Effects of menstrual cycle on induction dose of propofol

Objective To observe the effects of menstrual cycle on induction dose of propofol. Methods Sixty patients aged 20-40 years were scheduled for gynecological laparoscopic surgery under general anesthesia and were divided into two groups according to their preoperative levels of estradiol and progesterone, that is, the follicular group and the luteal group. Anesthesia was first induced with target controlled infusion system (TCI) of propofol using Marsh pharmacokinetic model at an initial target plasma concentration of 1.5 mg/L followed by increments of 0.5 mg/L per 30 s until loss of eyelash reflex and bispectral index (BIS) reduced to 50. BIS, mean artery pressure (MAP), heart rate (HR), plasma concentration of propofol, and the total induction dose of propofol when BIS reduced to 50 were recorded. Results In the luteal group, the levels of E2 and P were significantly higher than those in the follicular group at each time point (P0.05). However, there was no statistical difference in MAP, HR, and BIS at each time point (P0.05). In the luteal group, the plasma concentration of propofol when loss of eyelash reflex ([3.12±0.37] mg/L) and BIS reduced to 50 ([3.52±0.49] mg/L) were significantly lower than those in the follicular group ([3.38±0.41], [3.79±0.67] mg/L, P0.05). Simultaneously, the total induction dose of propofol when BIS reduced to 50 was significantly lower in the luteal group than the follicular group ([89.7±12.2] vs. [106.3±13.3] mg, P0.05). Conclusion For female patients in the luteal phase, the induction dose needed for propofol is significantly reduced compared with those in the follicular phase.