Patent Application
20160361228
The invention disclosed herein relates in general to the field of medical devices used for cardiopulmonary resuscitation (CPR) of patients suffering cardiac arrest or shock, and more particularly, to devices that provide or enhance hemodynamics during CPR.
It is possible to induce forward blood flow to during cardiac arrest by application of external force to the thorax. (Kouwenhoven, Jude, and Knickerbocker 1064-67) Most commonly, this has been achieved by providing anteroposterior compression of the mid-chest in the area of the sternum, either manually or mechanically with a piston like mechanism.
The specific mechanisms by which external chest compression achieves forward blood flow remains unclear. Two competing theories have been proposed, the cardiac pump mechanism and the thoracic pump mechanism. It is generally believed that anteroposterior compression of the sternum achieves forward blood flow principally through the cardiac pump mechanism, (Rudikoff et al. 345-52) and that circumferential constriction CPR functions through the thoracic pump. (Niemann et al. 141-46)
The failure to differentiate between these two theories may reflect the possibility that both mechanisms can contribute to forward blood flow. Either the cardiac or thoracic mechanism may be more or less predominant in any given patient depending on their body habitus and individual physiology.
It has been demonstrated that, compared to classical anteroposterior compression, circumferential constriction may be associated with higher intrathoracic pressure changes, greater blood flow, and increased rates of return of spontaneous circulation. (Halperin et al. 2214-20) Typically, such constriction is generally achieved by inflation of a circumferential pneumatic bladder, or semi-circumferentially with a band. (Halperin et al. 2214-20)
The efficacy of anteroposterior compression may be improved by the addition of forceful decompression during the upstroke of the piston. (Plaisance, Lurie, and Payen 989-94) Such active decompression requires attachment of the piston device to the chest. Typically, this is achieved by use of a suction cup device at the end of the piston.
The improvement in hemodynamics associated with active decompression may be mechanistically mediated by creation of increased negative intrathoracic pressure during the decompression phase of CPR, with resulting enhancement of venous return. Additional enhancement of negative intrathoracic pressure and venous return may be achieved by briefly obstructing the airway during the decompression release phase. (Aufderheide et al. 734-40; Plaisance et al. 990-94) Typically, this is achieved through utilization of a cracking valve mechanism called an impedance threshold device.
Although circumferential constriction devices may have advantages over anteroposterior compression devices, they do not allow for active decompression or optimize airway impedance threshold devices.
Additional interventions that may improve either circumferential constriction or anteroposterior compression of the chest include adjunctive therapy with pressor drugs, techniques that actively compress or decompress the abdomen, (Ralston, Babbs, and Niebauer 645-51) techniques that synchronize components with residual cardiac function, (Paradis et al. 1287-91) among others.
Since its first description, external chest compression as a therapy for cardiac arrest, and in particular sudden death, has been extensively studied, and numerous refinements have occurred. (CARDIAC ARREST—The Science and Practice of Resuscitation Medicine). Despite this significant effort, a large majority of patients suffering sudden death will not be successfully resuscitated to discharge from the hospital capable of independent function. This is even true for patients whose cardiac arrest occurs within the hospital and who receive immediate therapy. The inability of medical science to improve the efficacy of resuscitative treatment is one of the great enigmas in modern medicine. (Paradis 97-99)
From its inception, mechanical CPR has been bifurcated into devices that provide anteroposterior compression of the sternum, (Barkalow 509) and devices that utilize circumferential constriction for all or a portion of the chest. (Ong et al. 2629-37) Prior to this disclosure, it has not been appreciated that a more effective method might incorporate a combination of anteroposterior compression of the sternum and circumferential constriction of the remainder of the chest. Such a method would engage both the cardiac pump and thoracic pump hemodynamic mechanisms. The failure to combine these differing approaches may underlie the inability to improve the efficacy of cardiopulmonary resuscitation.
Devices for providing anteroposterior compression CPR are well known. (McDonald 292-95) (Barkalow 509) Generally, these are piston based devices, with the piston held in position anterior to the patient by a structural arm or arch that acts like a gantry.
Devices for providing circumferential and partial circumferential constriction CPR are well known. (Halperin et al. 762-68) Generally, these incorporate either a band around the front and sides of the patient, or a pneumatic bladder with a constricting outer circumference. In either case, force is applied to the thorax in a circumferential or semi-circumferential manner.
