Respiratory heat exchange in normal subjects and in patients with pulmonary disease

Publication Type Journal Article
Year 1969
Journal Journal of Applied Physiology
Primary Author Caldwell, P. R.
Author Gomez, D. M.
Author Fritts, H. W.
Volume 26
Issue 1
Pages 82-88
Abstract Respiratory water loss was measured at rest and during exercise in normal subjects, patients with chronic airway obstruction, and patients with pulmonary sarcoidosis. Whereas in all three groups the average concentration of water in the expired gas was 29 mg/liter, the calculated respiratory evaporative heat loss, expressed as a fraction of total body heat production, tended to be higher in the patients with lung disease during exercise, This observation was best explained by the high ratio of exercise ventilation to oxygen consumption which occurred in half the patients. The same mechanism probably accounted for the larger than normal total respiratory heat loss (hT) seen in the patients, when hT was defined as the sum of four components of heat exchange: I) the evaporative loss; 2) the convective loss; 3) the loss due to the endothermic evolution of carbon dioxide; and 4) the gain resulting from the exothermic combination of oxygen with blood. These results indicate that lung disease does not interfere with the warming and humidification of respired air. Rather they demonstrate that the fraction of body heat dissipated via the respiratory tract may be higher in patients with lung disease.
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