Best evidence in anesthetic practice Prevention: supplemental oxygen reduces the incidence of surgical-wound infection

Question

Can supplemental administration of oxygen during the perioperative period decrease the incidence of postoperative wound infections in patients undergoing colorectal resection?

Design

Multicenter, randomized, double-blind, controlled trial.

Setting

Three hospitals in Europe (Austria and Germany).

Patients

Five hundred patients between 18 to 80 yr of age (mean age 57 yr, 44% women) undergoing elective open colorectal resection. Exclusion criteria were minor colon surgery, recent history of fever or infection, serious malnutrition, and bowel obstruction.

Intervention

Two hundred fifty patients were allocated to 30% oxygen / 70% nitrogen (30% O₂ group); 250 patients were allocated to 80% oxygen / 20% nitrogen (80% O₂ group). Both received the assigned concentrations during anesthesia until immediately before extubation when oxygen was increased to 100%. After extubation, as soon as deemed safe by the anesthesiologist, the oxygen concentration was returned to the allocated levels for the first two hours of recovery.

Main outcomes

Fifteen-day incidence of surgicalwound infection was the primary outcome. ASEPSIS score, white-cell counts, time to first solid food, time to staples removal, duration of postoperative hospitalization, proportion of ICU admission, and 15-day mortality were secondary outcomes. Amounts of collagen and protein deposition were measured in a subgroup of patients (32 receiving 30% O₂; 22 receiving 80% O₂).

Main results

Analysis was intention-to-treat. Clinical characteristics, diagnoses, surgical procedures and duration, hemodynamic values, use of anesthetics, and types and duration of prophylactic antibiotic adminstration were similar between both groups. Overall incidence of surgical wound infections was 8%. The 80% O₂ group had fewer wound infections (5.2%) compared to the 30% O₂ group (11.2%) [absolute risk reduction 6.0%; 95% confidence interval 1.2–10.8%; number-needed-to-treat 17; P=0.01]. Similarly, the mean ASEPSIS score was lower in the 80% O₂ group (3 ±7) compared to the 30% O₂ group (5 ±9; P=0.01). There were no statistically significant differences between groups for the other outcomes.

Conclusion

Administration of 80% supplemental oxygen during colorectal resection and for two hours afterwards halved the 15-day incidence of surgicalwound infection.

Funding

U.S. National Institutes of Health, Fonds zur Förderung der wissenschafflichen Forschung, Joseph Drown Foundation, Anesthesia Patient Safety Foundation, Max Kade Foundation, Erwin-Schrödinger Foundation, Bürgermeister Fond der Stadt Wien, Austrian National Bank Fund.