Devices for providing forceful anteroposterior decompression are well known. (Cohen et al. 2916-23)
Devices to enhance negative intrathoracic pressure and venous return are well known. (Plaisance, Lurie, and Payen 989-94).
There do exist devices (US20070010765 A1) that are circumferential or semi-circumferential and that incorporate a bladder anterior to the patient such that a portion of the circumferential force may create some anteroposterior compression. However, this effect is passive and is likely not associated with greater force in the anteroposterior compression vector than in any other of the radial circumferential constriction vectors.
Previous to this disclosure, it has not been appreciated that a device combining anteroposterior compression and circumferential constriction may provide enhanced hemodynamics and clinical efficacy. Such an approach is absent from the medical and intellectual property literature. Additionally absent are any of the specific relationships between the circumferential constriction and anteroposterior compression mechanism's that may optimize efficacy.
The present invention is a method for improving CPR hemodynamics and clinical outcome of patients suffering cardiac arrest and other low-flow states by combination of circumferential constriction and anteroposterior compression of the chest. The efficacy of the method may be further enhanced by providing active decompression of the chest and full or partial obstruction of the airway during portions of decompression.
The component providing anteroposterior compression of the precordium is a powered piston mechanism attached to a gantry above the patient.
Circumferential constriction of the chest may be achieved in any number of ways including, but not limited to, inflation of a pneumatic device, inflation of a series of pneumatic chambers, shortening of a band device, or a combination of pneumatic chambers and inflexible bands.
The circumferential constriction and anteroposterior compression of the chest may be simultaneous or in a fixed phasic relationship that is not simultaneous. Such a system allows optimization of hemodynamics by variance of the timing and force of each component within each on-off CPR cycle.
The component performing anteroposterior compression of the chest may be attached to the component providing circumferential constriction. As such, they may share force. Alternatively, force may be applied preferentially to one of the two components. In a particular embodiment, the force and movement applied to sternal structures by the anteroposterior compression mechanism may be greater than the force applied elsewhere to the chest by the circumferential constriction mechanism.
In certain embodiments, a mechanism attaches the anteroposterior compression mechanism to the patient's anterior chest for provision of forceful anteroposterior decompression. Such mechanism may be a suction cup attached to the patient side of the piston, or even incorporated into the piston itself.
Generally, it is anticipated the mechanical or pneumatic force for circumferential constriction and anteroposterior compression of the chest will be provided by electrical, mechanical or pneumatic subsystems alone or in combination.
The circumferential or semi-circumferential constriction may be provided by a band alone, a band that has inflatable pneumatic chambers on all or portion of its inner circumference, a circumferential pneumatic bladder or series of bladders, or a combination of pneumatic platters and belts.
Of particular significance, the invention allows application of differential force to one portion of the chest compared to another. This would result in differing portions to be compressed or constricted further toward the center of the patient's chest. In a particular embodiment, 1) the circumferential constriction mechanism and the anteroposterior compression mechanism may both initiate simultaneously, 2) the circumferential constriction mechanism would complete its constriction before the anteroposterior compression mechanism, 3) and the anteroposterior compression would continue longer with greater force so as to move the sternal structures closer to the center of the patient's chest than other portions of the chest.
The present disclosure is for a system, method, or device intended generally to improve hemodynamics and clinical outcome of patients suffering cardiac arrest, or other low-flow states, by providing CPR that is a combination of circumferential constriction and anteroposterior compression.
It is anticipated that the system would be comprised of multiple components.
A practitioner of ordinary skill in the art, once taught the invention, would appreciate that a preferred, but not limiting, implementation of the method might include:
There are components of the invention that, while sufficient, are interchangeable within the context of the invention. A practitioner skilled in the art would know which specific embodiments of these components to utilize in optimizing performance of the invention.
For purposes of illustration and not limitation, a practitioner of ordinary skill in the art would, once taught the invention, be able to construct a particular preferred embodiment composed additionally of:
A hinged backboard 8 capable of changing the geometric relationship or relationships between the head, patient's chest 9, abdomen and extremities.
A section of circumferential pneumatic constrictor may be applied to a portion of the backboard next to the posterior aspect of the patient's chest 10.
