Extended term patient resuscitation/ventilation system

An extended term resuscitation system includes a plurality of inflatable cuffs adapted to extend around separate portions of the anatomy of a patient (i.e. the chest, abdomen and legs) for enhancing the circulation when inflated/deflated periodically. A primary low-pressure-high-volume air compressor is in fluid communication with each of the cuffs through individual air handlers. The air handlers are formed with an inflation and a deflation diaphragm valve which, under the control of an electronic timer and a pneumatic circuit, connect the respective cuff to the output of the compressor for inflation or to the atmosphere for deflation. A secondary air compressor provides air under suitable pressure to the pneumatic circuit for the control of the diaphragm valves. As an option the operator may change the cyclical rate and cuff pressure. A ventilator provides oxygen to the patient in selected volumes or on demand.

FIELD OF THE INVENTION

This invention relates to an apparatus or system for providing cardiac and/or pulmonary resuscitation and more particularly to such a system that is automated and capable of enhancing a patient's circulation and ventilation for an extended period.

BACKGROUND OF THE INVENTION

State of the art methods and apparatus for providing external cardiac resuscitation are discussed to some extent in U.S. Pat. No. 5,806,512 (“'512 patent”). The '512 patent teaches the use of inflatable cuffs surrounding a patient's chest, abdomen and legs which are periodically inflated and deflated to force blood from the extremities to and through the heart with the chest and abdomen functioning in an out-of-phase relationship. Ventilation via a patient mask is also disclosed in the patent.

More recently a portable resuscitation/ventilation system using inflatable chest, abdominal and leg cuffs and a ventilator coupled to self-contained cylinders of compressed gas is described in international publication WO 2010/151278 A1 (“'278 pub.”) and disclosed on the web site AutoCPR.net. Solenoid operated valves, controlled by an electronic timer, connect the cuffs alternately to the compressed gas cylinders and to the ambient or atmosphere to inflate and deflate the cuffs in a timed sequence. For example, the chest and abdominal cuffs are operated in an out-of-phase sequence at a 30 cycles per minute rate, i.e., one second on (inflation) and one second off (deflation). The leg cuffs can be inflated and deflated at the same or a different rate. For example, the leg cuffs can be inflated continuously or inflated/deflated every fifth cycle of the chest cuff with the inflation period exceeding the deflation period. The portable gas supply is designed to provide adequate time to achieve the return of spontaneous circulation (ROSC) and patient transport to a hospital emergency department. A face mask and a tank of breathable gas provide ventilation for the patient. The resuscitator/ventilator of the '278 pub. is small enough to fit into a suitcase easily handled by a paramedic or other first responder. While it is believed to be cutting edge for its intended purpose, the use of compressed gas cylinders limits its operating time.

Recent clinical studies have demonstrated that the continued support of a patient's circulation (such as uninterrupted chest compression) after ROSC significantly improves the survival rate of patients after leaving the hospital. See, for example, the Journal of Emergency Medicine, 1008, Feb. 12, 2009 by M. Riscon, et al; the European Resuscitation Council Guideline for Resuscitation 2005 by A J Hadley, et al; Critical Care 2005, 9:287-290 by M H Weil and Shijie Sun; and Burst Stimulation Improves Hemodynamics during resuscitation etc. in Circulation: 2009, 2:57-62 by G. Walcott et al.

There is a need for a system/apparatus which will not only aid in achieving a patient's ROSC but in addition continue to support the patient's circulatory system over an adequate time period after ROSC to improve the out of hospital survival rates for patients suffering cardiac arrest or other serious heart problems.

SUMMARY OF THE INVENTION

A patient resuscitation system, in accordance with the present invention, includes a plurality of inflatable cuffs adapted to extend around separate portions of a patient's anatomy (e.g, chest, abdomen and legs) for increasing the patient's blood flow when periodically inflated/deflated (1) to achieve ROSC and subsequently (2) to continue the support of his/her circulatory system. A timer, such as the timer disclosed in the '278 pub., sets the inflation/deflation periods. Air for the inflation steps is provided by a primary low-pressure-high-volume-air-compressor connected to a volume chamber (i.e. to smooth out pressure fluctuations). A pneumatic circuit, including a pressurized gas source, such as a secondary compressor, provides a separate pneumatic control signal associated with each cuff bracketing each inflation period set by the timer. An air handler is individually connected between each cuff, the volume chamber and the atmosphere (or ambient) and responsive to the pneumatic control signals for inflating/deflating each cuff in accordance with the inflation/deflation periods set by the timer.

