CARDIAC ARREST, or as it is more correctly called, cardiopulmonary arrest, resulting from ventricular standstill or fibrillation is an unpredictable complication in 8,000 to 10,000 surgical procedures performed in this country each year (1-3). Cardiopulmonary arrest is also the presumed cause of death in many of the 500,000 persons per year who die suddenly from coronary artery disease (3-5). Proper application of current concepts of cardiopulmonary resuscitation may save many of those affected while in operating room areas (6, 7), and an estimated one-half to two-thirds of sudden coronary deaths may be ultimately avoided through prompt institution of therapy (4-6, 8). Cardiopulmonary arrest cani result from a wide variety of circumstances including anoxia, drug t,oxicity or idiosyncrasy, and coronary occlusion. It is often a relatively transient phenomenon (9), occurring in hearts with an essentially intact myocardium (10); thus it has been stated that the heart needs only a second chance to survive (11). Cardiopulmonary arrest has been managed in the past by open-chest cardiac massa.ge and direct application of electrical currents to the myocardium (6, 12, 13). Because of the special qualities of training and initiative required, however, to perform emergency thoracotomy and direct cardiac massage and the possibility of serious sequelae to such a vigorous procedure, efforts have been directed toward developing simpler techniques of stimulating and defibrillating human hearts, such as application of electric shocks to the chest externally. This work led to the successful reports by Zoll and associates (14) in 1956 and of Kouwenhoven and associates in 1957 (15). More widespread clinical application of pacemakers and alternating current external defibrillators resulted. It was further recognized that successful application of these electrical techniques depends upon the avoidance of myocardial and cerebral anoxia. After circulation has ceased for 3 to 4 minutes, the possibility of successful resuscitation is markedly decreased unless adequate circulatory and ventilatory support is maintained (16). A great stride in the development of effective emergency ventilatory therapy was taken in 1958 when expired air respiration was demonstrated to be superior to previously accepted manual methods (17-19). An initial attempt to combine this technique with internal cardiac massage occurred through the efforts of Dr. Claude S. Beck, professor at Western Reserve University School of Medicine, Cleveland, and the work of the National Resuscitation Society, which with the American College of Cardiology conducted several 2-day courses in 1958 in the treatment of acute respirocardiac failure (13,20,21). Concomitant experimental studies exploring the physiology and technique of closed-chest cardiac massage showed that satisfactory cardiac output during cardiac arrest could be maintained by this method (12,22). It soon became clear that expired air respiration and closed-chest cardiac massage when performed properly in combination provide effective emergency ventilatory and circulatory support in cases of cardiac arrest and a suitable physiological environment for the successful application of external electric currents where such application is indicated (3, 6, 9, 12, 23, 24). Dr. Schrogie is assistant chief of the Coronary Heart Disease Section, Heart Disease Control Branch, Division of Chronic Diseases, Public Health Service.