title: Neuroprotective effect of mild hypothermia in patients undergoing coronary artery surgery with cardiopulmonary bypass: five-year follow-up of a randomized trial.
abstract: OBJECTIVE
  In a randomized trial of 223 patients undergoing coronary artery surgery with cardiopulmonary bypass, we have reported a neuroprotective effect of mild hypothermia. To determine whether the beneficial effect of mild hypothermia was long-lasting, we repeated the psychometric tests in 131 patients after 5 years.
  
  
  METHODS
  Patients were cooled to 32 degrees C during aortic crossclamping and then randomized to rewarming to either 34 degrees C or 37 degrees C, with no further rewarming until arrival in intensive care unit. Cognitive function was measured preoperatively and 1 week and 5 years postoperatively with a battery of 11 psychometric tests interrogating verbal memory, attention, and psychomotor speed and dexterity.
  
  
  RESULTS
  Patients who had greater cognitive decline 1 week after surgery showed poorer performance 5 years later. The magnitude of cognitive decline over 5 years was modest. The incidence of deficits defined as a 1 standard deviation [SD] decline in at least 1 of 3 factors was not different between temperature groups. Fewer patients in the hypothermic group had deficits that persisted over the 5 years, but this difference did not attain statistical significance (RR = 0.64, P = .16).
  
  
  CONCLUSIONS
  The effect of surgery on cognitive function observed early after surgery is an important predictor of cognitive performance 5 years later. Although there was evidence of a neuroprotective effect of mild hypothermia early after surgery in the original cohort, the results after 5 years were inconclusive. In general, the magnitude of cognitive changes over 5 years was modest. We believe that further trials investigating the efficacy of mild hypothermia in patients having cardiac surgery are warranted.
authors.affiliation: Department of Anesthesiology, University of Ottawa, Ottawa, Canada. hnathan@ottawaheart.ca
authors.forename: Howard J
authors.initials: HJ
authors.lastname: Nathan
authors.forename: Rosendo
authors.initials: R
authors.lastname: Rodriguez
authors.forename: Denise
authors.initials: D
authors.lastname: Wozny
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Dupuis
authors.forename: Fraser D
authors.initials: FD
authors.lastname: Rubens
authors.forename: Gregory L
authors.initials: GL
authors.lastname: Bryson
authors.forename: George
authors.initials: G
authors.lastname: Wells
mesh_terms: D000368:Aged; D002315:Cardiopulmonary Bypass / Q000009:adverse effects*; D003072:Cognition Disorders / Q000175:diagnosis / Q000209:etiology / Q000517:prevention & control*; D001026:Coronary Artery Bypass / Q000009:adverse effects*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007036:Hypothermia, Induced; D008297:Male; D009483:Neuropsychological Tests; D011594:Psychometrics