GUIDED ACTIVE COMPRESSION DECOMPRESSION

CARDIOPULMONARY RESUSCITATION SYSTEMS AND METHODS

CROSS-REFERENCES TO RELATED APPLICATIONS This application is a PCT application of U.S. Patent Application No. 13/026,459 filed February 14, 2011, and is related to and claims the benefit of the filing date of U.S.

Provisional Patent Application No. 61/304,148 filed February 12, 2010. This application is also related to U.S. Patent Nos. 5,454,779 and 5,645,522, the contents of which are incorporated herein by reference for all purposes.

BACKGROUND OF THE INVENTION

Embodiments of the present invention relate generally to systems and methods for active compression decompression (ACD) cardiopulmonary resuscitation (CPR), and in particular to guided approaches which assist an operator in administering appropriate technique in an effective manner.

Sudden cardiac arrest is a major cause of death worldwide and can arise from a variety of circumstances, including heart disease and trauma such as electrical shock and suffocation. To improve a patient's chance of survival (and diminish the likelihood of brain and heart damage resulting from oxygen deprivation), it is important that measures be taken as soon as possible to at least partially restore the patient's respiration and blood circulation. Many years ago, techniques for external chest compression, generally referred to as

cardiopulmonary resuscitation (CPR), were developed and have enjoyed great success in reducing mortality resulting from sudden cardiac arrest. Certain aspects of such techniques, however, have remained largely unchanged over recent years.

External chest compression relies on actively applying pressure to the patient's chest in order to increase intrathoracic pressure. Such pressure increase will induce blood movement from the region of the heart and lungs through the peripheral arteries, thus partially restoring the patient's circulation. Phase 1 of traditional CPR is referred to as the "active compression phase" where the chest is compressed by the direct application of external pressure. Phase 2, referred to as the "relaxation phase," occurs when pressure is withdrawn and the natural elasticity of the patient's chest wall causes expansion. While such expansion is generally sufficient to refill the cardiac chambers with some blood, it is insufficient to ventilate the patient, i.e., fill the lungs with sufficient air to oxygenate the blood. Thus, conventional CPR further requires periodic ventilation of the patient, e.g., mouth-to-mouth ventilation, in order to provide the air necessary for blood oxygenation. Manual CPR procedures generally require performers to lean over the patient and to apply pressure using the palms of their hands to the patient's sternum as the patient lies supine on a flat surface. If no one else is available, the performer must periodically shift position to ventilate the patient through a mouth-to-mouth procedure. Such manual procedures are thus very tiring to the performer and furthermore have been found to result in only marginal circulation.

Manual CPR procedures can also result in injury to the patient. For example, pressure applied by the palm of the hand can fracture the patient's sternum and/or ribs and cause other traumatic injury, especially if the performer's hand position is inadvertently shifted laterally to an improper location on the patient's chest. The performance and safety of CPR procedures can be enhanced through the use of various mechanical and automatic machines for applying external chest compression and optionally ventilating the patient by providing supplemental oxygen or air. The machines may be as simple as a "cardiac press" which is a manually operated lever which provides a mechanical advantage in performing chest compression. More sophisticated machines can provide chest compression and/or ventilation through a variety of other mechanisms, including the use of pressurized chambers for compressing the chest cavity. While such machines can be effective, their bulk, weight, and cost limit their availability. In particular, such machines are not widely available outside of medical facilities and their size is a deterrent to providing such equipment in emergency vehicles. CPR is often administered in conjunction with other procedures which, taken together, are referred to as advanced cardiac life support (ACLS). Most commonly, CPR is administered while the patient undergoes both electrocardiographic monitoring (ECM) and electrical defibrillation. Although currently available CPR devices can provide real benefits to patients in need thereof, in some cases operator error or misuse may lead to ineffective treatment or patient injury. Hence, further advances would be desirable. For example, it would be desirable to provide improved systems and methods for guiding a system operator who may be involved with administering a treatment to a patient. Moreover, it would be desirable to provide systems and methods that help to ensure treatment is administered within desired or appropriate parameters. Embodiments of the present invention provide solutions that address the problems described above, and hence provide answers to at least some of these outstanding needs.

BRIEF SUMMARY OF THE INVENTION

Embodiments of the present invention provide improved systems and methods for performing external chest compression, optionally in conjunction with CPR procedures. Such methods and systems provided enhanced ventilation and blood circulation in the patient undergoing treatment, preferably reducing or eliminating the need to separately ventilate the patient. Desirably, the methods and systems can be simple and easily stored so that they can be maintained in emergency vehicles, non-medical facilities, and even the home. The systems can be suitable for performing enhanced manual CPR, in particular by converting Phase 2 chest expansion from a passive event to an active process to improve venous blood return from the heart and enhance airflow into the lungs (facilitated ventilation). Systems can provide guidance to operators or technicians, such as digital outputs showing the amount of force to be applied to a patient during a chest compression or decompression. Further, systems may include handle configurations which ensure appropriate forces are applied to the patient. Chest compression or decompression systems according to embodiments of the present invention also provide a device contact area or adhesive pad that is 2 to 4 times larger than the compressive area. Such configurations can allow an operator to physically lift or decompress a large surface area of the patient's chest. Relatedly, such large surface contact areas can make it easier for an operator or user to generate a full or greater decompression, thus resulting in more blood flow back to the heart. What is more, embodiments of the present invention provide compression surface areas which are sufficiently large to confer enhanced coronary perfusion pressure or increased blood flow from the heart to other organs or tissue during compression.

Systems and methods disclosed herein can be used for actively compressing and expanding an area of the human body, such as the thoracic cavity or chest, the abdomen, the back, and the like. Embodiments are useful for treating a variety of ailments wherein such compression and expansion may be beneficial; for example, heart failure, cardiac arrest, low blood pressure, poor blood circulation, shock and other maladies affecting internal organs such as the heart, stomach, intestines, liver, spleen, pancreas, and the like. In some cases, embodiments may be particularly useful for lowering or otherwise altering intrathoracic pressure (ITP) and for ventilating patients who are not breathing. An exemplary embodiment provides devices and methods for actively compressing and decompressing the thoracic cavity in the performance of cardiopulmonary resuscitation (CPR) and advanced cardiac life support (ACLS) procedures.

In one aspect, embodiments of the present invention encompass systems and methods for ACD CPR. An exemplary system for applying guided active compression decompression cardiopulmonary resuscitation to an individual in need thereof can include, for example, a handle, a load cell in operative association with the handle, and an adhesive pad. The handle and the adhesive pad can be configured for releasable coupling. In some cases, the handle and the adhesive pad are configured for releasable magnetic coupling. In some cases, a handle of an ACD CPR system can be coupled with a drive element of an automated reciprocating system. In some cases, an ACD CPR system may include or be used in conjunction with an intrathoracic pressure regulator (ITPR) system that modulates pressure within an airway of the individual.

In another aspect, embodiments of the present invention provide systems and devices for actively compressing and expanding an area of the body. A device can include a

compression element that is configured to be pressed and lifted, and a flexible surface element operably coupled with the compression element and configured to be removably attached to a body part over a contact area. In some cases, the compression element is adapted to apply a compressive force to the body part through the surface element over a compressive area when the compression element is pressed. The contact area can be sized to be at least twice as large as the compressive area. In some cases, the contact area can be sized to be in the range of two to three times as large as the compressive area. Optionally, the surface element can be a generally planar flexible contact pad the lower surface of which defines the contact area. In some instances, the lower surface of the contact pad includes an adhesive material. In some cases, the compression element includes a dome-shaped handle disposed on the top end of a centrally-located rigid connecting stem. Optionally, the bottom end of the connecting stem can be connected to the top surface of a generally planar flexible contact pad and define the compressive area. The handle can include a dome-shaped upper surface and an annular planar lower surface surrounding the top end of the connecting stem, and the upper surface and lower surface can be separated by a peripheral flange. In some cases, a device includes at least one measuring element associated with the contact pad. A measuring element can be configured to measure a physiological parameter of the patient. A device may also include a display element associated with the contact pad. In some cases, the display element is configured to provide patient feedback information. A device may also include at least one electrode associated with the surface element for applying electricity to the body part. In some cases, a device includes means associated with the surface element for applying a drug. Optionally, a device may include at least one sensor associated with the surface element. In some instances, a device may include at least one reference element associated with the surface element to aid in the proper placement of the surface element on the body part.

