support. Other embodiments may omit the use of rollers entirely. In some embodiments, the mechanism may be a substantially friction free sliding arrangement, while in others, the mechanism may be biased toward the thoracic plate 406 by a spring force. As one example, the upper support may be supported on one or more pivoting telescopic rods that allow a relative position of the upper support to be adjusted by extending and contracting the rods.
In some embodiments, a chest compression/decompression system may be coupled with a support structure. Proper initial positioning and orientation, as well as maintaining the proper position, of the chest compression/decompression system, is essential to ensure there is not an increased risk of damage to the patient's rib cage and internal organs. This correct positioning includes positioning and orienting a piston type automated CPR device. Additionally, testing has shown that such CPR devices, even when properly positioned, may shift in position during administration of head up CPR. Such shifts may cause an upward motion of the device relative to the sternum, and may cause an increased risk of damage to the rib cage, as well as a risk of ineffective CPR. If a piston of the CPR or chest compression/decompression device has an angle of incidence that is not perpendicular to the sternum (thereby resulting in a force vector that will shift the patient's body), there may be an increased risk of damage to the patient's rib cage and internal organs. However, it will be appreciated that certain chest compression devices may be designed to compress the chest at other angles.
The degree of upward shift was studied in normal human volunteers. During the elevation to a head up position, subjects were moved out of the initial sniffing position. This was due to the upper torso curling during the lifting or elevation of the patient's upper body. Such torso curling also created a significant thoracic shift, meaning that as the upper body and head lifted, the thoracic plate and chest pivoted forward. The shift is significant when a support structure is used in conjunction with an automated chest compression or active compression decompression (ACD) CPR device, such as the LUCAS device, as the thoracic shift effectively changes an angle of the plunger and/or suction cup of the ACD CPR device relative to the thorax. Such an angle change may cause the plunger to be out of alignment, which may result in undesired effects. The results of thoracic shift were tested using a support structure having an extendable upper support. Table 1 shows the thoracic shift measured in 11 subjects using the support structure. The listed shifts represent a distance change of where the plunger contacts the subject's chest when the subject is manipulated between supine and head up positions.
To record the thoracic shift, each subject was positioned on the support structure positioned on a table. The subject's nipple line was positioned approximately at a center of the thoracic plate of the support structure. The upper support of the support structure was adjusted, insuring that the subject was in the sniffing position. A plunger of an active compression decompression device (LUCAS device) was lowered and positioned on the subject's chest according to device requirements. The position of the suction cup of the plunger was marked on the subject using a marker while in the supine position (with a lower edge of the suction cup as a trace edge). The position of the sliding upper support of the support structure was recorded. The support structure was then elevated to 15° above the horizontal plane defined by the table. A new position of the suction cup was marked on the subject while in the elevated position. The position of the sliding upper support was again recorded. The support structure was then elevated to 30° above the horizontal plane. The position of the suction cup was again marked on the subject's chest. The subject was then lowered to the supine position and the process was repeated two times with the LUCAS suction cup in the same starting position. The process was then repeated another two times with the subject's arms strapped to the LUCAS device. In some of these test subjects, the center of the piston moved as little as 0.95 cm to over 2.0 cm. The potential for piston movement is a potential significant clinical concern. Based upon this study in human cadavers, a means to adjust the compression piston angle with the chest during elevation of the heart and thorax is needed to avoid damage during CPR.
Thoracic plate 606 includes a pivoting base 608. As shown in
During administration of various types of head and thorax up CPR, it is advantageous to maintain the patient in the sniffing position where the patient is properly situated for endotracheal intubation. In such a position, the neck is flexed and the head extended, allowing for patient intubation, if necessary, and airway management. During elevation of the upper body, the sniffing position may require that a center of rotation of an upper support structure supporting the patient's head be co-incident to a center of rotation of the upper head and neck region. The center of rotation of the upper head and neck region may be in a region of the spinal axis and the scapula region. Maintaining the sniffing position of the patient may be done in several ways.
In some embodiments, the motors may be coupled with a processor or other computing device. The computing device may communicate with one or more input devices such as a keypad, and/or may couple with sensors such as flow and pressure sensors. This allows a user to select an angle and/or height of the heart and/or head. Additionally, sensor inputs may be used to automatically control the motor and angle of the supports based on flow and pressure measurements, as well as a type of CPR and/or ITP regulation.
To confirm the effectiveness of the use of devices such as the support structure 600 described above, a study was performed using 20 human cadavers. The study confirmed that such a device is capable of elevating the head and thorax while at the same time assuring that the chest compression device, suction cup and piston, sternal interface remained at right angles to the cadaver and did not migrate upwards or downwards on the chest during chest elevation. Chest x-rays were used to assess if the correct position was maintained between the body and the CPR device so CPR would be performed orthogonally to the body according to AHA Guidelines, and not orthogonally to the ground. A HUD, similar to support structure 600, was used to automatically elevate the head and shoulders and thorax. This HUD was coupled to a LUCAS device to standardize the chest compression. The suction cup of the LUCAS device was positioned as recommended by the manufacturer. Several anatomical reference points were recorded in the supine and head up positions for the chest and the head.
