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1. (WO1980000006) APPAREIL DE DIAGNOSTIC
Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

CLAIMS:

1. Apparatus for detecting ventricular fibrillation, comprising a pair of electrodes capable of being put in electrical contact with the body of a patient, a circuit capable of distinguishing a signal received from the
electrodes characteristic of ventricular fibrillation from signals characteristic of other heart conditions, and
indicating means to indicate to an operator when said signal is characteristic of ventricular fibrillation.

2. Apparatus according to Claim 1, in which said circuit comprises an amplifier and automatic gain control unit to amplify the signals received from the electrodes to a uniform maximum amplitude, an integrating unit to integrate the amplified signal, and a comparator to measure the energy of the integrated signal.

3. Apparatus according to Claim 2, in which the
circuit comprises clipping means for clipping the positive and negative peaks from the signal received from the
automatic gain control unit, integrating units to integrate separately the positive and negative clipped signals and a dual comparator arranged to operate the indicating means when the magnitudes of the integrated positive and negative signals are characteristic of ventricular fibrillation.

4. Apparatus according to Claim 1, in which the circuit comprises an analogue switch operable to actuate said
indicating means and circuit means connected to the analogue switch to allow it to operate only when a continuous signal substantially free from peaks characteristic of ventricular fibrillation is fed to the analogue switch.

5. Apparatus according to Claim 4, in which the circuit comprises summing means for summing the positive and negative components of the signal received from the electrodes, an automatic gain control unit to amplify the summed signal, a peak detector to receive the amplified signal, and an
analogue switch operable by the signal from the peak detector to operate the indicating means.

6. Apparatus according to Claim 5, in which the circuit includes means for splitting the summed signal, a buffer
amplifier to receive one component of the split signal and a peak signal capacitor decay circuit and buffer to receive the other component, said buffer amplifier and said buffer being connected to a comparator which is itself connected to the automatic gain control, the arrangement being such that the comparator emits a substantially continuous output to the automatic gain control when the signals received are
characteristic of ventricular defibrillation and emits a
pulsed output when the signals are characteristic of Sinus
Rhythm and the automatic gain control cannot pass an
amplified signal to the peak detector when the comparator emits a pulsed signal.

7. Apparatus according to Claim 5 or 6, in which the circuit includes means for splitting the summed signal, a buffer amplifier to receive one component of the split
signal and a peak signal capacitor delay circuit and buffer to receive the other component, said buffer amplifier and said buffer being connected to an event comparator with a direct current pump with decay unit and an OR gate connected to the analogue switch, the arrangement being such that the OR gate emits an output only when the signal received by the event comparator is characteristic of ventricular defibrillation and the analogue switch is operable to actuate the indicating means on receipt of this output.

8. Apparatus according to Claim 5 , 6 or 7 , in which the circuit comprises a direct current pump and buffer connected to the analogue switch to transmit the signal received
therefrom to the indicating means, and a reset device and means for generating a reset signal at intervals connected to the pump and buffer to effect resetting at intervals.

9. Apparatus according to any preceding claim, in which the circuit contains a band pass filter capable of passing frequencies from 2 to 17 Hz from the signals received from the electrodes.

10. Apparatus according to any preceding claim, in which the circuit contains a filter to remove from the signals received from the electrodes components having a frequency corresponding to that of the alternating-current mains supply.

11. Apparatus according to any preceding claim, provided with a defibrillator circuit arranged to be discharged through said electrodes to administer a shock to the patient.

12. Apparatus according to any preceding claim, in which said circuit, indicating means and electrodes are mounted in or on a housing, or housings connected together, to form a portable unit.

13. Apparatus for detecting ventricular fibrillation, substantially as hereinbefore described with reference to Figure 4 or Figure 5 of the accompanying drawings.