Abnormal control of ventilation in high-altitude pulmonary edema.
We wished to determine the role of hypoxic chemosensitivity in high-altitude pulmonary edema (HAPE) by studying persons when ill and upon recovery. We studied seven males with HAPE and seventeen controls at 4,400 m on Mt. McKinley. We measured ventilatory responses to both O2 breathing and progressive poikilocapnic hypoxia. Hypoxic ventilatory response (HVR) was described by the slope relating minute ventilation to percent arterial O2 saturation (delta VE/delta SaO2%). HAPE subjects were quite hypoxemic (SaO2% 59 +/- 6 vs. 85 +/- 1, P less than 0.01) and showed a high-frequency, low-tidal-volume pattern of breathing. O2 decreased ventilation in controls (-20%, P less than 0.01) but not in HAPE subjects. The HAPE group had low HVR values (0.15 +/- 0.07 vs. 0.54 +/- 0.08, P less than 0.01), although six controls had values in the same range. The three HAPE subjects with the lowest HVR values were the most hypoxemic and had a paradoxical increase in ventilation when breathing O2. We conclude that a low HVR plays a permissive rather than causative role in the pathogenesis of HAPE and that the combination of extreme hypoxemia and low HVR may result in hypoxic depression of ventilation.
Hackett
P H
PH
Denali Medical Research Project, Center for High Latitude Health Research, University of Alaska, Anchorage 99508.
Roach
R C
RC
Schoene
R B
RB
Harrison
G L
GL
Mills
W J
WJ
D000328:Adult; D000531:Altitude; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D008297:Male; D010100:Oxygen / Q000378:metabolism; D010102:Oxygen Inhalation Therapy; D011654:Pulmonary Edema / Q000503:physiopathology* / Q000628:therapy; D012119:Respiration
D010100:Oxygen