In the supine position, a mark was drawn on the cadaver skin at the LUCAS cup lower point. After elevation, the LUCAS cup lower point movement was compared to this reference line and the result was recorded. Prior to the performance of CPR, there was essentially no movement of the lower cup point relative to the reference line, indicating that the support structure was appropriately designed to prevent any migration of the LUCAS cup relative to the patient's chest during the elevation process.
CPR was also performed on some cadavers with the LUCAS device to confirm that during actual chest compression the cup lower point stayed at the skin mark. Elevation of the head and thorax using the HUD was performed. The movement of the body to the main part of the HUD was recorded with arms immobilized in this manner.
A series of X-rays were performed to demonstrate that during CPR the LUCAS device remained orthogonal to the sternum. There was no movement at all of the suction cup on the sternum on 20 cadavers in any direction with elevation of the head and thorax with the HUD. The study also found that the difference of angle with each cadaver between the LUCAS and the body was not significantly different in the supine and the head up position. It is important to note that the HUD itself, even in the flat position, elevated the heart and head about 5 cm relative to the flat surface upon which the HUD rested, whereas the lower back, buttocks and legs, which were not on the HUD itself but resting on a flat surface, were not elevated at all.
One result of this study is that during elevation of the head and thorax with the HUD, CPR could be continued at the recommended compression point and angle on all cadavers at the anatomically AHA recommended location with no migration of the compression location. The CPR compression point and the sternal manubrium rose significantly relative to the floor or bed. The head also elevated as expected. The HUD, by its design, enables the performance of CPR at the correct spot and at the correct angle relative to the chest when the head and thorax are both supine and elevated.
In some embodiments, a support structure may include additional patient positioning aids. For example, a thoracic plate 700 of
In some embodiments, the support structure 800 may include a rail (not shown) that extends at least substantially horizontally along the upper support 804 and/or the thoracic plate 806, with a fixed pivot point near the thoracic plate 806, such as near a pivot point of the thoracic plate 806. The rail is configured to pivot about the fixed pivot point and is coupled with the thoracic plate 806 such that pivoting of the rail causes a similar and/or identical pivot or tilt of the thoracic plate 806. A collar (not shown) may be configured to slide along a length of the rail. The collar may include a removable pin (not shown) that may be inserted through an aperture defined by the collar, with a portion of the pin extending into one of a series of apertures defined by a portion of the upper support 804. By inserting the pin into one of the series of apertures on the upper support 804, pivoting or tilting of the rail, and thus the thoracic plate 806, is effectuated by the elevation of the upper support 804. By moving the position of the pin closer to the fixed pivot point, a user may reduce the angle that the thoracic plate 806 pivots or tilts, while moving the pin away from the fixed pivot point increases the degree of elevation of the rail, and thus increases the amount of tilting of the thoracic plate 806 while still allowing both the thoracic plate 806 and the upper support 804 to return to an initial supine position. In this manner, a user may customize an amount of thoracic plate tilt that corresponds with a particular amount of elevation. For example, with a pin in a middle position along the rail, elevating the upper support 804 to a 45° angle may cause a corresponding forward tilt of the thoracic plate 806 of 12°. By moving the pin to a position furthest from the fixed pivot point along the rail, upper support 804 to a 45° angle may cause a corresponding forward tilt of the thoracic plate 806 of 20°. It will be appreciated that any combination of upper support 804 and thoracic plate 806 elevation and/or tilting may be achieved to match a particular patient's body size and that the above numbers are merely two examples of the customization achievable using a pin and rail mechanism.
For example, a gas strut may be used to elevate the upper support 804 in a similar manner.
In some embodiments, additional support may be needed for a patient's head as it extends through an opening of the shaped area of an upper support to prevent the neck from hyperextending and to maintain the patient in the sniffing position.
In some embodiments, additional head support may be desired during the elevation of the upper support, which may also cause the upper support to extend along a length of the support structure.
It will be appreciated that other cradle mechanisms may be used in conjunction with the support structures described herein. For example, an adjustable plate may be coupled with the upper support, allowing a user to adjust a height of the plate to provide a desired level of support. Other embodiments may include a net or cage that may extend below an opening of the upper support to maintain the head in a desired position. In some embodiments, a cradle mechanism may be coupled with the upper support using surgical tubing, a bungee cable, or other flexible or semi-rigid material to provide support for patients of different sizes.
While shown here as a sleeve, it will be appreciated that some embodiments may utilize a channel or indentation to receive a thoracic plate of a chest compression device. Other embodiments may include one or more fastening mechanisms, such as snaps, clamps, magnets, hook and loop fasteners, and the like to secure a thoracic plate onto a support structure. In some embodiments, a thoracic plate may be permanently built into the support structure. For example, a thorax-supporting or lower portion of a support structure may be shaped to match a patient's back and may include one or more mounting features that may engage or be engaged with corresponding mounting features of a chest compression device.
