Mechanism of circulatory failure in fresh and sea water drowning.

O LDER concepts as to the cause of death from drowning postulated that spasm of the glottis prevents entry of water into the lungs, that impairment or cessation of the heart beat is due to asphyxia and that use of artificial respiration offers the greatest chance for revival. Recent experimental studies have revealed that this mechanism is dominant in a minority of cases only: 20 per cent in our series'" 3 and about 40 per cent in the series reported by Fainer, Martin and Ivy. 4 In the majority of animals submitted to experimental drowning in fresh water, death is due to ven-tricular fibrillation within a few minutes after submersion. While the mechanisms which incite fibrillation are still not fully understood, considerable experimental information has become available about events leading up to such a state. It is the purpose of this editorial to review briefly the known facts and the working hypothesis to which they have given rise. When dogs are submerged in fresh water, sooner or later, they make a strong inspiratory movement and aspirate a large volume of water. This floods the bronchial tree and the water then enters the blood stream rapidly. The course of the inundation was followed using deuterium oxide in the water as a tracer; some 50 ml. of water are added to each 100 ml. of circulating blood in the course of only 3 or 4 minutes of submersion. In one extreme case, the "blood" was found to be 51 per cent of the "drowning water" at 2 minutes after sub-mergence and 72 per cent at 3 minutes. 1 The absorption of water dilutes correspondingly all of the blood constituents: Na, Cl, Ca, proteins, hemoglobin, etc. An exception is the behavior of K: this rises to about 8 mEq./L. To the dilution of salts may be ascribed the considerable hemolysis that may take place, e.g., plasma hemoglobin of 6 Gm. per cent. Soon ventricular fibrillation supervenes which, of course, arrests at once the function of the heart as a pump. During the submersion a fulminating pulmonary edema also occurs, probably due to irritation of the pharyngo-bronchial regions. This results in the movement of many of the blood constituents into the intrapulmonic spaces; for example, just after death, the Na of the lung fluids is about 25 mEq./L. and the plasma proteins about 2 Gm. per cent.' The latter accounts for the frothy fluid, …