In another aspect, embodiments provide systems and methods for increasing and reducing intrathoracic pressure wherein a flexible contact pad is removably attached to a patient's chest over a contact area, and a handle configured to be pressed and lifted is operably connected to the contact pad so that pressing down of the handle applies a compressive force over a compressive area to compress the chest, and lifting up of the handle applies a lifting force over the contact area to expand the chest. In some cases, the contact area is sized to be at least twice as large as the compressive area. Optionally, the contact area is sized to be from 2 to 3 times as large as the compressive area. In still another aspect, embodiments of the present invention encompass systems and methods for compressing and expanding a body part that include, for example, providing a

compression element that is configured to be pressed so as to apply a compressive force over a compressive area, operably coupling the compression element with a flexible surface element having a top surface including the compressive area and a bottom surface, removably attaching the bottom surface of the surface element to a body part to define a contact area that is at least twice as large as the compressive area, pressing the compression element against the surface element to compress the body part over the compressive area, and lifting the surface element to actively expand the body part over the contact area. In some cases, the surface element is a contact pad attached to a patient's chest with adhesive. In some cases, the compression element is a handle that is pressed and lifted by hand. Optionally, the contact area is sized to be in the range of two to three times as large as the compressive area. In still another aspect, embodiments of the present invention encompass systems and methods and devices for the performance of volume exchange CPR, wherein during the compression of the chest the pressure inside the thorax rises and blood is propelled forward out of the heart and lungs to the brain and other organs outside the thorax. At the same time respiratory gases are pushed out of the lungs as the lungs are compressed. During the decompression phase the anterior chest wall is lifted upward and at the same time respiratory gases are prevented or inhibited from entering the lungs by transiently blocking or occluding the airway. By preventing or inhibiting respiratory gases from entering the lungs during the decompression phase of the thorax, more blood volume is drawn into the thorax, into the heart and lungs, in exchange for the volume of respiratory gas that was pushed out of the lungs on the prior compression and not allowed back into the lungs by occluding the airway. The means to occlude the airway could be a one-way valve or preferably a valve system that allows for the rescuer to ventilate the patient. One way to ventilate the patients would be to periodically provide a positive pressure ventilation through or around the one-way valve. Thus, volume exchange CPR allows for blood flow out of the heart or the brain during the compression phase, and allows for more blood, rather than respiratory gases, to enter the lungs during the decompression phase. In one aspect of volume exchange CPR, respiratory gases could be actively removed from the lungs with a low-level vacuum that could be continuous or intermittent, during CPR. In another aspect of volume exchange CPR respiratory gases could be actively withdrawn from the lungs and then a positive pressure breath could be delivered, with or without a period of positive end-expiratory pressure before or after the positive pressure ventilation.

In another aspect, embodiments of the present invention encompass systems and methods for applying guided active compression decompression cardiopulmonary resuscitation to an individual in need thereof. Exemplary systems may include a handle, a measuring assembly in operative association with the handle, and an adhesive pad. The handle and the adhesive pad can be configured for releasable coupling. In some cases, the measuring assembly includes a force measuring device. In some cases, the measuring assembly includes a distance measuring device. In some cases, the measuring assembly includes a force and distance measuring device. Optionally, a force and distance measuring device may include an accelerometer.

In another aspect, embodiments of the present invention encompass automated systems for applying guided active compression decompression cardiopulmonary resuscitation to an individual in need thereof. Exemplary systems may include an automated compression decompression generation assembly, a measuring assembly in operative association with the automated compression decompression generation assembly, and an adhesive pad. The automated compression decompression generation assembly and the adhesive pad can be configured for releasable coupling.

In another aspect, embodiments of the present invention encompass systems and methods for applying guided active compression decompression cardiopulmonary resuscitation to an individual in need thereof. Exemplary systems may include a handle, a measuring assembly in operative association with the handle, and an adhesive pad. The handle and the adhesive pad can be configured for releasable coupling via a mechanical interlock. In some instances, the mechanical interlock includes a ball and socket assembly. Optionally, a mechanical interlock can include a cantilevered arm assembly. In some cases, the mechanical interlock includes a detent mechanism assembly.

In some aspects, embodiments of the present invention encompass systems and methods for providing a volume exchange cardiopulmonary resuscitation treatment to a patient.

Exemplary methods may include compressing the patient's chest during a compression phase, and lifting upward the patient's anterior chest wall and occluding the patient's airway during a decompression phase. Relatedly, systems may include means for compressing the patient's chest during a compression phase, and for lifting upward the patient's anterior chest wall and occluding the patient's airway during a decompression phase. In some cases, the step of occluding the patient's airway includes occluding the airway with a one way valve. In some cases, the step of occluding the patient's airway includes occluding the airway with a valve system that allows an operator to ventilate the patient. Optionally, methods may include ventilating the patient with the valve system. In some cases, methods may include ventilating the patient by provide a positive pressure ventilation through or around the one-way valve.

Methods may also include actively removing respiratory gases from the patient's lungs with a low-level vacuum. Relatedly, systems may include means for providing a low-level vacuum. In some instances, the low-level vacuum is continuous. In some instances, the low-level vacuum is intermittent. Some methods may include actively withdrawing respiratory gases from the patient's lungs, and subsequently delivering a positive pressure breath to the patient. Related systems may include means for actively withdrawing respiratory gases from the patient's lungs, and for subsequently delivering a positive pressure breath to the patient. In some cases, the positive pressure breath is delivered with a period of positive end-expiratory pressure, either before or after the positive pressure ventilation.

In still another aspect, embodiments of the present invention include systems and methods for providing a volume exchange cardiopulmonary resuscitation treatment to a patient.

Exemplary systems may include a compression element that is configured to be pressed and lifted, a flexible surface element operably coupled with the compression element and configured to be removably attached to a body part, and an occlusion mechanism for occluding the patient's airway during a decompression phase. In some instances, the occlusion mechanism includes a one way valve. In some instances, the occlusion mechanism includes a valve system that allows an operator to ventilate the patient. In some instances, systems may include a vacuum source for actively removing respiratory gases from the patient's lungs with a continuous or intermittent low level vacuum.

In another aspect, embodiments of the present invention encompass systems and methods for actively compressing and expanding an area of the body. Exemplary devices may include a compression element that is configured to be pressed and lifted, a flexible surface element operably coupled with the compression element and configured to be removably attached to a body part, an interface for displaying information to and receiving information from an operator, a processor coupled with the interface, and a memory coupled with the processor. The memory can be configured to store a plurality of code modules for execution by the processor. The plurality of code modules can include a module for recording a compression event history, a module for storing the compression event history, a module for assessing a cardiopulmonary resuscitation quality factor, and a module for providing feedback to the operator based on the cardiopulmonary resuscitation quality factor.

In still another aspect, embodiments of the present invention encompass systems and methods for actively compressing and expanding an area of the body. Exemplary devices may include a compression element that is configured to be pressed and lifted, a flexible surface element operably coupled with the compression element and configured to be removably attached to a body part, an interface for displaying instructions to an operator, a processor coupled with the interface, and a memory coupled with the processor. The memory can be configured to store a plurality of code modules for execution by the processor. The plurality of code modules can include a module for providing operator instructions to perform a number of

compressions prior to initiating active compression and decompression. In still a further aspect, embodiments of the present invention encompass systems and methods for treating a patient. Exemplary methods may include providing a compression element that is configured to be pressed so as to apply a compressive force to the patient's chest, operably coupling the compression element with a flexible surface element having a top surface and a bottom surface, removably attaching the bottom surface of the surface element to the patient's chest, attaching a lower compression device to at least a portion of a lower extremity of the patient, repetitively pressing the compression element against the surface element to compress the patient's chest and lifting the surface element to actively expand the patient's chest, so that the patient's chest experiences a compression phase and a recoil phase, and compressing the person's lower extremity using the lower compression device during at least some of the recoil phases.

For a fuller understanding of the nature and advantages of the present invention, reference should be had to the ensuing detailed description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates aspects of an ACD CPR system according to embodiments of the present invention.

FIGS. 1A and IB illustrate aspects of ACD CPR systems according to embodiments of the present invention.

FIG. 2 shows aspects of adhesive pad placement on a patient according to embodiments of the present invention.

FIG. 3 depicts aspects of an adhesive pad according to embodiments of the present invention.

FIG. 4 provides a block diagram of an exemplary module system according to embodiments of the present invention.

FIGS. 5A to 5D depict aspects of a magnetic coupling mechanism in an external chest compression and decompression system according to embodiments of the present invention.

FIGS. 6A to 6D illustrate features or properties of a load cell or preload spring mechanism according to embodiments of the present invention. FIG. 7 is a perspective top view of a device in accordance with embodiments of the present invention.

FIG. 8 is a perspective side view of the device shown in FIG. 7.

FIG. 9 is an exploded perspective view of the device shown in FIG. 7. FIGS. 10A to IOC are schematic illustrations of the device shown in FIG. 7 in use during the positioning (FIG. 10A), compression (FIG. 10B) and expansion (FIG. IOC) steps of a method according to embodiments of the present invention.

FIG. 11 is a perspective view of a device in accordance with embodiments of the present invention. FIG. 12 is a schematic illustration of a powered automatic system using a device according to embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Systems and methods are provided for performing manual and automated cardiopulmonary resuscitation (CPR), optionally in combination with electrocardiographic monitoring (ECM) and/or electrical defibrillation as part of advanced cardiac life support (ACLS) procedures. However, it will be recognized by one skilled in the art that embodiments of the present invention may also find other uses wherein compression and expansion of a body part or body area is required or beneficial, optionally in combination with decompression maneuvers. Therefore, the invention is not intended be limited to the specific embodiments described herein.