In some embodiments, the thoracic plate 1402 may be positioned on the support structure 1400 by manipulating both sides of clamping arms 1406 and setting the thoracic plate 1402 on top of the support structure 1400 with the apertures 1404 aligned with the clamping arms 1406. The mechanisms 1408 for each of the sides of clamping arms 1406 may then be manipulated to move the clamping arms 1406 into the locked position. This may be done simultaneously or one by one.
Such an embodiment also allows for easy cleaning of the thoracic plate 1602 and the support structure 1600. The thoracic plate 1602 may include clips that allow for easy engagement with the upper support 1606 and engagement with a front edge of a pocket between the upper support 1606 and the base 1610 of the support structure 1600 that creates a fixed point and a lifting/sliding point. A further advantage of this is that the thoracic plate 1602 can be readily exchanged as required for various medical reasons. In this embodiment, the rail 1604 and/or any clips may be formed of metal plates and screws, however in some embodiments plastic or radio-transparent materials can be used to allow for x-ray fluoroscopy.
Support structure 1800 may also include non-slip pads 1806 and 1808 that further help maintain the patient in the correct position without slipping. Non-slip pad 1806 may be positioned on a lower or thorax support 1812, and non-slip pad 1808 may be positioned on an upper or head and neck support 1814. While not shown, it will be appreciated that a neck support, such as described elsewhere herein, may be included in support structure 1800. Support structure 1800 may also include motor controls 1810. Motor controls 1810 may allow a user to control a motor to adjust an angle of elevation and/or height of the lower support 1812 and/or upper support 1814. For example, an up button may raise the elevation angle, while a down button may lower the elevation angle. A stop button may be included to stop the motor at a desired height, such as an intermediate height between fully elevated and supine. It will be appreciated that motor controls 1810 may include other features, and may be coupled with a computing device and/or sensors that may further adjust an angle of elevation and/or a height of the lower support 1812 and/or the upper support 1814 based on factors such as a type of CPR, a type of ITP regulation, a patient's body size, measurements from flow and pressure sensors, and/or other factors.
It will be appreciated that the components of the elevation systems described herein may be interchanged with other embodiments. For example, although some systems are not shown in connection with a feature to lengthen or elongate the upper support, such a feature may be included. As another example, the various head stabilizers, neck positioning structures, positioning motors, and the like may be incorporated within or interchanged with other embodiments.
In some embodiments, active decompression may be provided to the patient receiving CPR with a modified load distributing band device (e.g. modified Zoll Autopulse® band) by attaching a counter-force mechanism (e.g. a spring) between the load distributing band and the head up device or support structure. Each time the band squeezes the chest, the spring, which is mechanically coupled to the anterior aspect of the band via an arch-like suspension means, is actively stretched. Each time the load distributing band relaxes, the spring recoils pulling the chest upward. The load distributing band may be modified such that between the band the anterior chest wall of the patient there is a means to adhere the band to the patient (e.g. suction cup or adhesive material). Thus, the load distributing band compresses the chest and stretches the spring, which is mounted on a suspension bracket over the patient's chest and attached to the head up device.
In other embodiments, the decompression mechanism is an integral part of the head up device and mechanically coupled to the load distributing band, either by a supermagnet or an actual mechanical couple. The load distributing band that interfaces with the patient's anterior chest is modified so it sticks to the patient's chest, using an adhesive means or a suction means. In some embodiments, the entire ACD CPR automated system is incorporated into the head up device, and an arm or arch is conveniently stored so the entire unit can be stored in a relative flat planar structure. The unit is placed under the patient and the arch is lifted over the patient's chest. The arch mechanism allows for mechanical forces to be applied to the patient's chest orthogonally via a suction cup or other adhesive means, to generate active compression, active decompression CPR. The arch mechanism may be designed to tilt with the patient's chest, such as by using a mechanism similar to that used to tilt the thoracic plate in the embodiments described herein.
In some embodiments, a motor (not shown) for the chest compression device 2212 may be housed within the base 2202, such that the motor may periodically wind and/or tension a band or cord coupled with the load distributing band 2210, causing the load distributing band 2210 to be pulled against the patient's chest to compress the chest, while also elongating the spring 2214 and causing the spring 2214 to store potential energy. As the motor releases tension on the band, the spring 2214 recoils, providing spring force that pulls the load distributing band 2210 away from the patient's chest, thereby decompressing the chest as the underside 2216 including the adhesive material and/or suction cup is moved upwards. In other embodiments, the motor may be positioned atop the load distributing band 2210, with the rotatable arm 2208 and spring 2214 coupled to a top of the motor such that the entire motor and strap assembly is lifted when the motor is not compressing the patient's chest.
While shown with a pivot point 2220 of rotatable arm 2208 positioned on an upper support side of the chest compression device 2212, it will be appreciated that this pivot point 2220 may be moved closer to the load distributing band 2210. For example, a sleeve 2218 of the upper support 2204 may extend along a side of base 2202 such that a portion of the sleeve 2218 overlaps some or all of the load distributing band 2210. The pivot point 2220 of the rotatable arm 2208 may then be positioned proximate to the load distributing band 2210. In this manner, a force generated by the chest compression device 2212 may be substantially aligned with the rotatable arm 2208.
