INTEGRATED RESUSCITATION

Abstract

Apparatuses, systems and methods are provided that may include a system for patient monitoring and defibrillation. The system may include at least two defibrillation electrodes. The system may further include a first unit for physiological monitoring of a patient, including ECG monitoring circuitry for monitoring ECG of the patient. The first unit may store CPR chest compression data. The system may further include a second unit, separate from the first unit, which may communicatively couple with the first unit, for providing defibrillation pulses to the patient. The second unit may include a processor, communicatively coupled with the at least two defibrillation electrodes, for providing defibrillation pulses to the patient via the at least two defibrillation electrodes.

Claims

1-20. (canceled)

21. A patient monitoring and defibrillation system, comprising: at least two defibrillation electrodes; a first unit configured for physiological monitoring of a patient, comprising ECG monitoring circuitry configured for monitoring ECG of the patient, and the first unit configured to store CPR chest compression data in a memory of the first unit; and a second unit, separate from and configured to communicatively couple with the first unit, configured for providing defibrillation pulses to the patient, the second unit comprising: a processor, communicatively coupled with the at least two defibrillation electrodes, for providing defibrillation pulses to the patient via the at least two defibrillation electrodes.

22. The system of claim 21, wherein the second unit is configured to wirelessly couple with the first unit.

23. The system of claim 22, wherein the second unit is configured to wirelessly couple with the first unit via Bluetooth.

24. The system of claim 21, wherein the second unit comprises a defibrillator.

25. The system of claim 24, wherein the second unit is configured to provide a defibrillation pulse at an energy of 200 joules.

26. The system of claim 21, wherein the second unit comprises buttons for control of the second unit.

27. The system of claim 21, wherein the first unit is configured to be capable of functioning without being electrically coupled to the second unit.

28. The system of claim 21, wherein the first unit comprises a first battery and wherein the second unit comprises a second battery.

29. The system of claim 21, wherein the first unit is configured to store recorded information collected during use of the first unit in a memory of the first unit.

30. The system of claim 29, wherein the recorded information comprises the chest compression data.

31. The system of claim 29, wherein the recorded information comprises voice data.

32. The system of claim 29, wherein the recorded information comprises ECG data.

33. The system of claim 21, wherein the first unit is configured to be communicatively coupled with a pulse oximetry system.

34. The system of claim 21, wherein the first unit is configured to be communicatively coupled with a blood pressure measurement device.

35. The system of claim 21, wherein the system is configured to be communicatively coupled with an accelerometer used in obtaining measurements related to chest compressions.

36. The system of claim 21, wherein the system is configured to provide at least one of: visual prompts and audio prompts relating to performance of CPR chest compressions.

37. The system of claim 36, wherein the system provides the visual prompts via a display.

38. The system of claim 36, wherein the system provides the audio prompts via a speaker.

39. The system of claim 36, wherein the at least one of: visual prompts and audio prompts relate to CPR chest compression timing.

40. The system of claim 36, wherein the at least one of: visual prompts and audio prompts relate to CPR chest compression force to be applied.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG. 1 is a drawing of a defibrillation electrode pad according to the invention, positioned over the chest of a patient.

[0025] FIG. 2 is a view of the front display panel of a resuscitation control box according to the invention that houses electronic circuitry and provides audible and visual prompting.

[0026] FIG. 3 is a cross-sectional drawing of the defibrillation electrode pad of FIG. 1 taken along line 3-3.

[0027] FIG. 4 is a cross-sectional drawing of the defibrillation pad of FIG. 1 taken along line 4-4.

[0028] FIG. 5 is a circuit diagram illustrating the circuit interconnections between the defibrillation electrode pad of FIG. 1 and the resuscitation control box of FIG. 2.

[0029] FIGS. 6A and 6B are a flowchart illustrating the initial routine of a resuscitation system according to the invention.

[0030] FIGS. 7A, 7B, and 7C are a flowchart illustrating the “circulation help” routine of the resuscitation system.

[0031] FIG. 8 is a flowchart illustrating the “breathing help” routine of the resuscitation system.

[0032] FIGS. 9A and 9B are a flowchart illustrating the “airway help” routine of the resuscitation system.

[0033] FIG. 10 is a block diagram of the electronic circuitry of an alternative implementation.

[0034] FIG. 11 is a drawing of the defibrillation electrode assembly of another alternative.

[0035] FIGS. 12A-12C are diagrammatic views of three possible implementations of first and second units.

[0036] FIGS. 13A and 13B are drawings of two alternative implementations of the electrode pad assembly in which a handle is provided for the rescuer.

DETAILED DESCRIPTION

[0037] There are a great many possible implementations of the invention, too many to describe herein. Some possible implementations that are presently preferred are described below. It cannot be emphasized too strongly, however, that these are descriptions of implementations of the invention, and not descriptions of the invention, which is not limited to the detailed implementations described in this section but is described in broader terms in the claims.

