The hazard of electrocution during patient monitoring.

The ever-present hazard in patient monitoring is electrocution resulting in ventricular fibrillation. Fire and explosion hazards are possibilities but seem to be very remote. Iatrogenic electrocution can occur when: (a) more than one piece of electrical equipment is connected to the patient. (b) the distal end of an intracardiac electrode is handled. (c) pericardiocentesis is carried out with ECG monitoring. Under these circumstances, small currents, of the order of 100-200 ,uA, may cause ventricular fibrillation. There is evidence that the ventricular fibrillation threshold is substantially lowered by anoxia and acidosis but it seems to be unaffected by barbiturate anaesthesia. This paper suggests that the physician or surgeon should understand the risks but may need the expert advice of an electrical engineer. Ventricular fibrillation which has occurred under these circumstances requires careful, expert investigation to establish whether or not it was electrically induced.