Effect of perioperative oxygen supplementation on 30-day surgical site infection rate in abdominal, gynecologic, and breast surgery: the ISO2 randomized controlled trial.

Background: Benefits and limitations of supplementation with 80% fraction of inspired oxygen for preventing surgical site infections have not yet been clearly defined. Some studies have reported benefits in colorectal surgery, whereas trials in abdominal and gynecologic surgery have reported either no effect or a deleterious effect.

Methods: Controlled, randomized, assessor-blind multicenter trial, the ISO2 study, comparing the effects of hyperoxygenation (fraction of inspired oxygen, 80%) with those of 30% oxygen on the frequency of surgical site infections in routine abdominal, gynecologic, and breast surgery on 434 patients. Patients not seen in consultation after discharge were contacted.

Results: In total, 208 patients received 30% perioperative oxygen and 226 received 80%. There was no difference between the two groups for baseline, intraoperative, and postoperative characteristics, except for oxygen saturation at closure, higher in the 80% group (P=0.01). The frequency of 30-day surgical site infections was 7.2% (15/208) in the 30% group and 6.6% (15/226) in the 80% group (relative risk, 0.92; 95% CI [0.46-1.84], P=0.81). Frequency of adverse events (nausea and vomiting, sternal pain, cough, hypotension) was similar in the two groups. Desaturation and bradycardia were more frequent in the 30% group. In an updated meta-analysis including the result of this trial and those of eight published randomized trials, the overall relative risk was 0.97; 95% CI (0.68-1.40), I2 (inconsistency degree)=73%, (P=0.88).

Conclusions: The routine use of hyperoxygenation throughout abdominal, gynecologic, and breast surgery had no effect on the frequency of 30-day surgical site infections and was not accompanied by more frequent adverse effects.