System and method embodiments provided herein are well suited for administering enhanced ACD CPR and ACLS procedures. Exemplary systems include a disposable adhesive pad which sticks to the chest of the patient, a detachable handle that detaches from the adhesive pad when excessive decompression force (upward pull) is applied, and a display which indicates to the operator the appropriate amount of force to be applied. Moreover, systems can be configured or customized for use on a particular individual based on body weight or size, for example. In some cases, systems and methods can be used by rescuers to perform ACD CPR on patients in cardiac arrest, or in patients showing a lack of signs of circulation. ACD CPR systems and techniques provided herein can enable a rescuer or operator to perform ACD CPR, which differs from standard CPR in that it actively re-expands

(decompresses) the chest after each compression. This approach allows the operator to use the same body position and compression technique as in standard CPR. Active chest decompression is achieved when the rescuer maintains a firm grip on the ACD CPR system and swings his or her body weight upwards after compression. A single-use disposable adhesive pad can be applied to the chest and transfers the lifting force to the lower part of the ribcage. Compression force is transferred to the chest as in standard CPR via the device's piston and compression pad. A force gauge in the handle assists the rescuer in applying the force needed to achieve desired compression (e.g. 1 1/2 to 2 inches), and the lift necessary for adequate decompression. A visual metronome can guide the rescuer to compress and decompress at the appropriate rate and force.

In use, the operator can attach the system with the patient's chest via the adhesive pad, and apply compressive and decompressive forces to the patient by maneuvering the system handle. For example, the operator can press downwardly on the handle with a sufficient force so as to compress the patient's chest and induce blood circulation from the chest. The operator can then pulls upwardly on the handle so that the adhesive pad actively expands the patient's chest to induce blood circulation into the chest and ventilate the patient's lungs. The downward and upward strokes can be repeated at a rate sufficient to maintain blood circulation and enhance ventilation, typically with a compression distance in the range from about 3.5 cm to about 5 cm and a rate in the range from about 60 repetitions to about 100 repetitions per minute. This technique may be particularly effective when the operator kneels beside the patient and grasps the handle with fully-extended arms, with the operator's palms engaging the upper surface of the handle and fingers grasped around the peripheral flange of the handle. The operator may then apply the necessary or desired downward and upward strokes with fully-extended, locked arms while holding the system in a very stable configuration.

Turning now to the drawings, Fig. 1 illustrates aspects of an ACD CPR system according to embodiments of the present invention. The stem 107 of the system handle 105 contains a load cell 1 10 that measures the compression and decompression forces applied to the patient P. In some embodiments, a load cell 110 which measures the compression and

decompression forces is in compression during its resting state. Accordingly, the load cell 110 can provide measurements for both upward and downward forces. The handle 105 can be designed to provide a convenient grip 106 that transfers compression via the heels of the hand and lift via the fingers. Hence, no change of grip may be needed between compression and decompression. The system 100 may be configured so that the handle 105 is

automatically positioned by magnets 120, 130 when the handle 105 comes into contact with the adhesive pad 140. According so some embodiments, system 100 may include a detachable magnetic connection mechanism 150 disposed between the handle 105 and the adhesive pad 140. The connection mechanism 150 can be configured so that the handle 105 decouples from the adhesive pad 140 on the chest when the decompression force exceeds a predetermined limit. For example, the handle 105 may become unattached at a pull force of 25 lbs, thereby not allowing the user to pull up with more than 25 lbs force. Furthermore, the handle 105 can be easily attached to the adhesive pad 140 when it is brought close to the pad 140 via the magnetic interlock or connection mechanism 150.

Fig. 1A provides a top view of an ACD CPR system 100a according to embodiments of the invention. System 100a includes a handle 105 a having two handgrips 110a, 112a and a graphical user interface 120a. Handle 105 a is intended for multiple uses and is easily attached and removed from an adhesive pad 130a. In some cases, adhesive pad 130a is disposable. For example, in use the adhesive pad may be applied to a patient during an ACD CPR procedure, and discarded following the treatment. Handle 105 a may be attached with adhesive pad 130a via a magnet. In some instances, the magnetic coupling is configured such that handle 105a becomes detached from adhesive pad 130a when excessive decompression force (upward pull) is applied. Other means to couple the handle to the adhesive pad include various mechanical connections including ball and socket, cantilevered arm, or detent mechanism or the like.

Fig. IB depicts an exemplary graphical user interface (GUI) 120b according to embodiments of the present invention. As shown here, GUI 120b includes a body size input 140b having a small body size selection 142b, a medium body size selection 144b, and a large body size selection 146b. These three inputs or buttons allow a user to select the patient chest size or stiffness. GUI 120b also includes a target compression/decompression numerical rate display 152b, an actual or applied compression/decompression numerical rate display 154b, and a power indicator or button 156b. Target rate display 152b can be configured to provide a numerical display or output of the desired or appropriate compression rate, decompression rate, or both. Actual rate display 154b can be configured to provide a numerical display of the actual or applied compression rate, decompression rate, or both. Further, GUI 120b includes a force application display 160b that includes a force guide 170b and a force display 180b.

Force guide 170b provides an indication or guide to the operator of how hard to push during a chest compression, how hard to pull during a chest decompression, and how fast to push and pull while administering the compressions and decompressions. For example, in some cases the system may determine that a compression force of 100 lbs and a decompression force of 20 lbs should be applied during the treatment, at a rate of 120 compressions per minute. Table 1 shows an exemplary set of prescribed compression and decompression forces associated with indicator bars of force guide 170b, for such treatment parameters. During the compression and decompression phases of the cycle, indicator bars 17 lb- 178b light up or activate in sequence at the prescribed rate, to provide the operator with a visual guide of how forcefully and how quickly to administer the compressions and decompressions.

Table 1

Indicator Bar Force Time

ACD CPR cycle (compression)

171b 20 lbs 0.025 seconds

172b 40 lbs 0.050 seconds

173b 60 lbs 0.075 seconds

174b 80 lbs 0.100 seconds

175b 100 lbs 0.125 seconds

(compression target)

174b 80 lbs 0.150 seconds

173b 60 lbs 0.175 seconds

172b 40 lbs 0.200 seconds

171b 20 lbs 0.225 seconds

O lbs 0.250 seconds

ACD CPR cycle (decompression)

176b 6.7 lbs 0.292 seconds

177b 13.4 lbs 0.333 seconds

178b 20 lbs 0.375 seconds

(decompression target)

177b 13.4 lbs 0.416 seconds

176b 6.7 lbs 0.458 seconds

O lbs 0.500 seconds

Ventilations can be provided to the patient, for example according to current American Heart Association recommendations. In some cases, ventilations can be administered to the patient at a compression-ventilation ratio of about 30:2 (i.e. 30 chest compressions given for every two rescue breaths).

Force display 180b provides an indication of how hard the operator is actually pushing during the compression phase and pulling during the decompression phase, and how fast the operator is pushing and pulling when administering the compressions and decompressions. For example, during the compression and decompression phases of the cycle, indicator bars 181b- 188b light up or activate depending on how forcefully and how quickly the operator administers the compressions and decompressions. Accordingly, force display 180b enables the operator to track or visualize his or her actual applied force and rate, and compare the applied force and rate with the target force and rate as provided by force guide 170b. By using force guide 170b as a target reference and force display 180b as an indication of the efforts applied during treatment, the operator can realize or approach the goal of matching the applied forces and rates with the target forces and rates.

Force application display 160b also includes a decompression indicator 162b, a compression indicator 164b, a decompression limit warning indicator 166b, and a compression limit warning indicator 168b. According to the embodiment depicted here, decompression indicator 162b provides the user with a reference or indication that force guide 170b and force display 180b signals displayed toward the top of GUI 120b are associated with the decompression phase of ACD CPR. Likewise, compression indicator 164b provides the user with a reference or indication that force guide 170b and force display 180b signals displayed toward the bottom of GUI 120b are associated with the compression phase of ACD CPR. The system can be configured so that decompression limit warning indicator 166b lights up or activates when the operator applies a decompression force that exceeds a prescribed decompression force or force range. Similarly, system can be configured so that compression limit warning indicator 168b lights up or activates when the operator applies a compression force that exceeds a prescribed decompression force or force range. These features can help the operator avoid application of excessive forces during treatment, which in some cases could cause injury to the patient.

In some cases, red caution lights may illuminate when the applied force exceeds the prescribed force range. For example, if the operator approaches or exceeds the

decompression target limit, a caution light may illuminate and the handle can disconnect from the adhesive pad either immediately or shortly thereafter. In the event the handle becomes detached, the rescuer may reattach the handle by bringing the handle close to the adhesive pad, whereby the handle and the adhesive pad are coupled via magnetic attraction. Once the handle and the pad are attached, the operator can resume the compression and decompression actions of the ACD CPR method. The rescuer can avoid or minimize frequent handle detachment by following the direction provided by a force guide. When preparing the system for use on a patient, the operator can power on the system by pushing the power button 156b. According to some embodiments, the lights on the right side of the display will illuminate in response to activation of the power switch. In some cases, the operator may take caution not to push on the chest when pressing the power button. For example, in order for the force gauge to appropriately calibrate, it may be beneficial to have no load placed on the handle when the system is initially powered on.

