We evaluated the effect and safety of the immediate postoperative continuous infusion of remifentanil at two doses in patients undergoing laparoscopic-assisted vaginal hysterectomy (LAVH) with alfentanil-based patient-controlled analgesia (PCA).

The study enrolled 50 ASA physical status 1 or 2 patients scheduled to undergo LAVH. Anesthesia was maintained with sevoflurane-remifentanil-air. At the last skin suture, the sevoflurane was discontinued, and patients were randomized to receive remifentanil 0.05 µg/kg/min (group I) or 0.1 µg/kg/min (group II). PCA was started at the time of eye opening and response to a verbal command. In the recovery room, we monitored the mean arterial blood pressure (MAP), heart rate (HR), respiratory rate (RR), SpO₂, and bispectral index (BIS) at 5-minute intervals. Thirty minutes after starting PCA, the remifentanil was discontinued. Pain was assessed using a visual analog scale (0 = no pain; 100 = the worst possible pain) at 0, 5, 10, and 30 minutes after stopping the remifentanil infusion.

The eye opening time, BIS, MAP, and HR did not differ significantly between the two groups, and pain scores were similar between the two groups. Respiratory depression (SpO₂ < 90% or RR < 8/min) did not occur in group I but did occur in three patients in group II.

Continuous remifentanil infusion (0.05 µg/kg/min) immediately postoperatively with alfentanil-based PCA had a similar effect as a 0.1 µg/kg/min infusion with respect to pain control without side effects. However, special attention must be given to respiratory depression.