CPR chest compression machine

Embodiments of a Cardio-Pulmonary Resuscitation (“CPR”) device are disclosed. A CPR device can include a compression mechanism configured to perform successive CPR compressions on a chest of a patient, the compression mechanism including a support portion configured to be placed underneath a patient, a piston, and a contact surface configured to make contact with the chest at a first orientation with respect to the support portion; and a controller communicatively coupled with the compression mechanism. The controller can be configured to receive at least one input and determine whether the first orientation of the contact surface should be adjusted based on the at least one input. The controller can further, responsive to a determination that the first orientation of the contact surface should be adjusted, cause the contact surface to move so that the contact surface makes contact with the chest at a second orientation with respect to the support portion.

BACKGROUND

In certain types of medical emergencies a patient's heart stops working. This stops the blood flow, without which the patient may die. Cardio Pulmonary Resuscitation (CPR) can forestall the risk of death. CPR includes performing repeated chest compressions to the chest of the patient so as to cause their blood to circulate some. CPR also includes delivering rescue breaths to the patient. CPR is intended to merely maintain the patient until a more definite therapy is made available, such as defibrillation. Defibrillation is an electrical shock deliberately delivered to a person in the hope of correcting their heart rhythm.

Guidelines by medical experts such as the American Heart Association provide parameters for CPR to cause the blood to circulate effectively. The parameters are for aspects such as the frequency of the compressions, the depth that they should reach, and the full release that is to follow each of them. The depth is sometimes required to exceed 5 cm (2 in.). The parameters also include instructions for the rescue breaths.

Traditionally, CPR has been performed manually. A number of people have been trained in CPR, including some who are not in the medical professions just in case. However, manual CPR might be ineffective, and being ineffective it may lead to irreversible damage to the patient's vital organs, such as the brain and the heart. The rescuer at the moment might not be able to recall their training, especially under the stress of the moment. And even the best trained rescuer can become quickly fatigued from performing chest compressions, at which point their performance might be degraded. Indeed, chest compressions that are not frequent enough, not deep enough, or not followed by a full decompression may fail to maintain blood circulation.

The risk of ineffective chest compressions has been addressed with CPR chest compression machines. Such machines have been known by a number of names, for example CPR chest compression machines (CCCM), mechanical CPR devices, cardiac compressors and so on.

CPR chest compression machines repeatedly compress and release the chest of the patient. Such machines can be programmed so that they will automatically compress and release at the recommended rate or frequency, and can reach a specific depth within the recommended range. Some of these machines can even exert force upwards during decompressions. Sometimes the feature can even pull the chest higher than it would be while at rest—a feature that is called active decompression.

The repeated chest compressions of CPR are actually compressions alternating with releases. They cause the blood to circulate some, which can prevent damage to organs like the brain. For making this blood circulation effective, guidelines by medical experts such as the American Heart Association dictate suggested parameters for chest compressions, such as the frequency, the depth reached, fully releasing after a compression, and so on. The releases are also called decompressions.

At present, most CPR chest compression machines repeat the same type of compressions over and over, pressing each time at the same location of the patient chest. This precise consistency is non-physiologic and may miss an opportunity to better move blood through each part of the patient's circulatory systems.

There remain challenges. Sometimes, due to the repeated and forceful compressions, the body's position may shift within the CPR chest compression machine, in which case the compressions may become less effective. The body's shifting, seen from the perspective of the body, can be characterized as the CPR machine shifting, or a piston migrating or walking, etc.

Mechanical CPR machines today either press with a piston-based solution or a belt-driven solution on the chest during a cardiac arrest to revitalize the patient with the help of a suction cup, hard plate, or belt. Many of these solutions work fine if the device is placed correctly in the middle of the chest of the patient and the patient has the heart placed somewhat to the left of the chest. But, if placed poorly, the devices do not press the heart as they should to get the right compressions during the cardiac arrest.

Mechanical chest compression devices can be challenging to put on the patient, and getting the piston or plunger having a contact surface to be positioned at the intended point on the chest is not easy. Once the device is applied, if the initial positioning was not correct, readjusting its position while the weight of a large patient presses down on the back plate is not easy. Furthermore, the chest compression device can creep in one direction or another during operation, moving it to a suboptimal position and thus requiring adjustment. Also, it is likely that the optimal position for a chest compression device is different from one patient to another.

