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BACKGROUND:
Common causes of neurologic disorders following cardiopulmonary bypass (CPB) are micro- or macroembolization and hypoperfusion, possibly due to excessive hemodilution, microbubble formation and blood contact with air and foreign material. The use of a closed minimized extracorporeal circulation (MECC) system during CABG surgery may improve cerebral perfusion and reduce these complications.
METHODS:
In a prospective trial, 40 patients were randomized to undergo either standard CPB or MECC-assisted CABG surgery (n=20, each). MECC is a closed, fully heparinized circuit with reduced foreign surface (prime volume=400ml). Non-invasive cerebral monitoring using near infrared spectroscopy (NIRS) to measure changes in hemoglobin oxygen saturation, as well as transcranial Doppler for detection of microemboli were performed intraoperatively. Mini-mental state examination (MMSE) was performed preoperatively and on POD7.
RESULTS:
Pre- and perioperative characteristics were similar in both groups. The decrease in cerebral HbO2 was significantly less pronounced in MECC patients (-2.0 vs. -8.8µM;p<0.001) and they also had less cerebral microemboli than standard CPB patients (404 vs. 1133p=0.01). Norepinephrine boluses to maintain sufficient arterial perfusion pressure were less frequently required in MECC patients (25% vs. 60%,p<0.01) and blood loss, transfusion requirement and myocardial ischemia markers were also significantly reduced. MMSE revealed no differences between the groups but 2 cases of transitory psychotic syndrome occurred in the standard CPB group, whereas no such morbidity was observed in the MECC group
CONCLUSIONS:
MECC is safe, significantly less traumatic and reduces cerebral injury compared with standard CPB. However, long-term follow-up is needed to determine the clinical relevance for neurocognitive function.