Support structure 2300 may also include a rotatable arm 2308 that may rotate about a pivot point 2310. Rotatable arm 2308 that may rotate between and be locked into a stored position in which the rotatable arm 2308 is at least substantially in plane with the support structure 2300 when the upper support 2304 is lowered as shown in
The base 2302 may house a motor (not shown) that is used to tension a cord or band 2314 that extends along a width of base 2302 and extends to the rotatable arm 2308. The band 2314 may extend through an interior channel (not shown) of rotatable arm 2308 where it may couple with a piston or other compression mechanism that is driven to move the suction cup 2312 up and/or down. In some embodiments, the band 2314 may be coupled with a cord and/or a pulley system that extends through some or all of the rotatable arm 2308 to transmit force from the motor to the piston or other drive mechanism. As just one example, the compression mechanism may include a worm gear (not shown) that is turned by a tensioning cord coupled with the band 2314. For example, the cord may be wound around one end of the worm gear, such that as the cord is tensioned, the cord pulls on the worm gear, causing the worm gear to rotate. As the worm gear rotates, the worm gear may drive a lead screw (not shown) downward to compress the patient's chest. The suction cup 2312 may be coupled with the lead screw. In some embodiments, the motor may be operated in reverse to release tension on the band 2314, allowing the piston or lead screw to return to an upward position. In other embodiments, the motor may be controlled electronically by control switches attached to structure 2300, or remotely using Bluetooth communication or other wired and/or wireless techniques. Further, the compression/decompression movement may be regulated based upon physiological feedback from one or more sensors directly or indirectly attached to the patient.
In some embodiments, to provide a stronger decompressive force to the chest, the rotatable arm 2308 may include one or more springs. For example, a spring 2316 may be positioned around the lead screw and above the suction cup 2312. As the lead screw is extended downward by the motor, the screw 2316 may be stretched, thus storing energy. As the tension is released and the lead screw is retracted, the spring 2316 may recoil, providing sufficient force to actively decompress the patient's chest. In some embodiments, a spring (not shown) may be positioned near each pivot point 2310 of rotatable arm 2308, biasing the rotatable arm in an upward, or decompression state. As the motor tightens the band and causes the rotatable arm 2308 and/or suction cup 2314 to compress the patient's chest, the pivot point springs may also be compressed. As the tension is released by the motor, the pivot point springs may extend to their original state, driving the rotatable arm 2308 and suction cup 2314 upward, thereby decompressing the patient's chest.
It will be appreciated that any number of tensioning mechanisms and drive mechanisms may be used to convert the force from the tensioning band or motor to an upward and/or downward linear force to compress the patient's chest. For example, rather than using worm gears and lead screws, a conventional piston mechanism may be utilized, such with tensioned bands and/or pulley systems providing rotational force to a crankshaft. In other embodiments, an electro-magnetically driven piston or plunger may be used. Additionally, the motor may be configured to deliver both compressions and decompressions, without the use of any springs. In other embodiments, both a spring 2316 and/or pivot point springs may be used in conjunction with a compression only or compression/decompression motor to achieve a desired decompressive force applied to the patient's chest. In still other embodiments, the motor and power supply, such as a battery, will be positioned in a portion of base 2302 that is lateral or superior to the location of the patient's heart, such that they do not interfere with fluoroscopic, x-ray, or other imaging of the patient's heart during cardiac catheterization procedures. Further, the base 2302 could include an electrode, attached to the portion of the device immediately behind the heart (not shown), which could be used as a cathode or anode to help monitor the patient's heart rhythm and be used to help defibrillate or pace the patient. As such, base 2302 could be used as a ‘work station’ which would include additional devices such as monitors and defibrillators (not shown) used in the treatment of patients in cardiac arrest.
In some embodiments, the elevation device further includes a thoracic plate operably coupled with the base. The thoracic plate may be configured to receive a chest compression device, which may include an active compression-decompression device and/or a device configured only to deliver chest compressions. In some embodiments, process 2400 may include pivoting the thoracic plate relative to the base, thereby adjusting an orientation of the chest compression device. In some embodiments, the thoracic plate may be slid lengthwise relative to the base, thereby adjusting a position of the chest compression device. In other embodiments, expanding the upper support causes a corresponding adjustment of the thoracic plate such that the chest compression device is in a proper orientation and in which the chest compression device is properly aligned with the individual's heart, such as at a substantially orthogonal angle relative to the individual's sternum. The corresponding adjustment may include a change in angle of the thoracic plate relative to a horizontal plane.
For example, the upper support may slide or extend from an initial position over an excursion distance (measured from the initial position) of between about 0 and 2 inches, which may depend on various factors, such as the amount of elevation and/or the size of the individual. The initial position may be measured from a fixed point, such as a pivot point of the upper support. The initial position of the upper support may vary based on the height of the individual, as well as other physiological features of the individual.
