Hypoxic challenge assessment in individuals with obstructive sleep apnea

Area of Science:

• Aerospace Medicine
• Sleep Medicine
• Pulmonology

Background:

• The risk of arterial hypoxemia during air travel for individuals with obstructive sleep apnea (OSA) is not well-defined.
• The Aerospace Medical Association suggests a ground-level arterial oxygen tension (PaO₂) above 9.3 kPa is safe for air travel.

Purpose of the Study:

• To investigate the degree of arterial hypoxemia during a hypoxic challenge test (HCT) in individuals with untreated and treated obstructive sleep apnea (OSA).
• To identify predictors of hypoxemia during simulated air travel in OSA patients.

Main Methods:

• Fifteen subjects with untreated OSA and 14 with treated OSA underwent a hypoxic challenge test (HCT).
• Demographic data, baseline oxygen saturation, and arterial oxygen tension were recorded.
• Apnea-hypopnea index (AHI) was used to quantify OSA severity.

Main Results:

• Four untreated OSA subjects experienced significant hypoxemia during HCT (PaO₂ <6.6 kPa and/or SpO₂ <85%), despite safe baseline oxygen levels.
• Minimum overnight SpO₂ showed a significant correlation with PaO₂ during HCT (r=.754, p=.002).
• A minimum overnight SpO₂ cutoff of 65% demonstrated 100% negative predictive value for identifying individuals at risk of hypoxemia.

Conclusions:

• Obstructive sleep apnea (OSA) is a risk factor for significant arterial hypoxemia during simulated air travel.
• Baseline oxygen saturation and tension are insufficient predictors of hypoxemia during HCT.
• Minimum overnight SpO₂ <65% may guide further assessment for air travel suitability, and effective OSA treatment is recommended prior to flying.