[0038] With reference to FIG. 1, a defibrillation electrode pad 10, which includes high-voltage apex defibrillation electrode 12 and high-voltage sternum defibrillation electrode 14, is placed on the patient's chest 16 and includes a region 18 on which a user may press to perform CPR. Legends on pad 10 indicate proper placement of the pad with respect to the patient's collarbones and the chest centerline and the proper placement of the heel of the rescuer's hand.

[0039] A low-profile button panel 20 is provided on the electrode assembly. Button panel 20 has buttons 22, including buttons A (Airway Help), B (Breathing Help), C (Circulation Help) and PAUSE, and may also include adjacent light emitting diodes (LEDs) 24 that indicate which button has been most recently pressed. Button panel 20 is connected by a cable 23 to a remote resuscitation control box 26, shown in FIG. 2. Button panel 20 provides rigid support underneath buttons A, B, C, and PAUSE against which the switches can be pushed in order to ensure good switch closure while the electrode rests on a patient. Button panel 20 includes components that make electrical contact with silver/silver-chloride electrical circuit components screen-printed on a polyester base of defibrillation electrode pad 10, as is described in detail below.

[0040] A pulse detection system based on shining light through the patient's vascular bed, e.g., a pulse oximetry system 52, is incorporated into defibrillation electrode pad 10. Pulse oximetry system 52 includes a red light-emitting diode, a near-infrared light-emitting diode, and a photodetector diode (see FIG. 5) incorporated into defibrillation electrode pad 10 in a manner so as to contact the surface of the patient's chest 16. The red and near-infrared light-emitting diodes emit light at two different wavelengths, which is diffusely scattered through the patient's tissue and detected by the photodetector diode. The information obtained from the photodetector diode can be used to determine whether the patient's blood is oxygenated, according to known noninvasive optical monitoring techniques.

[0041] In another implementation, the pulse detection system is a phonocardiogram system for listening to the sound of the victim's heart, rather than a pulse oximetry system. The phonocardiogram system includes a microphone and an amplifier incorporated within the electrode pad. Because a heart sound can be confused with microphone noise, the signal processing that must be performed by the microprocessor inside the control box will be more difficult in connection with a phonocardiogram system than in connection with a pulse oximetry system. Nevertheless, there are programs available that can enable the microprocessor to determine whether an ECG signal is present as opposed to microphone noise.

[0042] Pulse oximetry is a well-developed, established technology, but it requires good contact between the light sources and the victim's skin so that light can shine down into the victim's vascular bed. Many victims have lots of chest hair, which can interfere with good contact. It may be desirable for different types of electrode pads to be available at a given location (one having a pulse oximetry system and one having a phonocardiogram system) so that a rescuer can select an appropriate electrode pad depending on the nature of the victim.

[0043] In another implementation, instead of providing a low-profile button panel, a button housing can be provided that is affixed to an edge of the defibrillation electrode. The housing may be in the form of a clamshell formed of single molded plastic element having a hinge at an edge of the clamshell around which the plastic bends. The two halves of the clamshell can be snapped together around the electrode assembly.

[0044] The resuscitation control box (FIG. 2) includes an internal charge storage capacitor and associated circuitry including a microprocessor, an further includes off/on dial 28, and a “READY” button 30 that the rescuer presses immediately prior to application of a defibrillation shock in order to ensure that the rescuer is not in physical contact with the patient. The microprocessor may be a RISC processor such as a Hitachi SH-3, which can interface well with displays and keyboards, or more generally a processor capable of handling DSP-type (digital signal processing) operations.

[0045] The resuscitation control box has printed instructions 32 on its front face listing the basic steps A, B, and C for resuscitating a patient and giving basic instructions for positioning the defibrillation electrode pad on the patient. A speaker 32 orally prompts the user to perform various steps, as is described in detail below.

[0046] For example, the resuscitation control box instructs the user, by audible instructions and also through a display 34 on the resuscitation control box, to check the patient's airway and perform mouth-to-mouth resuscitation, and if the patient's airway is still blocked, to press the A (Airway Help) button on the button panel (FIG. 1), upon which the resuscitation control box gives detailed prompts for clearing the patient's airway. If the patient's airway is clear and the patient has a pulse but the patient does not breathe after initial mouth-to-mouth resuscitation, the resuscitation control box instructs the user press the B (Breathing Help) button, upon which the resuscitation control box gives detailed mouth-to-mouth resuscitation prompts. If, during the detailed mouth-to-mouth resuscitation procedure, the rescuer checks the patient's pulse and discovers that the patient has no pulse, the resuscitation control box instructs the user to press the C (Circulation Help) button.