The gantry may be adjustable as to shape, so as to maximize the application and effectiveness of the pneumatic constrictor function with respect to the patient's chest. The gantry may be adjustable as to location over the patient such that the location and vector of the anteroposterior compression mechanism.
Adjustable vertical lateral struts on either side of the patient's chest, each with a section of circumferential pneumatic constrictor between the strut and the patient's lateral chest. This may be adjustable as to shape and location, so as to maximize the application and effectiveness of the pneumatic constrictor function chamber to the patient's chest.
A band device 12 capable of wrapping around the patient's anterior and lateral chest and contributing to both anteroposterior compression and circumferential constriction. A section of circumferential pneumatic constrictor system might be applied to a portion of the band so as to further enhance efficacy. This may be adjustable as to shape, so as to maximize the application and effectiveness of the pneumatic constrictor function chamber to the patient's chest. The band itself 12 may be attached to a motor 13 or mechanical device, such that it's length may be forcibly shortened to create chest constriction.
A piston component 3 capable of anteroposterior compression of the chest. This would be attached a motor 2, mechanical or pneumatic device at a point sagittal and centrifugal to the patient, most likely above the mid-anterior chest. The attachment to the gantry 5 and the gantry itself may be adjustable so as to allow change in the vector force of the piston. The patient side of the piston would be capable of attachment to the patient's chest such that the piston could apply upward decompressive force, so called active decompression. This could be accomplished by a suction cup or adhesive component 3, 4.
A mechanical system capable of sending force to the constricting band 12, 13 and piston 1, 3.
A pneumatic system capable of sending inflation-deflation to the chambers of the pneumatic circumferential constricting system 7.
A feedback control component capable of utilizing indicators of tissue perfusion and varying the parameters of the compression and constricting systems so as to improve tissue perfusion and the probability of successful resuscitation.
A control component capable of varying the force or timing of chest compression or constriction so as to increase the likelihood that electrical defibrillation will result in return of spontaneous circulation.
A component capable of providing electrical defibrillation without stopping chest compression or constriction, and at a specific time in the chest compression or constriction cycle.
A particular refinement to improve the efficacy of the system would be enclosure of the pneumatic bladder or bladders within a three sided gantry. The bladder or bladders would incorporate an accordion like mechanism such that the volume has significant capacity to expand. The sidewalls of the gantry would be adjusted to minimize the open space between the gantry and the patient's chest. A practitioner with ordinary skill wound know that the volume and stiffness of the pneumatic bladder, characteristics of the accordion sides and the degree of friction between the sides of the bladder and the adjustable sides of the gantry 5 would determine the force and speed of the circumferential constriction mechanism.
An additional particular refinement would be integration of the anteroposterior compression-decompression piston 3 and the gantry portions 7 of the circumferential constriction mechanism. This integration may be within the gantry structure.
The construction of the attachment capability of active decompression mechanism may be by means of a flexible diaphragm 4 within a hardened hemisphere or bell-like structure 3. This would allow it to be a component of, and functionally contribute to, both the active decompression and the circumferential constriction mechanisms. Application of negative pressure above the diaphragm would engage the attachment-adhesive capability for active decompression. Application of positive pressure above the diaphragm would engage additional compression to the mid-anterior chest, contributing to anteroposterior compression.
Further, a practitioner of ordinary skill in the art would, once taught the invention, further understand that:
Usefulness of the Disclosed Invention
Once it is understood and appreciated that the invention disclosed herein is for a method to improve CPR hemodynamics and the clinical outcome of patients suffering cardiac arrest, the usefulness will be manifest to anyone with ordinary skill in the art.
Non-Obviousness
The non-obviousness of the invention herein disclose is clear from the complete absence of its appreciation or discussion in the medical literature. Additionally, a number of large commercial enterprises produce devices for mechanical CPR; despite extensive research and development enterprises, none of these companies have disclosed or developed methods or systems such as disclosed herein.
Modifications
It will be understood that many changes in the details, materials, steps and arrangements of elements, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art without departing from the scope of the present invention. Since many modifications, variations and changes in detail can be made to the described embodiments of the invention, it is intended that all matters in the foregoing description and shown in the accompanying drawings be interpreted as illustrative and not in a limiting sense. Thus, the scope of the invention should be determined by the appended claims and their legal equivalents.
Now that the invention has been described,
| Number | Date | Country | |
|---|---|---|---|
| 62174839 | Jun 2015 | US |
