Effect of sex differences in remifentanil requirements for inhibiting the response to a CO2 pneumoperitoneum during propofol anesthesia: an up-and-down sequential allocation trial.

Background A CO2 pneumoperitoneum during a laparoscopic procedure causes violent hemodynamic changes. However, the remifentanil required to inhibit the cardiovascular response to a CO2 pneumoperitoneum combined with propofol remains unknown. Moreover, the sex of the patient may influence the response to opioids, which can affect this requirement. The main objective of this study was to compare the required median effective concentration (EC50) of remifentanil for inhibiting the cardiovascular response to a CO2 pneumoperitoneum between female and male patients during propofol anesthesia.