“…2,3 Surprisingly, this was not observed here. Conversely, oxygenation in the 30-degree head-of-bed elevation group was inferior to that in the supine position (table 2 1 ). Curiously, although the combination of high-flow nasal oxygen and 30-degree head-of-bed elevation showed additive or even synergistic effects, neither alone showed much impact on the apnea-hypopnea index.…”