Objective: This study aimed at determining the optimal dose combination of alfentanil and propofol for outpatient abortion anesthesia.
Patients and methods: The study was separated into two parts. In the first part, patients were to determine the median effective dose (ED50) and the 95% effective dose (ED95) of alfentanil in combination with 2.5 mg·kg-1 propofol to inhibit body movements during the abortion using the Dixon up-and-down sequential allocation method. In the second part, 170 patients were randomly divided into group C (2.0 mg·kg-1 propofol with alfentanil 12.16 μg·kg-1) and group E (2.5 mg·kg-1 propofol with its ED95) to compare the anesthetic effect. The primary outcome was the sedation level during general anesthesia. The secondary outcomes were circulation, respiratory complications, and postoperative recovery quality.
Results: The ED50 and the ED95 values of alfentanil were 3.37 μg·kg-1 (95% CI: 2.58-3.97 μg·kg-1) and 4.68 μg·kg-1 (95% CI: 4.04-9.32 μg·kg-1). The frequency of deep sedation in group E was significantly higher than in group C (76.5% vs. 60%). Patients in group C showed more wakefulness even during the surgery (14.3% vs. 4.4%). The results of our exploratory analyses did not reveal differences in respiratory depression, circulatory depression, postoperative side effects, or recovery outcomes.
Conclusions: The combination of 2.5 mg·kg-1 propofol and 4.68 μg·kg-1 alfentanil produces a better sedative effect than the combination of 2.0 mg·kg-1 propofol and 12.16 μg·kg-1 alfentanil without increasing additional risks associated with anesthesia.