US3547108A - Combination defibrillator and heartbeat monitoring system - Google Patents

Description

United States Patent [72] Inventor Stanley V. Seifl'ert 3,109,430 11/1963 Tischler 128/422 Seattle, Wash. 3,135,264 6/1964 Tischler et a1. 128/423 [21] App]. No. 760,434 3,224,447 12/1965 Becker et al..... 128/421 [22] Filed Sept. 18, 1968 3,431,912 5/1969 Keller, Jr 128/422 [45] Patented Dec. 15, 1970 Primary Exammer- -william E. Kamm [73] Asslgnee grgz rgazg Att0rneyChristensen, Sanborn & Matthews a corporation of Delaware [54] COMBINATION DEFIBRILLATOR AND HEARTBEAT MONITORING SYSTEM ABST RA( IT: This application discloses a system wherein 5Claiins,2Drawing Figs. defibnllation signals are provided to a pair of defibrillator electrodes having control switches associated therewith for [52] [LS-Cl 128/106, selectively activating the Source of defibrillation signals and 128/419 simultaneously deactivating the ECG system coupled with the [Si] [111. Cl A6lb5/04 electrudes A Single set of electrodes is utilized as the ECG [50] Field otSeargh 128/1058, p p electrodes and as the defibrillator electrodes with the I 41911 HDlgesnAlg monitoring equipment being protected against the high volt- {561 References Cited ages associated with the defibrillator circuitry. As a result the speed with which an operator can monitor a patient under UNITED STATES PATENTS emergency conditions and then apply defibrillation signals if 3,050,695 8/1962 Du Vall 128/419D required is greatly increased.

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COMBINATION DEFIBRILLATOR AND HEARTBEAT MONITORING SYSTEM This invention relates to the field of monitoring the electrical activity of the heart of a person and selectively applying an electric impulse to thepatient to stop fibrillation of the heart. In the past a set of ECG electrodes have been applied to the chest area of a patient using a conductive pastelike material to assure a good electrical connection between the ECG moni toring equipment and the patient. By monitoring the heartbeat it can be recognized when the heart is fibrillating and hence is in immediate need of a defibrillation signal to terminate the fibrillation. Once the need for a defibrillation signal has been recognized, a separate set of electrodes has been applied to the chest of the patient (again using a conductive paste to get good contact) and a high-voltage pulse signal then utilized via the defibrillation electrodes to momentarily stop the heart. In the case of an intensive care section of a hospital the monitoring electrodes are normally maintained in position on the patient.

It has long been recognized that in emergency situations the speed with which an operator can first determine whether or not a defibrillation pulse should be applied tothe patient and then actually carry out the application of such pulse can literally mean the difference between life and death of the patient. In many emergency situations the time required to first monitor the patient and then apply the defibrillation electrodes for applying the defibrillation signal is further increased by the need to remove clothing from the chest area for the application of the multiple electrodes. It would therefore be advantageous to have some way of reducing the time element associated with detecting the need for a defibrillation pulse and actually applying the required pulse to the patient.

It is therefore an object of the present invention to provide an improved combination heart monitoring and defibrillation signal system wherein a single set of electrodes are utilized for purposes of monitoring the electrical activity of the heart of a patient and for selectively applying a defibrillation signal to the patient.

Another object of the present invention is to provide a set of defibrillation electrodes having additional control circuits as sociated therewith for selectively activating a source of defibrillation pulses and deactivating the monitoring equipment coupled to the electrodes.

Another object of the present invention is to provide a heart monitoring and defibrillating system utilizing a single set of electrodes for the signal pickup and for the application of defibrillation signals to the patient.

The above as well as additional advantages of the invention are achieved through the use of a set of relatively heavy electrodes capable of handling high-voltage signals and having additional control switches associated therewith for selectively activating a source of defibrillation signals and deactivating the heart monitoring equipment coupled to the patient via the defibrillation electrodes. ln one preferred embodiment the high-voltage defibrillation signal source is coupled to the electrodes via a high-voltage switch controlled by a pair of control switch elements respectively positioned on the handles of the defibrillation electrodes. Thus when the'defibrillation electrodes have been properly positioned on and in good electrical contact with the patient, the depression of-the switches carried on the handles of the electrodes are closed to activate the high-voltage switch associated with the defibrillation signal source for the application of the defibrillation signal to the patient. By connecting the ECG monitoring scope or other monitoring equipment to the patient via the same electrodes and including appropriate protection circuitry for the monitoring equipment it is found that the single set of electrodes can be utilized for both functions of applying defibrillation signals and of picking up signals associated with the electric activity of the heart for the monitoring equipment.

In accordance with one preferred embodiment a relay is closed in response to the closure of a pair of control switches connected in series circuit and respectively positioned on the two defibrillation electrode handles. When the relay is energized a pair of high voltage switch contacts'are closed causing a DC supply and control circuit to provide the required highvoltage pulse to the patient. A second relay associated with the input circuit of the heartbeat monitoring equipment is energized by closure of the switches on the handles of the defibrillation electrodes so that the input circuit for the monitoring equipment is effectively short circuited during the application of the defibrillation signal and hence the monitoring equipment is protected against any harm which might be caused by the high-voltage signal.

The above as well as additional advantages and objects of the invention will be more clearly understood from the following description when read with reference to the accompanying drawings wherein:

FIG. 1 is a block diagram of a preferred embodiment of the invention utilizing the novel combination pulse applying and signal pickup electrodes. r

FIG. 2 is a system diagram similar to that of F IG. 1 showing the specific circuit arrangement for one preferred technique of carrying out the concepts of the present invention.