[0047] During the circulation procedure, the resuscitation control box receives electrical signals from the defibrillation electrodes and determines whether defibrillation or CPR should be performed. If the resuscitation control box determines that defibrillation is desirable, the resuscitation control box instructs the user to press the “ready” button on the resuscitation control box and to stand clear of the patient. After a short pause, the resuscitation control box causes a defibrillation pulse to be applied between the electrodes. If at any point the resuscitation control box determines, based on the electrical signals received from the electrodes, that CPR is desirable, it will instruct the user to perform CPR.

[0048] Thus, the key controls for the system are on the electrodes attached to the patient rather than the resuscitation control box. This is important because it enables the rescuer to remain focused on the patient rather than the control box. The resuscitation control box gets its information directly from the electrodes and the controls on the electrodes.

[0049] The resuscitation control box can sense electrical signals from the patient's body during pauses between CPR compressions. Also, as is described below, a compression-sensing element such as an accelerometer or a force-sensing element is provided in the region of the defibrillation electrode pad on which the user presses to perform CPR. The purpose of the compression-sensing or force-sensing element is to allow the resuscitation control box to prompt the user to apply additional compression or force, or to prompt the user to cease CPR if the user is performing CPR at an inappropriate point in time.

[0050] Referring to FIG. 4, in one implementation, each electrode 12, 14 (only electrode 12 is shown) of defibrillation electrode pad 10 includes a polymer-based ink containing a silver/silver-chloride suspension, which is screen-printed on a polyester or plastic base 36. The ink is used to carry the defibrillation current. The screen-printing process first involves applying a resist layer to the polyester base 36. The resist layer is basically a loose mesh of nylon or the like, in which the holes have been filled in at some locations in the mesh. Then, the silver/silver-chloride ink is applied as a paste through the resist layer in a squeegee-like manner. The ink squeezes through the screen and becomes a solid layer. The ink may then be cured or dried. The silver/silver-chloride ink provides good conductivity and good monitoring capabilities.

[0051] Thus, the ink can be applied as pattern, as opposed to a solid sheet covering the entire polyester base. For example, U.S. Pat. No. 5,330,526 describes an electrode in which the conductive portion has a scalloped or daisy shape that increases the circumference of the conductive portion and reduces burning of the patient. A conductive adhesive gel 38 covers the exposed surface of each electrode.

[0052] In addition, electrical circuit components are also be screen printed on the base, in the same manner as flat circuit components of membrane-covered, laminated panel controls.

[0053] Referring to FIG. 3, a rigid piece 40 of hard plastic, such as PVC or polycarbonate, is laminated beneath substrate 36 and supports buttons A, B, C, and PAUSE. The rigid plastic piece 40 is glued onto substrate 36. Buttons A, B, C, and PAUSE consist of small metal dome snap-action switches that make contact between an upper conductive ink trace 42 and lower conductive ink traces 44, 46, 48, and 50. Buttons A, B, C, and PAUSE serve as controls that can be activated by the user that are physically located either on or immediately adjacent to the electrode assembly itself. Each of buttons A, B, C, and PAUSE may be associated with an adjacent light-emitting diode (LED). For example, LEDs may be glued, using conductive epoxy, onto silver/silver-chloride traces on substrate 36. An embossed polyester laminate layer 54 covers conductive ink trace 42 of buttons A, B, C, and PAUSE, and a foam layer 56 is laminated beneath rigid plastic piece 40.

[0054] Referring again to FIG. 4, defibrillation electrode pad 10 includes an extension piece that is placed directly over the location on the patient's body where the rescuer performs chest compressions. This extension piece includes substrate 36, and a semi-rigid plastic supporting member 58 laminated underneath substrate 36 that covers the chest compression area. Semi-rigid supporting member 58 provides somewhat less rigidity than rigid plastic piece 409 provided at the location of buttons A, B, C, and PAUSE (illustrated in FIG. 3).

[0055] In implementations having a force-sensing element, a polyester laminate 60, and a force-sensing resistor having two layers of carbon-plated material 62 and 64, are laminated between polyester substrate 36 and semi-rigid supporting member 58. A suitable construction of the force-sensing resistor is illustrated in the FSR Integration Guide & Evaluation Parts Catalog with Suggested Electrical Interfaces, from Interlink Electronics. The electrical contact between the two carbon-plated layers of material increases with increased pressure, and the layers of force-sensing resistive material can provide a generally linear relationship between resistance and force. Conductive ink traces 66 and 68 provide electrical connections to the two layers of the force-sensing resistor.

[0056] During chest compressions, the rescuer's hands are placed over the extension piece, and the force-sensing resistor of the extension piece is used to sense the force and the timing of the chest compressions. The force-sensing resistor provides information to the resuscitation control box so that the resuscitation control box can provide the rescuer with feedback if the rescuer is applying insufficient force. The resuscitation control box also provides coaching as to the rate at which CPR is performed. In certain situations, the resuscitation control box indicates to the rescuer that CPR should be halted because it is being performed at an inappropriate time, such as immediately prior to application of a defibrillation shock when the rescuer's hands should not be touching the patient, in which case the resuscitation control box will also indicate that the rescuer should stay clear of the patient because the patient is going to experience a defibrillation shock.