Additionally, each patient has a sternum with a different tilt angle, or sternal angle, between the lower part of the sternum (towards the feet) and the upper part of the sternum (towards the head). The fact that the sternum is at an angle means that the sternum will swing when performing chest compressions, manually or with a CCCM. Furthermore, the sternum will move different distances depending on the location along the sternum that contact for a compression is made. If the pressure for the compression is strictly perpendicular, even if a CCCM is set to perform compressions at a depth of 5 cm, the inner movement (deflection of the sternum) will be different in different patients depending on the length and angle of the sternum, the size of the pressure point and the pressure point's location from the sternum's fulcrum during a compression. Additionally, the sternal angle can change during a CPR session. There is therefore a risk of performing too deep of compressions or too shallow of compressions.

BRIEF SUMMARY

An exemplary embodiment of a Cardio-Pulmonary Resuscitation (“CPR”) device can include a compression mechanism configured to perform successive CPR compressions on a chest of a patient, the compression mechanism including a support portion configured to be placed underneath a patient, a piston, and a contact surface configured to make contact with the chest at a first orientation with respect to the support portion; and a controller communicatively coupled with the compression mechanism. The controller can be configured to receive at least one input and determine whether the first orientation of the contact surface should be adjusted based on the at least one input. The controller can further, responsive to a determination that the first orientation of the contact surface should be adjusted, cause the contact surface to move so that the contact surface makes contact with the chest at a second orientation with respect to the support portion.

In some embodiments, the at least one input includes a physiological parameter sensor signal from a physiological parameter sensor for sensing a physiological parameter of a patient. In some embodiments, the at least one input includes an input provide by a user. Additionally and/or alternatively, the compression mechanism can include a pressure sensor configured to generate a pressure sensor signal, the pressure sensor signal representative of contact with a patient's chest at the first orientation, and further wherein the at least one input includes the pressure sensor signal.

In some embodiments, the CPR device includes a contact member pivotally attached to the piston, wherein the contact surface is disposed on the contact member. The CPR device can further include an angle sensor, wherein the piston includes a piston center axis and the angle sensor is configured to sense the orientation of the contact surface with respect to the piston center axis.

In some embodiments, the CPR device includes at least one leg pivotally attached to the support portion, wherein the at least one leg has a first position and a second position, further wherein at the first position the contact surface is configured to make contact with a patient's chest at the first orientation and at the second position the contact surface is configured to make contact with a patient's chest at the second orientation. The CPR device can further include an angle sensor configured to sense the orientation of the at least one leg with respect to the support surface.

Some embodiments of a CPR device can include a piston having a piston center axis, a driver coupled to the piston configured to extend and retract the piston, and a contact member pivotally attached to the piston, the contact member having a contact surface configured to make contact with a patient's chest at a first orientation with respect to the piston center axis and at a second orientation with respect to the piston center axis. In some embodiments, the contact member includes a suction cup. Additionally and/or alternatively, some embodiments include an angle sensor is configured to sense the orientation of the contact surface with respect to the piston center axis. Additionally and/or alternatively, some embodiments include a controller configured to receive at least one input, determine whether the orientation of the contact surface with respect to the piston center axis should be adjusted based on the at least one input, responsive to a determination that the contact surface should be adjusted, cause the contact surface to move from the first orientation to the second orientation. Additionally and/or alternatively, the contact member can include a pressure sensor configured to generate a pressure sensor signal, the pressure sensor signal representative of contact with a patient's chest at the first orientation.