Turning now to the drawings, it will be seen that the system includes a pair of heavy defibrillation electrodes 10 and 11 each of which includes a heavy plate of conductive material shown as the platelike electrodes I2 and 13 on the ends of the insulating handles 14 and 15 used for applying the metallic surfaces 12 and 13 to the chest of the patient in accordance.

with the manner presently common in the art. The electrodes 10 and 11 are coupled by leads 16 and 17 to a source of highvoltage defibrillation signals 18 by way of the high-voltage switch 19. The switch 19 is normally open and is closed in response to an input signal on the control lead 20 associated therewith. The lead 20 is seen to be connected to the thumb switches 21 and 22 respectively associated with the defibrillation electrodes 10 and 11. In the specific eirample given the switches 21 and 22 are connected in series circuit and must both be closed in order for the high-voltage switch 19 to be closed. This assures the safety of the operator in that both hands must be on the insulating handles of the electrodes before the high-voltage pulse signal can be applied to the patient.

The leads 16 and 17 are seen to be connected to the leads 26 and 27 which go to the signal input control circuit 28 associated with the amplifier 29. The output circuit 30 of amplifier 29 provides monitoring signals to the ECG monitor scope 31 which can be of the type well known'and widely used at the present time. The signal input control circuit 28 has an input circuit 38 connected thereto which will be seen to be connected to the handle switches 21 and 22. The circuit 28 is normally in a closed condition so that the monitoring equipment normally provides a visual indication of the heartbeat of the patient having electrodes 10 and 11 applied to his chest. The operator is therefore able to determine whether or not fibrillation of the patients heart is occurring. If it is determined that fibrillation is taking place, the patient is immediately provided with a defibrillation pulse by the operator closing switches 21 and 22. Closure of switches 21 and 22 serves to close the highvoltage switch 19 and open the signal input control circuit 28. As a result there is no substantial time lag associated with determining the fact that a defibrillation pulse is needed and applying the defibrillation pulse to the patient.

In the circuit of FIG 2 the pulse source is shown as including the DC power supply and control circuit 39 and a capacitor 40 connected by the'pulse-shaping inductor 41 to a first set of relay contacts 42. The lead 43 connects capacitor 40 to the second set of relay contacts 44. The winding 45 associated with contacts 42 and 44 serves to close the contacts when the winding 45 is energized by the voltage supply 46. This occurs only when both of the thumb-operated switches 21 and 22 on the handles of the electrodes 10 and 11 are closed.

While various circuit protection arrangements can be utilized in the input circuitry for the amplifier 29 to avoid damage thereto by the high-voltage signals, it will be seen in FIG. 2 that the input circuit for the amplifier 29 includes the highvalue impedance elements 47 and 48 connected in the input leads 26 and 27. for the amplifier. The value of the resistance --eleinents 47 and 48 is not critical but need only be relatively large by comparison to the resistance ofiered by the body of the patient (typically in the order of 70 ohms) and small with 'respect to the input impedance of the amplifier. In the specific system illustrated resistors 47 and 48,were K ohms each.

. They therefore present a high impedance to the high-voltage pulse when the relay contacts 50 are closed by energization of the relay winding 51. It will be seen that the input circuit of the amplifier under' such conditions will be short circuited and hence damage to the monitoring equipment is avoided due to the inherent capability of the amplifierito accommodate a "short-circui'ted condition on the input terminals. Simultane- =ously the large value of the resistors 47'a'nd48 avoids any substantial effect on the defibrillation pulse being applied to the *patient by the electrodeslO and 1 l.

' There has thus been disclosed an improved and simplified ,combination defibrillation and heartbeat monitoring system 1. A heart monitoring and defibrillating system comprising :in combination: a defibrillation signal source, heart signal dis- ,play means, a set of electrodes engageable with a patient, and circuit means connecting said set of electrodes across said source and to said display means including manually-operated switch means controlling the selective application by an operator of a defibrillation signal to a patient from said source via said set of electrodes and further including means protecting said display means against damage from-said defibrillation signal.

2. The system of claim 1 including an insulating handle connected to one of said electrodes and wherein said manuallyoperated switch means includes a first high-voltage switch connected to said source, a second control switch on said handle, and circuit means connecting said second switch with said first switch and maintaining the condition of said first switch under the control of said second switch.

3. The system of claim 2 including a second insulating handle connected to a second of said electrodes, and a third control switch onsaid second handle connected in circuit with said second control switch, such that said second and third switches must each be operated for the application of a defibrillation signal to the patient.

4. The system of claim 1 wherein said means protecting said displaymeans includes a relay having controlled contacts in the circuit between said display means and said electrodes and controlled by said manually-operated switch means.

5. In a heart defibrillating and monitoring system having a source of high-voltage defibrillationsignals and signal monitor means for monitoring signals indicating heart activity, the improvement comprising a single set of electrodes connected to the source and to the means for monitoring signals, manuallyoperated switch means connected between the electrodes and the source for controlling the application of defibrillation signals to a patient via the electrodes, and protection circuit means connected between the electrodes and said monitor Dedication 3,547,108.Stanley V. Sez'ffert, Seattle, Wash. COMBINATION DEFIBRIL- LATOR AND HEARTBEAT MONITORING SYSTEM. Patent dated Dec. 15, 1970. Dedication filed Jan. 15, 1975, by the assignee, Physio-Control Corporation. Hereby dedicates to the Public the entire remaining term of said patent.

[Ofiaial Gazette March 25, 1.975.]

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