Effect of Moderate Elevation above Sea Level on Blood Oxygen Saturation in Healthy Young Adults

Background: Arterial hemoglobin oxygen saturation (SaO(2)) decreases at an altitude of 1 1,500 m. There are no reports on normal SaO(2)2 at altitudes between 0 and 1,500 m. The clinical significance of decreased SaO(2) at such altitudes is unclear. Objective: To test the hypothesis that in healthy volunteers normal SaO(2) at moderate altitude (MA; 725 m) is lower than that at almost sea level (SL; 43 m). Methods: SaO(2) 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 SaO(2) 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 SaO(2) was 95% at MA compared to 97% at SL. Mean SaO(2) 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, SaO(2) 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 SaO(2) was higher at MA than at low altitude. Conclusions: We found a low but significant difference in SaO(2) between near-SL and at an altitude of 725 m. The clinical significance of this difference, in terms of human health, is probably minimal. Copyright (c) 2012 S. Karger AG, Basel