title: Sleep and breathing in high altitude pulmonary edema susceptible subjects at 4,559 meters.
abstract: OBJECTIVE
  Susceptible subjects ascending rapidly to high altitude develop pulmonary edema (HAPE). We evaluated whether HAPE leads to sleep and breathing disturbances that are alleviated by dexamethasone.
  
  
  METHODS
  Double-blind, randomized, placebo-controlled trial with open-label extension.
  
  
  METHODS
  One night in sleep laboratory at 490 m, 2 nights in mountain hut at 4,559 m.
  
  
  METHODS
  21 HAPE susceptibles.
  
  
  METHODS
  Dexamethasone 2 × 8 mg/d, either 24 h prior to ascent and at 4,559 m (dex-early), or started on day 2 at 4,559 m only (dex-late).
  
  
  METHODS
  Polysomnography, questionnaires on sleep and acute mountain sickness.
  
  
  RESULTS
  Polysomnographies at 490 m were normal. In dex-late (n = 12) at 4,559 m, night 1 and 3, median oxygen saturation was 71% and 80%, apnea/hypopnea index 91.3/h and 9.6/h. In dex-early (n = 9), corresponding values were 78% and 79%, and 85.3/h and 52.3/h (P < 0.05 vs. 490 m, all instances). In dex-late, ascending from 490 m to 4,559 m (night 1), sleep efficiency decreased from 91% to 65%, slow wave sleep from 20% to 8% (P < 0.05, both instances). In dex-early, corresponding sleep efficiencies were 96% and 95%, slow wave sleep 18% and 9% (P < 0.05). From night 1 to 3, sleep efficiency remained unchanged in both groups while slow wave sleep increased to 20% in dex-late (P < 0.01). Compared to dex-early, initial AMS scores in dex-late were higher but improved during stay at altitude.
  
  
  CONCLUSIONS
  HAPE susceptibles ascending rapidly to high altitude experience pronounced nocturnal hypoxemia, and reduced sleep efficiency and deep sleep. Dexamethasone taken before ascent prevents severe hypoxemia and sleep disturbances, while dexamethasone taken 24 h after arrival at 4,559 m increases oxygenation and deep sleep.
authors.affiliation: Pulmonary Division and Sleep Disorders Center, University Hospital of Zurich, and Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Nussbaumer-Ochsner
authors.forename: Nicole
authors.initials: N
authors.lastname: Schuepfer
authors.forename: Justyna
authors.initials: J
authors.lastname: Ursprung
authors.forename: Christoph
authors.initials: C
authors.lastname: Siebenmann
authors.forename: Marco
authors.initials: M
authors.lastname: Maggiorini
authors.forename: Konrad E
authors.initials: KE
authors.lastname: Bloch
mesh_terms: D000328:Adult; D000531:Altitude; D000532:Altitude Sickness / Q000188:drug therapy* / Q000503:physiopathology; D000893:Anti-Inflammatory Agents / Q000494:pharmacology / Q000627:therapeutic use*; D003907:Dexamethasone / Q000494:pharmacology / Q000627:therapeutic use*; D004198:Disease Susceptibility; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D011654:Pulmonary Edema / Q000503:physiopathology*; D012119:Respiration / Q000187:drug effects; D012890:Sleep / Q000187:drug effects / Q000502:physiology*; D011795:Surveys and Questionnaires
chemical_list: D000893:Anti-Inflammatory Agents; D003907:Dexamethasone