Patent Publication Number: US-2015073314-A1

Title: Mechanical chest compression plunger adapter and compression pad

Description:
RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 13/629,434, filed Sep. 27, 2012, now U.S. Pat. No. 8,888,725. 
    
    
     FIELD OF THE INVENTIONS 
     The inventions described below relate to the field of emergency medical devices and methods and more specifically to methods and device to optimize the resuscitation of cardiac arrest patients. 
     BACKGROUND OF THE INVENTIONS 
     According to the American Heart Association nearly 383,000 out-of-hospital sudden cardiac arrests occur annually in the United States. These patients may be saved by the timely application of life saving measures such as Cardiopulmonary resuscitation (CPR). 
     CPR is a well-known and valuable method of first aid used to resuscitate people who have suffered from cardiac arrest. CPR requires repetitive chest compressions to squeeze the heart and the thoracic cavity to pump blood through the body. Artificial respiration, such as mouth-to-mouth breathing or a bag mask device, is used to supply air to the lungs. When a first aid provider performs manual chest compression effectively, blood flow in the body is about 25% to 30% of normal blood flow. However, even experienced paramedics cannot maintain adequate chest compressions for more than a few minutes. Hightower, et al., Decay In Quality Of Chest Compressions Over Time, 26 Ann. Emerg. Med. 300 (September 1995). Thus, CPR is not often successful at sustaining or reviving the patient. Nevertheless, if chest compressions could be adequately maintained, then cardiac arrest victims could be sustained for extended periods of time. Occasional reports of extended chest compression efforts (45 to 90 minutes) have been reported, with the victims eventually being saved by coronary bypass surgery. See Tovar, et al., Successful Myocardial Revascularization and Neurologic Recovery, 22 Texas Heart J. 271 (1995). 
     In efforts to provide better blood flow and increase the effectiveness of bystander resuscitation efforts, various mechanical devices have been proposed for performing AUTOMATED CHEST COMPRESSIONS. In one variation of such devices, a belt is placed around the patient&#39;s chest and the belt is used to effect chest compressions. Our own patents, Mollenauer, et al., Resuscitation Device having a Motor Driven Belt to Constrict/Compress the Chest, U.S. Pat. No. 6,142,962 (Nov. 7, 2000); Sherman, et al., CPR Assist Device with Pressure Bladder Feedback, U.S. Pat. No. 6,616,620 (Sep. 9, 2003); Sherman, et al., Modular CPR Assist Device, U.S. Pat. No. 6,066,106 (May 23, 2000); and Sherman, et al., Modular CPR Assist Device, U.S. Pat. No. 6,398,745 (Jun. 4, 2002), and our application Ser. No. 09/866,377 filed on May 25, 2001, show chest compression devices that compress a patient&#39;s chest with a belt. Various other mechanisms may be used to tighten the belt, including the mechanisms shown in Lach, et al., Resuscitation Method and Device, U.S. Pat. No. 4,774,160 (Sep. 13, 1988) and in Kelly, et al., Chest Compression Device for Cardiac Arrest, U.S. Pat. No. 5,738,637 (Apr. 14, 1998). 
     Piston based chest compression systems are illustrated in Nilsson, et al., CPR Device and Method, U.S. Patent Publication 2010/0185127 (Jul. 22, 2010), Sebelius, et al., Support Structure, U.S. Patent Publication 2009/0260637 (Oct. 22, 2009), Sebelius, et al., Rigid Support Structure on Two Legs for CPR, U.S. Pat. No. 7,569,021 (Aug. 4, 2009), Steen, Systems and Procedures for Treating Cardiac Arrest, U.S. Pat. No. 7,226,427 (Jun. 5, 2007) and King, Gas-Driven Chest Compression Device, U.S. Patent Publication 2010/0004572 (Jan. 7, 2010) all of which are hereby incorporated by reference. 
     As mechanical compressions are performed by piston based chest compression systems, the compression pads may shift position relative to the patient and the effectiveness of the automated chest compressions are diminished. The repeated extension and retraction of the piston often results in the piston and compression cup moving or “walking” up the patient&#39;s chest toward the neck or moving down toward the patient&#39;s abdomen. 
