Effect of high-flow nasal oxygen on postoperative oxygenation in obese patients: A randomized controlled trial

Postoperative hypoxemia is common after general anesthesia in obese patients. We investigated if early application of high-flow nasal oxygen (HFNO) improved postoperative oxygenation in obese patients compared with standard oxygen therapy following general anesthesia for laparoscopic bariatric surgery.

This was an open labeled randomized controlled trial conducted at a university hospital in Sweden between October 23, 2018 and February 11, 2020. The study was performed as a substudy within a previously published trial. After ethics committee approval and written informed consent, 40 obese patients (body mass index [BMI] ≥ 35 kg m^-2) scheduled for laparoscopic bariatric surgery were randomized to receive oxygen using a standard low-flow nasal cannula (NC group) or HFNO at 40 L min^-1 (HF group) immediately upon arrival to the post-anesthesia care unit. Flow rate (NC group) or FiO₂ (HF group) was titrated to reach an initial SpO₂ of 95%-98% after which settings were left unchanged. The primary outcome was PaO₂ at 60 min following postoperative baseline values. Secondary outcomes included PaCO₂, SpO₂, hemodynamic variables, and patient self-assessed discomfort.

Thirty-four patients were available for analysis. PaO₂ was similar between groups at postoperative baseline. After 60 min, PaO₂ had increased to 12.6 ± 2.8 kPa in the NC group (n = 15) and 14.0 ± 2.7 kPa in the HF group (n = 19); (mean difference 1.4 kPa, 95% confidence interval -0.6 to 3.3; p = 0.16). There were no differences in PaCO₂, hemodynamic variables, or self-assessed discomfort between groups after 60 min.

In obese patients, HFNO did not improve postoperative short-term oxygenation compared with standard low-flow oxygen following general anesthesia for laparoscopic bariatric surgery.