Chest compression device

Abstract

A chest compression device includes a piston to apply compression to the sternum and incorporates leaf springs simultaneously driven by the piston to apply lateral compression to the thorax during chest compressions. A motor in the chest compression device provides motive power to cyclically extend and contract the piston to provide therapeutic chest compressions. One end of each leaf spring is operably connected to the piston and the other end of each leaf spring is secured to the backboard/base or to a support leg of the chest compression device such that during extension of the piston, each leaf spring is compressed against the device base or leg which causes the springs to flex and provide lateral compression of the patient's thorax in addition to the sternal compression of the piston.

Description

FIELD OF THE INVENTIONS

The inventions described below relate to the field of cardiopulmonary resuscitation (CPR) chest compression devices.

BACKGROUND OF THE INVENTIONS

Cardiopulmonary resuscitation (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 bag mask respiration, 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.

In efforts to provide better blood flow and increase the effectiveness of bystander resuscitation efforts, various mechanical devices have been proposed for performing CPR. Among the variations are pneumatic vests, hydraulic and electric piston devices as well as manual and automatic belt drive chest compression devices.

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.

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 Escudero, et al., Compression Belt System for Use with Chest Compression Devices, U.S. Pat. No. 7,410,470 (Aug. 12, 2008), show chest compression devices that compress a patient's chest with a belt. Our commercial device, sold under the trademark AUTOPULSE®, is described in some detail in our prior patents, including Jensen, Lightweight Electro-Mechanical Chest Compression Device, U.S. Pat. No. 7,347,832 (Mar. 25, 2008) and Quintana, et al., Methods and Devices for Attaching a Belt Cartridge to a Chest Compression Device, U.S. Pat. No. 7,354,407 (Apr. 8, 2008).

As mechanical compressions are performed by piston-based chest compression systems, the patient's rib cage hinges or shifts about the sternum resulting in lateral spreading of the thorax 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's chest toward the neck or moving down toward the patient's abdomen.

SUMMARY

The devices and methods described below provide for a chest compression device using a piston to apply compression to the sternum and incorporating leaf springs simultaneously driven by the piston to apply lateral compression to the thorax during chest compressions. A motor in the chest compression device provides motive power to cyclically extend and contract the piston to provide therapeutic chest compressions. One end of each leaf spring is operably connected to the piston and the other end of each leaf spring is secured to the backboard/base or to a support leg of the chest compression device such that during extension of the piston, each leaf spring is compressed against the device base or leg which causes the springs to flex and provide lateral compression of the patient's thorax in addition to the sternal compression of the piston.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the chest compression device engaging a patient.

FIG. 2 is an end view of the chest compression device ready to commence compressions.

FIG. 3 is an end view of the chest compression device at full compression.

FIGS. 4A, 4B and 4C are end views of the chest compression device with adjustable springs ready to commence compressions.

FIG. 5 is an end view of the chest compression device with dual springs ready to commence compressions.

FIG. 6 is an end view of the chest compression device with dual springs at full compression.

DETAILED DESCRIPTION OF THE INVENTIONS

FIG. 1 illustrates the chest compression device fitted on a patient 1. The chest compression device 6 applies compressions with the piston 7. The piston is disposed within compression unit 8 which is supported over the patient with a frame or gantry 9 having two legs 9L and 9R fixed to a backboard 10. Compression unit 8 is connected to legs 9L and 9R at hinges 13R and 13L. Leaf springs 11A and 11B are operably connected between piston 7 and either backboard 10 or to support legs 9L and 9R through hinges 13R and 13L. Springs 11A and 11B may be formed of a single layer of material or they may be formed of two or more layers or two or more parallel springs.

When disposed about the patient, the frame extends over thorax 2 of the patient so that the piston is disposed apposing sternum 2A to contact the patient's chest directly over the sternum, to impart compressive force on the sternum of the patient as shown in FIG. 2. Piston 7 may include a removable compression pad 14 adapted to contact the patient's chest. The chest compression device is controlled using controller 17 which is operated by a rescuer through interface 15, which includes a display to provide instructions and prompts to a rescuer and includes an input device to accept operating instructions from the rescuer.

