Hypoxic challenge testing useful for predicting in-flight hypoxia in obese individuals
Hypoxic challenge testing (HCT) yields better accuracy than simple walking tests for determining fitness for air travel in individuals with obesity, according to a recent study.
In 21 adults (mean age, 51 years; 47.62 percent female; 11 had comorbid chronic obstructive pulmonary disease) with mean body mass index of 36 kg/m2, researchers evaluated the diagnostic accuracy of HCT (during which patients breathed 15% oxygen and submitted to continuous monitoring of their oxygen saturation) and 50 meter (50mWT) and 6 minutes (6MWT) of walking for predicting in-flight hypoxia. The diagnostic potential of perceived dyspnoea, as measured with the Borg scale, was additionally evaluated, given that this parameter is frequently recorded following walking tests.
In-flight hypoxia was defined as oxygen saturation <90 percent, and the reference standard was established in an altitude chamber. Diagnostic accuracy of each index test was estimated by area under the receiver operating characteristic curve (AUC).
HCT yielded the best result, with AUC of 0.87 (95 percent CI, 0.62–0.96). On the other hand, the accuracy of predicting in-flight hypoxia in obese adults failed to noticeably rise above chance level: 50mWT with AUC of 0.63 (0.36–0.84) and 6MWT with AUC of 0.64 (0.35–0.86).
Meanwhile, subjective dyspnoea assessment showed good prognostic ability when recorded after 6MWT (AUC, 0.80, 0.55–0.93).The present data indicate that HCT may be used to adequately assess fitness to fly in individuals with obesity.