title: Administration of oxygen before tracheal extubation worsens gas exchange after general anesthesia in a pig model.
abstract: Administration of 100% oxygen before tracheal extubation is common clinical practice. We determined the effect of this technique on postoperative gas exchange in a porcine model using the multiple inert gas elimination technique. After general anesthesia with mechanical ventilation for a period of 30 min (inspiratory fraction of oxygen of 0.3), anesthesia was discontinued, and the pigs were randomized to an inspiratory fraction of oxygen of 0.3 or 1.0 until they could be safely extubated. Thirty minutes after extubation while breathing air, blood flow to poorly ventilated units had significantly increased in pigs that had been administered 100% oxygen as compared with those receiving 30% oxygen (17% +/- 15% versus 7% +/- 5%; P = 0.009). We conclude that exposure to 100% oxygen before extubation may cause an undesirable alteration in gas exchange.
  
  
  CONCLUSIONS
  Blood flow to lung units with a low V(A)/Q ratio was significantly larger in pigs that had been exposed to 100% oxygen before extubation as compared with those exposed to 30% oxygen before extubation.
authors.affiliation: Department of Anesthesiology, Critical Care and Emergency Medicine, The Leopold-Franzens University Innsbruck, Austria. alex.loeckinger@uibk.ac.at
authors.forename: Alexander
authors.initials: A
authors.lastname: Loeckinger
authors.forename: Axel
authors.initials: A
authors.lastname: Kleinsasser
authors.forename: Christian
authors.initials: C
authors.lastname: Keller
authors.forename: Andreas
authors.initials: A
authors.lastname: Schaefer
authors.forename: Christian
authors.initials: C
authors.lastname: Kolbitsch
authors.forename: Karl H
authors.initials: KH
authors.lastname: Lindner
authors.forename: Arnulf
authors.initials: A
authors.lastname: Benzer
mesh_terms: D000768:Anesthesia, General; D000818:Animals; D005260:Female; D007442:Intubation, Intratracheal; D008297:Male; D023421:Models, Animal; D010100:Oxygen / Q000633:toxicity*; D011659:Pulmonary Gas Exchange; D013552:Swine; D014692:Ventilation-Perfusion Ratio
chemical_list: D010100:Oxygen