Hypoxic challenge assessment in individuals with obstructive sleep apnea

Abstract

Background The degree of arterial hypoxemia during air travel in individuals with obstructive sleep apnea (OSA) is not known. The Aerospace Medical Association considers a ground level arterial oxygen tension (PaO 2) above 9.3 kPa as safe before air travel. Methods Fifteen subjects with untreated OSA (mean apnea–hypopnea index [AHI] 43/h) and 14 with treated OSA (mean AHI on CPAP 1.9/h) completed an assessment including hypoxic challenge test (HCT). The groups had similar mean age, mean BMI and pre-treatment OSA severity. Results Four subjects, all in the untreated group and with resting PaO 2 >9.3 kPa and oxygen saturation (SpO 2) >95%, had a positive HCT (PaO 2 <6.6 kPa and/or SpO 2 <85%). The PaO 2 at the end of the HCT was significantly correlated with the minimum overnight SpO 2 ( r = .754, p = .002) but not with the daytime PaO 2 and SpO 2. Using a cut off value of 65%, the minimum overnight SpO 2 had positive and negative predictive values of 57% and 100% respectively. Conclusions OSA can be an additional risk factor for developing significant arterial hypoxemia during HCT. Baseline PaO 2 and SpO 2 did not predict arterial hypoxemia during the HCT. Minimum overnight SpO 2 <65% may be used as a cut off to advise further assessment. Effective treatment of OSA seems to be the best option before air travel.