THE RESPIRATORY AND CARDIOVASCULAR RESPONSE TO IMMERSION IN COLD AND WARM WATER

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Abstract
During their first few minutes of immersion in stirred water at 5 and 15° C. the pulmonary ventilation of twelve unclothed men was high, and their end‐tidal pCO2 fell. The pCO2 then returned to or a little above its original level but did not greatly exceed it even in working experiments lasting 20 min. in water at 5° C. or 40 min. in water at 15° C. Although work reduced or reversed the initial fall in pCO2, these results therefore do not bear out predictions that the pCO2 would rise to dangerous levels during hard work in cold water, at least in immersions of moderate duration.In water at 37·8° C. the men's heart rates rose steadily, in water at 25° C. they fell and remained low, and in water at 5 and 15° C. they rose and then fell. Repeated immersion at 15° C. reduced or abolished the early respiratory and heart rate responses to immersion and the metabolic response, but did not significantly increase the falls in rectal temperature. Clothing also reduced the reflex responses to immersion. A number of ventricular extrasystoles were observed during the first 2 min. of immersion in water at 15° C., and it is suggested that ventricular fibrillation due to increased venous and arterial pressures, adrenaline, and hyperventilation, may be responsible for some cases of sudden death in cold water.