To the Editor:
We read not only with interest but also with some surprise the review on high intraoperative oxygen concentration by Hovaguimian et al.1
that appeared recently in ANESTHESIOLOGY. The authors selected 9 to 11 of 21 studies and by a meta-analysis they concluded that “Intraoperative high inspired oxygen fraction decreases the risk of surgical-site infection in surgical patients receiving prophylactic antibiotics, has a weak beneficial effect on nausea, and does not increase the risk of postoperative atelectasis.” We notice that two of the four largest studies that were included in the meta-analysis (434 and 1,386 patients) showed no better result with high oxygen2
and that the largest study (2,012 patients)4
was designed to evaluate effects of nitrous oxide (0 or 70%) rather than oxygen. In another three studies, the nitrous oxide concentration was also varied. This must be considered a confounding factor when aiming at an analysis of oxygen effects. Among the remaining studies, one was discontinued because of more adverse effects by the high oxygen concentration.5
In a study by Meyhoff et al.
high oxygen concentrations increased mortality in patients undergoing cancer surgery. Whether high oxygen concentrations are good or harmful in a surgical wound can thus still be discussed and is indeed a hot issue in redox signaling and tissue repair.7
The other result that surprises us is the conclusion that high oxygen concentration (80 vs
. 30%) does not increase the risk of postoperative atelectasis. The anesthesia was presumably induced by preoxygenation with 100% oxygen in both groups and this causes atelectasis within a few minutes of anesthesia.8
The atelectasis remains during the whole anesthetic period and the switch to either 30 or 80% oxygen does not add much to the initial atelectasis.9
Moreover, the atelectasis remains for some time postoperatively. One may rather conclude that with present standard routines for anesthesia and ventilation atelectasis will develop in the vast majority of patients (90% or more) with no additional effect by the intraoperative oxygen concentration. If the intention is to avoid atelectasis, the lung has to be recruited after induction of anesthesia. Continuation with 30 or 80% oxygen will then show a clear difference between the groups with more atelectasis in the high oxygen group.9
A rationale to avoid atelectasis, besides its impairment of oxygenation, may be that proliferation and translocation of bacteria to promote pneumonia have been shown in the atelectatic lung in anesthetized, mechanically ventilated animals.10
All taken together, whether high or low oxygen concentration is to be used, atelectasis can and should be avoided.
Supported by grants from the Swedish Research Council, No. 5315, Stockholm, Sweden, and the Swedish Heart-Lung Fund, Stockholm, Sweden.
The authors declare no competing interests.
Goran Hedenstierna, M.D., Ph.D., Lennart Edmark, M.D., Ph.D.
University Hospital, Hedenstierna Laboratory, Uppsala, Sweden (G.H.). firstname.lastname@example.org
1. Hovaguimian F, Lysakowski C, Elia N, Tramèr MR. Effect of intraoperative high inspired oxygen fraction on surgical site infection, postoperative nausea and vomiting, and pulmonary function: Systematic review and meta-analysis of randomized controlled trials. ANESTHESIOLOGY. 2013;119:303–16
2. Meyhoff CS, Wetterslev J, Jorgensen LN, Henneberg SW, Høgdall C, Lundvall L, Svendsen PE, Mollerup H, Lunn TH, Simonsen I, Martinsen KR, Pulawska T, Bundgaard L, Bugge L, Hansen EG, Riber C, Gocht-Jensen P, Walker LR, Bendtsen A, Johansson G, Skovgaard N, Heltø K, Poukinski A, Korshin A, Walli A, Bulut M, Carlsson PS, Rodt SA, Lundbech LB, Rask H, Buch N, Perdawid SK, Reza J, Jensen KV, Carlsen CG, Jensen FS, Rasmussen LSPROXI Trial Group. . Effect of high perioperative oxygen fraction on surgical site infection and pulmonary complications after abdominal surgery: The PROXI randomized clinical trial. JAMA. 2009;302:1543–50
3. Thibon P, Borgey F, Boutreux S, Hanouz JL, Le Coutour X, Parienti JJ. Effect of perioperative oxygen supplementation on 30-day surgical site infection rate in abdominal, gynecologic, and breast surgery: The ISO2 randomized controlled trial. ANESTHESIOLOGY. 2012;117:504–11
4. Myles PS, Leslie K, Chan MT, Forbes A, Paech MJ, Peyton P, Silbert BS, Pascoe EENIGMA Trial Group. . Avoidance of nitrous oxide for patients undergoing major surgery: A randomized controlled trial. ANESTHESIOLOGY. 2007;107:221–31
5. Pryor KO, Fahey TJ III, Lien CA, Goldstein PA. Surgical site infection and the routine use of perioperative hyperoxia in a general surgical population: A randomized controlled trial. JAMA. 2004;291:79–87
6. Meyhoff CS, Jorgensen LN, Wetterslev J, Christensen KB, Rasmussen LSPROXI Trial Group. . Increased long-term mortality after a high perioperative inspiratory oxygen fraction during abdominal surgery: Follow-up of a randomized clinical trial. Anesth Analg. 2012;115:849–54
7. Jiang F, Zhang Y, Dusting GJ. NADPH oxidase-mediated redox signaling: Roles in cellular stress response, stress tolerance, and tissue repair. Pharmacol Rev. 2011;63:218–42
8. Rothen HU, Sporre B, Engberg G, Wegenius G, Reber A, Hedenstierna G. Prevention of atelectasis during general anaesthesia. Lancet. 1995;345:1387–91
9. Hedenstierna G, Edmark L. Mechanisms of atelectasis in the perioperative period. Best Pract Res Clin Anaesthesiol. 2010;24:157–69
10. van Kaam AH, Lachmann RA, Herting E, De Jaegere A, van Iwaarden F, Noorduyn LA, Kok JH, Haitsma JJ, Lachmann B. Reducing atelectasis attenuates bacterial growth and translocation in experimental pneumonia. Am J Respir Crit Care Med. 2004;169:1046–53
© 2014 American Society of Anesthesiologists, Inc.