Low-dose Dexmedetomidine and Postoperative Delirium After Cardiac Surgery

Delirium is an acutely occurred and fluctuating cerebral dysfunction characterized with inattention, altered consciousness, cognitive decline and/or abnormal perception. It is common in the elderly after cardiac surgery and is associated with worse outcomes. Causes leading to delirium are multifactorial but sleep disturbances remains an important one. In previous studies, sedative-dose dexmedetomidine improves sleep quality in ICU patients with mechanical ventilation; and low-dose dexmedetomidine improves sleep quality in postoperative patients without mechanical ventilation. In recent studies of elderly after noncardiac surgery, night-time infusion of low-dose dexmedetomidine reduces delirium and improves 2-year survival. The investigators hypothesize that, for elderly patients after cardiac surgery, night-time infusion of dexmedetomidine may also improve sleep quality, reduce delirium development and improve 2-year survival.