ABSTRACT
Objective To investigate the effectiveness of entropy in measuring the level of sedation during target controlled infusion (TCI) of propofol in patients of different ages. Methods Twenty-nine ASA Ⅰ-Ⅱ patients undergoing elective surgery under general anesthesia were divided into two age groups: Ⅰ adult group (20-64 yr) (n = 16) and Ⅱ the aged group (65-85 yr) ( n = 13). The patients were unpremedicated. The level of sedation was assessed using OAA/S scale. Propofol was given by TCI. The effect-site concentration (Ce) of propofol was set first at 1 ?g?ml-1 and then increased step by step by 0.5 ?g?ml-1 every 60 seconds until Ce reached 6 ?g?ml-1. Response entropy ( RE), state entropy ( SE), BP, HR, SpO2 were monitored and recorded at each Ce, before intubation, and immediately and 1, 2, 3, 4, 5, 10 min after intubation. The predictive performance of entropy was evaluated by prediction probability (Pk) .Results The two groups were comparable with respect to sex (M/F ratio), body weight and body weight index (kg?m-2). The RE and SE values decreased as Ce increased. The difference between RE and SE was also reduced. In adult group when Ce reached 2.0 ?g?ml-1, the RE and SE values were lower than the baseline values ( P