Some embodiments of a CPR device can include a support portion configured to be placed underneath a patient, a compression mechanism configured to perform successive CPR compressions on a chest of a patient, the compression mechanism including a piston and a contact surface, and at least one leg pivotally attached to the support portion, wherein the at least one leg has a first position and a second position, further wherein at the first position the contact surface is configured to make contact with a patient's chest at a first orientation with respect to the support portion and at the second position the contact surface is configured to make contact with a patient's chest at a second orientation with respect to the support portion. Additionally and/or alternatively, some embodiments include an angle sensor configured to sense an angle of the at least one leg with respect to the support portion. Additionally and/or alternatively, some embodiments include a controller configured to receive at least one input, determine whether the orientation of the contact surface with respect to the support portion should be adjusted based on the at least one input, responsive to a determination that the contact surface should be adjusted, cause the at least one leg to move from the first position to the second position. Additionally and/or alternatively, some embodiments include a pressure sensor configured to generate a pressure sensor signal, the pressure sensor signal representative of contact with a patient's chest at the first orientation.

These and other features and advantages of this description will become more readily apparent from the following Detailed Description, which proceeds with reference to the drawings.

DETAILED DESCRIPTION

The present disclosure relates to CPR chest compression machines, methods and software that can perform automatically a series of Cardio-Pulmonary Resuscitation (“CPR”) chest compressions on a patient and can accommodate different patient sternal angles. Embodiments are now described in more detail.

FIG. 1illustrates an example schematic block diagram of a mechanical CPR device100. As will be understood by one skilled in the art, the mechanical CPR device100may include additional components not shown inFIG. 1. The mechanical CPR device100includes a controller102, which may be in electrical communication with a chest compression mechanism or device104. The chest compression mechanism104may be any component that compresses a chest of a patient, such as a piston based chest compression device or a belt driven device that wraps around a chest of a patient.

The embodiment shown inFIG. 1includes a piston106and a contact member154. Contact member154can include a suction cup, a compression pad, or other device configured to make contact with a patient's chest. The chest compression mechanism104can further include a contact surface116configured to make contact with a patient's chest. The contact surface116can be disposed on the piston106or the contact member154. The chest compression mechanism104further can include retention structure108including one or more legs110and/or a support portion112configured to be placed underneath a patient114.

The chest compression mechanism104may include a driver118configured to drive the compression mechanism104to cause the compression mechanism104to perform compressions to a chest of patient114. The controller102, as will be discussed in more detail below, provides instructions to the chest compression mechanism104to operate the chest compression mechanism104at a number of different rates, depths, duty cycles. Controller102further provides instructions to the chest compression mechanism104to alter the orientation of the contact surface116and move one or more legs110into a new position.

The controller102may include a processor120, which may be implemented as any processing circuity, such as, but not limited to, a microprocessor, an application specific integration circuit (ASIC), programmable logic circuits, etc. The controller may further include a memory122coupled with the processor120. Memory can include a non-transitory storage medium that includes programs124configured to be read by the processor120and be executed upon reading. The processor120is configured to execute instructions from memory122and may perform any methods and/or associated operations indicated by such instructions. Memory122may be implemented as processor cache, random access memory (RAM), read only memory (ROM), solid state memory, hard disk drive(s), and/or any other memory type. Memory122acts as a medium for storing data126, such as event data, patient data, etc., computer program products, and other instructions.

Controller102may further include a communication module128. Communication module128may transmit data to a post-processing module130. Alternately, data may also be transferred via removable storage such as a flash drive. While in module130, data can be used in post-event analysis. Such analysis may reveal how the CPR machine was used, whether it was used properly, and to find ways to improve future sessions, etc.

Communication module128may further communicate with other medical device132. Other medical device132can be a defibrillator, a monitor, a monitor-defibrillator, a ventilator, a capnography device, or any other medical device. Communication between communication module128and other medical device132could be direct, or relayed through a tablet or a monitor-defibrillator. Therapy from other device132, such as ventilation or defibrillation shocks, can be coordinated and/or synchronized with the operation of the CPR machine. For example, compression mechanism104may pause the compressions for delivery of a defibrillation shock, afterwards detection of ECG, and the decision of whether its operation needs to be restarted. For instance, if the defibrillation shock has been successful, then operation of the CPR machine might not need to be restarted.

The controller102may be located separately from the chest compression mechanism104and may communicate with the chest compression mechanism104through a wired or wireless connection134. The controller102also electrically communicates with a user interface136. As will be understood by one skilled in the art, the controller102may also be in electronic communication with a variety of other devices, such as, but not limited to, another communication device, another medical device, etc.

