Inspiratory Oxygen Fraction and Postoperative Complications in Obese Patients

Abstract

Background: Obese patients are at a high risk of postoperative complication, including surgical site infection (SSI). Our aim was to evaluate the effect of a high inspiratory oxygen fraction (80%) on SSI and pulmonary complications in obese patients undergoing laparotomy. Methods: This study was a planned analysis of the obese patients (body mass index 30 kg/m 2 ) recruited in the Danish multicenter, patient- and observer-blinded, PROXI Trial of 1,400 patients undergoing acute or elective laparotomy.Patientswererandomizedtoreceiveeither80%or30% oxygen during and for 2 h after surgery. The primary outcome was SSI within 14 days. Secondary outcomes were atelectasis, pneumonia, and respiratory failure. Results: Two hundred thirteen patients had a body mass index 30 kg/m 2 . The median (5–95% range) body mass index was 34 kg/m 2 (30–44) and 33 kg/m 2 (30–41) in patients allocated to the 80% and 30% oxygen group. SSI occurred in 32 of 102 (31%)versus29 of 111 (26%) patients given 80% and 30% oxygen, respectively (odds ratio, 1.29; 95%CI,0.71–2.34;P0.40).Inaddition,theincidenceof pulmonary complications was not significantly different, with atelectasis occurring in 9% versus 6%, pneumonia in 6% versus 5%, and respiratory failure in 8% versus 5% in patients given 80% and 30% oxygen, respectively. Conclusion: Administration of 80% oxygen, compared with 30% oxygen, did not reduce the frequency of SSI in obese patients. Moreover, no significant association was found between oxygen fraction and the risk of pulmonary complications.