Predictors of duration of unconsciousness in patients with coma after cardiac surgery

Abstract

Objectives: To describe clinical and brain imaging characteristics of patients who recovered and did not recover consciousness from a coma after cardiac surgery and to investigate predictors of the duration of unconsciousness in those patients who ultimately recovered consciousness.

Design: A retrospective analysis from a cohort of patients who developed coma after cardiac surgery.

Setting: A single university hospital.

Participants: One hundred twelve patients with postoperative stroke, encephalopathy, and/or seizures who remained in coma longer than 24 hours after cardiac surgery.

Interventions: None.

Measurements and main results: The authors analyzed the patients' perioperative and intraoperative characteristics, laboratory values, noncontrast head computed tomography (CT) scans, and outcomes. Patients who did not recover consciousness (n = 16) were more likely to have been classified preoperatively as New York Heart Association class III/IV (p = 0.037). In patients who recovered consciousness (n = 96), only increased preoperative serum creatinine was an independent predictor of a longer duration of unconsciousness (p = 0.011). In patients who eventually recovered consciousness and had no acute findings on brain imaging, preoperative creatinine (p = 0.014), the lowest postoperative hemoglobin (p = 0.039), and surgical emergency (p = 0.045) were independent predictors of the duration of unconsciousness (p = 0.002). In patients who regained consciousness but had acute findings on brain imaging, cardiogenic shock (p = 0.012) and the insertion of an intra-aortic balloon pump before or during surgery (p = 0.025) predicted longer durations of unconsciousness (p < 0.001).

Conclusions: In patients who ultimately recovered consciousness after being in a coma for at least 24 hours after cardiac surgery and have no abnormality on a brain CT scan, elevated preoperative serum creatinine, urgent cardiac surgery, and lower postoperative hemoglobin were correlated with an increased duration of unconsciousness.