An exploration of the incidence, patterns and course, and correlates of delirium among patients undergoing off-pump coronary artery bypass graft surgery

“Off pump” coronary artery bypass (OPCAB) surgery is increasingly performed, but little is known about the incidence and nature of delirium after OPCAB. Delirium causes patient distress and recovery delay, threatens patient safety and increases healthcare costs. The purpose of this prospective, descriptive study was to identify the incidence, patterns, course, and correlates of delirium among a sample of OPCAB patients of a nationally leading cardiovascular surgical program followed at a Midwestern metropolitan area hospital. Thirty seven consenting patients (median age 68 years, the majority were White and male) with no history of cognitive impairment, alcohol or drug abuse were observed from preoperatively to a median of postoperative day three. Measures included demographic, medical, and perioperative variables; the Standardized Mini Mental State Exam (preoperatively and before discharge); a 12-hour delirium screening (from 24 hours postoperatively through discharge) and a 24-hour delirium assessment with the Confusion Assessment Method for the Intensive Care Unit and the NEECHAM Confusion Scale. The 13.5% incidence of delirium among the sample (the delirium group, n = 5; the non-delirium group, n = 32) was higher than that reported in prior studies. The higher delirium incidence may be attributed to the sample's demographic and medical variables that were potentially different from other studies, and the frequent and structured study protocol that identified hypoactive (n = 3) and hyperactive (n = 2) subtypes of delirium. The course of delirium was characterized by a “gradually improving” pattern without a lucid period (n = 2) and a “V-shape” pattern (n = 3) with a lucid period of 1–3 days. The delirium tended to be a short-term type with a length of 1 to 2 days, which could be attributed to the well-structured care of the study hospital. The delirium group had more vulnerability (predisposing factors: older age, p = .01, tendency to have poor cardiac, renal, and physiological function preoperatively); overall recovery delay (longer intensive care unit stay, p = .02; a tendency of longer hospital stays); and tendency to have more postoperative complications (precipitating factors) than the non-delirium group. A larger study that includes older patients with greater acuity and disease severity is recommended to evaluate whether the findings are robust.