The chest compression mechanism104may include one or more sensors configured to transmit information to controller102. For example, chest compression mechanism104can include a physiological parameter sensor138for sensing a physiological parameter of a patient and to output a physiological parameter sensor signal140that is indicative of a dynamic value of the parameter. The physiological parameter can be an Arterial Systolic Blood Pressure (ABSP), a blood oxygen saturation (SpO2), a ventilation measured as End-Tidal CO2 (ETCO2), a temperature, a detected pulse, etc. In addition, this parameter can be what is detected by defibrillator electrodes that may be attached to patient, such as ECG and impedance.

In some embodiments, controller102can receive the physiological parameter sensor signal140from the physiological parameter sensor138and determine whether a first orientation of the contact surface116should be adjusted based on the physiological parameter sensor signal140. Controller102can, responsive to a determination that the first orientation of contact surface116should be adjusted, cause contact surface116to move so that contact surface116makes contact with the chest at a second orientation. Additionally and/or alternatively, controller102can, responsive to a determination that the first orientation of contact surface116should be adjusted, cause one or more legs110to move from a first position to a second position so that contact surface116makes contact with the chest at a second orientation.

Additionally and/or alternatively, the chest compression mechanism can include a pressure sensor150configured to sense area(s) of pressure of the contact surface with the patient's chest and to output a pressure signal152, which is indicative of a dynamic value of pressure against the patient's chest. In some embodiments, controller102can receive the pressure signal152from the pressure sensor150and determine whether a first orientation of the contact surface116should be adjusted based on the pressure signal152. Controller102can, responsive to a determination that the first orientation of contact surface116should be adjusted, cause contact surface116to move so that contact surface116makes contact with the chest at a second orientation. Additionally and/or alternatively, controller102can, responsive to a determination that the first orientation of contact surface116should be adjusted, cause one or more legs110to move from a first position to a second position so that contact surface116makes contact with the chest at a second orientation.

Additionally and/or alternatively, the chest compression mechanism can include an angle sensor142configured to sense the orientation of the contact surface and to output an angle signal144, which is indicative of a dynamic value of the orientation of the contact surface. Additionally and/or alternatively, the chest compression mechanism can include an angle sensor146configured to sense an angle of the at least one leg110with respect to the support portion112and to output an angle signal148, which is indicative of a dynamic value of the angle of the at least one leg110.

Operations of the mechanical CPR device100may be effectuated through the user interface136. The user interface136may be external to or integrated with a display. For example, in some embodiments, the user interface136may include physical buttons located on the mechanical CPR device100, while in other embodiments, the user interface136may be a touch-sensitive feature of a display. The user interface136may be located on the mechanical CPR device100, or may be located on a remote device, such as a smartphone, tablet, PDA, and the like, and is also in electronic communication with the controller102. In some embodiments, controller102can receive an input from the user interface136and determine whether a first orientation of the contact surface116should be adjusted based on the input. Controller102can, responsive to a determination that the first orientation of contact surface116should be adjusted, cause contact surface116to move so that contact surface116makes contact with the chest at a second orientation. Additionally and/or alternatively, controller102can, responsive to a determination that the first orientation of contact surface116should be adjusted, cause one or more legs110to move from a first position to a second position so that contact surface116makes contact with the chest at a second orientation.

Additionally and/or alternatively, in some embodiments controller102can receive input from the other medical device132and determine whether a first orientation of the contact surface116should be adjusted based on the input. Controller102can, responsive to a determination that the first orientation of contact surface116should be adjusted, cause contact surface116to move so that contact surface116makes contact with the chest at a second orientation. Additionally and/or alternatively, controller102can, responsive to a determination that the first orientation of contact surface116should be adjusted, cause one or more legs110to move from a first position to a second position so that contact surface116makes contact with the chest at a second orientation. In some embodiments, the other medical device can be a device used to measure or calculate a patient's sternal angle.

During a CPR session of compressions, controller102can move the contact surface116and/or the one or more legs110periodically, according to a schedule, responsive to an input by an operator to a user interface, and/or responsive to a signal from one or more of sensors as described above. Movement of the contact surface116and/or the one or more legs110can be at any point during a CPR session and can occur a number of times turning a CPR session. For example, the orientation of the contact surface116can be changed at the beginning of the CPR session and again before the end of the CPR session, if, for example, the patient's sternal angle has changed during the CPR session.