Additional information and techniques related to head up CPR may be found in Debaty G, et al. “Tilting for perfusion: Head-up position during cardiopulmonary resuscitation improves brain flow in a porcine model of cardiac arrest.” Resuscitation. 2015: 87: 38-43. Print., the entire contents of which is hereby incorporated by reference. Further reference may be made to Lurie, Keith G. (2015) “The Physiology of Cardiopulmonary Resuscitation,” Anesthesia & Analgesia, doi:10.1513/ANE. 0000000000000926, in Ryu, et. al. “The Effect of Head Up Cardiopulmonary Resuscitation on Cerebral and Systemic Hemodynamics.” Resuscitation. 2016: 102: 29-34. Print., and in Khandelwal, et. al. “Head-Elevated Patient Positioning Decreases Complications of Emergent Tracheal Intubation in the Ward and Intensive Care Unit.” Anesthesia & Analgesia. April 2016: 122: 1101-1107. Print, the entire contents of which are hereby incorporated by reference. Moreover, any of the techniques and methods described therein may be used in conjunction with the systems and methods of the present invention.
An experiment was performed to determine whether cerebral and coronary perfusion pressures will remain elevated over 20 minutes of CPR with the head elevated at 15 cm and the thorax elevated at 4 cm compared with the supine position. A trial using female farm pigs was performed, modeling prolonged CPR for head-up versus head flat during both conventional CPR (C-CPR) and ACD+ITD CPR. A porcine model was used and focus was placed primarily on observing the impact of the position of the head on cerebral perfusion pressure and ICP.
Approval for the study was obtained from the Institutional Animal Care Committee of the Minneapolis Medical Research Foundation, the research foundation associated with Hennepin County Medical Center in Minneapolis, Minn. Animal care was compliant with the National Research Council's 1996 Guidelines for the Care and Use of Laboratory Animals, and a certified and licensed veterinarian assured protocol performance was in compliance with these guidelines. This research team is qualified and has extensive combined experience performing CPR research in Yorkshire female farm pigs.
The animals were fasted overnight. Each animal received intramuscular ketamine (10 mL of 100 mg/mL) for initial sedation, and were then transferred from their holding pen to the surgical suite and intubated with a 7-8 French endotracheal tube. Anesthesia with inhaled isoflurane at 0.8%-1.2% was then provided, and animals were ventilated with room air using a ventilator with tidal volume 10 mL/kg. Arterial blood gases were obtained at baseline. The respiratory rate was adjusted to keep oxygen saturation above 92% and end tidal carbon dioxide (ETCO2) between 36 and 40 mmHg. Central aortic blood pressures were recorded continuously with a micromanometer-tipped catheter placed in the descending thoracic aorta via femoral cannulation at the level of the diaphragm. A second Millar catheter was placed in the right external jugular vein and advanced into the superior vena cava, approximately 2 cm above the right atrium for measurement of right atrial (RA) pressure. Carotid artery blood flows were obtained by placing an ultrasound flow probe in the left common carotid artery for measurement of blood flow (ml Intracranial pressure (ICP) was measured by creating a burr hole in the skull, and then insertion of a Millar catheter into the parietal lobe. All animals received a 100 units/kg bolus of heparin intravenously and received a normal saline bolus for a goal right atrial pressure of 3-5 mmHg. ETCO2 and oxygen saturation were recorded with a CO2SMO Plus®.
Continuous data including electrocardiographic monitoring, aortic pressure, RA pressure, ICP, carotid blood flow, ETCO2 was monitored and recorded. Cerebral perfusion pressure (CerPP) was calculated as the difference between mean aortic pressure and mean ICP. Coronary perfusion pressure (CPP) was calculated as the difference between aortic pressure and RA pressure during the decompression phase of CPR. All data was stored using a computer data analysis program.
When the preparatory phase was complete, ventricular fibrillation (VF) was induced with delivery of direct intracardiac electrical current from a temporary pacing wire placed in the right ventricle. Standard CPR and ACD+ITD CPR were performed with a pneumatically driven automatic piston device. Standard CPR was performed with uninterrupted compressions at 100 compressions/min, with a 50% duty cycle and compression depth of 25% of anteroposterior chest diameter. During standard CPR, the chest wall was allowed to recoil passively. ACD+ITD CPR was also performed at a rate of 100 per minute, and the chest was pulled upwards after each compression with a suction cup on the skin at a decompression force of approximately 20 lb and an ITD was placed at the end of the endotracheal tube. If randomization called for head and thorax elevation CPR (HUP), the head and shoulders of the animal were elevated 15 cm on a table specially built to bend and provide CPR at different angles while the thorax at the level of the heart was elevated 4 cm. While moving the animal into the head and thorax elevated position, CPR was able to be continued. Positive pressure ventilation with supplemental oxygen at a flow of 10 L min−1 were delivered manually. Tidal volume was kept at 10 mL/kg and respiratory rate at 10 breaths per minute. If the animal was noted to gasp during the resuscitation, time at first gasp was recorded, and then succinylcholine was administered to facilitate ventilation after the third gasp.
