A comparison of patient-controlled analgesia fentanyl and alfentanil for labour analgesia

Abstract

Purpose: To determine the analgesic efficacy of equipotent doses of PCA (patient-controlled analgesia) fentanyl and PCA alfentanil for labour pain. Methods: Twenty three, ASA I - II parturients between 32-42 wk gestational age in whom epidural analgesia was contraindicated were randomized to receive PCA fentanyl (Group F) or alfentanil (Group A). Plain numbered vials contained 21 ml fentanyl 50 μg·ml-1 or alfentanil 500 μg·ml-1. A one millilitre loading dose was administered. The PCA solution was prepared by diluting 10 ml study drug with 40 ml saline and the PCA pump was programmed to deliver a dose of 2 ml, delay of five minutes and a basal rate of 2 ml·hr-1. Maternal measurements obtained were hourly drug dose, total dose, Visual Analog Pain Score (VAPS) q 30 min, sedation score q 1 hr and side effects. Neonates were assessed by 1,5, and 10-min Apgar scores, umbilical venous and arterial blood gases and neurobehavioural scores at four and 24 hr. Results: Mean VAPS from 7 - 10 cm cervical dilatation were higher in Group A than in Group F. (85.7 ± 13.9 vs 64.6 ± 12.1; P < 0.01). There were no inter-group differences in VAPS from 1 - 3 cm, or from 4 - 6 cm dilatation, in maternal sedation scores or side effects, or in neonatal outcomes. Conclusion: In the doses prescribed in this study, PCA fentanyl was found to provide more effective analgesia in late first stage labour than PCA alfentanil.