FIG. 2shows a CPR system200including a retention structure202. The retention structure202includes a central member204, a first leg206, a second leg208, and a support portion210configured to be placed underneath a patient. Central member204is coupled with first leg206and with second leg208via joints212and214, respectively. In addition, the far ends of legs206,208can become coupled with edges216,218of support portion210. These couplings form the retention structure202that retains a patient. In this particular case, central member204, first leg206, second leg208and support portion210form a closed loop, in which the patient is retained.

Central member204includes a battery that stores energy, a motor that receives the energy from the battery, and a compression mechanism that can be driven by the motor. The compression mechanism is driven up and down by the motor using a rack and pinion gear. The compression mechanism includes a piston220that emerges from central member204, and can compress and release the patient's chest. Piston220is sometimes called a plunger. Here, piston220terminates in a contact member222having a contact surface224. The contact member222can include a suction cup226. In this case the battery, the motor and the rack and pinion gear are not shown, because they are completely within a housing of central member204.

As described in further detail below, in some embodiments one or more of first leg206and second leg208can be pivotally attached to the support portion210. For example, both first leg206and second leg208can be pivotally attached to the support portion210such that when first leg206and second leg208are hingedly moved or tilted with respect to the support portion210, the central member204, piston220and contact surface224are also moved or tilted with respect to the support portion210.

Turning now toFIGS. 3A-3B, as discussed above CPR patients have different sternal angles, leading to potential for a CPR device, despite having a depth of compressions in accordance with guidelines, to provide too deep of compressions that could exert internal organ damage or too shallow of compressions that would impair organ perfusion.FIG. 3Ashows a side view of select components of a CPR system including a compression mechanism300having a piston302with a piston central axis304, a contact member306having a contact surface308, a support portion310configured to be placed underneath a patient312, and a central member314. The contact surface308is at a first orientation with respect to the support portion310and/or piston central axis304inFIG. 3A. As shown, the contact surface308is not substantially flush with the patient's chest and the compressive force of the compression mechanism is perpendicular to the support portion310, not the patient's chest, because the sternal angle is not parallel to the contact surface308. Therefore, if the pressure for a compression during a CPR session is strictly perpendicular, even if a CCCM is set to perform each compression at a fixed depth, the inner movement (deflection of the sternum) will be different in different patients depending on the length and angle of the sternum, the size of the pressure point and the pressure point's location from the sternum's fulcrum during a compression.

FIG. 3Bshows the side view ofFIG. 3A, wherein the contact surface308is at a second orientation with respect to the support portion310and/or piston central axis304. As shown, in the second orientation, the contact surface308is not parallel with the support surface310. In the second orientation, the contact surface308is substantially flush with the patient's chest and the compressive force is substantially perpendicular to the patient's chest. In the second orientation, the desired compression depth will be more accurate for the patient.

FIG. 4Ashows a partial view of a compression mechanism400including a piston402having a piston center axis404and a contact member406having a contact surface408in a first orientation with respect to the piston center axis404.FIG. 4Bshows the contact surface408in a second orientation with respect to the piston center axis404. The contact member406can include a suction cup408. The contact member406is pivotally attached to the piston402via a pivot attachment410. Examples of the pivot attachment410include but are not limited to a hinge joint and a ball joint. The compression mechanism400can further include an angle sensor412configured to sense the orientation of the contact surface408with respect to the piston center axis404. Additionally and/or alternatively, the compression mechanism400can include one or more pressure sensors414configured to generate pressure sensor signals, the pressure sensor signals representative of contact with a patient's chest.

Turning now toFIGS. 5A-5B,FIG. 5Ashows a side view of select components of a CPR system including a compression mechanism500having a piston502, a contact member504having a contact surface506, a central member508, a support portion510configured to be placed underneath a patient512and at least one leg514pivotally attached to the support portion510. The at least one leg514is in a first position and the contact surface506is at a first orientation with respect to the support portion510. As shown, the contact surface506is not substantially flush with the patient's chest and the compressive force of the compression mechanism is perpendicular to the support portion510, not the patient's chest, because the sternal angle is not parallel to the contact surface506.

