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

Abstract

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.