We determined the effect of breathing cold dry air (-39°C, 0.1% relative humidity, RH) and warm humid air (43°C, 100% RH) on airway mucosal blood flow (Q@Eaw) in normal human subjects (n = 8, age 25-53 years) at rest. Q@Eaw was measured with a dimethylether uptake technique which reflects blood flow in the mucosa of large airways corresponding to a 50 ml anatomical dead-space segment extending distally from the trachea. Mean Q@Eaw was 10.1 ± 1.9 ml min-1 (mean ± S.D.) during room air breathing (25°C, 70% RH) and decreased to 4.7 ± 2.1 ml min-1 during cold dry air breathing (p < 0.05). Within 20 min of resuming room air breathing, mean Q@Eaw had returned to baseline. Breathing warm humid air had no significant effect on mean Q@Eaw (8.2 ± 1.4 ml min-1). These results indicate that quiet breathing of frigid air causes vasoconstriction in central airways.
- Blood flow, bronchial
- Humidity, inspired gas
- Mammals, humans
- Temperature, inspired gas
- Upper airways, bronchial blood flow, air temperature, humidity
ASJC Scopus subject areas
- Pulmonary and Respiratory Medicine