Sudden cold water immersion.

Cold water is known to facilitate the drowning process. To gather information on the possible relationship between ventilation and cold stimuli, measurements of inspired and expired breath by breath ventilation and alveolar PCO2 were made on 8 male subjects suddenly immersed in both cold (11 degrees C) and warm water (28 degrees C). The mean ventilation for all subjects for the 1st three breaths following cold water immersion was 94.5, 71.3 and 94.6 L/min (BTPS) as compared to 60.0, 36.2 and 38.5 L/min (BTPS) for warm water immersion. Alveolar CO2 fell dramatically in cold water from a pre-immersion mean value of 36.4 torr to 23.9 torr, whereas there was only a change associated with the first few breaths following immersion in warm water. In prolonged cold exposure, ventilation was still markedly above that observed in warm water after 5 min. There was no relationship between skin fold thickness and ventilatory response over the period studied. A large increase in ventilations is likely to result in inefficient swim stroke mechanics. This, combined with a high probability of inspiration of water, may contribute to death as a consequence of cold water exposure.