Each air handle preferably includes an inflation and a deflation diaphragm valve with the valves being located between the cuff, the volume chamber and the atmosphere, respectively. Preferably each diaphragm valve is normally open connecting the cuff to the volume chamber and to the atmosphere with each valve being arranged to close in response to the receipt of a control signal and open in the absence of a control signal. Accordingly, each cuff will be connected to the volume chamber for inflation purposes in the absence of a control signal being applied to the inflation diaphragm valve and in the presence of a control signal being applied to the deflation diaphragm valve closing off the cuff from the atmosphere and visa versa. Alternatively the diaphragm valves connecting the cuffs to the volume chamber can be closed independently of the operation of the timer.

In a preferred embodiment the inflation diaphragm valve, in the form of an air module, connects the associated cuff to the volume chamber when open and the deflation valve, in the form of an air relay, connects the associated cuff to the atmosphere when open.

Preferably there is a chest, abdominal, and two leg cuffs. The pneumatic circuit includes a control valve for each air handler. The control valves for the chest and abdominal cuffs have (1) an auto position (responsive to the timer) in which the control signals are directed to the inflation and deflation diaphragm valves alternately to inflate and deflate the chest and abdominal cuffs in an out-of-phase relationship and (2) an off position in which the pneumatic control signals are continuously (when present) applied to the inflation diaphragm valves to close the same. At the same time the deflation diaphragm valves are opened by the absence of the next control signal, resulting in a deflation mode for the cuffs in the off mode.

The control valve for the leg cuffs has an auto position in which the cuffs are alternately inflated and deflated in accordance with the dictates of the timer, an on position in which the cuffs are continuously inflated, and an off position in which the cuffs are continuously deflated.

Preferably the diaphragm valves are mounted in a common manifold block with the block providing fluid communication between each pair of (inflation and deflation) valves and the associated cuff.

A manually adjustable pressure/cycle rate valve may be coupled to the volume chamber and the timer for allowing the operator to select different cyclical rates (e.g. 30 or 20 cycles per minute) and different pressures (e.g. 150 or 100 mm Hg.) in the volume chamber. A ventilator, like the one disclosed in the '278 pub., may be included in the apparatus.

The face mask and cuffs may be disposable to comply with applicable health standards. The content of the '278 pub. (now U.S. Pat. No. 8,277,399) are incorporated in their entirety herein, by reference.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Overview of the System Operating in an Exemplary Mode

Referring now toFIG. 1a patient11, shown in reclining position, is fitted with a chest cuff10, abdominal cuff12and leg cuffs14. A primary low-pressure-high-volume-compressor16supplies air to a volume chamber16a(for smoothing out pressure fluctuations resulting from the periodic inflation of the cuffs). The volume chamber is connected to air handlers18(chest) and20(abdomen) via lines16band to air handlers22(legs) via line16cand back flow valve64, to be described. A suitable compressor may be obtained from the Parker Hannifin Corporation under part no. 737-23-01. An adjustable flow restrictor16dconnected between the compressor and the volume chamber (in line16e) controls the flow rate to the volume chamber to say about 150 l/min. A pressure compensated relief valve (to be described) controls the volume chamber pressure, e.g., 2-3 psi. The individual air handlers are mounted in a common manifold block23to supply air, under the moderate volume chamber pressure, to the several cuffs through lines10a,12a, and14a(via quick disconnect couplings10b,12band14b), as shown. A source of pneumatic control signals, such as a secondary air compressor26, supplies a moderate control signal pressure, e.g. 15 psi., to a solenoid/pneumatic circuit28described in connection withFIG. 7. The circuit28responds to control signals routed through solenoid valves (hereinafter sometimes simply referred to as “solenoids”), under the control of a timer24(such as the solenoids and timer disclosed in FIG. 4B of the '278 pub.), to actuate the air handlers in accordance with the dictates of the timer. A ventilator30provides breathable gas, such as oxygen, to the patient11through a conventional face mask30aand quick disconnect coupling30b′ in the manner disclosed in the '278 pub.

In an automated exemplary mode, the chest and abdominal cuffs are continuously inflated and deflated in an out of phase relationship in one second intervals, that is, one second inflated and one seconded deflated, while the leg cuffs are inflated and deflated in 10 second and 2 second intervals, respectively. SeeFIG. 14for a graphic depiction of this exemplary mode of operation. A cyclical rate/pressure switch (to be described) allows an operator, to set the rate and volume chamber pressure. For example, the rates may be set at 30 cycles/minute and the volume chamber pressure at 150 mmHg for resuscitation purposes and at 20 cycles/minute with the pressure at 100 mmHg for circulation support. The solenoid/pneumatic circuit28incorporates manually operated ball valves allowing an operator to override the timer and close the inflation diaphragm valves of the air handlers for all of the cuffs and, if desired, continuously apply a control signal to the leg cuffs' deflation diaphragm valve while isolating the control signal from the leg cuffs' inflation diaphragm valve, leaving the left cuffs continuously inflated.

