2.1. Patient information
This was a randomized consort trial. The study was approved by the Ethics Committee of Zhongshan Hospital Xiamen University (No. xmzsyyky-ethics-2017-033) on February 27, 2017. Informed written consent was obtained from each patient and his/her family members.The inclusion criteria were as follows: age > 65 years; operative time ≤ 3 hours; body mass index < 30 kg/mOne hundred fourteen elderly patients who underwent elective general anesthesia (all types) were assessed for eligibility. According to the inclusion and exclusion criteria, 70 patients were enrolled in the study (Fig. Flow diagram of patient enrollment.