Objective: To determine the incidence and risk factors for delirium after coronary artery bypass graft (CABG) surgery.
Design: Prospective cohort.
Setting: Cardiac surgery units of a tertiary care hospital.
Participants: Consecutive patients over age 65 years undergoing elective CABG surgery. Exclusion criteria included preoperative sensory or language barriers.
Interventions: Each patient was assessed within 24 h before surgery for baseline demographic, medical and functional data. Incident delirium (within four postoperative days) was diagnosed by a study physician. Nine potential risk factors for delirium were subjected to univariate and multivariate analysis.
Main results: Of 75 consenting patients, three died during or soon after surgery and one was still comatose at follow-up. Of the remaining 71 participants, 23 (32%) experienced delirium. Those with delirium were more likely than those without delirium to have a history of a stroke (21% versus 4%, respectively, P=0.032) and to have had a longer duration of cardiopulmonary bypass (CPB) (113 mins versus 95 mins, respectively, P=0.025). A tendency to have experienced low cardiac output (83% versus 58%, respectively, P=0.061) postoperatively was also noted. Multivariate analysis confirmed past stroke and duration of cardiopulmonary bypass as risk factors.
Conclusions: Delirium in the elderly after CABG surgery is common. Its occurrence may be predisposed by a history of a stroke and precipitated by a longer duration of CPB.