Heart difibrillator with independently operating starting pulse generator

Abstract

A heart defibrillator having mechanical means for producing a mechanical energy pulse which is then converted to an electrical energy pulse by a piezo-electric element, the electrical energy pulse activating a high voltage pulse supplying means which delivers a high voltage pulse to defibrillator electrodes pressed against a patient. Since the high voltage pulse is delivered in response to a pulse which derives its energy from a mechanical rather than an electrical source, inadvertent activation due to electrical open and short circuit malfunctions is avoided.

Description

The invention relates to a heart defibrillator comprising a high voltage pulse generator having at least one electrode for applying an electrical pulse to a patient and a device, coupled to an externally operable control member, for activating the high voltage pulse generator.

Such a heart defibrillator is known from the U.S. Pat. No. 3,196,877. The heart defibrillator described therein comprises an electrode holder in which a push-button is mounted. When this push-button is depressed, a switch is operated so that a relay is energized, said relay activating the high voltage pulse generator. A drawback of the use of a switch producing a short-circuit in a circuit arrangement is that this short-circuit may also be caused by faults, for example, by a short-circuit in a supply line. An untimely applied defibrillation pulse of a heart defibrillator may have serious consequences and it is therefore important to have a fail-safe circuit available for this purpose.

The invention has for its object to comply with this requirement with the aid of simple means. The heart defibrillator set forth in the preamble according to the invention is characterized in that the device for activating the high voltage pulse generator comprises a member for converting a mechanical pulse into an electrical pulse, the control member being coupled to said converting member by means of a mechanism for transmitting a mechanical pulse.

In the heart defibrillator according to the invention a starting pulse is supplied by a member for converting a mechanical pulse into an electrical pulse, this mechano-electrical member acting as an independently operating starting pulse generator which cannot, contrary to the known devices for activating the high voltage pulse generator, give a starting pulse due to short-circuits or similar faults. The circuit to which the starting pulse is supplied can be easily so proportioned that short-circuits or other failures can never release sufficient power to act as a starting pulse.

In a preferred embodiment according to the invention the control member and the mechano-electrical member are accommodated in an electrode holder of the heart defibrillator. It may be advantageous to mount the control member in such a manner that it becomes operable only after a minimum pressure on an electrode is exceeded.

In a preferred embodiment a mechano-electrical member contains a piezo-electrical material to which a mechanical pulse is applied by a mallet when the control member is depressed.

In order that the invention may be readily carried into effect, one preferred embodiment thereof will now be described in detail, by way of example, with reference to the accompanying diagrammatic drawings, in which

FIG. 1 is a diagrammatic perspective view of a heart defibrillator,

FIG. 2 is a cross-sectional view of an electrode holder according to the invention, provided with a control member and a mechano-electrical member, and

FIG. 3 is a circuit diagram for a starting mechanism for the high voltage pulse generator of a heart defibrillator according to the invention.

The heart defibrillator shown in FIG. 1 has a housing 1 in which all electronic control means are accommodated and which is preferably provided with a keyboard 2, with the aid of which the strength of the defibrillation pulse to be supplied can be selected. A meter 3 indicates, for example, the maximum potential for the pulse to be supplied. The housing 1 with accessories may be of a portable design, in which case an energy source, for example, in the form of a 24 V battery, is incorporated in the housing. The housing may also be provided with a connection for an external energy source, which may serve both for external energy supplies and for charging an internal energy source, if applicable. Via a high voltage cable 4, electrodes 5 and 6 which preferably form part of electrode holders 7 and 8, are connected to the housing 1. The electrode holders 7 and 8, which are preferably made of an electrically insulating synthetic resin, are provided with handles 9 and 10, supporting rims 11 and 12, and have widened ends 13 and 14 on which the electrodes 5 and 6 are mounted. In a preferred embodiment small electrodes are mounted on the electrode holders for use on children.

Around these small electrodes larger electrodes can simply be mounted for use on adult patients. In a portable heart defibrillator both electrode holders are preferably provided with handles. In a heart defibrillator for clinical use one of the electrodes may be mounted, for example, on an examining table. Various electrodes may also be connected to a single handle.

