title: Effect of Prewarming during Induction of Anesthesia on Microvascular Reactivity in Patients Undergoing Off-Pump Coronary Artery Bypass Surgery: A Randomized Clinical Trial.
abstract: BACKGROUND
  General anesthesia may induce inadvertent hypothermia and this may be related to perioperative cardiovascular complications. Microvascular reactivity, measured by the recovery slope during a vascular occlusion test, is decreased during surgery and is also related to postoperative clinical outcomes. We hypothesized that microvascular changes during surgery may be related to intraoperative hypothermia. To evaluate this, we conducted a randomized study in patients undergoing off-pump coronary artery bypass surgery, in which the effect of prewarming on microvascular reactivity was evaluated.
  
  
  METHODS
  Patients scheduled for off-pump coronary artery bypass surgery were screened. Enrolled patients were randomized to the prewarming group to receive forced-air warming during induction of anesthesia or to the control group. Measurement of core and skin temperatures and vascular occlusion test were conducted before anesthesia induction, 1, 2, and 3 h after induction, and at the end of surgery.
  
  
  RESULTS
  In total, 40 patients were enrolled and finished the study (n = 20 in the prewarming group and n = 20 in the control group). During the first 3 h of anesthesia, core temperature was higher in the prewarming group than the control group (p < 0.001). The number of patients developing hypothermia was lower in the prewarming group than the control group (4/20 vs. 13/20, p = 0.004). However, tissue oxygen saturation and changes in recovery slope following a vascular occlusion test at 3 h after anesthesia induction did not differ between the groups. There was no difference in clinical outcome, including perioperative transfusion, wound infection, or hospital stay, between the groups.
  
  
  CONCLUSIONS
  Prewarming during induction of anesthesia decreased intraoperative hypothermia, but did not reduce the deterioration in microvascular reactivity in patients undergoing off-pump coronary artery bypass surgery.
  
  
  BACKGROUND
  ClinicalTrials.gov NCT02186210.
authors.affiliation: Department of Anesthesiology and Pain Medicine, Seoul National University Hospital, Seoul, South Korea.
authors.forename: Youn Joung
authors.initials: YJ
authors.lastname: Cho
authors.affiliation: Department of Anesthesiology and Pain Medicine, Seoul National University Hospital, Seoul, South Korea.
authors.forename: Seo Yun
authors.initials: SY
authors.lastname: Lee
authors.affiliation: Department of Anesthesiology and Pain Medicine, Seoul National University Hospital, Seoul, South Korea.
authors.forename: Tae Kyong
authors.initials: TK
authors.lastname: Kim
authors.affiliation: Department of Anesthesiology and Pain Medicine, Seoul National University Hospital, Seoul, South Korea.
authors.forename: Deok Man
authors.initials: DM
authors.lastname: Hong
authors.affiliation: Department of Anesthesiology and Pain Medicine, Seoul National University Hospital, Seoul, South Korea.
authors.forename: Yunseok
authors.initials: Y
authors.lastname: Jeon
mesh_terms: D000368:Aged; D000768:Anesthesia, General / Q000009:adverse effects; D001831:Body Temperature; D016022:Case-Control Studies; D015897:Comorbidity; D047549:Coronary Artery Bypass, Off-Pump / Q000379:methods; D005260:Female; D006439:Hemodynamics; D006801:Humans; D006979:Hyperthermia, Induced / Q000379:methods; D007035:Hypothermia / Q000209:etiology; D008297:Male; D008833:Microcirculation / Q000528:radiation effects; D008875:Middle Aged; D011300:Preoperative Care; D012881:Skin Temperature; D016896:Treatment Outcome