Exercise-related change in airway blood flow in humans: relationship to changes in cardiac output and ventilation

Abstract

This study examined the relationship between airway blood flow ( .Q aw), ventilation ( .V E) and cardiac output ( .Q tot) during exercise in healthy humans (n = 12, mean age 3411 yr). .Q aw was estimated from the uptake of the soluble gas dimethyl ether while .V E and .Q tot were measured using open circuit spirometry. Measurements were made prior to and during exercise at 345 W (Load 1) and 6810 W (Load 2) and following the cessation of exercise (recovery). .Q aw increased in a stepwise fashion (P<0.05) from rest (52.8  19.5 ulmin-1ml-1) to exercise at Load 1 (67.0  20.3 ulmin-1ml-1) and Load 2 (84.0  22.9 ulmin-1ml-1) before returning to pre-exercise levels in recovery (51.7  13.2 ulmin-1ml-1). .Q aw was positively correlated with both .Q tot (r=0.58, P<0.01) and .V E (r=0.50, P<0.01). These results demonstrate that the increase in .Q aw is linked to an exercise related increase in both .Q tot and .V E and may be necessary to prevent excessive airway cooling and drying