ACD CPR systems disclosed herein may be operated in any of a variety of ways. For example, in one exemplary method, the operator uses the system to initially compress the chest about 1 ½ to about 2 inches and hold the compression for about 2 seconds. During this time, the system can measure the applied force and determine the target force automatically. In this sense, the target force corresponds to an amount of force applied so as to compress the chest about 1 ½ to about 2 inches. It is understood that the target force may be set at a different amount by initially compressing the chest to a different distance. Hence, the initial compression distance can determine the target force. The system may also indicate the patient's chest size by illuminating the appropriate button. In this case, the user does not have to select the chest compliance, and the system automatically determines the amount of force required to compress the patient's chest by 1 ½ or 2 inches. However, at any time the user can push a desired body size input (e.g. 142b, 144b, or 146b) so as to select an alternate size/compliance and the target force will update to the selected size.

In another exemplary method, the operator may manually select the S (142b), M (144b), or L (146b) chest size on the handle by pressing the appropriate button of the body size input 140b. The system can recognize that the user has selected a predefined force target and then guide the user accordingly. In some embodiments, the target force values are as depicted in Table 2 below.

As noted elsewhere herein, in some embodiments caution lights 166b, 168b may illuminate when the applied force exceeds the prescribed force range. At any time, the operator can change the force target by pushing an alternate chest size or body size input 140b. In this way, the operator may determine the appropriate force target during a rescue treatment, and such adjustments may be made on the fly. For example, there may be instances where a small chest is extremely rigid and may require more than 80 lbs for effective CPR. In some cases, during CPR the chest may become more compliant, and hence it may be desirable to use less force if the rescuer feels that the chest is being compressed excessively, for example by more than about 2 inches. In yet another exemplary method, the rescuer may simply start compressions by following the pacing guide as provided by the system itself. The system can be configured to default to a target compression force associated with the medium body size selection 144b or the average adult chest size, and the compression force delivered will be targeted within a range from about 80 to about 95 lbs, for example. In some cases, the decompression force target can be set at a fixed value (e.g. 20 lbs), regardless of chest size. Optionally, the decompression force target can be set at a value that is a function of chest or patient size, or compliance.

In many instances, it is beneficial for the operator to compress the chest a certain number of times (e.g. about 30) without actively pulling up beyond neutral or applying a decompression force, to ensure appropriate adhesion of the adhesive pad before beginning active

decompressions. Hence, the system can be configured or programmed to illuminate the guiding light or force guide 170b so as to guide the user to perform a certain number of compressions (e.g. about 30) before beginning ACD CPR. For example, the force guide 170b may initiate a series of signal displays for indicators 17 lb- 175b (compression phase), but not for indicators 176b-178b (decompression phase). When the predetermined number of compressions are complete, the guiding light or force guide 170b can then direct the operator to compress and decompress in accordance with ACD CPR procedures.

According to some embodiments of the present invention, the decompression force target may be set to a predetermined value (e.g. 20 lbs), regardless of chest size. If the operator exceeds the decompression target limit, a caution light 166b may illuminate and the handle can disconnect from the adhesive pad either immediately or shortly thereafter. In the event the handle becomes detached, the rescuer may reattach the handle by bringing the handle close to the adhesive pad, attaching the handle and pad via magnetic attraction, and resuming ACD CPR. The rescuer can avoid or minimize frequent handle detachment by following the direction provided by force guide 170b. Exemplary system embodiments may include a timer. For example, a system may include a timer display on the graphical user interface. A timer can be configured to keep a running count of the amount of time (e.g. number of minutes) the system has been powered on, and can be used as a guide to time medication administration or rescuer rotation. To avoid fatigue, it may be beneficial for multiple rescuers to take turns performing the

compression/decompressions, changing every 2 to 3 minutes.

When the system is in place on the patient, the rescuer can kneel close to the patient's side. For optimal position, shorter rescuers may find it beneficial to elevate themselves slightly by kneeling on padding. If the patient is in bed (with hard surface under torso), it may be helpful for the rescuer to kneel next to the patient or stand on a platform of sufficient height. When the rescuer is appropriately positioned, he or she can grab the system handle with both hands, placing the heels of their hands on the handle grips or palm pads with wrists bent. The rescuer can then compress and decompress with their shoulders directly over the sternum with arms outstretched and elbows locked. The rescuer may use the large muscles in their thighs to lift and compress, bending at the waist.

According to some embodiments, the system can be configured to provide a soft start in which the initial target compression forces are not as high as the target compression forces encountered later on during CPR.

Fig. 2 shows an example of adhesive pad placement on a patient, according to embodiments of the present invention. As depicted here, an adhesive pad 210 is placed on patient 200, such that a nipple line 220 of pad 210 extends between the patient's nipples 202a, 202b. Further, adhesive pad 210 is placed such that sternum notch 230 of pad 210 is placed in the center of the patient's chest, directly over the sternum. Adhesive pad 210 may have a sternum line 240 which can be placed in alignment with the patient's sternum. When applying the system to the patient, the operator may orient the system such that the compression point of the system, which can be aligned with an adhesive pad compression point 250, is on the lower half of the sternum or center of the chest, which is at or near the compression point as prescribed in manual CPR techniques.

Fig. 3 illustrates an adhesive pad 300 according to embodiments of the present invention. Adhesive pad 300 includes a nipple line 320 which can be placed in alignment with the patient's nipples, and a sternum notch 330 that can be aligned with the patient's sternum. As shown here, adhesive pad 300 may include a liner 360 and an adhesive face 370. When applying the adhesive pad 300 to the patient, the operator may peel or remove liner 360 of the adhesive pad away from adhesive face 370, and place adhesive face 370 toward the patient's chest, for example on the sternum at the mid-nipple line as indicated on the adhesive pad shown in Figs. 2 and 3.

When administering an ACD CPR treatment to an individual, it may be helpful to assess the condition of the patent prior to the treatment. In some cases, it may be desirable to determine that patient exhibits no signs of circulation, such as consciousness, breathing, coughing, movement, pulse, or the like. Such assessments may be performed according to local standards.

The system can be turned off after use by pressing and holding down the power button for a predetermined amount of time, for example 5 seconds. During this time, the timer may display the battery life remaining in hours. If the power button is not held for a sufficient amount of time (e.g. 5 seconds) the system may remain on, but may automatically power off after 5 minutes if no compressions are sensed. The handle can be configured to provide a predetermined number of hours of use. For example, the handle can be designed to provide about 30 hours of use. At any time, the user can determine the remaining battery life by pressing and holding the power button. The timer can display the amount of time remaining, for example by displaying the letter H followed by a number. The number can indicate the number of hours of battery life remaining. Optionally, the system can be configured so that when there is less than one hour of battery life remaining, the rate display will begin flashing whenever the device is turned on. In some embodiments, when battery life is depleted, the unit will not power up. Optionally, the handle can then be returned to the manufacturer and the unit will be refurbished and a new battery supplied.

Fig. 4 is a simplified block diagram of an exemplary module system that broadly illustrates how individual system elements for a module system 400 may be implemented in a separated or more integrated manner. Module system 400 may be part of or in connectivity with an ACD CPR system according to embodiments of the present invention. Module system 400 is well suited for receiving input or information from an operator, a patient, or both, and for displaying output or information as part of an ACD CPR treatment. Module system 400 as shown here includes hardware elements that are electrically coupled via a bus subsystem 402, including one or more processors 404, one or more input devices 406 such as user interface input devices, one or more output devices 408 such as user interface output devices, a network interface 410, and a load system interface 440 that can receive signals from and transmit signals to load system 442. In some embodiments module system 400 also comprises software elements, shown as being currently located within working memory 412 of memory 414, including an operating system 416 and other code 418, such as a program designed to implement methods of the invention.

Likewise, in some embodiments module system 400 may also include a storage subsystem 420 that can store the basic programming and data constructs that provide the functionality of the various embodiments of the present invention. For example, software modules implementing the functionality of the methods of the present invention, as described herein, may be stored in storage subsystem 420. These software modules are generally executed by the one or more processors 404. In a distributed environment, the software modules may be stored on a plurality of computer systems and executed by processors of the plurality of computer systems. Storage subsystem 420 can include memory subsystem 422 and file storage subsystem 428. Memory subsystem 422 may include a number of memories including a main random access memory (RAM) 426 for storage of instructions and data during program execution and a read only memory (ROM) 424 in which fixed instructions are stored. File storage subsystem 428 can provide persistent (non- volatile ) or non-transitory storage for program and data files, and may include tangible storage media which may optionally embody patient, treatment, assessment, or other data. File storage subsystem 428 may include a hard disk drive, a floppy disk drive along with associated removable media, a Compact Digital Read Only Memory (CD-ROM) drive, an optical drive, DVD, CD-R, CD RW, solid-state removable memory, other removable media cartridges or disks, and the like. One or more of the drives may be located at remote locations on other connected computers at other sites coupled to module system 400. The modules implementing the functionality of the present invention may be stored by file storage subsystem 428. In some embodiments, the software or code will provide protocol to allow the module system 400 to communicate with communication network 430. Optionally, such communications may include dial-up or internet connection communications.