In an electrode holder as shown in FIG. 2, a control member 15 is mounted according to the invention, which control member is coupled to a mechano-electrical converter 16. In a preferred embodiment, for example, a tension spring 18 is provided for this purpose which is coupled to a push-button 17, and which is tensioned by depressing the push-button 17. Further depressing of the push-button disengages, for example, by means of a slanted side portion 19 of the push-button 17, a pawl 20 from a slot 21 so that a second tension spring 22, which is also pretensioned by the depressing of the push-button, drives a mallet 23 against a block 24 of piezo-electrical material. The tension spring 18 forces the mallet 23 back again and hence drives the pawl 20 into the slot 21 again. Due to the mechanical pulse exerted on the piezo-electrical material by the mallet 23, an electrical pulse is generated which is used as a starting pulse. It is irrelevant for the invention how the piezo-electrical member is constructed or how the mechanical pulse is produced. The piezo-electrical member may be replaced by a coil of electrically conducting wire, in which a bar of magnetized material can be displaced in the axial direction by means of an operating mechanism. The magnetic flux variation caused by this displacement will generate an electrical pulse on the ends of the coil wire, which can be used as a starting pulse.

Any mechanism by means of which a mechanical pulse is independently converted into an electrical pulse, the mechanical pulse being produced by external intervention, may be used as a starting pulse generator.

The control member and the mechano-electrical converter may also be accommodated elsewhere inside the apparatus, for example, in the housing 1. Usually the physician will determine the instant at which a defibrillation pulse is to be supplied, and in such a case incorporation in an electrode holder is to be preferred. In the case of internal applications, such as during surgery, electrode holders of a simple shape are preferably used, in which case mounting in or on the housing may be more advantageous. There are always various persons present which may give the starting pulse and the control member does not have to be within the immediate reach of the physician. In order to make these various applications possible in a simple manner the electrode holders are mounted on the housing so as to be readily exchangeable.

If the patient still shows remnants of a normal heart function (auricular vibration), the defibrillation pulse must be applied in the correct phase with the cardiogram. This synchronization is provided by an electronic circuit which is automatically actuated by the cardiogram because the latter releases the defibrillation pulse after the generating of a starting pulse only at the correct instant determined by the electro-cardiogram. The cardiogram recorded during the treatment can cause a lamp mounted in the electrode holder to light up so that the physician can follow the action of the heart.

FIG. 3 shows very schematically aa preferred embodiment for some circuit elements for a heart defibrillator. A potential pulse supplied by the mechano-electrical converter is supplied via a line 30 to a control device 31 and forms for this control device the starting signal, for example, by bringing a transistor out of the cut-off condition, on which a relay 32 is energized, perhaps delayed with electronic means for adaptation to the cardiogram, which cardiogram signal is also supplied to the control device 31. This relay 32 operates a switching mechanism 33 having, for example, two switches 34 and 35. If the relay 32 is not energized, the switching mechanism 33 is in the charging position corresponding to the solid-line position for the switches 34 and 35. In this position a capacitor 36, having a capacitance of, for example, 16 .mu.F is charged via a rectifier element 37 to a potential from some kV to, for example, maximum 7 kV, determined by depressing the relevant button of the keyboard 2.

The energizing of the relay 32 brings the switching mechanism into the discharging position because the switches 34 and 35 assume the broken-line position. The capacitor 36 discharges via an inductance 38 of, for example, 0.2 H and a patient lying between the electrodes 5 and 6 in, for example, approximately 5 ms. The switches 34 and 35 snap back immediately into the charging position and a next defibrillation pulse can be given by depressing the control member.

Claims

What is claimed is:

1. A heart defibrillator comprising:

mechanically activatable means for generating a mechanical energy pulse;

means responsive to said mechanical energy pulse for converting said mechanical energy pulse into an electrical energy pulse;

two electrodes for contacting the body of a patient;

means for supplying a high voltage pulse to said electrodes, said pulse supplying means being normally deactivated; and

means responsive to said electrical energy pulse for activating said pulse supplying means,

whereby a high voltage pulse is supplied to said electrodes upon mechanical activation of said mechanical energy pulse generating means.

2. A heart defibrillator, comprising:

a mallet;

a releasable pretensioned spring for driving said mallet;

a manually operated push button for releasing said pretensioned spring;

a piezo-electric element positioned in the path of said mallet to receive a sharp blow from said mallet when said mallet is driven by said spring and to convert the mechanical energy of the mallet into an electrical energy pulse;

two electrodes for contacting the body of a patient;

means for supplying a high voltage pulse to said electrodes, said pulse supplying means being normally deactivated; and

means responsive to said electrical energy pulse for activating said pulse supplying means,

whereby a high voltage pulse is supplied to said electrodes upon operation of said push button.