title: Small-dose propofol sedation attenuates the formation of reactive oxygen species in tourniquet-induced ischemia-reperfusion injury under spinal anesthesia.
abstract: The release of a tourniquet produces reactive oxygen species (ROS), which can cause ischemia-reperfusion injury. We investigated the effects on ROS production in 22 adult ASA physical status I-II patients sedated with small-dose propofol infusion and IV midazolam undergoing elective total knee replacement under intrathecal anesthesia, allocated randomly to one of two groups. In the Propofol group, sedation was performed with propofol 0.2 mg/kg followed by infusion at a rate of 2 mg. kg(-1). h(-1). In the Control group, IV midazolam 5 mg was given. ROS production was measured by lucigenin chemiluminescence analysis. Blood samples were obtained from the radial artery after spinal anesthesia, 1 min before release of the tourniquet and 5 and 20 min after reperfusion. The ischemic time was approximately 70 min. ROS production decreased nonsignificantly before reperfusion in both groups but increased significantly 5 and 20 min after reperfusion in the Midazolam group. In the Propofol group, no significant increase of ROS production was found. We conclude that small-dose propofol infusion attenuates ROS production in tourniquet-induced ischemia-reperfusion injury.
  
  
  CONCLUSIONS
  Small-dose propofol sedation, compared with IV midazolam, attenuates free radical production after release of the tourniquet during total knee replacement under spinal anesthesia.
authors.affiliation: Department of Anesthesiology, Office for Medical Research Administration, National Taiwan University Hospital, No. 7 Chung-Shan South Road, Taipei, Taiwan 10016, Republic of China.
authors.forename: Ya-Jung
authors.initials: YJ
authors.lastname: Cheng
authors.forename: Yong-Ping
authors.initials: YP
authors.lastname: Wang
authors.forename: Chiang-Ting
authors.initials: CT
authors.lastname: Chien
authors.forename: Chau-Fong
authors.initials: CF
authors.lastname: Chen
mesh_terms: D000368:Aged; D000775:Anesthesia, Spinal; D019645:Arthroplasty, Replacement, Knee; D005260:Female; D016166:Free Radical Scavengers; D006801:Humans; D006993:Hypnotics and Sedatives; D008163:Luminescent Measurements; D008297:Male; D008874:Midazolam; D015742:Propofol; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015427:Reperfusion Injury / Q000378:metabolism*; D014111:Tourniquets / Q000009:adverse effects*
chemical_list: D016166:Free Radical Scavengers; D006993:Hypnotics and Sedatives; D017382:Reactive Oxygen Species; D008874:Midazolam; D015742:Propofol