Discussion of the Air Handlers

All of the air handlers are identical with the chest cuff air handler18which is shown in a cross sectional view inFIGS. 2-4. The air handler18comprises an air module32, in the form of an inflation diaphragm valve, and an air relay34, in the form of a deflation diaphragm valve, mounted on a common manifold block23. The air modules for the abdomen and legs cuffs are identified by the reference numerals36and40, respectively, inFIGS. 1 & 7, while the air relays for the abdomen and leg cuffs are identified by the reference numerals38and42, respectively, in those figures.

Referring again toFIGS. 2-4, the air module32, having an outer body32aand an inner tubular member32b, is secured within a bore23ain the block23. The tubular member32bterminates at its distal end32cwithin the longitudinal bore23aof the block and at its proximal end32da short distance from the inner surface of an end cap32e, as shown. The longitudinal bore23aterminates in the quick disconnect coupling10bfor transferring air to and from the chest cuff. A flexible diaphragm32f, mounted within the body32a, is normally spaced from the proximal end32dof the tubular member as is shown inFIG. 2. A tubular inlet32gof the inflation diaphragm valve or air module is arranged to be connected to the volume chamber16avia the hose connection16b(FIG. 1). A control signal inlet nipple32his arranged to conduct pneumatic control signals, emanating from the secondary compressor, to a chamber32i, to force the diaphragm32fagainst the proximal end32dof the member32band close the air module or inflation diaphragm valve, as will be discussed in more detail.

The air relay34(deflation diaphragm valve), mounted to the block23as shown, includes a tubular member34aextending (at its distal or inlet end34b) from a lateral bore23bin the manifold block (which terminates at outlet23cin the common longitudinal bore23a) to a proximal end34c. The proximal end is normally spaced a short distance from a flexible diaphragm34dwith an annular volume34e, surrounding the tube34a, which opens to the atmosphere or ambient via an outlet orifice34fto exhaust the chest cuff when the diaphragm valve is open. A nipple34gis arranged to conduct (pressurized) control signals to a chamber34hwhich closes the deflation diaphragm valve.

The air handler18is shown in its normal state inFIG. 2(with both diaphragm valves open in the absence of the application of control signals) so that air is free to flow between the cuff, the volume chamber and the atmosphere.

FIG. 3shows the same air handler with the diaphragm valves of the air module and air relay open and closed, respectively, inflating the chest cuff.FIG. 4shows the air handler with the diaphragm valves of the air module and the air relay closed and open, respectively deflating the cuff.

SeeFIGS. 5a,5b,6aand6bfor front and perspective views of the air modules and air relays, respectively.

Discussion of the Pneumatic/Solenoid Circuitry and Accessory Components

Referring now toFIG. 7which represents the pneumatic/solenoid circuit28and ventilator30depicted inFIG. 1. The ventilator, chest, abdomen and leg solenoids are given reference numerals44,46,48and50and correspond to solenoids 140-1, 140-2, 140-3 and 140-4 in FIG. 1A of the '278 pub., respectively. The secondary compressor26supplies a constant pressurized (say 15 psi) control signal on line26a. The solenoid ports46a,48aand50aare open to the atmosphere and serve the purpose of evacuating lines connected thereto by the solenoids.

The Pneutronics Division of Parker Hannifin Corporation offers such solenoids under the X-valve designation.

The pneumatic circuit includes manually adjustable ball valves52,54and56with solenoid receptive ports S for accommodating automatic operation of the system in cooperation with air module interrelated ports A. Closure ports C provide closure of the air modules in cooperation with the control signal ports A, as will be explained. Ball valve56includes an additional function of allowing the continuous inflation of the leg cuffs by preventing control signals from reaching the air module40. An exhaust diaphragm valve43, when closed due to the absence of a control signal applied to nipple43g, allows the control signal passing through the restrictor26jto close the air relay42allowing the cuffs to inflate. Air bleed orifice41aalso plays a part in controlling the operation of exhaust valve43by exhausting the pressure present at nipple43gwhen the associated control signal is absent.