[0057] As is noted above, during CPR the rescuer pushes on the patient's chest through the extension piece in the vicinity of the electrodes. If the resuscitation control box were to perform analysis during the chest compressions, the chest compressions would be likely to affect the sensed electrical rhythm. Instead, during the pauses between sets of compressions (for example, the pause after every fifth chest compression), the resuscitation control box can perform an electrocardiogram (ECG) analysis. The resuscitation control box might discover, for example, that the patient who is undergoing CPR is experiencing a non-shockable rhythm such as bradycardia, in which case the CPR is required in order to keep the patient alive, but then the resuscitation control box may discover that the rhythm has changed to ventricular fibrillation in the midst of CPR, in which case the resuscitation control box would instruct the rescuer to stop performing CPR so as to allow the resuscitation control box to perform more analysis and possibly apply one or more shocks to the patient. Thus, the rescuer is integrated into a sophisticated scheme that allows complex combinations of therapy.

[0058] In another implementation, a compression-sensing element such as an accelerometer may be used in place of a force-sensing element. The accelerometer, such as a solid-state ADXL202 accelerometer, is positioned at the location where the rescuer performs chest compressions. In this implementation, the microprocessor obtains acceleration readings from the accelerometer at fixed time intervals such as one-millisecond intervals, and the microprocessor integrates the acceleration readings to provide a measurement of chest compression. The use of an accelerometer is based on the discovery that it is more important to measure how deeply the rescuer is compressing the chest than to measure how hard the rescuer is pressing. In fact, every victim's chest will have a different compliance, and it is important that the chest be compressed about an inch and a half to two inches in a normal sized adult regardless of the victim's chest compliance.

[0059] FIG. 5 is a circuit diagram illustrating the circuit interconnections between the defibrillation electrode pad of FIG. 1 through the cable to the resuscitation control box of FIG. 2. Sternum electrode 14 is connected to HV+ at the resuscitation control box, and apex electrode 12 is connected to HV−. A ground GND is connected to the upper conductive ink trace of buttons A, B, C, and PAUSE and to one of the layers of the force-sensing resistor. The other layer of the force-sensing resistor is connected to CPR FORCE, and the lower conductive ink traces associated with buttons A, B, C, and PAUSE are connected to BUTTON_DETECT through resistors R1, R2, R3, and R4. As an alternative to the use of a force-sensing resistor, a compression-sensing accelerometer 76 may be employed, in which case CPR FORCE is replaced by CPR_ACCEL connected to accelerometer 76. Red light-emitting diode 70, near-infrared light-emitting diode 72, and photodetector diode 74 of the pulse oximetry system are connected to RLED, ILED, and ISENSE respectively, as well as ground AGND. As an alternative to the use of a pulse oximetry system, a phonocardiogram system may be employed, in which case RLED, ILED, and ISENSE is replaced by SENSE connected to microphone 78 and amplifier 80.

[0060] FIGS. 6-9 illustrate the routine of the resuscitation system, which is based on steps A, B, and C (airway, breathing, and circulation). Because step C includes defibrillation as well as chest compressions, all of the aspects of resuscitation are tied together in one protocol (actually, if defibrillation were considered to be a step D distinct from step C, the sequence of steps would be A, B, D, C).

[0061] The first thing the rescuer must do upon arriving at the patient is to determine whether the patient is unconscious and breathing. The rescuer opens the patient's airway, administers breaths to the patient if the patient is not breathing, and checks to determine whether a pulse is present. If there is no pulse, rather than perform chest compressions as in standard CPR, the rescuer allows the resuscitation control box to analyze the patient's electrical rhythm, and if the resuscitation control box determines that the rhythm is shockable, the resuscitation control box causes one or more shocks to be applied to the patient, and then the rescuer performs chest compressions. Thus, there is provided a first response system that can keep the patient viable until an advanced life support time arrives to perform advanced techniques including pacing, further defibrillation, and drug therapy.

[0062] If the resuscitation control box determines that it should apply one or more defibrillation shocks to the patient, it is important that the rescuer not be anywhere near the patient when the shocks are applied to the patient. Prior to application of each shock, the resuscitation control box instructs the rescuer to please press the “ready” button when everybody is clear of the patient. The pressing of the “ready” button verifies that the rescuer's hands are off of the patient.

[0063] When the resuscitation control box detects a shockable rhythm, the resuscitation control box provides shocks of appropriate duration and energy (such as a sequence of shocks of increasing energy from 200 Joules to 300 Joules to the highest setting, 360 Joules, with the resuscitation control box performing analysis after each shock to determine whether another shock is required). If the defibrillation therapy is successful, the patient's rhythm is typically converted from ventricular fibrillation, ventricular tachycardia, or ventricular flutter to bradycardia, idio-ventricular rhythm, or asystole, all of which require CPR. It is rare to convert to a normal rhythm. Once the resuscitation control box has caused defibrillation shocks to be applied to the patient, the resuscitation control box automatically senses the patient's condition, and depending on the patient's condition will either prompt the responder to perform CPR or will not prompt the respond to perform CPR.

