Hemodynamic responses to acute hypoxia, hypobaria, and exercise in subjects susceptible to high-altitude pulmonary edema.
To verify the presence of the constitutional abnormality implicated in the pathogenesis of high-altitude pulmonary edema (HAPE), we evaluated the hemodynamic responses to hypoxia, hypobaria, and exercise in HAPE-susceptible subjects (HAPE-S). HAPE-S were five males with a history of HAPE. Five healthy volunteers who had repeated experiences of mountain climbing without any history of altitude-related problems served as controls. HAPE-S showed much greater increase in pulmonary vascular resistance index (PVRI) than the control subjects, resulting in a much higher level of pulmonary arterial pressure (Ppa), under both acute hypoxia of 15% O2 (Ppa = 29.0 +/- 2.8 vs. 17.8 +/- 0.3 Torr, P less than 0.05) and acute hypobaria of 515 Torr (32.3 +/- 2.8 vs. 19.1 +/- 0.8 Torr, P less than 0.05). Also, PVRI in HAPE-S exhibited a tendency to increase even during light exercise with supine bicycle ergometer (50 W), whereas PVRI in the control subjects significantly decreased, so that HAPE-S showed a greater increase in Ppa (delta Ppa = 16.0 +/- 1.5 vs. 4.9 +/- 1.1 Torr, P less than 0.001) and a greater decrease in arterial oxygen tension (17.8 +/- 4.7 vs. 5.6 +/- 1.7 Torr, P less than 0.05). We thus conclude that HAPE-S have a constitutional abnormality, which can be evaluated at low altitude, in the pulmonary circulatory responses to possible causative factors of HAPE such as hypoxia, hypobaria, and exercise.
Kawashima
A
A
First Department of Internal Medicine, Shinshu University School of Medicine, Matsumoto, Japan.
Kubo
K
K
Kobayashi
T
T
Sekiguchi
M
M
D015121:6-Ketoprostaglandin F1 alpha / Q000097:blood; D000328:Adult; D000532:Altitude Sickness / Q000097:blood / Q000503:physiopathology*; D001274:Atmospheric Pressure; D009320:Atrial Natriuretic Factor / Q000097:blood; D001784:Blood Gas Analysis; D004198:Disease Susceptibility; D006439:Hemodynamics; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D008297:Male; D005082:Physical Exertion; D011654:Pulmonary Edema / Q000097:blood / Q000209:etiology* / Q000503:physiopathology; D013929:Thromboxane B2 / Q000097:blood
D013929:Thromboxane B2; D015121:6-Ketoprostaglandin F1 alpha; D009320:Atrial Natriuretic Factor