title: High intraoperative inspired oxygen does not increase postoperative supplemental oxygen requirements.
abstract: BACKGROUND
  Although a high fraction of inspired oxygen (FIO2) could reduce surgical site infection, there is concern it could increase postoperative pulmonary complications, including hypoxemia. Intraoperative positive end-expiratory pressure can improve postoperative pulmonary function. A practical measure of postoperative pulmonary function and the degree of hypoxemia is supplemental oxygen requirement. We performed a double-blind randomized 2 × 2 factorial study on the effects of intraoperative FIO2 0.3 versus more than 0.9 with and without positive end-expiratory pressure on the primary outcome of postoperative supplemental oxygen requirements in patients undergoing lower risk surgery.
  
  
  METHODS
  After Institutional Review Board approval and consent, 100 subjects were randomized using computer-generated lists into four treatment groups (intraoperative FIO2 0.3 vs. more than 0.9, with and without 3-5 cm H2O positive end-expiratory pressure). Thirty minutes and 24 h after extubation, supplemental oxygen was discontinued. Arterial oxygen saturation by pulse oximetry was recorded 15 min later. If oxygen saturation decreased to less than 90%, supplemental oxygen was added incrementally to maintain saturation more than 90%.
  
  
  RESULTS
  Nearly all subjects required supplemental oxygen in the postanesthesia care unit. Nonparametric Wilcoxon rank sum test demonstrated no statistically significant difference between groups in supplemental oxygen requirements at 45 min and 24 h after tracheal extubation (P = 0.56 and 0.98, respectively).
  
  
  CONCLUSIONS
  Use of intraoperative FIO2 more than 0.9 was not associated with increased oxygen requirement, suggesting it does not induce postoperative hypoxemia beyond anesthetic induction and surgery. Therefore, it may be reasonable to use high inspired oxygen in surgical patients with relatively normal pulmonary function.
authors.affiliation: Department of Anesthesiology, University of Utah School of Medicine, Salt Lake City, UT, USA.
authors.forename: Natalie
authors.initials: N
authors.lastname: Mackintosh
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Gertsch
authors.forename: Harriet W
authors.initials: HW
authors.lastname: Hopf
authors.forename: Nathan L
authors.initials: NL
authors.lastname: Pace
authors.forename: Julia
authors.initials: J
authors.lastname: White
authors.forename: Rebecca
authors.initials: R
authors.lastname: Morris
authors.forename: Candice
authors.initials: C
authors.lastname: Morrissey
authors.forename: Victoria
authors.initials: V
authors.lastname: Wilding
authors.forename: Seth
authors.initials: S
authors.lastname: Herway
mesh_terms: D004311:Double-Blind Method; D006801:Humans; D000860:Hypoxia / Q000097:blood / Q000517:prevention & control; D007430:Intraoperative Care / Q000379:methods*; D010092:Oximetry / Q000379:methods; D010100:Oxygen / Q000008:administration & dosage* / Q000097:blood; D010101:Oxygen Consumption; D011175:Positive-Pressure Respiration / Q000379:methods*; D011183:Postoperative Complications / Q000097:blood / Q000517:prevention & control*; D011652:Pulmonary Circulation; D011659:Pulmonary Gas Exchange; D016896:Treatment Outcome
chemical_list: D010100:Oxygen