Stress Doppler echocardiography for identification of susceptibility to high altitude pulmonary edema

OBJECTIVE This prospective single-blinded study was performed to quantitate noninvasive pulmonary artery systolic pressure (PASP) responses to prolong ed acute hypoxia and normoxic exercise. BACKGROUND Hypoxia-induced excessive rise in pulmonary artery pressure is a key factor in high-altitude pulmonary edema (HAPE). We hypothesized that s ubjects susceptible to HAPE (HAPE-S) have increased pulmonary artery pressu re response not only to hypoxia but also to exercise. METHODS PASP was estimated at 45, 90 and 240 min of hypoxia (FiO(2) = 12%) and during supine bicycle exercise in normoxia using Doppler-echocardiograp hy in nine HAPE-S and in 11 control subjects. RESULTS In the control group, mean PASP increased from 26 +/- 2 to 37 +/- 4 mm Hg (Delta PASP 10.3 +/- 2 mm Hg) after 90 min of hypoxia and from 27 +/ - 4 to 36 +/- 3 mm Hg (Delta PASP 8 +/- 2 mm Hg) during exercise. In contra st, all HAPE-S subjects revealed significantly greater increases (p = 0.002 vs. controls) in mean PASP both during hypoxia (from 28 +/- 4 to 57 +/- 10 mm Hg, Delta PASP 28.7 +/- 6 mm Hg) and during exercise (from 28 +/- 4 to 55 +/- II mm Hg, Delta PASP 27 +/- 8 mm Hg) than did control subjects. Stre ss echocardiography allowed discrimination between groups without overlap u sing a cut off PASP value of 45 mm Hg at work rates less than 150 W. CONCLUSIONS These data indicate that HAPE-S subjects may have abnormal pulm onary vascular responses not only to hypoxia but also to supine bicycle exe rcise under normoxic conditions. Thus, Doppler echocardiography during supi ne bicycle exercise or after 90 min of hypoxia may be useful noninvasive sc reening methods to identify subjects susceptible to HAPE. (C) 2000 by the A merican College of Cardiology.