title: Do changes in lung function predict high-altitude pulmonary edema at an early stage?
abstract: OBJECTIVE
  Ascent to high altitude is associated with alterations in lung function. The mechanisms of these changes and whether they reflect early stages of high-altitude pulmonary edema (HAPE) has been debated. Therefore, we investigated the time course of pulmonary function in relation to hemodynamics and clinical symptoms in mountaineers ascending rapidly to high altitude.
  
  
  METHODS
  In 26 unacclimatized subjects we assessed spirometry, single-breath nitrogen washout, diffusing capacity (DLCO), and Doppler echocardiography in Zurich, 490 m, after climbing within 24 h to Monte Rosa, 4559 m, and after one night at 4559 m.
  
  
  RESULTS
  Mean (+/- SD) FVC fell from 103 +/- 9% predicted in Zurich to 96 +/- 10% predicted at 4559 m, FEV1/FVC increased from 0.82 +/- 0.06 to 0.84 +/- 0.08, and closing volume increased from 0.35 +/- 0.14 to 0.44 +/- 0.11 L above residual volume (P < 0.05, all changes). On the following day at 4559 m, closing volume remained elevated in 9 of 21 subjects who had a lower DLCO but similar pulmonary artery systolic pressures compared with the remaining 12 subjects (40 +/- 8 vs 43 +/- 7 mm Hg, P = NS). None of the subjects had overt HAPE.
  
  
  CONCLUSIONS
  We conclude that changes in pulmonary function after rapid ascent to high altitude were consistent with interstitial fluid accumulation, but they were not related to changes in pulmonary artery pressure. Individual lung function responses to high-altitude exposure varied largely and did not predict subsequent HAPE.
authors.affiliation: Pulmonary Division, University Hospital of Zurich and Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland.
authors.forename: Oliver
authors.initials: O
authors.lastname: Senn
authors.forename: Christian F
authors.initials: CF
authors.lastname: Clarenbach
authors.forename: Manuel
authors.initials: M
authors.lastname: Fischler
authors.forename: Rahel
authors.initials: R
authors.lastname: Thalmann
authors.forename: Hanspeter
authors.initials: H
authors.lastname: Brunner-La Rocca
authors.forename: Patrick
authors.initials: P
authors.lastname: Egger
authors.forename: Marco
authors.initials: M
authors.lastname: Maggiorini
authors.forename: Konrad E
authors.initials: KE
authors.lastname: Bloch
mesh_terms: D000293:Adolescent; D000328:Adult; D000532:Altitude Sickness / Q000097:blood / Q000503:physiopathology*; D001794:Blood Pressure / Q000502:physiology*; D002302:Cardiac Output / Q000502:physiology*; D015150:Echocardiography, Doppler; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000097:blood / Q000503:physiopathology*; D008168:Lung / Q000502:physiology; D008176:Lung Volume Measurements / Q000379:methods; D008297:Male; D005082:Physical Exertion / Q000502:physiology*; D011237:Predictive Value of Tests; D011654:Pulmonary Edema / Q000209:etiology / Q000503:physiopathology*; D012720:Severity of Illness Index; D013147:Spirometry