Risk factors for delirium after cardiac surgery: a historical cohort study outlining the influence of cardiopulmonary bypass

Abstract

Purpose Cardiopulmonary bypass (CPB) induces a significant inflammatory response that may increase the risk for delirium. We hypothesized that exposure to CPB during coronary artery bypass grafting surgery would correlate with an increased risk of delirium and would be associated with several other outcomes. Methods We reviewed clinical data from two databases at our medical center, the Cardiac Surgery Perioperative Outcomes Database and the Society of Thoracic Surgeons Database. Patients undergoing elective coronary artery bypass grafting surgery (on-pump and off-pump) from November 1, 2009 to September 30, 2015 were included in the study. Delirium was defined as any positive CAM-ICU exam following surgery during the ICU course. We performed logistic regression to isolate the association between CPB exposure and delirium adjusted for predetermined risk factors and potential confounders. Results During the study period, a total of 2,280 patients underwent elective coronary artery bypass grafting surgery with 384 patients (16.9%) exposed to CPB. Delirium was diagnosed in 451 patients (19.8%). CPB exposure demonstrated a significant independent association with delirium (P = 0.002). The adjusted relative risk (RR) of delirium was 2.18 (95% CI, 1.39 to 3.07; P = 0.002) among patients exposed to CPB for 142 minutes (90th percentile of CPB duration), compared to a RR of only 1.51 (95% CI, 0.92 to 2.29; P = 0.10) for those on CPB for 54 minutes (10th percentile). Conclusions CPB use and duration of use were associated with an increased risk of delirium in patients undergoing coronary artery bypass grafting surgery.

The Healthy Heart‐Mind Trial: Randomized Controlled Trial of Melatonin for Prevention of Delirium

“…The pathogenesis of delirium in cardiac surgery patients is uncertain, but neuroinflammation exacerbated by the use of CPB may play a role . Overall, 177 (177/202 [87.6%]) participants had CPB during surgery (melatonin 86.7% vs placebo 88.5%; χ 2 = .14; P = 710) in our sample, but exposure to this was not associated with an increase in delirium risk (OR = 1.44; 95% CI = .46‐4.43).…”

Commentary: Does a “less is more” approach reduce delirium in patients undergoing coronary artery bypass grafting?

“…Cognitive performance 7 days after surgery followed a similar trend: anaortic OPCAB had the lowest incidence of cognitive decline (9.5%), followed by CO 2 field flooding (28.1%), and then conventional OPCAB (34.4%), mirroring previous observational studies. 4 Interestingly, the relative ratio of delirium to postoperative cognitive decline followed a similar pattern (76% vs 85% vs 95%) for anaortic, carbon dioxide field flooding, and conventional OPCAB, respectively.…”

Road to recovery: a study protocol quantifying neurological outcome in cardiac surgery patients and the role of cerebral oximetry

“…Research groups have shown that patients after valve replacement surgery have significantly worse cognitive functioning than patients following coronary artery bypass grafting (CABG) surgery 7 8. Combined surgeries, often involving longer bypass times, may also increase the risk of delirium 9. Procedures requiring entry into the heart involve increased embolic load, generating the possibility of postoperative neurological impairment 10…”