     SUMMARY 
     The devices and methods described below provide for a plunger adapter and a detachable compression pad for piston driven chest compression devices that maintain the compression force in the proper position on the patient&#39;s chest. The detachable compression pad is removably secured to the patient above the patient&#39;s sternum to ensure that the compression pressure from the piston through the piston adapter is applied to a fixed location on the patient&#39;s chest. As the piston and piston adapter retract from the chest, the compression pad remains fixed to the patient&#39;s chest, and as the piston and piston adapter extend from the chest compression unit, the distal end of the plunger adapter reengages the compression pad to apply compression to the patient&#39;s chest at the same location above the patient&#39;s sternum as the previous compressions. 
     Any suitable set of corresponding shapes may be provided in the plunger adapter and compression pad to minimize movement of the compression pad relative to the patient&#39;s chest and to optimize application of compressive force to the patient&#39;s chest. Complementary convex and concave shapes on the plunger adapter and the compression pad enable the plunger adapter and the compression pad to engage and focus the compression force to the patient&#39;s chest for each extension of the plunger. In a more detailed example, the distal end of the plunger adapter may have a conical or frusto-conical socket and the compression pad may include a corresponding conical or frusto-conical portion or extension on the proximal end to engage the socket in the plunger adapter. The plunger adapter socket and the compression pad extension will adapt any round, ovoid or spherical shape to provide positive engagement while avoiding any rotational forces generated by the plunger about the long axis of the plunger. By securing the compression pad to the patient&#39;s chest, the application of compressive force is maintained in the selected location. 
     The compression pad is a generally incompressible pad configured to adapt to the shape of the patient&#39;s chest. The compression pad may be formed of one or more layers to optimize the application of CHEST COMPRESSIONS to the patient. The proximal or upper end of the compression pad is a generally hard convex portion or extension that may include a concave socket for engaging the plunger adapter. The central layer may be a flexible and incompressible layer to conform to the shape of the patient&#39;s chest. The lower or distal end of the compression pad may include one or more flexible cups for creating one or more areas of vacuum between the compression pad and the patient&#39;s chest. 
     Suitable engagement mechanisms may be included in the plunger and the plunger adapter to provide a preselected level of chest expansion force in addition to chest compression force. A magnet may be provided in the distal end of the plunger and a corresponding magnet or ferrous material may be included in the proximal end of the plunger adapter to provide a preselected retention force between the plunger and the plunger adapter. The retention force is selected to provide some expansion force to the patient&#39;s chest between compressions without applying enough expansion force to the patient&#39;s chest to tear the patient&#39;s skin or underlying tissue. Similarly an electromagnet may be provided in distal end of the plunger to provide an adjustable level of retention force, or to provide timed release of the plunger adapter from the plunger. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front view of a piston driven chest compression device with a detachable plunger adapter and compression pad and a cross section of a patient&#39;s chest showing landmark skeletal structures. 
         FIG. 2  is a cross section of the chest compression device of  FIG. 1  taken along A-A with an alternate plunger adapter and compression pad. 
         FIG. 3  is a side view of a plunger adapter and compression pad. 
         FIG. 4  is an end view of the distal end of a plunger adapter with a frusto-conical socket. 
         FIG. 5  is an end view of the proximal end of a compression pad with an extension corresponding to the frusto-conical socket of the plunger adapter of  FIG. 4 . 
         FIG. 6  is a side view of an alternate plunger adapter and compression pad. 
         FIG. 7  is an end view of the distal end of the plunger adapter of  FIG. 6 . 
         FIG. 8  is an end view of the proximal end of a compression pad with an extension corresponding to the plunger adapter of  FIG. 6 . 
         FIG. 9  is a side view of an octagonal plunger adapter and compression pad. 
         FIG. 10  is an end view of the distal end of the plunger adapter of  FIG. 9 . 
         FIG. 11  is an end view of the proximal end of a compression pad with an extension corresponding to the plunger adapter of  FIG. 9 . 
         FIG. 12  is a perspective view of a mechanical chest compression device engaging a patient with an electrode assembly and a compression monitor puck. 
         FIG. 13  is a close up perspective of the electrode assembly and compression monitor puck of  FIG. 12 . 