As discussed above, in an exemplary mode, the chest and abdomen cuffs are inflated and deflated alternately. As a result, when the chest cuff solenoid46is actuated to connect the pneumatic line26bto the pressurized line26a, the abdomen solenoid48is inactivated disconnecting the line26cfrom the control signal source, i.e. line26a. The control signal applied to nipple38gof air relay38closes off the abdomen cuff from the atmosphere while the abdomen cuff is connected to the volume chamber16aas a result of the absence of a control signal being applied to the nipple36hof the abdomen air module36, thereby allowing the abdomen cuff to inflate. At the same time the control signal on line26bis routed through ports S and A of the three-way valve52to the nipple32hof the chest air module via line26e. The presence of the control signal closes off the chest cuff from the volume chamber, while the air relay34is open due to the absence of a control being applied to nipple34g, connecting the chest cuff to the atmosphere.

When the abdomen solenoid is activated the control signal is applied to the chest air relay34(via nipple34g) and to abdomen air module36(via line26fand nipple36h) disconnecting the abdomen cuff from the volume chamber and the chest cuff from the atmosphere. The absence of a control signal being applied to the air relay38and the air module32results in inflating the chest cuff and deflating the abdomen cuff.

The ball valves52and54can be rotated to connect the A ports to the C ports for closing the chest and abdominal air modules by connecting line26ato the nipples32hand36h, thereby overriding the operation of the respective solenoid valves. In response to the absence of the next control signal the air relays34and38will open to connect the associated cuffs to the atmosphere resulting in the deflation of the cuffs.

Since the leg cuff(s)' air handler operates independently, several accessories, namely exhaust valve43, bleed orifice41aand flow restrictor26jare needed for its control. The exhaust valve43has its input nipple43gconnected in parallel with the input nipple to the leg cuff(s)' air module as shown. As a result when solenoid50is activated (as shown) a control signal is applied to the input nipples40hand43gof the air module40and exhaust valve43, respectively, via ports S and A in the ball valve56to close the air module and open the exhaust valve. At the same time the control signal pressure at the input nipple42gof air relay42is exhausted to the atmosphere through exhaust valve43allowing this relay to open. Restrictor26iserves the function of allowing the exhaust valve, when open, to drop the pressure at the nipple42gthereby removing the control signal to that relay and allowing it to open, deflating the cuffs The restrictor26iaids in the accomplishment of this function by restricting the flow through line26a.

When the solenoid50is inactivated (or open) the control signal disappears from the air module40and the exhaust valve43. This action connects the air module to the volume chamber, closes the exhaust valve43and applies the control signal (say 15 psi), via restrictor26j, to the air relay42. This control signal closes the air relay42and disconnects the leg cuff(s) from the atmosphere, allowing the cuff(s) to inflate.

Cross-sectional views of the ball valves52,54and56are shown inFIGS. 8a-8cwith the ports S, A and C.FIG. 8c, illustrates the configuration of valve56in a position to disconnect the leg cuff(s)' air module40and the exhaust valve43from the source of control signals. This action allows the bleed orifice41ato bleed off any residual pressure existing at the inlet nipples40hand43g(1) causing the air module to open connecting the cuff to the volume chamber and (2) closing the exhaust valve43. At the same time the pressurized control signal flowing through restrictor26jcloses the air relay42disconnecting the cuff from the atmosphere. As a result the cuff(s) are continuously inflated as long as the valve56is set in this position as discussed above. Suitable ball valves may be acquired from the Hy-Lok Corporation under its 112 series designation.

Referring now toFIGS. 9aand9b, the exhaust valve43is in the form of a poppet valve having an inlet43f(arranged to be connected to the nipple42g,FIG. 7), an axially moveable shaft43abiased into a closed position (via spring43b) so that O ring43cseats against valve seat43d. Outlet43his open to the atmosphere. A flexible diaphragm43eis spaced between the proximal end43a′ of the shaft43aand a control signal receptive cavity43g′ in fluid communication with the control signal nipple43g. Pressure of the control signal in the cavity43g′ forces the diaphragm against the proximal end of the shaft43aand opens the valve connecting the inlet43fto the outlet43hi.e. the atmosphere.

The backflow or check valve64, illustrated inFIGS. 10aand10b, includes a housing64ain which are mounted a valve plate64b, having a plurality of central openings64c, and a valve stem64dwith a deformable head64e. An inlet64fis arranged to be connected to the volume chamber16awhile the outlet64gis arranged to be connected to the inlet32gof the air module40via line16c. SeeFIGS. 1&7. The operation of such a simple backflow valve is simple and will be well understood by those skilled in the art. Its purpose is to isolate the leg cuff(s) from the volume chamber while the chest and abdominal cuffs are being inflated and thereby eliminate pressure fluctuations in the cuffs which might otherwise occur.

