Increased systemic perfusion pressure during cardiopulmonary bypass is associated with less early postoperative cognitive dysfunction and delirium.

OBJECTIVE

Patients undergoing cardiac surgery procedures are thought to be at risk of early neuropsychological deficits and delirium. Regional cerebral hypoperfusion may play a role in the etiology of this complication. We hypothesized that low systemic perfusion pressure during cardiopulmonary bypass (CPB) would correlate with early postoperative cognitive dysfunction in on-pump patients.

METHODS

In this prospective, randomized, single-center trial, we assigned 92 patients scheduled for elective or urgent coronary artery bypass grafting (CABG) to high-pressure (HP: 80-90 mm Hg, n = 44) or low-pressure (LP: 60-70 mm Hg, n = 48) perfusion groups during CPB. Patients with prior cerebrovascular or psychiatric disorders were excluded. Primary end point was the cognitive outcome as measured by Mini-Mental-Status examination before and 48 h after surgery.

RESULTS

Patients' pre- and intra-operative characteristics did not differ between groups. Significantly more patients in the LP group developed postoperative delirium than in the HP group (LP 13%. vs HP 0%, p = 0.017). The postoperative drop in Mini-Mental-Status scores was significantly greater in the LP group (LP 3.9 ± 6.5 vs HP 1.1 ± 1.9; p = 0.012). No group differences were detected in cerebral oxygenation measured by near-infrared spectroscopy during CPB. The LP group's postoperative arterial lactate concentration in the intensive care unit was significantly higher as compared with the HP group (LP 2.0 ± 1.1 mmol l(-1) vs HP 1.4 ± 0.6 mmol l(-1); p < 0.001). We observed no differences between the groups in any other postoperative clinical, functional, or laboratory parameters.

CONCLUSION

Maintaining perfusion pressure at physiologic levels during normothermic CPB (80-90 mm Hg) is associated with less early postoperative cognitive dysfunction and delirium. This perfusion strategy neither increases morbidity, nor does it impair organ function.