         FIG. 14  is a side view of a plunger adapter configured to engage a compression monitor puck. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTIONS 
     In  FIG. 1 , mechanical chest compression device  10  is oriented to apply compressions to the chest  2  of patient  1 . Chest compression device  10  includes support structure  11  and backboard  11 B which supports and orients chest compression unit  12  apposing sternum  2 A. Chest compression unit  12  includes any suitable drive means such as motor  13  which may be a reversible electromotor, a linear actuator or the like. Plunger  14  has a distal end  14 D and a proximal end  14 P, and proximal end  14 P of the plunger is operably coupled to motor  13 . Distal end  14 D of the plunger extends from and withdraws into the housing upon operation of motor  13 . A motor control unit such as controller  15  is operably connected to motor  13  and includes a microprocessor to control the operation of the motor and the plunger. Plunger adapter  16  is secured to the distal end of the plunger and compression pad  17  removably engages the plunger adapter. 
     Distal end  16 D of plunger adapter  16  is sized and shaped to avoid injury to a patient if plunger  14  is extended to contact the patient without a compression pad between the plunger adapter and the patient. Distal end  16 D of plunger adapter  16  includes a socket  16 S that is sized and shaped to engage a correspondingly shaped element on a compression pad which may be called a key, a portion or an extension such as extension  17 A on proximal end  17 P of compression pad  17 . Compression pad extension  17 A operates as a locator pin or key for preventing the locator bushing, plunger adapter  16 , and chest compression unit  12  from changing the point of application of compression force on the patient or “walking” across the patients chest. 
     In use, compression pad  17  is removably secured to the patient&#39;s chest at force application location  18 , which is in a superior position relative to sternal notch  2 N as illustrated in  FIG. 2 . Compression pad  17  may be secured to the patient with any suitable biocompatible tape or adhesive such as adhesive  19 . The mechanical chest compression device  10  is oriented around the patient&#39;s chest  2  with chest compression unit  12  apposing compression pad  17 . Plunger  14  is extended to confirm proper siting of compression pad  17  on the patient and to confirm mating and orientation of plunger adapter  16  with compression pad  17  and compression pad extension  17 A with socket  16 S. Upon confirmation of proper alignment and orientation, controller  15  is instructed, through any suitable interface such as interface  12 A, to perform cyclic compressions and decompressions for CPR. 
     As illustrated in  FIG. 2 , plunger adapter  24  is configured with a generally cylindrical shape. Compression pad  25  includes a corresponding cylindrical shaped socket  26  in proximal end  25 P of compression pad  25 . In configurations with the plunger adapter operating as the male component in the plunger adapter/compression pad interface, the plunger adapter should be sized such that the force per unit area applied by the plunger adapter, if applied directly to the patient&#39;s chest, does not damage the patient. 
     The combination of plunger adapter and compression pad may be sized along the anterior-posterior axis to enable a chest compression unit with a fixed length plunger with a fixed extension length to accommodate patients with different anterior-posterior dimensions. 
     In  FIGS. 3 ,  4  and  5 , plunger adapter  30  has a height or anterior posterior dimension  30 D and compression pad  31  has a height or anterior posterior dimension  31 D. Plunger adapter  30  is removably secured to plunger  32  using any suitable technique such as mating threads, keyed slots, locator pin or pins, friction engagement or other. The height of a plunger adapter and the height of a compression pad may be individually selected to conform to the anterior posterior dimensions of a patient and the length and extension capability of a plunger and compression unit. Compression pad  31  includes extensions such as extension  33  sized to engage a comparably sized socket such as socket  34  in any suitable plunger adapter such as plunger adapter  30 . The inner surfaces, surface  34 A and surface  34 B, of a plunger adapter socket such as socket  34  may include an adhesive or coating such as adhesive layer  35  with a preselected level of adhesion to maintain a limited engagement between a plunger adapter, such as adapter  30 , and a compression pad such as compression pad  31 , to produce a preselected level of decompression during each retraction of the plunger while performing automated chest compressions with minimal damage to the patient. Adhesive layer  35  may also be applied to compression pad surfaces  33 A and or  33 B. 
