GB976994A - Electrodes for cardiac defibrillator - Google Patents

Abstract

976,994. Defibrillator. MINE SAFETY APPLIANCES CO. July 13, 1962 [June 25, 1962], No. 27005/62. Heading A5R. An electrode for a defibrillator incorporates a switch which is actuated by pressure of the electrode against the patient's body. The metal, body-contacting plate 51, Fig. 2, is carried on an insulating disc 52 which has a stem 53 so as to be slidable, against the force of a spring 59, in a hollow handle 56. The plate 51 is connected by a metal rod 54 with contact blades 67 which, when the handle is pressed downward, engage a contact ring 68 and serve to connect the electrode to the high voltage source. Further pressure on the handle causes another contact 72, mounted on an insulating rod 73, to bridge blades 71 and thereby actuate the source. The equipment is supplied through a converter 3, Fig. 1, which raises the input voltage to 2,500 volts and charges condensers C1, C2 in parallel. A switching device 21 comprising two contacts 24, 26 on a slidable rod 23 urged to the right by a spring 34, is initially set by being drawn back to the position shown dotted, where it is held by the catch 28. Pressing the electrodes E1, E2 against the patient first closes contacts S1 and the subsequent closure of contacts S2, in series, energizes a solenoid 43 and releases the catch 28. The rod 23 consequently moves rapidly to the right and contacts 24, 26 bridge fixed contacts A-A1 &c. in pairs, so that condenser C1 is first discharged through the patient and then C2 is discharged in the opposite direction. Specifications 976,992 and 976,993 are referred to.