Effect of hyperventilation on airway mucosal blood flow in normal subjects.
The purpose of this study was to determine the effect of hyperventilation (40 L/min) with room air (25 degrees C; 70% relative humidity) and frigid air (-10 degrees C; 0% relative humidity) on airway mucosal blood flow (Qaw) in normal subjects (n = 7; 26 to 54 yr of age). Qaw was measured with the dimethyl ether uptake technique, which reflects blood flow in the mucosa of large airways corresponding to a 50-ml anatomic dead space segment extending distally from the trachea. Mean (+/- SE) baseline Qaw during quiet (room air) breathing was 6.6 +/- 0.6 ml/min (range, 3.9 to 10.9). Qaw failed to change significantly during and after eucapnic hyperventilation with room air (thermal stress, 224 cal/min). In contrast, eucapnic hyperventilation with frigid air (thermal stress, 720 cal/min) increased Qaw in every subject, with the peak value occurring either during or over a 30-min period after hyperventilation; by 60 min, Qaw had returned toward baseline. The mean maximal Qaw was 310 +/- 49% of baseline (p < 0.05). Neither type of hyperventilation had an effect on airway resistance. We conclude that in normal subjects, Qaw increases during and/or after eucapnic hyperventilation with frigid air, and that this response is related to the magnitude of the thermal stress rather than to the level of ventilation.
Kim
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HH
Division of Pulmonary and Critical Care Medicine, Mount Sinai Medical Center, University of Miami School of Medicine, Florida, USA.
LeMerre
C
C
Demirozu
C M
CM
Chediak
A D
AD
Wanner
A
A
D000328:Adult; D000403:Airway Resistance; D003080:Cold Temperature; D005260:Female; D006801:Humans; D006813:Humidity; D006985:Hyperventilation / Q000503:physiopathology*; D007820:Laryngeal Mucosa / Q000098:blood supply*; D008297:Male; D008875:Middle Aged