After 8 minutes of untreated ventricular fibrillation 2 minutes of automated CPR was performed in the 0° supine (SUP) position. Pigs were then randomized to CPR with 30° head and thorax up (HUP) versus SUP without interruption for 20 minutes. In group A, all pigs received C-CPR, randomized to either HUP or SUP, and in Group B, all pigs received ACD+ITD CPR, again randomized to either HUP or SUP. After 22 total minutes of CPR, all pigs were then placed in the supine position and defibrillated with up to three 275 J biphasic shocks. Epinephrine (0.5 mg) was also given during the post CPR resuscitation. Animals were then sacrificed with a 10 ml injection of saturated potassium chloride.
The estimated mean cerebral perfusion pressure was 28 mmHg in the HUP ACD+ITD group and 19 mmHg in the SUP ACD+ITD group, with a standard deviation of 8. Assuming an alpha level of 0.05 and 80% power, it was calculated that roughly 13 animals per group were needed to detect a 47% difference.
Descriptive statistics were used as appropriate. An unpaired t-test was used for the primary outcome comparing CerPP between HUP and SUP CPR. This was done both for the ACD+ITD CPR group and also the C-CPR group at 22 minutes. All statistical tests were two-sided, and a p value of less than 0.05 was required to reject the null hypothesis. Data are expressed as mean±standard error of mean (SEM). Secondary outcomes of coronary perfusion pressure (CPP, mmHg), time to first gasp (seconds), and return of spontaneous circulation (ROSC) were also recorded and analyzed.
Group A:
Table 2A below summarizes the results for group A.
Both HUP and SUP cerebral perfusion pressures were similar at baseline. Seven pigs were randomized to each group. For the primary outcome, after 22 minutes of C-CPR, CerPP in the HUP group was significantly higher than the SUP group (6±3 mmHg versus −5±3 mmHg, p=0.016).
Elevation of the head and shoulders resulted in a consistent reduction in decompression phase ICP during CPR compared with the supine controls. Further, the decompression phase right atrial pressure was consistently lower in the HUP pigs, perhaps because the thorax itself was slightly elevated. Coronary perfusion pressure was 6±2 mmHg in the HUP group and 3±2 mmHg in the SUP group at 20 minutes (p=0.283) (Table 1A). None of the pigs treated with C-CPR, regardless of the position of the head, could be resuscitated after 22 minutes of CPR.
Time to first gasp was 306±79 seconds in the HUP group and 308±37 in the SUP group (p=0.975). Of note, 3 animals in the HUP group and 2 animals in the SUP group were not observed to gasp during the resuscitation.
Group B:
Table 2B below summarizes the results for group B.
Both HUP and SUP cerebral perfusion pressures were similar at baseline. Eight pigs were randomized to each group. For the primary outcome, after 22 minutes of ACD+ITD CPR, CerPP in the HUP group was significantly higher than the SUP group (51±8 mmHg versus 20±5 mmHg, p=0.006). The elevation of cerebral perfusion pressure was constant over time with ACD+ITD plus differential head and thorax elevation. This is shown in
In pigs treated with ACD+ITD, the systolic blood pressure was significantly higher after 20 minutes of CPR in the HUP position compared with controls and the decompression phase right atrial pressures were significantly lower in the HUP pigs. Further, the ICP was significantly reduced during ACD+ITD CPR with elevation of the head and shoulders compared with the supine controls.
Coronary perfusion pressure was 32±5 mmHg in the HUP group and 19±5 mmHg in the SUP group at 20 minutes (p=0.074) (Table 1B). Both groups had a similar ROSC rate; 6/8 swine could be resuscitated in both groups.
Time to first gasp was 280±27 seconds in the head up tilt (HUT) group and 333±33 seconds in the SUP group (p=0.237).
The primary objective of this study was to determine if elevation of the head by 15 cm and the heart by 4 cm during CPR would increase the calculated cerebral and coronary perfusion pressure after a prolonged resuscitation effort. The hypothesis stated that elevation of the head would enhance venous blood drainage back to the heart and thereby reduce the resistance to forward arterial blood flow and differentially reduce the venous pressure head that bombards the brain with each compression, as the venous vasculature is significantly more compliance than the arterial vasculature. The hypothesis further included that a slight elevation of the thorax would result in higher systolic blood pressures and higher coronary perfusion pressures based upon the following physiological concepts. A small elevation of the thorax, in the study 4 cm, was hypothesized to create a small but important gradient across the pulmonary vascular beds, with less congestion in the cranial lung fields since elevation of the thorax would cause more blood to pool in the lower lung fields. This would allow for better gas exchange in the upper lung fields and lower pulmonary vascular resistance in the congested upper lung fields, allowing more blood to flow from the right heart through the lungs to the left ventricle when compared to CPR in the flat or supine position. In contrast to a previous study with the whole body head up tilt, where there was a concern about a net decrease in central blood volume over time in greater pooling of venous blood over time in the abdomen and lower extremities, it was hypothesized that the small 4 cm elevation of the thorax with greater elevation of the head would provide a way to increase coronary pressure (by lower right atrial pressure) and greater cerebral perfusion pressure (by lowering ICP) while preserving central blood volume and thus mean arterial pressure.
