Predictors of Duration of Unconsciousness in Patients With Coma After Cardiac Surgery

ObjectivesTo 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.DesignA retrospective analysis from a cohort of patients who developed coma after cardiac surgery.SettingA single university hospital.ParticipantsOne hundred twelve patients with postoperative stroke, encephalopathy, and/or seizures who remained in coma longer than 24 hours after cardiac surgery.InterventionsNone.Measurements and Main ResultsThe 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).ConclusionsIn 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.