title: Effect of moderate elevation above sea level on blood oxygen saturation in healthy young adults.
abstract: BACKGROUND
  Arterial hemoglobin oxygen saturation (SaO₂) decreases at an altitude of >1,500 m. There are no reports on normal SaO₂ at altitudes between 0 and 1,500 m. The clinical significance of decreased SaO₂ at such altitudes is unclear.
  
  
  OBJECTIVE
  To test the hypothesis that in healthy volunteers normal SaO₂ at moderate altitude (MA; 725 m) is lower than that at almost sea level (SL; 43 m).
  
  
  METHODS
  SaO₂ was measured by transcutaneous pulse oximetry in young healthy volunteers at MA and was compared to equivalent measurements at SL. In addition, a 6-min walk test was performed and SaO₂ at the end of the walk was compared between the two locations.
  
  
  RESULTS
  111 males were checked at MA and 101 at SL. At rest, nadir SaO₂ was 95% at MA compared to 97% at SL. Mean SaO₂ at rest was slightly higher at SL (98.53 ± 0.52) compared to MA (98.11 ± 0.8; p < 0.01). In subjects who completed the 6-min walk test, SaO₂ slightly decreased after the test in both locations, by 0.38 ± 0.65% in the SL group and by 0.37 ± 1.12% in the MA group. This difference is not statistically significant by univariate analysis; however, a multiple regression analysis indicated that the drop in SaO₂ was higher at MA than at low altitude.
  
  
  CONCLUSIONS
  We found a low but significant difference in SaO₂ between near-SL and at an altitude of 725 m. The clinical significance of this difference, in terms of human health, is probably minimal.
authors.affiliation: Pediatric Pulmonology Unit, Shaare Zedek Medical Center Affiliated to The Hebrew University, School of Medicine, Jerusalem, Israel. sgoldberg@szmc.org.il
authors.forename: Shmuel
authors.initials: S
authors.lastname: Goldberg
authors.forename: Eadit
authors.initials: E
authors.lastname: Buhbut
authors.forename: Francis B
authors.initials: FB
authors.lastname: Mimouni
authors.forename: Leon
authors.initials: L
authors.lastname: Joseph
authors.forename: Elie
authors.initials: E
authors.lastname: Picard
mesh_terms: D000328:Adult; D000531:Altitude; D000532:Altitude Sickness / Q000097:blood*; D001785:Blood Gas Monitoring, Transcutaneous / Q000379:methods*; D006454:Hemoglobins / Q000378:metabolism*; D006801:Humans; D008297:Male; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption / Q000502:physiology*; D012016:Reference Values; D055815:Young Adult
chemical_list: D006454:Hemoglobins; D010100:Oxygen