Neuromonitoring and neurocognitive outcome in off-pump versus conventional coronary bypass operation

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Background. Cardiopulmonary bypass seems to be a major cause for both intraoperative microemboli and cerebral hypoperfusion. This study investigates high intensive transient signals (HITS) in transcranial Doppler ultrasound (TCD) and serum levels of the neurobiochemical marker protein S-100 in patients who underwent coronary artery bypass operation without cardiopulmonary bypass (off-pump CABG) in comparison with the conventional procedure using cardiopulmonary bypass (CPB). The results are related to the neuropsychologic outcome in both surgical groups.Methods. Forty patients were randomized in 2 groups (20 conventional and 20 off-pump CABG). Neurocognitive status was assessed preoperatively and postoperatively. Venous serum levels of S-100 protein were measured before and after coronary operation, HITS were measured in the middle cerebral artery during the operation.Results. The median value of HITS was 394.5 (0 to 2217) in the conventional versus 11 (0 to 50) in the off-pump group, p less than 0.0001 (Table 1). Table 1Preoperative and Perioperative Characteristics (n = 40)legendVariableGroup A (n = 20)aGroup B (n = 20)bp ValueMeanSDMeanSDAge (years)63.87.765.66.4NSAffected vessels2.40.62.50.5NSAnastomoses proximal2.40.52.20.4NSAnastomoses distal1.20.51.10.2NSSinus rhythm (%)100…100…NSEjection fraction57.46.360.86.1NSUse of IMA graft (%)100…100…NSOperation time (min)129.736.2105.724NSCPB time (min)72.221.8………MAP (mm Hg)54.47.258.011.7NSaConventional coronary artery bypass graft.bOff-pump coronary artery bypass graft.legendCPB = cardiopulmonary bypass; IMA = internal mammary artery; MAP = mean arterial pressure; NS = not significant; SD = standard deviation.Postoperative S-100 serum levels were: 3.76 (0.13 to 11.2) μg/L (conventional) versus 0.13 (0.04 to 1.01) μg/L (off-pump), p less than 0.0001. Postoperative cognitive testing showed significantly different results with a postoperative impairment of 90% of the patients in the conventional group versus no impairment in the off-pump group.Conclusions. Cognitive impairment seems to be strongly associated to CPB and the occurrence of microemboli. The off-pump technique appears to be promising in order to eliminate the source of these neuropyschologic impairments following CABG operation.