It has been previously reported that whole body head tilt up at 30° during CPR significantly improves cerebral perfusion pressure, coronary perfusion pressure, and brain blood flow as compared to the supine, or 0° position or the feet up and head down position after a relatively short duration of 5 minutes of CPR. Over time these effects were observed to decrease, and we hypothesized diminished effect over time was secondary to pooling of blood in the abdomen and lower extremities. The new results demonstrate that after a total time of 22 minutes of CPR, the absolute ICP values and the calculated CerPP were significantly higher in the head and shoulders up position versus the supine position for both automated C-CPR and ACD+ITD groups. The absolute HUP effect was modest in the C-CPR group, unlikely to be clinically significant, and none of the animals treated with C-CPR could be resuscitated. By contrast, differential elevation of the head by 15 cm and the thorax at the level of the heart by 4 cm in the ACD+ITD group resulted in a nearly 3-fold higher increase in the calculated CerPP and a 50% increase in the calculated coronary perfusion pressure after 22 minutes of continuous CPR. The new finding of increased coronary and CerPP in the HUP position during a prolonged ACD+ITD CPR effort is clinically important, since the average duration of CPR during pre-hospital resuscitation is often greater than 20 minutes and average time from collapse to starting CPR is often >7 minutes.
Other study endpoints included ROSC and time to first gasp as an indicator of blood flow to the brain stem. No pigs could be resuscitated after 22 minutes in the C-CPR group. ROSC rates were similar in Group B, with 6/8 having ROSC in both HUP and SUP groups.
From a physiological perspective, these findings are similar to those in the first whole body head up tilt CPR study. While ICP decreases with the HUP position, it is critical to maintain enough of an arterial pressure head to pump blood upwards to the elevated brain during HUP CPR. In a previous HUP study, removal of the ITD from the circuit resulted in an immediate decrease in systolic blood pressure. In the current study, the arterial pressures were lower in pigs treated with C-CPR versus ACD+ITD, both in the SUP and HUP positions. It is likely that the lack of ROSC in the pigs treated with C-CPR is a reflection of the limitations of conventional CPR where coronary and cerebral perfusion is far less than normal. As such, the absolute ROSC rates in the current study are similar to previous animal studies with ACD+ITD CPR and C-CPR.
Gasping during CPR is positive prognostic indicator in humans. While time to first gasp within Groups A and B was not significant, the time to first gasp was the shortest in the ACD+ITD HUP group of all groups. All 16 animals treated with ACD+ITD group gasped during CPR, whereas only 5/16 pigs gasped in the C-CPR group during CPR (3 HUP, 2 SUP).
Differential elevation of the head and thorax during C-CPR and ACD+ITD CPR increased cerebral and coronary perfusion pressures. This effect was constant over a prolonged period of time. In the absence of any vasopressor drugs, such as adrenaline, CerPP in the pigs treated with ACD+ITD CPR and the HUP position was nearly 50 mmHg, strikingly higher than the ACD+ITD SUP controls. In addition, the coronary perfusion pressure increased by about 50%, to levels known to be associated with consistently higher survival rates. By contrast, the modest elevation in CerPP in the C-CPR treated animals is likely clinically insignificant, as no pig treated with C-CPR could be resuscitated after 22 minutes of CPR. These observations provide strong support of the benefit of the combination of ACD+ITD CPR with differential elevation of the head and thorax. Using the same model of prolonged CPR as described by Ryu et. al, it was subsequently observed that adrenaline (epinephrine), administered at the end of the prolonged period of CPR to help resuscitate the pigs, increased CerPP in animals treated with ACD+ITD and 30° head up to higher levels than those treated with ACD+ITD and head flat.
A separate study was performed to better understand the potential to increase neurologically intact 24-hour survival in pigs with head up ACD+ITD CPR, as shown in
CPR was administered on pigs with various positions of the head and body according to the methodology described by Debaty G, et al. in “Tilting for perfusion: Head-up position during cardiopulmonary resuscitation improves brain flow in a porcine model of cardiac arrest.” Resuscitation. 2015: 87: 38-43. Specifically CPR was administered to pigs in the supine position, in a 30° head up position, and in a 30° head down position using the combination of the LUCAS 2 device to perform chest compressions at 100 compressions per minute and a depth of 2 inches along with an ITD. The data collected demonstrates that elevation of the head during CPR has a profound beneficial effect on ICP, CerPP, and brain blood flow when compared with the traditional supine horizontal position. With the body supine and horizontal, each compression is associated with the generation of arterial and venous pressure waves that deliver a simultaneous high pressure compression wave to the brain. With a pig's head up, gravity drains venous blood from the brain back to the heart, resulting in a greater refilling of the heart after each compression, strikingly lower compression and decompression phase ICP, and a higher compression and decompression phase cerebral perfusion pressure (CerPP). By contrast, CPR with the patient's feet up and head down resulted in a marked decrease in CerPP with a simultaneous increase in ICP as shown in
Blood flow to the brain was assessed during CPR using the LUCAS device and the ITD when pigs were on a tilt table in the flat (supine) position, and in the 30 degree head up tilt and 30 degree head down tilt position. The methods were described in the article by Debaty et al, referenced above. The findings are shown in
Another study was performed with head up CPR using the same protocol and device as described by Drs. Ryu et al in Resuscitation, previously incorporated by reference. In this study, blood flow to the heart and brain of pigs was examined using microspheres 5 and 15 minutes after CPR was started. CPR was performed with the ACD+ITD device with just the head and thorax elevated. The microsphere technique was similar to the reported by Debaty et al, previously incorporated by reference. The protocol started by injecting a baseline microsphere. Ventricular fibrillation (VF) was induced and left untreated for 8 minutes. Automated ACD+ITD was performed for 2 minutes with the pigs (n=2) flat. The head and thorax were elevated, per the paper by Ryu et al, and ACD+ITD CPR was continued in the head up position for a total of 20 minutes. After 5 minutes of automated ACD+ITD CPR, the second microsphere injection was made. After 15 minutes of ACD+ITD CPR, the third microsphere injection was made. The animals were shocked back after 20 minutes.