It is appreciated that system 400 can be configured to carry out various aspects of methods of the present invention. For example, processor component or module 404 can be a microprocessor control module configured to receive physiological, device, or treatment parameter signals from sensor input device or module 432 or user interface input device or module 406, and to transmit treatment signals to output device or module 436, user interface output device or module 408, network interface device or module 410, or any combination thereof. Each of the devices or modules according to embodiments of the present invention can include one or more software modules on a computer readable medium that is processed by a processor, or hardware modules, or any combination thereof. Any of a variety of commonly used platforms, such as Windows, Macintosh, and Unix, along with any of a variety of commonly used programming languages, may be used to implement embodiments of the present invention.

User interface input devices 406 may include, for example, a touchpad, a keyboard, pointing devices such as a mouse, a trackball, a graphics tablet, a scanner, a joystick, a touchscreen incorporated into a display, audio input devices such as voice recognition systems, microphones, and other types of input devices. User input devices 406 may also download a computer executable code from a tangible storage media or from communication network 430, the code embodying any of the methods of the present invention. It will be appreciated that terminal software may be updated from time to time and downloaded to the terminal as appropriate. In general, use of the term "input device" is intended to include a variety of conventional and proprietary devices and ways to input information into module system 400. User interface output devices 406 may include, for example, a display subsystem, a printer, a fax machine, or non-visual displays such as audio output devices. The display subsystem may be a cathode ray tube (CRT), a flat-panel device such as a liquid crystal display (LCD), a projection device, or the like. The display subsystem may also provide a non- visual display such as via audio output devices. In general, use of the term "output device" is intended to include a variety of conventional and proprietary devices and ways to output information from module system 400 to a user.

Bus subsystem 402 provides a mechanism for letting the various components and subsystems of module system 400 communicate with each other as intended. The various subsystems and components of module system 400 need not be at the same physical location but may be distributed at various locations within a distributed network. Although bus subsystem 402 is shown schematically as a single bus, alternate embodiments of the bus subsystem may utilize multiple busses.

Network interface 410 can provide an interface to an outside network 430 or other devices. Outside communication network 430 can be configured to effect communications as needed or desired with other parties. It can thus receive an electronic packet from module system 400 and transmit any information as needed or desired back to module system 400. In addition to providing such infrastructure communications links internal to the system, the communications network system 430 may also provide a connection to other networks such as the internet and may comprise a wired, wireless, modem, and/or other type of interfacing connection.

It will be apparent to the skilled artisan that substantial variations may be used in accordance with specific requirements. For example, customized hardware might also be used and/or particular elements might be implemented in hardware, software (including portable software, such as applets), or both. Further, connection to other computing devices such as network input/output devices may be employed. Module terminal system 400 itself can be of varying types including a computer terminal, a personal computer, a portable computer, a workstation, a network computer, or any other data processing system. Due to the ever- changing nature of computers and networks, the description of module system 400 depicted in Fig. 4 is intended only as a specific example for purposes of illustrating one or more embodiments of the present invention. Many other configurations of module system 400 are possible having more or less components than the module system depicted in Fig. 4. Any of the modules or components of module system 400, or any combinations of such modules or components, can be coupled with, or integrated into, or otherwise configured to be in connectivity with, any of the treatment system embodiments disclosed herein. Relatedly, any of the hardware and software components discussed above can be integrated with or configured to interface with other medical assessment or treatment systems used at other locations.

In some embodiments, the module system 400 can be configured to receive a physiological parameter of the patient at an input module. Physiological parameter data can be transmitted to an assessment module where a physiological profile is determined. The profile can be output to a system user via an output module. In some cases, the module system 1300 can determine a treatment protocol for the patient, based on a physiological parameter or profile, for example by using a treatment module. The treatment can be output to a system user via an output module. Optionally, certain aspects of the treatment can be determined by an output device, and transmitted to a treatment system or a subdevice of a treatment system. Any of a variety of data related to the patient can be input into the module system, including age, weight, sex, treatment history, medical history, and the like. Parameters of treatment regimens or diagnostic evaluations can be determined based on such data. Figs. 5A to 5D depict aspects of an exemplary magnetic coupling mechanism in an external chest compression and decompression system. Fig. 5A provides a top view of compression and decompression system 500. Fig. 5B provides a cross-section view of compression and decompression system 500, which includes a handle assembly 510 releasably coupled with an adhesive pad assembly 520. As shown here, system 500 may include a coupling mechanism 530 between a disposable adhesive pad 520 and a system handle 510. The coupling mechanism 530 can include a magnet 540 and a magnet keeper 550. In some cases, as depicted in Fig. 5C, a magnet 540c may include or be part of a magnet assembly 560c having a magnet 540c, a non-ferrous spacer 542c, and a ferrous container 544c for directing the magnetic flux from the pole of the magnet furthest away from the magnet keeper to the magnet keeper. The poles of the magnet can be arranged such that the poles are aligned along the axis 580 of the system piston 570. As shown in Fig. 5D, a magnetic keeper 550d on the disposable adhesive pad assembly 520d of system 500d can include a magnet 552d with poles arranged in the opposite direction of the system handle magnet 540d or of a ferrous material such as 12L14 carbon steel having a high capacity for carrying magnetic flux. A magnetic coupling between system handle assembly 51 Od and adhesive pad assembly 520d can be made quickly. Relatedly, the amount of effort involved with establishing a magnetic coupling is typically less than the effort involved with disengaging the magnetic coupling. Further, the force of the disconnection of the magnetic coupling can be stable over a wide range of operating environments.

According to some embodiments, a magnetic coupler mechanism can include a magnet assembly disposed on or coupled with a handle, and a keeper assembly disposed on or coupled with a pad. For example, a magnetic coupler mechanism 530d as shown in Fig. 5D may include magnet 540d, or magnet assembly (such as magnet assembly 560c shown in Fig. 5C), and keeper assembly 550d. The magnet 540d or magnet assembly can be coupled with or part of system handle assembly 5 lOd. Keeper assembly 550d can be coupled with or part of adhesive pad assembly 520d. The magnet assembly and keeper assembly in combination may be referred to as a coupler assembly. In some cases, the coupler assembly can operate to provide a consistent release force allowing the handle to separate from the pad prior to the pad releasing from the patients skin. In addition, it may be desirable that the magnet assembly does not have a magnetic field that is widely dispersed, but rather focused in the direction of the keeper. To focus the magnetic field, the magnet assembly can include a magnetic core, a non-magnetic sleeve, and a ferromagnetic pot which conducts the magnetic flux from the pole on the enclosed side of the magnet to the open side of the magnet. The arrangement of a jacket with the magnet can focus the majority of the magnetic flux to the open end of the assembly. For example, as shown in Fig. 5C, magnet assembly 560c may include a magnetic core 540c, a non-magnetic sleeve 542c, and a ferromagnetic pot 544c which conducts the magnetic flux from the pole on the enclosed side 540c' of the magnet to the open side 540c"of the magnet. The arrangement of a jacket 544c with the magnet can focus the majority of the magnetic flux to the open end of the assembly 560c. Control or selection of the material properties of the keeper 550d can be helpful to achieve a consistent release force. In some cases, the material can have a high magnetic saturation such as a 12L14 or AISI 1010 or 1020 material and the magnetic properties of the material can be controlled through the control of material temper. For example, materials can be processed to a fully annealed condition.

In addition to the magnetic coupling mechanism described herein, other types of breakaway mechanisms can be used in an external chest compression and decompression for coupling a disposable adhesive pad with a system handle. Exemplary breakaway mechanisms can be configured to allow the handle to disengage from the pad in a controlled manner.

Figs. 6A to 6C illustrate features of an exemplary load cell or preload spring mechanism, according to embodiments of the present invention. Fig. 6A provides a top view of compression and decompression system 600. Fig. 6B provides a cross-section view of compression and decompression system 600, which includes a handle assembly 610 releasably coupled with an adhesive pad assembly 620. As shown here, system 600 may include a coupling mechanism 630 between a disposable adhesive pad 620 and a system handle 610. The coupling mechanism 630 can include a load cell assembly 645 and a preload spring assembly 655. Such load cell or spring mechanisms can be incorporated in a system for performing external chest compressions and decompressions. In some cases, a baseline level of compression can be applied to the load cell via a preload spring. The preload spring can apply enough force to a device piston in a direction simulating compression such that the device piston is in kept in contact with the load cell throughout the

compression/decompression cycle. For example, as shown in Fig. 6C, system 600c includes a handle assembly 610c, a load cell assembly 645c, a preload spring assembly 655c having a spring 656c, a magnet assembly 660c for releasable coupling with a keeper assembly of a pad assembly. System 600c also includes a spacer mechanism 665 c in operative association with spring assembly 655c or spring 656c and magnet assembly 660c. In some cases, spacer mechanism 665 c includes a post 666c coupled with a shoulder mechanism 667c such as a disc. System 600c may also include a fastener 668c or fastener means for fixedly attaching disc 667c, post 666c, and magnet 660c. Hence, the disc, post, and magnet may operate in unison, such that compression or decompression force applied to the magnet can be transmitted to the disc, and vice versa. As depicted in Fig. 6C, load cell 645c can contact spacer mechanism 665c or piston at a contact point 675c. Preload spring 656c can operate to maintain or facilitate contact between magnet 660c and load cell 645c, for example via spacer mechanism 665c. Optionally, the use of the preload spring may eliminate a need for independent sensors for both compression and decompression. According to some embodiments, both compression and decompression forces can be measured with a load cell. To accomplish measuring decompression forces the handle can include an internal spring mechanism that creates a compressive load on the load cell when the handle is experiencing no external loading. The internal spring mechanism can apply a compressive force to the load cell at certain times or periods. For example, the internal spring mechanism can apply a compressive force to the load cell at all times or at

substantially all times. The handle can include a means of compensation for this initial compressive force. Compensation for the internal spring mechanism can be accomplished by zeroing the load cell output, in software, upon each startup which can eliminate or reduce effects of sensor and spring force drift due to age, temperature, or other sources. The graph in Fig. 6D shows exemplary relationships between (a) the force that is applied to the system handle and transferred at least in part to the patient, for example via the magnet [x-axis], and (b) the force transferred to the load cell [y-axis]. Positive forces are

compressive and negative forces are decompressive. This graph illustrates the effect of preload application on the load cell, and shows how a preload spring can condition the forces applied to the magnet prior to transmission to the load cell. As depicted in this embodiment, the force on the magnet can be in a range between about -60 lbs to about 110 lbs, and the force transferred to the load cell can be in a range between about 0 lbs and about 1501bs. Systems can be configured to provide any of a variety of force profiles, as desired.

