Cold environment may alter cardiopulmonary function. The alteration of pulmonary blood flow (Q
C), respiratory water loss (V
H2O), convective heat loss (CHL) and respiratory heat loss (RHL) were studied with subjects exposed to cold environment (5°C) and to thermoneutral environment. Q
C varied according to posture (supine, sitting and standing) and there was no significant difference between cold and thermoneutral temperature at the same posture. Apparently cold exposure of short duration had no effect on Q
C At the same temperature, Q
C was larger in the supine position than in the other positions.
Before, during and after stepwise exercise in normal subjects, there was no significant difference in Q
C between cold and thermoneutral temperature.
CHL increased significantly during stepwise exercise in the cold environment in compared with those at the thermoneutral temperature, however, V
H2O and RHL also increased no significant degree. At both temperatures, V
H2O, CHL and RHL increased during exercise in compared with those before exercise. RHL was elevated according to the increment of ventilation, and this elevation was more marked in the cold environment.
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