To explore whether high-flow nasal cannula (HFNC) oxygen therapy can improve postoperative hypoxemia and improve patient comfort in obese patients after gastric volume reduction.

Obese patients who were transferred to the EICU after gastric volume reduction in Shanghai Tenth People's Hospital from October 2019 to September 2020 were selected as the study subjects by using prospective randomized controlled clinical research methods; according to the random coin throwing method, they were divided into HFNC group (n=22) and traditional oxygen therapy group (n=28). Patients' general information (gender, age, BMI, whether they have OSAHS), blood gas results at 0.5 h, 2 h and 24 h after admission, average heart rate at night (20：00-08：00 the next day), average oxygen saturation, minimum oxygen saturation, number of oxygen reduction, apnea hypopnea index(AHI) and comfort were compared between the two groups.

(1) There was no statistical difference in age, sex and BMI between the two groups; (2) The PO₂ and oxygenation index at 2 h, 24 h after admission in the high flow group were significantly higher than those in the traditional oxygen therapy group, and PCO₂ was lower than that in the traditional oxygen therapy group, with statistical difference (P＜0.05), and others were not statistically different between the two groups at different times. In high flow group, 2 h pH, PO₂ and oxygenation index were significantly higher than 0.5 h, with statistical difference (P＜0.05); the pH at 2 h and pH, PO₂, oxygenation index at 24 h after admission were significantly higher than 0.5 h after admission (P＜0.05). There were no significant differences in two group at different times. (3) Among the indicators related to the 12 h nocturnal sleep monitoring, the average oxygen saturation and minimum oxygen saturation at night in the high flow group were higher than those in the traditional oxygen therapy group, and the number of oxygen reduction and average heart rate were lower than those in the traditional oxygen therapy group, with statistical differences (P＜0.05), while there was no statistical difference in AHI between the two groups. (4) In general data, the subjective comfort of patients in the HFNC group was better than that in the traditional oxygen therapy group, with statistical difference (P＜0.05).

HFNC can effectively alleviate hypoxemia in obese patients after gastric volume reduction surgery and build better subjective comfort in them.