Age- and sex-specific differences in propofol consumption and extubation time : an analysis of a data set from an observational multicenter trial

The objective of the present analysis was to investigate the effect of age and sex on propofol doses and emergence times in a dataset of propofol/remifentanil anesthetics. A total of 876 patients (339 men, 537 women; age: 18-87 years) with target electroencephalogram (EEG) stage D/E during maintenance of anesthesia and EEG stage D2/E0 at the end of propofol infusion were included (EEG monitor: Narcotrend; EEG in D/E range is characterized by delta activity [0.5-3.5 Hz]). Multiple linear regression analysis showed that total propofol dose (mean [standard deviation (SD)]: 6.81 (2.16) mg/kg/h) was significantly predicted by age (unstandardized regression coefficient b = -0.033, 95% confidence interval [CI]: -0.048 to -0.019, P < .001), sex (b = 1.542 [w (for women)], 95% CI: 0.573-2.512, P = .002), and interaction of age and sex (b = -0.022 [w], 95% CI: -0.041 to -0.004, P = .016). Propofol steady state dose (mean [SD]: 4.77 [1.74] mg/kg/h) was significantly predicted by age (b = -0.021, 95% CI: -0.036 to -0.006, P = .005), sex (b = 1.811 [w], 95% CI: 0.795-2.828, P < .001), and interaction of age and sex (b = -0.028 [w], 95% CI: -0.048 to -0.009, P = .004). For time to extubation (mean [SD]: 9.67 [4.51] mg/kg/h), age (b = 0.042, 95% CI: 0.010-0.073, P = .009) was a significant predictor, while sex (b = -0.655 [w], 95% CI: -2.785 to 1.475, P =.546) and interaction of age and sex (b = -0.011 [w], 95% CI: -0.051 to 0.029, P = .585) were not significant predictors. The administered remifentanil steady state dose (mean [SD]: 0.26 [0.12] µg/kg/min) did not differ significantly between men and women (P = .156) and decreased significantly with increasing age in men (P < .001) and women (P < .001). Age- and sex-associated differences in propofol requirements and a wide variation in propofol doses were observed. On average, women aged ≤40 years required comparatively high doses of propofol. The observations underline the importance of individually adapted anesthesia management, including monitoring of cerebral effects of propofol.