Effect of patient sex on general anaesthesia and recovery

Numerous studies have shown that women emerge faster from general anaesthesia than men, and differ in their postoperative recovery profile. The extent and underlying mechanisms for these sex-related differences in general anaesthesia are unclear.

In a multicentre, prospective, matched cohort study, 500 ASA physical status I or II patients of either sex undergoing general anaesthesia for elective surgery were recruited. All subjects received a general anaesthetic through inhalation. Anaesthetic drugs and doses used, bispectral index (BIS) scores, recovery times, pain scores, and 40-item quality of recovery (QoR-40) scores for 3 days after general anaesthesia were recorded.

Women had higher BIS scores at similar concentrations of anaesthesia (P<0.05). Time to eye-opening (P<0.01) and time to obeying commands (P<0.01) were shorter in women. Duration of recovery room stay was longer in women, who also had higher pain scores and need for treatment of nausea and vomiting (all P<0.001). QoR-40 scores for the first 3 days after general anaesthesia were lower in women (P<0.001). Plasma progesterone concentrations in women negatively correlated with the time to eye-opening (ρ=-0.53, P=0.01).

Patient sex is an independent factor influencing the response to anaesthesia and recovery after surgery. Women emerged faster from general anaesthesia but their overall quality of recovery was poorer. Female sex hormones, particularly progesterone, might be involved, with premenopausal women having faster recovery time but poor overall recovery.