FIG. 5Bshows the side view ofFIG. 5A, wherein the at least one leg514is in a second position. Movement of the at least one leg514has caused corresponding movement of the central member508, piston502and contact surface506such that the contact surface506is at a second orientation with respect to the support portion510. As shown, in the second orientation, the contact surface506is substantially parallel with the patient's chest. In the second orientation, the contact surface506is substantially flush with the patient's chest and the compressive force is substantially perpendicular to the patient's chest.

FIG. 6Ashows a partial view of a compression mechanism600including a support portion602configured to be placed underneath a patient and at least one leg604pivotally attached to the support portion602, for example via one of a hinge joint608and a ball joint. The at least one leg604is in a first position inFIG. 6A. InFIG. 6B, the at least one leg604is in a second position. The compression mechanism600can further include an angle sensor606configured to sense an angle of the at least one leg604with respect to the support portion602.

FIGS. 7A-7Cshow partial views of a compression mechanism700including a piston702and a contact member704having a contact surface706. The contact surface may include one or more pressure sensors708that can span the entirety of the contact surface.FIGS. 7A-7Cfurther show the areas of contact between the contact surface and a patient's chest depending on the sternal angle of the patient's chest (see exemplary area of contact710inFIG. 7C). The one or more pressure sensors can be configured to generate a pressure sensor signal, the pressure sensor signal representative of contact with a patient's chest. The pressure sensor signal can be sent to the controller (not shown) for determination of whether the orientation of the contact surface with respect to the support portion or the piston center axis should be adjusted based on the pressure sensor signal.

The devices and/or systems made according to embodiments perform functions, processes and/or methods, as described in this document. These functions, processes and/or methods may be implemented by one or more devices that include logic circuitry, such as was described for controller102.

Moreover, methods and algorithms are described below. This detailed description also includes flowcharts, display images, algorithms, and symbolic representations of program operations within at least one computer readable medium. An economy is achieved in that a single set of flowcharts is used to describe both programs, and also methods. So, while flowcharts describe methods in terms of boxes, they also concurrently describe programs. A method is now described.

FIG. 8shows a flowchart800for describing methods according to embodiments. The methods of flowchart800may also be practiced by embodiments described elsewhere in this document for performing automatically a series of successive compressions to a chest of a patient.

A compression mechanism of a CPR device is used to perform successive CPR compressions on a chest of a patient. The compression mechanism may include a piston and a contact surface configured to make contact with the chest at a first orientation. At step802, the CPR device receives an instruction to move the contact surface to a second orientation. The instruction may be based at least in part on at least one physiological parameter determined by the CPR device, a pressure sensor signal, an input from an other medical device, an input provided by a user, or a combination thereof.

At step804, the CPR device, responsive to receiving the instruction, may cause the contact surface to be moved from the first orientation to the second orientation. For example, the contact surface may be disposed on a contact member pivotally connected to the piston. The CPR device may cause the contact member to pivot with respect to piston. Additionally and/or alternatively, the CPR device can include a support portion and at least one leg pivotally connected to the support portion having a first position in which the contact surface is in the first orientation, and a second position in which the contact surface is in the second orientation. The CPR device may cause the at least one leg to move from the first positon to the second position.

At step806, the CPR device may receive instruction to perform CPR compressions on the patient. In some embodiments, the method may return to step802for further refinement of the orientation of the contact surface during a CPR session, for example if a patient's sternal angle changes during a CPR session.

The previously described versions of the disclosed subject matter have many advantages that were either described or would be apparent to a person of ordinary skill. Even so, these advantages or features are not required in all versions of the disclosed apparatus, systems, or methods.

Additionally, this written description makes reference to particular features. It is to be understood that the disclosure in this specification includes all possible combinations of those particular features. Where a particular feature is disclosed in the context of a particular aspect or example, that feature can also be used, to the extent possible, in the context of other aspects and examples.

Although specific examples of the invention have been illustrated and described for purposes of illustration, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, the invention should not be limited except as by the appended claims.