Evid Based Nurs 9:52 doi:10.1136/ebn.9.2.52
  • Treatment

Supplemental perioperative oxygen at 80% FIO2 reduced surgical site infections in elective colorectal surgery

 Q In patients having elective colorectal resection, does supplemental perioperative oxygen reduce the risk of surgical site infection (SSI)?



randomised controlled trial (RCT).




blinded (patients, surgical team, data collectors, outcome assessors, and monitoring committee).

GraphicFollow up period:

14 days after surgery.


14 hospitals in Spain.


300 patients 18–80 years of age who were having elective colorectal resection. Exclusion criteria were minor colon surgery (eg, polypectomy or isolated colostomy) or laparoscopic surgery, expected duration of surgery <1 hour, fever or existing signs of infection, diabetes mellitus, HIV infection, >20% weight loss in past 3 months, serum albumin concentration <30 g/l, or leucocyte count <2500 cells/ml.


during surgery, patients were administered an oxygen/air mixture with a fraction of inspired oxygen (FIO2) of 80% (n = 150) or 30% (n = 150). After surgery was completed, the inhaled anaesthetic was stopped, and FIO2 was increased to 100% during extubation. During the first 6 postoperative hours, patients were given their allocated oxygen concentrations at a total flow of 16 l/min using non-rebreathing masks with a reservoir (Intersurgical, Wokinham, Berkshire). Subsequently, patients breathed ambient air, although supplemental oxygen was given as needed to maintain ⩾92% oxygen saturation.


main outcome was SSI as defined by the US Centers for Disease Control and Prevention; secondary outcomes included time to return of bowel function, ability to tolerate solid food, ambulation, staple removal, and duration of hospital stay.

GraphicPatient follow up:

291 patients (97%) were included in the analysis (mean age 63 y, 56% men).


Risk of SSI was lower in the 80% FI02 group than the 30% FI02 group (table), even after adjustment for sex, weight, age, coexisting respiratory disease, allergy, lymphocyte count, haemoglobin, glucose, and other potential wound infection predictive factors (adjusted relative risk reduction 54%, 95% CI 5 to 78). The groups did not differ for time to return of bowel function (3.0 v 3.1 d, p = 0.54), first solid food intake (4.2 v 4.4 d, p = 0.57), ambulation (3.9 v 4.2 d, p = 0.28), removal of staples (10.5 v 10.3 d, p = 0.71), or duration of hospital stay (11.7 v 10.5 d, p = 0.09).


In patients having elective colorectal surgery, supplemental perioperative oxygen at 80% reduced surgical site infections more than oxygen at 30% during the first 14 days after surgery.


  1. Emil Schmidt, RN, BN(Hon)
  1. Dunedin Hospital, Dunedin, New Zealand

      Patients with SSIs experience substantial pain and inconvenience and may die. Such patients remain in hospital about twice as long as uninfected patients.1 The study by Belda et al found that patients who received supplemental oxygen during colorectal surgery and for 6 hours after surgery had a reduced risk of SSI. An earlier RCT with nearly identical treatment and control conditions also supported the use of perioperative supplemental oxygen as an effective adjunctive therapy to reduce SSIs.2 However, a third RCT found a higher rate of SSIs in patients receiving supplemental oxygen at an FIO2 of 80% than those receiving oxygen at an FIO2 of 35%.3 Which to believe? The third study had several methodological problems that cannot counter the rigour of the other 2 trials.

      If an intervention costs little, has a low risk profile, and appears to be effective in rigorous trials, its use should be encouraged until overwhelming evidence shows that it does not work.4 Some questions remain: what is the optimal FIO2 concentration and duration of treatment? Is oxygen delivery by nasal prongs as effective as delivery by mask? But we should not wait for these issues to be resolved. Although supplemental oxygen is a routine part of perioperative and postoperative care, practices regarding the frequency and concentration of oxygen vary. Oxygen therapy lacks clear protocols, and the patterns that guide oxygen prescription administration differ from those guiding other medications.5 The findings of Belda et al could assist in standardising oxygen therapy to the greater benefit of our patients.


      80% v 30% FI02 perioperative supplemental oxygen in elective colorectal resection*

 Q In patients having elective colorectal resection, does supplemental perioperative oxygen reduce the risk of surgical site infection (SSI)?


      • For correspondence: Dr F J Belda, Department of Anesthesiology and Critical Care, Hospital Clínico Universitario de Valencia, Valencia, Spain. fjbelda{at}

      • Sources of funding: in part, Air-Liquide Medicinal, Spain and Air-Liquide Santé, France.

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