Quantitative measurements of the alcohol concentration and the temperature of breath during a prolonged exhalation

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Abstract
After healthy men drank a moderate dose of alcohol their breath-alcohol concentrations and breath-temperatures were quantitatively determined as a function of expired-volume. All tests were made in the post-absorptive phase of ethanol metabolism and breath samples were analyzed by GLC. The temperatures of breath rose steadily from start to end of exhalation with a mean of 34.48.degree. C after a forced vital capacity (FVC) maneuver. The SD of a single measurement of breath-temperature in randomly selected subjects was .+-. 0.402.degree. C. No statistically significant increases in the temperature of breath were noted after an expired volume of 70% FVC [forced vital capacity]. At average expired-breath volumes of 13.5%, 26.2%, 52.2%, 71.7% and 94.2% FVC the breath-temperatures were 33.3.degree., 33.5.degree., 33.9.degree., 34.1.degree. and 34.4.degree. C; breath-alcohol concentration were 79.7%, 85.9%, 90.5%, 95.9% and 98.8% of the 100% FVC alcohol levels. When I corrected for the lower temperatures of breath in the early stages of expiration, the concentrations of alcohol were 86.6%, 90.8%, 93.5%, 96.5% and 98.5% of the 100% FVC levels. At least 70% of a man''s VC must be discarded before a breath-concentration plateau for ethanol develops. But even after a discard breath-volume of 10% FVC the concentration of alcohol reaches 80% of the level in end-expiratory breath. Ethanol evidently dissolves in the mucous membranes of the upper respiratory tract and equilibrates with breath in the airway dead-space and in the mouth.