Effects of Normothermia versus  Hypothermia during Cardiopulmonary Bypass on Postsurgical Cognitive Function. Grigore et al. (page 1110)

Despite advances in cardiopulmonary bypass (CPB), central nervous system complications occur in a large percentage of patients. Grigore et al.  conducted a prospective randomized trial of normothermic versus  hypothermic CPB to assess whether hypothermic CPB resulted in less neurologic damage after the procedure. They enrolled 300 patients and randomly assigned them to one of two groups: normothermic (35.5–36.5°C) CPB systemic perfusion (warm group) or hypothermic (28–30°C) CPB systemic perfusion (cold group). Both groups received intermittent hypothermic (8°C) antegrade blood cardioplegic solution for myocardial protection during CPB.

A battery of neurocognitive tests was given to participants preoperatively on postoperative days 3–5 and again at 6 weeks after surgery. Global neurologic scores were determined based on the Western Perioperative Neurologic Scale, which assesses 14 items in 8 domains, including speech, motor ability, reflexes, and gait. At the 6-week reassessment, investigators determined whether there were any neurologic changes based on specific outcomes, including the Western Perioperative Neurologic Scale score and clinical evidence of new stroke or neurologic deficit. Of the 300 patients enrolled in the study, 227 completed the 6-week postoperative testing—117 patients from the warm group and 110 patients from the cold group. The authors found that there were no differences in neurologic or neurocognitive outcomes between the two groups. Therefore, the current practice of using hypothermia (at temperatures of 28–30°C) during CPB, followed by rewarming, does not seem to be neuroprotective. Further investigation into the mechanisms of neurologic injury after CPB are necessary to discover other strategies for neuroprotection during CPB.