title: Supplemental postoperative oxygen and tissue oxygen tension in morbidly obese patients.
abstract: BACKGROUND
  Subcutaneous tissue oxygen tension (PsqO(2)) is a major predictor for wound healing and the occurrence of wound infections. Perioperative subcutaneous wound and tissue oxygen tension is significantly reduced in morbidly obese patients. Even during intraoperative supplemental oxygen administration, PsqO(2) remains low. Tissue hypoxia is pronounced during surgery and might explain the substantial increase in infection risk in obese patients. It remains unknown whether long-term supplemental postoperative oxygen augments tissue oxygen tension. Consequently, we tested the hypothesis that 80% inspired oxygen administration during 12-18 postoperative hours significantly increases PsqO(2) compared to 30% inspired oxygen fraction.
  
  
  METHODS
  After IRB approval and informed consent, 42 patients undergoing laparoscopic bariatric surgery were randomly assigned to receive either 80% inspired oxygen via a PULMANEX Hi-Ox Mask (Viasys MedSystems, Wheeling, IL) (10 L/min) or 30% oxygen via nasal cannula (2 L/min) after surgery until the next morning. PsqO(2) was measured with a temperature-corrected Clark-type electrode in the subcutaneous tissue of the upper arm and adjacent to the wound.
  
  
  RESULTS
  Postoperative subcutaneous tissue oxygen tension was significantly increased in the Hi-Ox group: 58 (47.7, 74.1) mmHg vs. 43 (38.7, 55.2) mmHg, P = 0.002. Also, wound tissue oxygen tension was improved during supplemental oxygen administration: 75.2 (69.8, 95.5) mmHg vs. 52.4 (46.3, 66.1) mmHg, P < 0.001.
  
  
  CONCLUSIONS
  Subcutaneous tissue oxygen tension was significantly increased by supplemental postoperative oxygen administration. Whether there is an effect on the incidence of wound infection in morbidly obese patients is matter of further research.
authors.affiliation: Department of Anesthesiology and General Intensive Care, Medical University of Vienna, Waehringerguertel 18-20, 1090 Vienna, Austria. barbara.kabon@meduniwien.ac.at
authors.forename: Barbara
authors.initials: B
authors.lastname: Kabon
authors.forename: Romana
authors.initials: R
authors.lastname: Rozum
authors.forename: Corinna
authors.initials: C
authors.lastname: Marschalek
authors.forename: Gerhard
authors.initials: G
authors.lastname: Prager
authors.forename: Edith
authors.initials: E
authors.lastname: Fleischmann
authors.forename: Astrid
authors.initials: A
authors.lastname: Chiari
authors.forename: Andrea
authors.initials: A
authors.lastname: Kurz
mesh_terms: D000328:Adult; D005260:Female; D015390:Gastric Bypass; D006801:Humans; D010535:Laparoscopy; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000378:metabolism* / Q000601:surgery; D010100:Oxygen / Q000097:blood / Q000378:metabolism*; D010101:Oxygen Consumption; D010102:Oxygen Inhalation Therapy; D011182:Postoperative Care; D011184:Postoperative Period; D012881:Skin Temperature / Q000502:physiology; D013530:Surgical Wound Infection / Q000378:metabolism; D016896:Treatment Outcome; D014945:Wound Healing / Q000502:physiology
chemical_list: D010100:Oxygen