[Skip to Content]
[Skip to Content Landing]
October 6, 1956


JAMA. 1956;162(6):559-561. doi:10.1001/jama.1956.72970230001009

Cardiac arrest, ventricular fibrillation, and profound shock demand immediate diagnosis during surgery or resuscitative emergencies so that proper and adequate treatment can be instituted.1 This requires a reliable portable instrument for continuous instantaneous monitoring of the cardiac impulse during surgery and for immediate application during nonsurgical emergencies both in and outside of the hospital. Recognition of this need prompted us to develop a simple, compact, portable transistorized device, which provides an immediate diagnosis of cardiac arrest, ventricular fibrillation, and certain other arrhythmias. It allows continuous visual monitoring of the heart rate, even during profound shock, when the patient may be clinically pulseless. The use of transistors and small batteries makes the unit small, lightweight, and portable. It is explosion-proof because of the low-voltage power supply. Nurses, technicians, and even nonmedical rescue personnel can operate it readily because of the simplicity of design and interpretation. In addition, it is sufficiently