GB1535413A - Electro-anaesthesia apparatus - Google Patents

Abstract

1535413 Electro - anaesthesia apparatus MOSKOV OBLAST N I INST AKUSHERST I GINEKOLOG 9 April 1976 14645/76 Heading A5R Electro-anaesthesia apparatus has a current pulse generator 1, means 3 for adjusting the pulse width, means 5 for adjusting the current amplitude of the pulses, means 6 for indicating the mean output current, and a patient protection circuit 7 which discontinues application of the current pulses to the patient if the output current amplitude exceeds a predetermined value. Circuit 1 comprises a multivibrator 20, 21 giving a square wave output at a p.r.f. set by adjustable resistor 29 of 100 Hz to 7 KHz. Circuit 2 acts to differentiate this output and gives 0.05 n sec pulses at the p.r.f. set in circuit 1 to a multivibrator 39, 40 circuit 3 giving an output at the same p.r.f. and having an adjustable resistor 46 to select the pulse width. A pulse shaper circuit 4 processes the output of circuit 3 and has a switch 65 to select either a square wave output, formed by differential amplifier 50, 51, or a pulse shape with an exponential trailing edge, formed by tranistor 60 and associated components. The selected pulse output passes to circuit 5 which is formed as a voltage generator and includes an adjustable resistor 68 to set the current amplitude of the pulses. The output of circuit 5 passes to the patient via a mean current indicating meter 79 of circuit 6. Circuits 1, 2, 3 &c. receive power from a battery 113 via a voltage stabilizer 106 to 110, and an inverter 96, 97, 102 and rectifier 103 give a supply at a second voltage to circuits 4, 5, 8. The output to the patient is monitored by a circuit 8, constructed as a peak voltage detector and having a peak current indicating meter 94, and by the circuit 7 which has a relay 83 which when the output current exceeds a preset level opens a switch 112 to disconnect the battery. In a modification, Fig. 7 (not shown), the input to circuit 5 may be connected to the output of circuit 2 selectively either via circuits 3 and 4 to give a continuous pulse train output or via a circuit (18) comprising a J-K flip-flop to give intermittent analgesia. The electrodes 11, 12 connected to the output of circuit 6 are each formed as a concave disc and are attached to a rubber band head harness (16), Figs. 5, 6 (not shown), with two earthed cathodes 11 at the forehead area and two anodes 12 at the neck area below the mastoids.