[0064] Defibrillation equipment can be somewhat intimidating to rescuers who are not medical professionals because the equipment can lead the rescuer to feel responsibility for having to save a loved one's life. It is important that the defibrillation equipment reduce this sense of responsibility. In particular, when the rescuer presses the “ready” button, rather than apply a shock immediately that will cause the patient's body to jump dramatically, the resuscitation control box will thank the rescuer and instruct the rescuer to remain clear of the patient and then wait for about two seconds (the resuscitation control box may describe this period to the rescuer as being an internal safety check, even if no substantial safety check is being performed). This process has an effect similar to a conversation that hands responsibility to the resuscitation control box, which makes the decision whether to apply the shock. Thus, the system maintains the rescuer safety features of a semi-automatic external defibrillator, because the rescuer must press the “ready” button before each shock, while appearing to operate more as a fully automatic external defibrillator because the time delay immediately prior to each shock leaves the rescuer with the impression that operation of the equipment is out of the hands of the rescuer. The use of CPR prompts in combination with the defibrillation also adds to the sense that the rescuer is simply following instructions from the resuscitation control box.

[0065] With reference to FIGS. 6-9, when the rescuer turns the resuscitation control box on (step 101), the resuscitation control box first informs the rescuer that the rescuer can temporarily halt prompting by pressing the PAUSE button (step 102), and then, after a pause, instructs the rescuer to check responsiveness of patient, and if the patient is non-responsive to call an emergency medical service (EMS) (steps 103, 104). The resuscitation control box then instructs the rescuer to check the patient's airway to determine whether the patient is breathing (steps 105-107).

[0066] After a pause, the resuscitation control box then instructs the rescuer that if the patient is breathing the patient should be placed on the patient's side, unless trauma is suspected, and that the rescuer should press the PAUSE button (steps 108-109). Then the resuscitation control box instructs the rescuer to perform mouth-to-mouth resuscitation if the patient is not breathing (steps 110-114). Then the resuscitation control box instructs the rescuer to press an Airway Help button A if the patient's airway is blocked, so that the resuscitation control box can give prompts for clearing obstructed airways (steps 115 of FIG. 6B and 147-158 of FIGS. 9A-9B).

[0067] Next, after a pause (step 116a), if the resuscitation control box does not include pulse oximetry or phonocardiogram capability (step 116b), the resuscitation control box instructs the rescuer to check the patient's pulse (step 117). After another pause, the resuscitation control box instructs the rescuer to press a Breathing Help button B if the patient's pulse is okay but the patient is not breathing, so that the resuscitation control box can give prompts for assisting the patient's breathing (steps 118 and 119 of FIG. 7A and 140-146 of FIG. 8). Light-emitting diodes adjacent the various buttons indicate which button has been pressed most recently (only one light remains on at a time). The resuscitation control box next prompts the rescuer to contact an emergency medical system (step 120) and to open the patient's shirt or blouse and attach the adhesive pads (steps 122f-122h).

[0068] If the resuscitation control box does include pulse oximetry or phonocardiogram capability (step and 116b), the resuscitation control box prompts the rescuer to open the patient's shirt or blouse and attach the adhesive pads (steps 121 and 122a). If the pulse oximetry or phonocardiogram system does not provide a valid pulsatile reading (step 122b), then the flow chart proceeds to step 117. If the pulse oximetry or phonocardiogram system does provide a valid pulsatile reading and detects a pulse (steps 122b and 122c), then the resuscitation control box begins the breathing help routine (steps 122d of FIG. 7B and step 140 of FIG. 8). If the pulse oximetry or phonocardiogram system does not detect a pulse, then the resuscitation control prompts the rescuer to contact an emergency medical system (step 122e), measures the impedance of the patient to determine whether it is within an acceptable range for application of shocks (step 123) and determines whether the patient's rhythm is shockable (steps 124). If the rhythm is shockable, the resuscitation control box causes a sequence of shocks to be applied to the patient, each shock requiring the rescuer first to press the “READY” button on the resuscitation control box (steps 124-131). After the last shock in the sequence, or if the rhythm is non-shockable, the resuscitation control box prompts the rescuer in CPR (steps 132-139). The flowchart then returns to step 117.

[0069] FIG. 8 shows the steps 140-146 for prompting the rescuer to assist the patient's breathing. After 12 breaths have been completed (step 144), the pulse oximetry or phonocardiogram system attempts to detect a pulse (step 145a), or, if the system does not include a pulse oximetry or phonocardiogram system, the resuscitation control box prompts the rescuer to check the patient's pulse. If no pulse is present, the resuscitation control box prompts the rescuer to press a Circulation Help button C (step 145b) that brings the rescuer back to the circulation portion of the flowchart. Otherwise, if a pulse is detected, then the flow chart of FIG. 8 returns to step 142.