As illustrated in FIG. 2, compression unit 8 is enclosed by housing 8H. Piston 7 is driven, either directly or indirectly, by motor 16 under control of controller 17 to extend and retract piston 7. Controller 17 may include one or more microprocessors such as microprocessor 17A. Cyclic extension and retraction of piston 7 causes cyclic exertion of compressive force 18 to patient's sternum 2A. Controller 17 actuates and controls operation of motor 16 and other elements or components of chest compression device 6. Controller 17 may include one or more sets of instructions, procedures or algorithms to control actuation and operation of the motor and other elements or components of device 6. Piston based chest compression devices often include one or more coiled springs around the piston to speed the retraction of the piston during the decompression phases of the chest compression-decompression cycles. Inclusion of springs 11A and 11B provide sufficient upward force to obviate the need for coiled springs for decompression.

Springs 11A and 11B are connected between piston 7 and legs 9L and 9R and the springs pass through a slot or other opening in hinges 13R and 13L such as slots 19A and 19B. Passage of the springs through slots 19A and 19B prevents the upper portions of the springs from flexing or bending during compression. Shoulders or other frictional elements such as shoulders 20 may be provided on, or attached to legs 9L and 9R to engage the springs and redirect the compressive force applied to the top of the springs down to the distal end of the springs where they engage the backboard or the legs. The redirection of force permits the lower or distal portion of each spring, distal portions 22A and 22B respectively, to flex or bow to apply lateral force during chest compression. During application of a compressive force such as force 18 to a patient's sternum, ribs 2B move as if hinged about sternum 2A. There is a reactive movement of ribs 2B which results in rotation of the ribs and lateral movement 23 of the ribs as shown. The extension of piston 7 to apply compressive force to the patient's sternum causes springs 11A and 11B to slide through slots 19A and 19B respectively and engage shoulders 20 and flex and apply lateral resistive force to the patient's ribs.

Referring now to FIG. 3, leaf springs 11A and 11B are connected between both piston 7 and legs 9L and 9R or backboard 10 such that extension of piston 7 causes leaf spring 11A and leaf spring 11B to form load bearing arch shape such as arch 26 to exert a lateral resistive force 27 against ribs 2B as illustrated.

To engage a patient in chest compression device 6 of FIG. 1, chest compression device 6 may be slid over patient 1 until the patient is oriented with piston 7 apposing sternum 2A. Alternatively, support legs 9L and 9R may be separated from backboard 10 at attachment points 28. Patient 1 is then oriented on backboard 10, support legs 9L and 9R are reengaged to backboard 10 with piston 7 apposing sternum 2A of patient 1. Chest compression device 6 may then be activated to provide chest compressions to patient 1.

Referring now to FIGS. 4A, 4B and 4C, chest compression device 30 enables springs 11A and 11B to be preloaded to accommodate patients of different sizes. Patient 1 of FIG. 4A has a large chest, patient 3 of FIG. 4B has a medium size chest and patient 4 of FIG. 4C has a small chest. Springs 11A and 11B of FIG. 4A are adjusted for minimal preload and distal ends 31 of the springs engage legs 9L and 9R at or near attachment points 28. This configuration results in little or no preload of the springs and minimal load bearing arch 32 when the piston is fully retracted. With patient 3 of FIG. 4B, the distal ends 31 of the springs engages legs 9L and 9R a first distance 34 away from attachment points 28. This intermediate preload position results in first preload arch 35 which adds to the load bearing arch created by the compression of the springs to engage the medium size chest of patient 3 during chest compressions. With patient 4 of FIG. 4C, the distal ends 31 of the springs engages legs 9L and 9R a second distance 37 away from attachment points 28. This maximum preload position results in second preload arch 38 which adds to the load bearing arch created by the compression of the springs to engage the small size chest of patient 4 during chest compressions.

Referring now to FIGS. 5 and 6, chest compression device 40 includes frame or gantry 41 supporting compression unit 42 and piston 44 to perform cyclic chest compressions. Primary springs 45 and 46 are oriented similar to springs 11A and 11B as discussed above. Primary springs 45 and 46 frictionally engage shoulders 47L and 47R respectively. Secondary springs 48 and 49 attach to piston 44 and frictionally engage secondary shoulders 50R and 50L respectively. Shoulders 51R and 50L are configured and oriented to enable secondary springs 48 and 49 to translate longitudinally and support and urge primary springs into a load bearing arch shape 52.