According to this graph, a preload mechanism, such as a preload spring assembly, allows the load cell to measure decompressive forces. The force at the magnet can be the same or substantially the same as the force at the handle, which can also be equivalent to the force applied to the patient, for example where the handle is considered a rigid mechanism.

According to some embodiments, the load cell or force sensor, which may be present in the handle or at another location in the system, may be configured to measure or sense compressive forces. In some instances, the system may be configured so that the preload spring or mechanism applies a compressive force to the load cell at all times.

Two load cell configurations are depicted in FIG. 6D. The dashed line represents a load cell or force profile without a preload spring or mechanism, and the solid line represents a load cell or force profile with a preload spring or mechanism. In the particular embodiment depicted here, the amount of preload is 40 lbs. In various embodiments, any amount of preload can be selected as desired. In the dashed line profile, where a preload spring or mechanism is not present, the force on the load cell is zero when the handle is pulled up, for example during the decompression phase. In some cases, a device may not have the capability to measure decompressive forces unless preload is provided. In the solid line profile, where a preload spring or mechanism is present, there is 40 lbs of preload force applied to the load cell in the absence of force applied to the handle. Hence, the preloaded configuration allows measurement of decompressive forces, for example up to the amount of the preload force. In some embodiments, the preload mechanism may include a coil spring. Optionally, a preload mechanism may include a Belleville washer. In some cases, preload can be provided by a resilient housing material, or otherwise built into the housing element in which the preload is applied by the resilience of the housing material. According to some embodiments, preload can be provided by preload mechanisms that include rubber, an elastomeric substance, fluid, or other compressible materials or assemblies.

In some instances, guided ACD CPR systems and methods can involve the use of a load cell in conjunction with an accelerometer. The load cell can provide a means of measuring active decompression and an auto zeroing of the accelerometer. The accelerometer can provide a direct measurement of chest wall displacement in techniques involving, for example, a 1.5 to 2.0 inch displacement.

Exemplary system and method embodiments may provide treatment with particularly effective compressive area and contact area configurations. For example, a device contact area or adhesive pad can be 2 to 4 times larger than the compressive area. Beneficially, a large contact area can make it easier for a user or operator to generate a full or greater decompression resulting in more blood flow back to the heart. This may be a result of the ability of a large contact area to physically raise or lift a corresponding large area of the patient's chest during a decompression maneuver. Moreover, a sufficiently large compression surface area can allow the operator or user to provide enhanced coronary perfusion pressure or more blood flow from the heart to other tissue or organs during compression, thus improving the likelihood of a successful medical outcome for the patient such as the return of spontaneous circulation. According to some embodiments, the systems and methods discussed herein can be used without preventing lateral displacement of the chest. For example, these techniques can be used without binding or constricting the chest with a CPR band device, or otherwise without applying a circumferential device to the patient.

Accordingly, embodiments of the present invention provide systems and methods for actively compressing and expanding an area of the body that involve a compression element operably coupled to a flexible surface element that is adapted to be removably attached to a body part over a contact area. The compression element is configured to be alternately pressed and lifted, thereby pressing upon and lifting the surface element. When the compression element is pressed, it applies a compressive force over a compressive area of the surface element and the body part to which it is attached. When the compression element is lifted, the contact area of the body part attached to the surface element is lifted by the surface element.

In one embodiment, the device may be used to compress and expand the thoracic cavity or chest, and to transform the chest into an active bellows. The increased active expansion of the chest which occurs when the surface element is lifted causes unexpectedly enhanced negative pressure within the intrathoracic region ("negative ITP"), thereby drawing a larger amount of air into the lungs to more effectively ventilate the patient than previous devices. Accordingly, the device may be used to enhance the expansion of the chest and resultant lowering of negative ITP for a variety of purposes, e.g. to perform active

compression/decompression CPR, to treat low blood pressure, to increase blood circulation, and the like. It has been found that the larger the body contact area provided by the surface element, the lower the negative ITP that can be achieved using the device if the chest is compliant or if a rib has been broken. In exemplary embodiments, the body contact area provided by the lower surface of the surface element can be between about two and about four times greater than the compressive area to which compressive force is applied on the upper surface of the surface element. Body contact areas less than the specified range may result in unsatisfactory expansion of the chest, excessive forces that are concentrated on a small area (which could damage the skin), and provide less than optimal negative ITP, whereas body contact areas more than the specified range can result in unsatisfactory compression of the chest.

The device may be used in both manual and powered systems. In a powered system, the compression element may be attached to a mechanical drive element, such as a mechanical link which is part of a powered automatic drive system which accomplishes the up and down motions of the compression and expansion strokes. In a manual system, the compression element may comprise a handle that can be grasped by the operator's hands and moved up and down to accomplish the required or prescribed strokes.

In one embodiment, the device includes a mushroom-shaped compressive element having a dome-shaped handle disposed on the top end of a centrally- located rigid connecting stem. The bottom end of the stem is connected to the top surface of a generally planar flexible contact pad and defines a compressive area. The lower surface of the contact pad may be covered with an adhesive adapted to adhere to the anterior surface of a patient's chest and defines a contact area. The handle's dome-shaped upper surface is separated from an annular planar lower surface by a peripheral flange, thereby allowing an operator to grasp the handle with the palms of both hands positioned on the upper surface, the fingers curled around the peripheral flange and the finger tips positioned against the lower surface.

According to certain method embodiments, the increased negative intrathoracic pressures of a patient may be effected using the device generally described herein. After positioning both hands on the handle, the operator may apply downward force against the handle with the palms of the hands. The downward force is transferred through the connecting stem to a compressive area of the contact pad which is generally defined by the cross-sectional area of the lower end of the connecting stem. The device may be positioned on the anterior surface of a patient's chest so that the compressive area is generally positioned over the patient's sternum. The downward force compresses the patient's chest over the compressive area and increases ITP sufficiently to induce blood circulation from the chest. Then, the operator may lift up the handle with the fingers under the lower surface of the handle to provide an upward force on the connecting stem, which in turn moves the top surface of the contact pad in an upward direction. Since the contact pad is adhered to the patient's chest across the entire contact area covered by the contact pad, the upward movement of the contact pad actively expands the patient's chest. This expansion reduces ITP to induce blood circulation into the chest and ventilates the patient's lungs. The downward and upward strokes are repeated at a rate sufficient to maintain blood circulation and enhance ventilation, typically with a compression distance in the range from about 3.5cm to 5 cm and a rate in the range of 60 repetitions to 100 repetitions per minute.

The devices and methods described herein have been found to be particularly useful in manual CPR when the performer kneels beside the patient and grasps the handle with fully- extended arms, with the performer's palms engaging the upper surface of the handle and fingers grasped around the peripheral flange of the handle. The performer may then apply the necessary downward and upward strokes with fully-extended, locked arms while holding the device in a very stable configuration. In some cases, the compression element connected to the upper surface of the surface element may be attached to a mechanical drive element, such as a mechanical link which is part of a powered automatic drive system. In this way, active automatic compression and expansion of the patient's chest can be performed.

Figs. 7-9 illustrate aspects of a device embodiment which can be used for manual operation. The same numbers appearing in these different figures refer to the same elements. Device 700 comprises a mushroom-shaped interface element 701 having a handle 702 operably connected through a connecting stem 703 to upper surface 705 of a flexible contact pad 704.

Contact pad 704 may be constructed from a layer of suitable resilient material such as a natural or synthetic foam. All or a substantial part of a lower surface 706 may be covered with adhesive material suitable for adhering contact pad 704 to the anterior surface of a patient's chest 710. The dimensions of contact area 707 are defined by the "footprint" of contact pad 704 that is adhered to the patient's chest 710 (or other body locations). Suitable adhesive materials may include pressure-sensitive adhesives such as those which are commonly used on medical bandages, transdermal patches, and other medical applications. Other useful adhesives may include natural and synthetic rubber-based formulations, such as polyisobutylenes, and acrylic and silicon-based materials. Swollen hydrogels, such as poly( vinyl pyrrolidone), may be suitable when used in conjunction with electrodes, as described hereinafter. When use of device 700 is completed, contact pad 704 may be removed by conventional means, e.g. by applying a solvent to the adhesive, simply pulling the pad away from the chest, and the like.

