The Influence of Oxygen Delivery During Cardiopulmonary Bypass on the Incidence of Delirium in CABG Patients; A Retrospective Study

INTRODUCTION:

Postoperative delirium is the most common neurological complication of cardiac surgery. Hypoxia has been shown to increase the risk of postoperative delirium. The possibility to continuously monitor oxygen delivery (DO₂) during cardiopulmonary bypass(CPB) offers an adequate approximation of the oxygen status in a patient. This study investigates the role of oxygen delivery during cardiopulmonary bypass in the incidence of postoperative delirium.

METHODS:

Three hundred and fifty-seven adult patients who underwent normothermic coronary artery bypass grafting (CABG) surgery were included in this retrospective study. The nadir indexed DO₂ (DO₂i) value on bypass, the total time under the critical DO₂i level and the area under the curve (AUC) for critical DO₂i were determined. Delirium was identified by the postoperative administration of haloperidol.

RESULTS:

The mean nadir DO₂i significantly differed, comparing the group of patients with postoperative delirium to the group without. Multivariate analysis only identified age, pre-existing cognitive impairment, preoperative kidney dysfunction and cross-clamp time as independent risk factors for delirium. The results also indicated that patients of older age were more sensitive to a declined DO₂i.

CONCLUSION:

A low DO₂i during cardiopulmonary bypass is significantly associated with the incidence of postoperative delirium in CABG patients. However, the role of DO₂ as an independent predictor of delirium could not be proven.