SESSION TITLE: Physiology/PFTs/Rehabilitation Posters
SESSION TYPE: Original Investigation Poster
PRESENTED ON: Wednesday, October 30, 2013 at 01:30 PM - 02:30 PM
PURPOSE: Oxygen saturation falls with ascent to altitude although individual responses are highly variable. The effect of positional changes on oxygen saturation (SpO2) as measured by pulse oximetry in hypoxic environments is unclear. Patients with pulmonary or cardiac disease may demonstrate marked positional changes in SpO2, whereas healthy individuals typically have little positional difference in their SpO2. It is unknown if healthy individuals without altitude illness exhibit significant positional differences in SpO2 following rapid ascent to altitude. Anecdotal observations at high altitude suggested decreased O2 saturation in supine subjects thus we analyzed SpO2 data collected during two recent altitude studies from our laboratory. The purpose of this study was to determine whether SpO2 was different in the upright seated position compared with the supine position under hypoxic conditions.
METHODS: SpO2 was recorded with a transcutaneous ear or finger electrode system in healthy, well-trained subjects following a rapid ascent over approximately 6 hours to 3800 m or 4344 m altitude. Subjects were tested within a few hours of arrival at altitude. Data were analyzed from 10 subjects aged 36 ± 11 years (mean ± SD). Saturation data was continuously recorded and averaged over several minutes. Subjects were blinded to the saturation values during the periods of measurement.
RESULTS: In the upright position SpO2 was 88 ± 7% while in the supine position it was 77 ± 13%, p = 0.02. None of the subjects had clinically significant altitude illness.
CONCLUSIONS: The mechanisms responsible for these positional changes in SpO2 are unknown but deserve further investigation.
CLINICAL IMPLICATIONS: These findings suggest that body position should be indicated when reporting data regarding oxygen saturation at altitude.
DISCLOSURE: The following authors have nothing to disclose: Chandra Patel, Sophia Larson, Paresh Giri, Gary Foster, James Anholm
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