The dimensions of contact pad 704 can be chosen to provide a desired contact area 707. In accordance with embodiments of the invention, the larger that contact area 707 is relative to compressive area 712, the more expansion of chest 710 can be achieved using device 700 if the chest is compliant or if a rib has been broken, for example. For example, if the dimensions of pad 704 are 8" x 10" and the operator applies a compressive force on handle 702 across compressive area 712 having dimensions of 3" x 3", chest 710 is subject to greater upward force (and therefore lower negative ITP) than if the dimensions of pad 704 are 4" x 6".

Typically, for adult patients, contact pad 704 will have a generally square or rectangular shape. For children, the dimensions may be in considerably smaller. Other shapes may also be useful, it being necessary only that contact pad 704 be shaped to provide for a desired force distribution over compressive area 712 as well as provide for contact area 707 to be at least twice to four times as large as compressive area 712 so that improved negative ITP in accordance with the invention can be achieved. For example, it may be desirable to shape the lower surface 706 of contact pad 704 to conform to the general contours of the patient's chest 710. In addition, it may be desirable to provide a plurality of sizes and shapes of contact pad 704 in a single kit so that a contact pad may be selected for the individual patient.

The thickness of contact pad 704 may depend on the resiliency of the material employed. For manual operation, an exemplary thickness for contact pad 704 is about 3/16".

Handle 702 comprises dome-shaped upper surface 708 and an annular planar lower surface 709 separated by peripheral flange 710. The top of stem 703 is centrally located within annular lower surface 709 of handle 702 and the bottom of stem 703 is centrally located on the planar upper surface 705 of contact pad 704. The cross-section of bottom end 713 of stem 703 defines the dimensions of compressive area 712. The shape of handle 702 allows the operator's hands 711 to grasp handle 702 with the palms resting on upper surface 708, the fingers wrapped around ridge 717 and the finger tips positioned against lower surface 709 (Fig. 8). This arrangement allows the operator to press down on upper surface 708 of handle 702 with the palms of the hands 711 to apply a compressive force against pad 704 and patient's chest 710 over a compressive area 712. The arrangement also allows the operator to lift up on lower surface 709 of handle 702 with the fingers of hands 711. Since lower surface 706 of pad 704 is adhered to contact area 707 of patient's chest 710, this lifting motion on handle 702 lifts and expands patient's chest 710 across contact area 107. Handle 702 and connective stem 703 may be constructed from a suitable rigid material, e.g. a molded plastic. Handle 702 may also be filled with a gel, foam, padding or the like to enhance its shock- absorbing and distributing capability.

Referring now to Figs. 1 OA- IOC, use of the device in resuscitating a patient will be described. The device is initially placed on the anterior surface of the patient's chest about mid-sternum, as illustrated in Fig. 10A. The operator then grasps handle 702 with both hands, as shown in Fig. 8, pressing the palms of the hands 711 against upper surface 708 while grasping the peripheral flange 710 with the fingers. The operator applies sufficient downward force on handle 702 through stem 703 so that the chest is compressed within compressive area 712, as shown in Fig. 10B. Typically a compressive force is used to depress the chest. Contact pad 704, coupled to stem 703, may be formed of a suitably resilient material, for example, silicone rubber, which softens the application of downward force through the stem 703 across compressive area 712. The initial position of the patient's chest is illustrated in broken line in Fig. 10B. During the compression stroke, the chest is compressed across compressive area 712 to the position illustrated in solid line in Fig. 10B. After the compression stroke is completed, the operator raises up on the handle 702 to expand the chest, as illustrated in Fig. IOC. Again, the rest position of the chest is illustrated in broken line and the expanded position is shown in solid line. During the chest expansion stroke, the upward movement of handle 702 through stem 703 raises contact pad 704, which is adhered to the chest across contact area 707. The chest is pulled upward with contact pad 704 to cause the desired chest expansion. Handle 702 may be raised in an amount sufficient to apply an expansion force. The compression and expansion steps may be alternated at a rate in the range from about 80 to 100 per minute. As previously explained, the larger contact area 707 is relative to compressive area 712, the more chest expansion (and negative ITP) that can be achieved with each stroke. As further described elsewhere herein, and as shown in Fig. IOC, an active compression decompression cardiopulmonary resuscitation device 700 may be used in conjunction with, or may be part of a system 750 which includes, a device 760 for providing, facilitating, or modulating patient airway pressure, such as an impedance threshold device (ITD) mechanism or an intrathoracic pressure regulator (ITPR) mechanism. In some cases, device 760 may include a mechanism, such as a one-way valve, for occluding the patient's airway during a decompression phase. Device 760 may be used during any portion of, or throughout the entirety of, a treatment protocol, for example during one or more of the steps illustrated in Figs. lOA-C, or in conjunction with any other method or system described herein. It may be desirable to provide at least one element associated with the device that can measure a physiological parameter and/or display patient status information and/or feedback to the person performing the CPR. Preferably, the measuring element is associated with the surface element. Examples of physiological parameters include ventilation rates, temperature, blood pressure, heart rate, respiratory rate, and other vital signs. Some parameters may require separate monitoring devices (not illustrated) attached to the patient, and the display on the device makes the information immediately available to the person performing the CPR. Feedback information includes pressure or force applied to the patient, depth of compression, compression rate (i.e., cycles per minute), duty cycle (i.e., portion of each cycle in which the patient is compressed), and the like. Such feedback information can be provided as discrete values, e.g., with gauges or digital readouts, or may be provided with a light or sound system which indicates when certain threshold values have been met or exceeded. It may be further desirable to provide a pacing signal, e.g., either a sound or flashing light, to facilitate maintaining a desired compression rate. Fig. 11 illustrates an embodiment of the invention wherein the device has associated therewith one or more measuring and/or display elements. Device 1 100 comprises handle or element 1 101 and flexible contact pad 1 102, and is similar in structure to device 700 shown in Figs. 7-9, except that contact pad 1 102 of device 1 100 may optionally include one or more measuring and/or display elements. For example, in addition to adhering to a patient's chest as previously described, contact pad 1 102 may serve as a platform for measuring a variety of physiological parameters, e.g. electrocardiogram parameters; provide a means to apply electricity to the body, e.g. accomplish defibrillation; provide a means to apply drugs to the body; provide a surface for installing a liquid crystal display (LCD) screen to display various feedback information; provide a means to house various body sensors, e.g. bioimpedance sensors; and provide reference features to aid in the proper placement of the device on the patient's chest.

Referring now to Fig. 11, contact pad 1 102 may include imbedded automated external defibrillator (AED) electrodes 1 103 and 1 104 connected to AED leads 1 105 and 1 106, respectively. Electrodes 1 103 and 1 104 extend to the lower surface of contact pad 1 102 and may be coated with the same adhesive material that covers the lower surface 1 1 12 to facilitate electrocardiographic monitoring (ECM) and/or electrical defibrillation. Leads 1 105 and 1 106 include wires or other electrical conductors for connecting electrodes 1 103 and 1 104 to external ECM and/or electrical defibrillation equipment in a conventional manner. Contact pad 1102 may also optionally include electronic LCD display 1107, which shows average compression forces applied over a certain number of cycles, and electronic LCD display 1108, which shows average decompression forces over the same number of cycles. In addition, contact pad 1102 may optionally include a blinking light-emitting diode (LED) metronome to aid in the timing of the compression and expansion strokes. In some embodiments, such displays or signaling mechanisms may be positioned on or coupled with handle 1101. Furthermore, contact pad 1102 may include reference notch 1110 on its forward edge (closest to the patient's head) to aid in properly locating the patient's sternum and a reference notch 1111 on its rearward edge (closest to the patient's feet) to aid in properly locating the xyphoid process. References notches 1110 and 1111 may be used to properly place device 1100 on the patient's chest so as to prevent injury to the patient during compression and expansion strokes.

The device of the present invention may also be employed in a powered or automated system, for example, such as the automated reciprocating system 1200 as illustrated in Fig. 12.

Surface element 1201 may be adhered to body surface 1208 in the manner previously described. Compression element or handle 1202 may be secured to a vertical drive element 1203, which is attached to a reciprocating lever arm 1204. Lever arm 1204 may be driven in a wide variety of ways. As illustrated, a fixed fulcrum point 1205 is provided by post 1206 and lever arm 1204 is reciprocated up and down by a piston and cylinder 1207 to provide the desired compression and expansion of chest 1208.

