Delirium after open cardiac surgery:systematic review of prevalence, risk factors and consequences

Delirium is a sudden and usually transient disturbance in consciousness, attention, cognition, perception and emotions. The pathophysiology is unknown but possible causes include neurotransmitter disturbances and inflammation reaction. Delirium is common in patients after open cardiac surgeries and can lead to serious consequences. Research shows that delirium is an underdiagnosed and undertreated problem. The purpose of this systematic review is to illuminate the prevalence, risk factors and outcome of postoperative delirium following open cardiac surgery. A systematic literature review from 2005-2013 was performed aiming to determine the prevalence, predisposing and precipitating factors and outcome after postoperative delirium following cardiac surgery. Web of Science, PubMed and Cinahl were searched. Findings of the systematic review shows that about one third of patients become delirious after cardiac surgery. Primary predisposing factors are advanced age, cognitive impairment, atrial fibrillation, depression and prior history of stroke. Among precipitating factors are pulmonary bypass, duration of mechanical ventilation, low cardiac output, respiratory failure, pneumonia, infections, blood cell transfusion and post-operative arrhythmias. Delirium causes prolonged hospital stay, reduced activity and higher mortality. Delirium prevention includes reducing risk factors. Delirium is a common and serious complication of open cardiac surgery. Knowledge of risk factors of delirium and regular screening for symptoms of delirium are important to reduce prevalence and to facilitate diagnosis and treatment.