Strikingly, the blood flow to the heart and brain increased over the time that ACD+ITD CPR was performed. As shown in
To show head up CPR as described in the multiple embodiments in this application, a human cadaver model was used. The body was donated for science. The cadaver was less than 36 hours old and had never been embalmed or frozen. It was perfused with a saline with a clot disperser solution that breaks up blood clots so that when the head up CPR technology was evaluated there were no blood clots or blood in the blood vessels. In these studies we used either the combination of ACD+ITD or LUCAS+ITD to perform CPR both in the flat and head up positions.
Right atrial, aortic, and intracranial pressure transducers were inserted into the body into the right atria, aorta, and the brain through an intracranial bolt. These high fidelity transducers were then connected to a computer acquisition system (Biopac). CPR was performed with a ACD+ITD CPR in the flat position and then with the head elevated with the device shown in
Then, the Lucas device plus ITD was applied to the cadaver and CPR was performed with the cadaver flat and with head up with a device similar to the device shown in
ACD+ITD CPR was performed on 3 human cadavers that were donated to the University of Minnesota (UMN) Anatomy Bequest Program. The bodies were perfused with a clot-busting solution Metaflow. Bilateral femoral arterial and venous access was obtained, the cadaver was intubated, and high fidelity pressure transducer (Millar) catheters were placed in the brain via a burr hole to monitor intracranial pressure (ICP) and in the aorta and right atrium to assess arterial and venous pressures. Manual ACD+ITD CPR was performed in the supine (SUP) and head up (HUP) positions, with each cadaver serving as her/his own control. The same device shown in
Specific details are given in the description to provide a thorough understanding of example configurations (including implementations). However, configurations may be practiced without these specific details. For example, well-known processes, structures, and techniques have been shown without unnecessary detail in order to avoid obscuring the configurations. This description provides example configurations only, and does not limit the scope, applicability, or configurations of the claims. Rather, the preceding description of the configurations will provide those skilled in the art with an enabling description for implementing described techniques. Various changes may be made in the function and arrangement of elements without departing from the spirit or scope of the disclosure.
Also, configurations may be described as a process that is depicted as a flow diagram or block diagram. Although each may describe the operations as a sequential process, many of the operations may be performed in parallel or concurrently. In addition, the order of the operations may be rearranged. A process may have additional steps not included in the figure.
Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.
This application is a continuation of U.S. application Ser. No. 15/160,492, filed May 20, 2016, which claims priority to U.S. Provisional Application No. 62/242,655, filed Oct. 16, 2015, the complete disclosures of which are hereby incorporated by reference for all intents and purposes. U.S. application Ser. No. 15/160,492 (referenced above) is also a continuation in part of U.S. application Ser. No. 15/133,967, filed Apr. 20, 2016, which is a continuation in part of U.S. application Ser. No. 14/996,147, filed Jan. 14, 2016, which is a continuation in part of U.S. application Ser. No. 14/935,262, filed Nov. 6, 2015, which is a continuation in part of U.S. application Ser. No. 14/677,562, filed Apr. 2, 2015, which is a continuation of U.S. patent application Ser. No. 14/626,770, filed Feb. 19, 2015, which claims the benefit of U.S. Provisional Application No. 61/941,670, filed Feb. 19, 2014, U.S. Provisional Application No. 62/000,836, filed May 20, 2014 and U.S. Provisional Application No. 62/087,717, filed Dec. 4, 2014, the complete disclosures of which are hereby incorporated by reference for all intents and purposes.
| Number | Date | Country | |
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| 62242655 | Oct 2015 | US | |
| 61941670 | Feb 2014 | US | |
| 62000836 | May 2014 | US | |
| 62087717 | Dec 2014 | US |
| Number | Date | Country | |
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| Parent | 15160492 | May 2016 | US |
| Child | 17668944 | US | |
| Parent | 14626770 | Feb 2015 | US |
| Child | 14677562 | US |
| Number | Date | Country | |
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| Parent | 15133967 | Apr 2016 | US |
| Child | 15160492 | US | |
| Parent | 14996147 | Jan 2016 | US |
| Child | 15133967 | US | |
| Parent | 14935262 | Nov 2015 | US |
| Child | 14996147 | US | |
| Parent | 14677562 | Apr 2015 | US |
| Child | 14935262 | US |