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.

Claims

1. A method for performing cardiopulmonary resuscitation on a patient, comprising: providing an automated chest compression device comprising a backboard,a support frame having two legs secured to the backboard, the two legs supporting a compression unit apposing the backboard,a motor enclosed within the compression unit, anda piston supported by the support frame above the backboard and operably connected to the motor, wherein the motor is configured to move the piston between a retracted position and an extended position;positioning the patient on the backboard with the patient's chest disposed beneath the piston;causing the motor to repeatedly actuate the piston in a compression-decompression cycle, wherein actuating comprises delivering a compressive force to the chest of the patient as the piston moves to the extended position; andproviding, by at least one spring operably secured to the support frame, an upward force on the piston for speeding the retraction of the piston during a decompression phase of the compression-decompression cycle.

2. The method of claim 1, wherein: the upward force is provided by the at least one spring, responsive to movement of the piston to the extended position to apply the compressive force, wherein the at least one spring flexes to form a compressed state; andproviding the upward force on the piston comprises, responsive to removal of the compressive force, providing the upward force by the at least one spring while the at least one spring returns to an uncompressed state, thereby assisting the piston in returning to the retracted position.

3. The method of claim 2, wherein the at least one spring comprises a leaf spring.

4. The method of claim 2, wherein the at least one spring comprises a first spring extending from the piston along a first leg of the two legs of the support frame and a second spring extending from the piston along a second leg of the two legs of the support frame.

5. The method of claim 4, wherein: the first spring connects, at an end opposite the piston, to the first leg; andthe second spring connects, at an end opposite the piston, to the second leg of the support frame.

6. The method of claim 4, wherein the first spring and the second spring each connect, at a respective end opposite the piston, to the backboard.

7. The method of claim 1, wherein: the automated chest compression device comprises a control unit operably connected to the motor and comprising a microprocessor; andcausing the motor to actuate the piston comprises causing the microprocessor to control operation of the motor to actuate the piston.

8. The method of claim 7, wherein the compression unit comprises the control unit.

9. The method of claim 1, wherein the automated chest compression device comprises a pad removably attached to an end of the piston and configured to press against the chest of the patient when the piston is in the extended position.

10. The method of claim 1, wherein the compression unit accepts at least a portion of the piston when the piston is in the retracted position.

11. A method for performing cardiopulmonary resuscitation on a patient, comprising: providing an automated chest compression device comprising a compression unit comprising a piston, anda motor configured to move the piston between a retracted position and an extended position, anda mounting structure comprising a base, anda support frame having two legs operably secured to the base, the two legs supporting the compression unit apposing the base,positioning the patient on the base with the patient's chest disposed beneath the piston;causing the motor to repeatedly actuate the piston in a compression-decompression cycle, wherein actuating comprises delivering a compressive force to the chest of the patient as the piston moves to the extended position; andproviding, by at least one spring operably secured to the mounting structure, an upward force on the piston for speeding the retraction of the piston during a decompression phase of the compression-decompression cycle.

12. The method of claim 11, wherein the at least one spring is operably secured to the base of the mounting structure.

13. The method of claim 11, wherein the at least one spring is operably secured to the support frame of the mounting structure.

14. The method of claim 11, wherein the two legs of the support frame are fixed to the base.

15. The method of claim 11, wherein the at least one spring comprises a leaf spring.

16. The method of claim 11, wherein the at least one spring comprises a first spring extending from the piston along a first leg of the two legs of the support frame and a second spring extending from the piston along a second leg of the two legs of the support frame.

17. The method of claim 16, wherein: the first spring connects, at an end opposite the piston, to the first leg; andthe second spring connects, at an end opposite the piston, to the second leg of the support frame.

18. The method of claim 11, wherein the at least one spring comprises: a first spring extending from the piston and connecting, at an end opposite the piston, to the base; anda second spring extending from the piston and connecting, at an end opposite the piston, to the base.

19. The method of claim 11, wherein: the automated chest compression device comprises a control unit operably connected to the motor and comprising a microprocessor; andcausing the motor to actuate the piston comprises causing the microprocessor to control operation of the motor to actuate the piston.

20. The method of claim 11, wherein the automated chest compression device comprises a pad removably attached to an end of the piston and configured to press against the chest of the patient when the piston is in the extended position.