Surgical patients with obstructive sleep apnea (OSA) are at increased risk for perioperative complications. Postoperative supplemental oxygen is commonly used but it may contribute to respiratory depression in OSA patients receiving opioids. The objective of the study is to investigate the effect of postoperative supplemental oxygen on SaO2, sleep respiratory events, and CO2 level in patients with untreated OSA.
Consented patients with an apnea hypopnea index (AHI) >5 events/h on a preoperative polysomnography were randomized (1:1) to oxygen (O2) or no oxygen (Control). Oxygen group received O2 at 3 l/min via nasal prongs for 3 postoperative nights. The primary outcomes were polysomnographic parameters measuring SaO2, sleep respiratory events, and PCO2 measured by transcutaneous CO2 monitor (PtcCO2) on night 1-3. The intention-to-treat and per protocol analysis were done.
123 patients were randomized; O2-group:62, and Control-group:61. On night-3, the O2 vs. Control-group had a higher average SaO2: 95.2±3% vs. 91.4±4% (p<0.001) and lower oxygen desaturation index: 2.3(0.2, 13.8) vs. 18.5(8.2, 45.9) events/h [median (25th,75th percentile), p<0.0001]. The O2 group had a decreased AHI, 8.0(2.1, 19.9) vs, 15.6(9.5, 45.8) (p=0.016) ; hypopnea index (p<0.001), central apnea index (p=0.026) and a shortened longest apnea-hypopnea duration (p=0.002). Although PtcCO2-CT55 ≥ 10% on postoperative night 1, 2 or 3 was found in 11.4% patients, there was no difference in PtcCO2 between the groups.
Postoperative supplemental O2 was found to improve oxygenation and decrease AHI without increasing the duration of apnea-hypopnea event or PtcCO2 level. A small number of patients had significant CO2 retention while receiving supplemental O2.