[0070] The combined defibrillation and CPR resuscitation assembly provided can be less intimidating than conventional AEDs because the assembly is not devoted solely to defibrillation. Moreover, the resuscitation assembly is less intimidating because it accommodates common skill retention problems with respect to necessary techniques ancillary to defibrillation such as mouth-to-mouth resuscitation and CPR, including the appropriate rates of chest compression, the proper location for performing compressions, the proper manner of tilting the patient's head. In addition, because the rescuer knows that it may never even be necessary to apply a defibrillation shock during use of the resuscitation assembly, the rescuer may be more comfortable using the resuscitation assembly for mouth-to-mouth resuscitation and CPR. Unlike previous CPR prompting devices, the rescuer would be required to place the electrode assembly on top of the patient, but the rescuer would do this with the belief that the resuscitation assembly will be sensing the patient's condition and that the likelihood that the resuscitation assembly is actually going to apply a shock is low. If, during this resuscitation process, the resuscitation control box instructs the rescuer to press the “READY” button so that a defibrillation shock can be applied, the rescuer will likely feel comfortable allowing the shock to be applied to the patient. Basically, the resuscitation assembly simply tells the rescuer what to do, and by that point, given that the rescuer is already using the assembly, the rescuer is likely simply to do what the rescuer is told to do. Essentially, the rescuer will be likely to view the resuscitation assembly as simply being a sophisticated CPR prompting device with an additional feature incorporated into it, and since rescuers are less likely to be intimidated by CPR prompting devices than AEDs, they will be likely to use the resuscitation assembly when it is needed.

[0071] FIGS. 10, 11, and 12A-12C show alternative implementations in which an electrode pad assembly 10 is connected by a cable 212 to a first unit 214 containing the electronics for CPR prompting and resuscitation control. Another cable 216 connects the first unit to a second unit 218 containing the electronics for defibrillation and pacing therapy. A third cable 220 could be provided for making a direct connection from the second unit to the electrodes (FIG. 12B). The first unit 214 could be configured to receive the second unit 218 as an inserted module (FIG. 12C), in which case the electrical connection between the units are made internally without the use of cable 216. The primary function of the first unit 214 is to provide processing and control for CPR functions such as CPR prompts. The primary function of the second unit 218 is to provide processing and control of electrical therapy functions. The first unit includes a CPR processor 170, a battery 178, ECG circuitry 177 for amplifying and filtering the ECG signal obtained from the defibrillation pads 12, 14, a microphone 78 for recording the rescuer's voice as well as ambient sounds, an accelerometer 76, a real time clock 187, and a speaker 182 for delivering prompts to the rescuer. The second unit includes a therapy processor 171, a battery 179, buttons and controls 180, and memory 191.

[0072] The first unit could also be incorporated into the electrode pad assembly rather than being a separate box. The electronics could be provided on the rigid substrate 40 of the electrode pad assembly (FIG. 1).

[0073] Separate batteries 178, 179 and controls 180, 181 may be provided for the first (CPR) and second (therapy) units, thereby allowing the electronics in the first unit to provide CPR prompting to the operator without the need for the second unit. The cable 216 that connects the first and second units may be detachable. Memory 189 is provided in the first unit for storing information such as voice recording, ECG data, chest compression data, or electronic system status such as device failures that occur during daily self checks of the electronics initiated by a real time clock circuit.

[0074] The defibrillation electrode pad assembly 10 may incorporate defibrillation electrodes composed of a material that can be held against a patient's skin for extended periods of time (e.g., up to 30 days).

[0075] As shown in FIGS. 13A and 13B, the pad assembly 10 may also incorporate features on its upper surface facing the rescuer that provide a handle 195 for the rescuer during performance of CPR. The handle could take the form of a fabric loop (FIG. 13B) or a more rigid polymer member (FIG. 13A). The fabric could be sewn or adhered by adhesive or ultrasonic bonding to the pad 10 (FIG. 13B). The polymer handle could also be bonded by adhesive or ultrasonic bonding to the pad (FIG. 13A). It has been shown in studies that the maintenance of pressure on the chest during the decompression phase of chest compression results in a significant decrease in the effectiveness of the chest compressions. The handle 195 motivates the rescuer to pull up at least slightly during the decompression phase. The adhesive gel of the electrode pad, or other adhesive, can extend under the region where the rescuer's hands are placed during compression thus providing adhesion of the pad to the skin while the rescuer pulls on the handle during the decompression phase. Pulling up on the chest during the decompression phase has been shown to heighten negative intrathoracic pressure, increasing venous return and thus increasing blood flow during chest compressions.