     Compression pad  31  is a generally incompressible pad configured to adapt to the shape of the patient&#39;s chest. A compression pad such as compression pad  31  may be formed of one or more layers such as first layer  31 A and second layer  31 B to optimize the application of compressive force to the patient. The proximal or upper end of the compression pad is a generally hard extension or socket such as extension layer  33  for engaging the plunger adapter. The first or central layer, layer  31 A may be a flexible and incompressible layer to conform to the shape of the patient&#39;s chest. The lower or distal end, second layer  31 B, of the compression pad is flexible and generally incompressible to adapt to the shape of the patient&#39;s chest and may include one or more flexible cups for creating one or more areas of vacuum between the compression pad and the patient&#39;s chest. 
     Suitable engagement mechanisms may be included in the plunger and the plunger adapter to provide a preselected level of chest expansion force in addition to chest compression force. A magnet may be provided in the distal end of the plunger and a corresponding magnet or ferrous material may be included in the proximal end of the plunger adapter to provide a preselected retention force between the plunger and the plunger adapter. The retention force is selected to provide some expansion force to the patient&#39;s chest between compressions without applying enough expansion force to the patient&#39;s chest to tear the patient&#39;s skin or underlying tissue. Similarly an electromagnet may be provided in distal end of the plunger to provide an adjustable level of retention force, or to provide timed release of the plunger adapter from the plunger. 
     As illustrated in  FIGS. 6 ,  7  and  8 , plunger adapter  40  includes socket  41  that is sized and dimensioned to engage extension  42  of compression pad  43 . Compression pad  43  may be removably secured to the chest of a patient as discussed above. To generate a predetermined decompression force  44  during the retraction of plunger  45 , magnets such as adapter magnet  40 M and compression magnet  43 M may be included in plunger adapter  40  and compression pad  43  to provide the predetermined retention force, such as force of attraction or magnetic force  46 , to hold compression pad  43  to plunger adapter  40  until the predetermined decompression force is exceeded. The predetermined level of decompression force is selected to be at a level below which, the chest tissue at force application location  18  will not be damaged before compression pad  43  releases from plunger adapter  40 . Any other suitable technique for providing a predetermined level of retention force  46  may be used such as electromagnetic attraction, frictional engagement or others. Any other suitable cooperative configurations of socket and extension may be used. 
     Referring now to  FIGS. 9 ,  10  and  11 , plunger adapter  50 , and compression pad  51  may adopt any suitable shape. Here, distal end  50 D of plunger adapter  50  is octagonal although any suitable regular or irregular shape may be used. Distal end  50 D includes socket  52  to engage proximal end  51 P of compression pad  51 . The distal end of compression pad  51 , end  51 D, may adopt any suitable shape regardless of the shape of the key on proximal end  51 P. Here, proximal end  51 P is keyed as a hexagon to conform to the shape of socket  52 . 
     Patient  1  illustrated in  FIG. 12  has electrode assembly  56  secured to chest  2 . Mechanical chest compression device  57  is oriented to apply compressions to the chest of patient  1 . Compression pad  56  includes chest compression monitor  58  used to provide feedback for manual CPR which is illustrated in greater detail in  FIG. 13 . The chest compression monitor is provided to detect compression depth and or rate according to Halperin, CPR Chest Compression Monitor, U.S. Pat. No. 6,390,996 issued May 21, 2002 incorporated herein by reference. 
     Plunger adapter  59  is sized and shaped to accommodate socket  62  which engages chest compression monitor or puck  58  as illustrated in  FIG. 14 . Chest compression monitors may also be separate and stand-alone from a compression pad and are known in the art as a puck. Stand-alone pucks may be adhered to the patient&#39;s chest, using adhesive  60  at the desired location  61 , for providing feedback for therapeutic chest compressions. An appropriately sized and shaped plunger adapter having a suitably sized and shaped socket  62  may be connected to the plunger of mechanical chest compression device  57  to prevent chest compression device from wandering, walking or otherwise providing chest compressions away from the desired location as discussed above. The plunger adapter is keyed to the size and shape of the puck and may be provided to accommodate pucks or chest compression monitors from any suitable manufacturer operating with any suitable sensor technology or combination of sensors such as accelerometers and or force sensors. 
     While the preferred embodiments of the devices and methods have been described in reference to the environment in which they were developed, they are merely illustrative of the principles of the inventions. The elements of the various embodiments may be incorporated into each of the other species to obtain the benefits of those elements in combination with such other species, and the various beneficial features may be employed in embodiments alone or in combination with each other. Other embodiments and configurations may be devised without departing from the spirit of the inventions and the scope of the appended claims.