METHODS: We conducted a single night, randomized double blinded cross over trial in which OSA patients who failed to respond to upper airway surgery were treated on separate nights with oxygen therapy (4 L/min) or placebo (medical air). Effect of oxygen/air on OSA on key polysomnography (PSG) outcomes were assessed: apnea-hypopnea index (AHI), AHI without desaturation (i.e. flow-based AHI [AHIfb]), arousal index and morning blood pressure. OSA endotypes were estimated from the PSG signals to determine whether baseline OSA physiology could be used to predict response to oxygen therapy.
RESULTS: There was a statistically significant reduction in AHI and AHIfb on oxygen versus placebo (AHIfb: 42.4±21.5 vs. 30.5±17.1 events/h, p = 0.008). Arousal index was also reduced on oxygen versus placebo (41.1±19.5 versus 33.0±15.3 events/h, p = 0.006). There was no significant difference in morning blood pressure between oxygen and placebo. While 7/20 subjects experienced a 50% reduction or greater in AHIfb on oxygen (responders), there was no difference in the baseline OSA endotypes (or clinical characteristics) between responders and non-responders.
CONCLUSIONS: Our findings demonstrate that a proportion of patients who fail to respond to upper airway surgery for OSA respond acutely to treatment with supplemental oxygen.
CLINICAL TRIAL REGISTRATION: Registry: Australian New Zealand Clinical Trials Registry; title: Oxygen therapy for treating patients with residual obstructive sleep apnoea following upper airway surgery; identifier: ACTRN12617001361392; URL: https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=373566