According to embodiments disclosed herein, devices and methods for actively compressing and expanding an area of the human body may include a compression element configured to pressed and lifted, and a flexible surface element operably coupled with the compression element and configured to be removably attached to a body part over a contact area. The compressive element can be adapted to apply a compressive force to the body part through the surface element over a compressive area when the compression element is pressed. The contact area can be sized to be at least twice as large as the compressive area. Certain embodiments of the present invention are useful in the performance of cardiopulmonary resuscitation and advanced cardiac life support procedures. By alternately pressing and lifting the surface element with the compression element, the patient's chest can be compressed and expanded to improve induced ventilation and circulation. In an exemplary device, a dome-shaped handle is attached to the upper surface of a flexible contact pad by a short connecting stem structure. The bottom end of the connecting stem defines the compressive area and the lower surface of the contact pad secured to a patient's chest defines the contact area. In other embodiments, various elements may be associated with the contact pad to, for example, measure a physiological parameter, display patient feedback

information, apply electricity, apply a drug, provide a sensor, provide a reference to aid in the proper placement of the surface element on the body part, etc. For automatic applications, a mechanical drive member may be secured to the compression element.

In some instances, a treatment device may include means to record the compression events, to store the data, to simultaneously or contemporaneously transmit or analyze data related to the treatment to the operator, or to transmit or analyze data related to the treatment to the operator following a patient arrest, to assess the quality of cardiopulmonary resuscitation administered by the operator, and to provide feedback to the operator regarding the quality of the administered cardiopulmonary resuscitation either during or after the arrest. Relatedly, an exemplary treatment device for actively compressing and expanding an area of the body can include a compression element that is configured to be pressed and lifted, a flexible surface element operably coupled with the compression element and configured to be removably attached to a body part, an interface for displaying information to and receiving information from an operator, a processor coupled with the interface, and a memory coupled with the processor. The memory can be configured to store a plurality of code modules for execution by the processor. The plurality of code modules can include a module for recording a compression event history, a module for storing the compression event history, a module for assessing a cardiopulmonary resuscitation quality factor, and a module for providing feedback to the operator based on the cardiopulmonary resuscitation quality factor.

Embodiments of the present invention encompass systems and methods for instructing the operator or user to perform a certain number of compressions prior to initiating active compression and decompression (pulling up on the chest). For example, systems and methods may involve instructing the operator to perform 30 compressions before they begin active compression and decompression. Such techniques can help to ensure that the pad appropriately adheres to the chest. In some cases, the device software can guide the user to perform a number of (e.g. 30) compressions before the display starts guiding the user to perform compressions and decompressions. Relatedly, a device for actively compressing and expanding an area of the body may include a compression element that is configured to be pressed and lifted, a flexible surface element operably coupled with the compression element and configured to be removably attached to a body part, an interface for displaying instructions to an operator, a processor coupled with the interface, and a memory coupled with the processor. The memory can be configured to store a plurality of code modules for execution by the processor. The plurality of code modules can include a module for providing operator instructions to perform a number of compressions prior to initiating active compression and decompression.

Further, methods and systems described herein can incorporate or be used in conjunction with techniques that involve providing a volume exchange cardiopulmonary resuscitation treatment to a patient that encompasses compressing the patient's chest during a compression phase and lifting upward the patient's anterior chest wall and occluding the patient's airway during a decompression phase. Optionally, the step of occluding the patient's airway can include occluding the airway with a one-way valve. In some cases, the step of occluding the patient's airway includes occluding the airway with a valve system that allows an operator to ventilate the patient. Techniques may also include ventilating the patient with the valve system. In some cases, it is possible to ventilate the patient by provide a positive pressure ventilation through or around the one-way valve. Optionally, techniques can include actively removing respiratory gases from the patient's lungs with a low-level vacuum. In some cases, the low-level vacuum can be continuous. In some cases, the low-level vacuum can be intermittent. These treatment approaches can also include actively withdrawing respiratory gases from the patient's lungs, and subsequently delivering a positive pressure breath to the patient. In some cases, the positive pressure breath can be delivered with a period of positive end-expiratory pressure, either before or after the positive pressure ventilation. These treatment method and device approaches can also include aspects of positive end expiratory pressure, positive pressure ventilation, or both, such as those described in U.S. Patent Application No. 61/218,763 filed June 19, 2009 (Attorney Docket No. 016354-006800US) and U.S. Patent Application No. 12/819,959 filed June 21, 2010 (Attorney Docket No.

016354-006810US), the contents of which are incorporated herein by reference for all purposes.

Relatedly, active compression decompression cardiopulmonary resuscitation treatments described herein can be performed in conjunction with the use of systems and methods for occluding the patient's airway, modulating airway pressure, or providing impedance- threshold therapy to a patient. Exemplary impedance-threshold techniques include those described in U.S. Patent Nos. 5,551,420, 5,692,498, 6,062,219, 6,526,973, 6,604,523, 7,210,480, 6,986,349, 7,204,251, 7,195,012, 7,185,649, 7,082,945, 7,195,013, 7,836,881, and 7,766,011, the contents of which are incorporated herein by reference for all purposes. For example, an impedance threshold device can be connected to a patient, optionally via a facemask, and active compression decompression CPR can be performed on the patient. The impedance threshold device can lower intrathoracic pressure during the decompression phase by impeding passive inspiratory gas exchange during the recoil phase, while also allowing periodic positive pressure ventilation. The impedance threshold device can be configured to provide an inspiratory resistance of 16 cm H ₂ 0 and less than 5 cm H ₂ 0 expiratory impedance, for example.

In some cases, active compression decompression cardiopulmonary resuscitation treatments described herein can be performed in conjunction with the use of systems and methods for providing, facilitating, or modulating negative airway pressure, such as impedance threshold device (ITD) techniques or intrathoracic pressure regulator (ITPR) techniques. Exemplary ITPR approaches are describe in previously incorporated U.S. Patent Application No.

12/819,959 filed June 21, 2010 (Attorney Docket No. 016354-006810US). ITD and ITPR techniques can be are used to enhance circulation, and may involve a valve system interfaced to a person's airway. Both can be used to lower intrathoracic pressure during the chest wall recoil phase of CPR, thereby enhancing the transfer of blood from outside the thorax into the right heart. Exemplary ITD systems can be configured to prevent or inhibit respiratory gas flow to the person's lungs during the decompression phase until a negative airway pressure achieved equals the opening pressure of the valve system. Exemplary ITPR systems can include a valve system that is used to withdraw air from the lungs via an active vacuum source until a negative airway pressure is achieved. According to some embodiments, ITD approaches can provide perfusion on demand by regulating pressures in the thorax during states of hypotension. ITD techniques may utilize the interdependence of the body's respiratory and circulatory systems to create a vacuum (negative pressure) within the chest during the recoil phase of CPR, which follows each chest compression. ITD techniques can regulate the influx of respiratory gases into the chest during the chest wall recoil (relaxation or decompression) phase, which lowers the intrathoracic pressure and draws more venous blood back to the heart. Improved blood return to the heart (preload) results in improved blood flow out of the heart (cardiac output) during the subsequent compression. Thus, despite its placement into the ventilation circuit, an ITD device can operate as a circulatory enhancer device that works during chest compressions, for example during the chest wall recoil phase of CPR. Whereas ITD techniques can be based on vacuum associated with recoil, ITPR techniques can involve the active application of a vacuum. Exemplary ITPR techniques can be used to generate controlled negative endotracheal pressure (ETP). In some cases, an ITPR system may include a pressure regulator that combines a continuous vacuum source, a regulator valve system, a means to provide intermittent PPV, and an inspiratory ITD, such as that described by Yannopoulos et al. in "Intrathoracic Pressure Regulation

Improves 24-Hour Survival in a Porcine Model of Hypovolemic Shock" Anesth. Analg., Vol. 104 No. 1 :157-162 (January 2007). Exemplary ITPR techiques are also described by

Yannopoulos et al. in "Intrathoracic pressure regulation improves vital organ perfusion pressures in normovolemic and hypovolemic pigs" Resuscitation70(3):445-53 (September 2006). The entire content of both of these journal articles is incorporated herein by reference for all purposes. In some cases, an ITPR system may include an ITD mechanism that, rather than operating to decrease intrathoracic pressure, instead functions as a safety valve to prevent the vacuum from going extremely negative, and can optionally be replaced by another type of safety valve. Thus, in some instance, in an ITPR technique the negative pressure can be generated by a vacuum line, and not by a ITD mechanism.

Systems and methods for applying guided active compression decompression

cardiopulmonary resuscitation as described herein are well suited for use in conjunction with abdominal counter-pulsation and/or compression of the lower extremities, and other treatment techniques such as those described in U.S. Patent Application No. 12/165,366 filed June 30, 2008 (Lower Extremity Compression Devices, Systems And Methods To Enhance Circulation, Atty. Docket No. 016354-006010US) for enhancing venous return. The entire content of this application is incorporated herein by reference for all purposes. For example, guided active compression decompression cardiopulmonary resuscitation can be used in combination with techniques or devices that compress the lower extremities using counter pulsation, gas inflated cuffs, fitted around a portion of the thighs or the entire lower body, which can be triggered by the decompression phase of CPR. The lower extremity device accomplishes two main objectives. Such combination treatments are well suited for use in increasing circulation during cardiac arrest and CPR and other states of low blood pressure.

Embodiments of the invention have now been described in detail for the purposes of clarity and understanding. However, it will be appreciated that certain changes and modifications may practiced within the scope of the appended claims.