Discussion of the Selector Switch for Setting the Cyclical Rate and Volume Chamber Pressure

Referring now toFIGS. 7,11a-11cand12a-12b, the rotary selector switch60performs two separate functions, namely providing one of two cyclical rates e.g. 30 cycles per minute (“cpm”) or 20 cpm and one of two volume chamber (cuff) pressures e.g. 150 mm or 100 mm of Hg. The switch has a first rotor assembly60awith a shaft60band a pneumatic inlet60c. The shaft60bwhen rotated, via manual actuated knob60d(FIG. 11a), connects the inlet60cto one of two relief valves60eand60f(FIG. 7), via pneumatic outlet nipples60kand60l, respectively. The relief valves may be set, for example, at 150 and 100 mmHg, respectively. The inlet60cis connected to the dome62f(via inlet62e) of a compensated relief valve62(FIG. 12b) secured to the volume chamber16a(FIG. 1) through an inlet62aand a fitting63(FIG. 7). Referring again toFIG. 12b, the poppet62bcarries a diaphragm62cpositioned between the atmosphere (via outlet62d) and the inlet62a. The pressure in the volume chamber cannot exceed the pressure in line63, as will be apparent to those skilled in the art.

Referring again toFIG. 11cthe rotary switch60includes a second rotor assembly60gcarrying a magnet60hwhich, when placed in close proximity to a Hall1C sensor60i, sends a digital signal, via output60j, to the timer to change the cyclical rate as will be explained with respect to a modification of the timer shown inFIG. 13.

Discussion of the Modification of the '278 Pub. Timer

A modification of the timer disclosed in FIG. 4B of the '278 pub., necessary to respond to the digital signal from the rate selector60(FIG. 8b), is illustrated inFIG. 13. The time base 140-A (oscillator components C2, R18) of FIG. 4B ('278 pub.) is deleted and replaced by (1) a crystal oscillator/divide by 256 (reference No.65inFIG. 13, herein) and (2) a dual J-K divide by 2 or 3 (reference66inFIG. 13). The particular divider ratio activated is determined by the digital signal received on input66afrom the output on line60iof the rate selector switch60. The divider67comprises the oscillator/divider U1from the '278 pub. Dividers U5A and U5B constitute the dual J-K dividers.

Discussion of the Ventilator Components

Referring again toFIG. 7, the ventilator is of the same type as described in the '278 pub. with a regulated oxygen supply30bconnected to a regulator30cand a tidal volume control unit30d. The output of the regulator30cis connected to the mask30athrough the tidal volume control unit30dand solenoid valve44. The timer integrates the ventilation cycle with the abdomen compression cycles so as to operate without interruption. The ventilation cycle is timed to synchronize during abdominal compressions to prevent gastric insufflations and to deliver the correct tidal volume of oxygen during each compression of the abdomen. The tidal volume control unit includes a five position rotary switch (labeled30e) within the control unit30dwhich may be calibrated to deliver 400 ml, 600 ml, 800 ml and 1000 ml of breathable gas such as oxygen. A fifth position is the demand mode for use when the patient is breathing spontaneously. A gage30fmeasures the pressure. In a preferred mode the oxygen is delivered for one second during every second cycle of the abdomen cuff inflation, followed by three seconds off.

CONCLUSION

There has been disclosed a simple and versatile system or apparatus for not only aiding a patient undergoing cardiac arrest to achieve the return of spontaneous circulation but to continue supporting the patient's circulation to improve his/her chances of long term survival after ROSC has been achieved. The diaphragm valves and air compressors are highly reliable and efficient, requiring little maintenance. It is to be noted that the various air pressures discussed above are by way of example only. Obviously the volume chamber pressure has to be adequate to properly inflate the cuffs; by the same token the control signal pressure must be sufficiently greater than the volume chamber pressure to insure closure of the diaphragm valves in the configuration as shown. While the apparatus is illustrated as operating in an automated mode with a higher cuff pressure and cyclical rate to achieve ROSC and with a lower pressure and cyclical rate subsequently, the invention is not so limited.

It is also to be noted that while the air modules and air relays are shown as being normally open and closed in response to the application of a control signal, one or both may be configured to be normally closed and opened in response to the control signal. As an example, the air relays may have a configuration similar to the exhaust valve43so that in the absence of a control signal the cuffs will be inflated and in response to a control signal the cuffs will be deflated. The system may be mounted on a wheeled cart for portability in a hospital or used in a paramedic's truck with compressors operating off of the truck's electrical system. While those skilled in the art may discover modifications or even improvements to the disclosed apparatus it is believed that such modifications will not involve a departure from the scope and spirit of our invention as defined in the appended claims.