Introduction
Off-pump coronary artery bypass grafting (OPCABG) involves the use of a vascular conduit to bypass atheromatous lesions in coronary arteries without the use of cardiopulmonary bypass (CPB) under general anesthesia at lower temperature, and need mechanical ventilation to aid breathing to maintaining oxygen supply to vital organs of the body which is essential for stability of respiratory and circulatory system1-4. Be alien to normal heart surgery by CPB, intraoperative anesthesia monitoring in OPCABG is critical to the operation and postoperative morbidities such as myocardial infarction, pulmonary and renal dysfunction, atrial fibrillation, blood transfusion and mental syndromes5-7. In patients following OPCABG surgery, manipulation on beating heart and calcified aorta, pain, anxiety and restlessness caused by critically illness, surgical trauma, inflammatory response and a variety of procedures and treatments often discourage the recovery of heart function.
Delirium is a common neuropsychiatric syndrome in the patients following OPCABG surgery.6,8,9The hallmark of delirium is acute cognitive disturbance with fluctuation in the level of consciousness and attention. The incidence of delirium in critically ill patients is high. Delirium is particularly problematic in patients receiving heart surgery because it increases the risk of self-extubation and removal of other essential medical devices10.
Previous studies show that postoperative sedation is important for prognosis. Therefore, the ideal sedative treatment is beneficial to reduce stress response in patients after cardiac surgery, reduce man-machine confrontation, reduce oxygen consumption, stabilize hemodynamics and reduce delirium or restlessness, to ensure the completion of the invasive operation11-14.
Some prophylactic strategies for the prevention of delirium have been proposed, but not routinely implemented because of the lack of convincing evidence15. Surgical Apgar Score (SAS) system was initially validated in patients undergoing general and vascular surgery and was subsequently expanded to a majority of surgical subspecialties16-21. SAS relies on three variables (lowest heart rate, lowest mean arterial pressure and estimated blood loss) that are easily obtained from the anesthesia records. There was no study having investigated the association between SAS score and prediction of risk of delirium incidence in patients underwent OPCABG who is at high risk of emotional incidents. This article aims to investigate the predictive value of SAS score on delirium incidence following OPCABG surgery.