[0076] In another implementation, the first unit may be adapted to be supported by the patient for long periods of time. The unit could be incorporated into the electrode pad assembly as suggested above, or it could be a separate unit configured to be worn by the patient. In such an implementation, the electronics of the first unit are designed to allow for long term monitoring of the patient's condition via the ECG 177 and physiological monitoring 176 circuitry. If a physiological condition is detected that is deemed hazardous to the patient by the CPR processor 170, based on analysis of the ECG and other physiological parameters, an alarm is sounded to the patient via the speaker 182.

[0077] An activity sensor and associated circuitry can inform the CPR processor of whether the patient is moving. For example, accelerometer 76 could serve as the activity sensor, and detect whether or not the patient is moving. Patient motion may be detected using a variety of different algorithms, including, for example the following: The acceleration signal is integrated over one-second intervals to provide an estimate of velocity. Velocity is integrated over the same one-second intervals to provide an estimate of displacement. The root means square velocity is calculated for each one-second interval. If either the RMS velocity exceeds 0.2 cm/s or the peak displacement exceeds 0.5 cm, the patient is determined to be moving.

[0078] If the algorithm determines that a cardiac emergency event is occurring, the first unit can send a message directly to a medical emergency response system, such as 911. This can be done using a variety of known communication techniques, e.g., Bluetooth, cellular phone, Ultra Wideband (UWB). If the activity sensor has determined that the patient is still moving during the cardiac emergency, the unit could also issue a prompt indicating, “Call 911 Immediately!”

[0079] The first unit will be able to determine the orientation of the patient, e.g., based on the accelerometer output. It can detect if a patient has fallen down and initiate a message to the emergency system. It can also determine whether the patient is lying on his back, the proper orientation for doing CPR. Thus, a specific prompt can be provided to the rescuer that tells them to roll the patient on their back prior to beginning CPR, should the device detect an improper orientation of the patient.

[0080] Other implementations may include signal analysis software for predicting the risk of a heart attack. When a threshold is exceeded in the value of that risk probability, a voice prompt may be provided to the patient via the speaker 182 to contact the medical emergency system. By using the motion detection capabilities of the accelerometer to measure and track a patient's activity level (PAL), and combining the activity level calculation with measurements of the ECG 177, e.g., ST-segment elevation (STE), the first unit is able to provide a predictor of the risk of an impending heart attack or cardiac arrest. An ST segment elevation exceeding a threshold such as 300 microvolts on the ECG provides an indicator of impending heart attack. In the preferred embodiment, ST segment elevation in the presence of increased physical activity is an indication of further risk of potential cardiac arrest. The calculation of risk probability may be accomplished by first performing a logistic regression of variables such as STE and PAL as predictors of cardiac arrest within 24 hours. The calculation may take the form of a linear regression equation such as

0.24STE+0.12PAL=RISK.

[0081] Alternatively, nonlinear regression may be performed to allow for a multiplicative term such as

0.24STE+0.12PAL+0.54(STE*PAL)=RISK.

The multiplicative term heightens the importance of STE in the presence of PAL.

[0082] Parameters such as STE, PAL and RISK may additionally be stored in memory and multiple readings and calculations performed over time. The sequence of readings may then be analyzed for trends in the physiological state of the patient that can augment the RISK calculation taken at a single point in time. For instance, if STE is found to be steadily rising over a series of readings, the voice prompt may be triggered sooner than at a fixed threshold of 300 microvolts.

[0083] Additionally, the ECG may be analyzed to determine the interval between adjacent R-waves of the QRS complexes and using this interval to calculate heart rate variability as a running difference between adjacent R-R intervals. It is known that the R-R interval will vary following an ectopic beat or ventricular premature contraction (VPC). In a healthy heart, the R-R interval will decrease immediately following the VPC followed by a gradual return to steady state; a heart with an increased risk of heart attack will show a decreased level of variability. This effect is sometimes called heart rate turbulence. Two variables are calculated: (1) the Relative Change in R-R interval (RCRR) between pre- and post-VPB R-R intervals,

RCRR=(R-R pre-VPB−R-R post-VPB)/R-R pre-VPB

and (2) the slope of the change of R-R interval (SRR) while it is undergoing its post-VPB decrease. If the RCRR is non-negative and the slope SRR does not steeper than −2 ms/R-R interval then the patient is considered as at risk. Alternatively, the individual calculations may be included along with STE and PAL to create an integrated measurement vector as discussed in the preceding paragraphs. Other signal analysis algorithms may incorporate analysis of heart rate variability in the frequency domain, wavelet domain or using non-linear dynamics-based methods.

[0084] Since VPBs are often rare events, the defibrillation electrode pad 10 may include circuitry to stimulate the patient with a single pulse of low enough amplitude to cause a VPB without undue discomfort to the patient, under the patient's control. An additional control is provided on the low-profile button panel 20 so that the patient may initiate the pulse under their control. Alternatively, the device is programmed to automatically deliver the pulse at regular intervals such as at 24-hour intervals, at a time of day when the patient may conveniently have access to the device, such as in the morning. While the pulse generator 186 may be located in the second (therapy) unit, it is preferably contained as part of the first (CPR) unit.

[0085] In another implementation, the activity monitoring capability of the first unit may be utilized so that the activity state of the patient is continuously monitored. Using the activity monitoring capability and a real time clock 187, the first unit may detect when a patient has woken up in the morning. After there has been 10 minutes of regular motion detected, the unit may prompt the patient that it would like to perform a test. If the patient assents to the test indicated by a press of the TEST button on the low-profile button panel 20, the unit will send out a small current pulse, preferably a 40 millisecond pulse of 75 mA amplitude that is synchronized to the patient's ECG so that it occurs approximately 200 mS prior to the R-wave and after the T-wave so as not to introduce any arrhythmias. The pulse will safely cause a VPB in the patient which can then be used to measure the autonomic response to a VPB to provide regular calculations of the autonomic response to a VPB as measured by such parameters, though not limited to, STE and PAL, and providing a daily update to the RISK calculation.

[0086] Additional physiological measurement, preferably that of blood pressure, may be incorporated into the RISK calculation. A sudden change in systolic or mean arterial blood pressure of greater than 10-15 points is indicative of an increased risk of cardiac arrest. In the preferred embodiment, the blood pressure measurement device would be a handheld, inflated cuff blood pressure device 188. The blood pressure cuff 188 would have wireless communication capability with the CPR Processor 170 and at the conclusion of each measurement, the blood pressure reading along with a date and time stamp would be stored in memory 189 of the CPR Processor 170 for subsequent use in calculating RISK. This scheme would allow the patient to carry the small blood pressure cuff along with them during their daily activities and take blood pressure measurements at regular intervals without having to return home. Alternatively, the blood pressure measurement device may communicate with the therapy processor and may additionally get power from and be physically connected to the second (therapy) unit by a cable. The patient will then be required to take regular blood pressure readings at the second unit, typically a larger device that may or may not be portable. Communication of the blood pressure readings may be accomplished over a cable between the first (CPR) and second units (therapy) units, e.g., cable 216, or wirelessly, using such technology as Bluetooth.

[0087] The second unit 218 may in some implementations be thought of as an energy delivery unit (EDU), in which case it would incorporate a defibrillator 172, pacer 173, or other electrical therapy 174. In some implementations, the EDU would be small and light enough to be worn in a harness or belt to be carried around continuously by the patient. The EDU 218 may in some cases not contain a therapy processor 171, but be a “dumb” device that requires the controls provided by connection to the processor in the first (CPR) unit, e.g., on the defibrillator pad 10, in order to deliver electrical therapy to the patient.

[0088] In some cases, the patient may not even own an EDU due to the significant costs inherent in the high-voltage components necessary. The patient would only own the first unit and defibrillator pad, as the components incorporated in them are less expensive, e.g., they can be manufactured from less-expensive, consumer-type electronics. In such a case, when the patient did not own the EDU, and had a heart attack, a bystander or family member who encountered the cardiac arrest victim would be prompted to begin CPR. It has been shown now in several studies that performing good CPR for extended periods prior to delivery of a shock are not only not detrimental to long term survival, but in fact increase survival rates. CPR would thus begin with built-in prompting and when the paramedic arrives with the defibrillator it can be connected to the pads to deliver the electrical therapy. If the first (CPR) unit is separate from the electrode pad assembly, the EDU connection to the electrodes could be direct, or via a cable connected to the first (CPR) unit. If the defibrillator is an EDU or other compatible device, patient and performance data stored by the first (CPR) unit may be downloaded to the defibrillator.

[0089] Many other implementations of the invention other than those described above are within the invention, which is defined by the following claims. For example, the defibrillation pads 10, 12 may be separable from the CPR-prompting first unit and be connected at the time that the EDU is brought to the scene; the defibrillation pads may be connected both electrically and mechanically to the CPR-prompting first unit at that time. A greater amount of the control functionality may be put into the first unit, leaving essentially only the circuitry for providing the defibrillation pulses in the second unit. The first unit may be incorporated into the defibrillation electrode pad assembly, or made a separate unit connected to the pad assembly by one or more cables. The second unit may connect to the first unit by one or more cables, or by a wireless connection. The defibrillation pulses may pass through the first unit (FIG. 12A), or be routed directly to the defibrillation electrodes via one or more cables running from the second unit to the electrodes (FIG. 12B). The second unit may connect to the first unit by being plugged into the first unit (FIG. 12C), without the need for a cable (e.g., the second unit could be a defibrillation module that plugs into the first unit).

[0090] In some implementations the second (therapy) unit can provide pacing therapy as well as defibrillation therapy. Pulse detection methods other than pulse oximetry and phonocardiogram may be employed. Any method capable of detecting a victim's pulse can be used for pulse detection.