Patient-controlled analgesia with fentanyl provides effective analgesia for second trimester labour: a randomized controlled study

Purpose: To examine dose and lockout intervals for effective fentanyl patient-controlled analgesia (PCA) in second trimester genetic termination of pregnancy, and compare three different fentanyl PCA regimes with morphine PCA. Methods: In a double-blind randomized study, 60 ASA physical status I-II patients received one of three fentanyl PCAs or morphine PCA. Labour was induced with prostaglandins and PCA use continued until delivery. Within two hours following delivery, four visual analogue scales (VAS) were administered measuring anticipated pain, pain relief in labour and delivery and overall satisfaction. The drug delivery/demand ratio for two hours preceding delivery was obtained from the PCA pump. The outcome variables were analyzed using the Chi square test and analysis of variance as appropriate. Results: The delivery/demand ratio was 0.71 +/- 0.27 (mean +/- standard deviation) for morphine; 0.67 +/- 0.21 for fentanyl 50 mug, lockout six-minute; 0.63 +/- 0.21 for fentanyl 25 mug, lockout three-minute; and 0.81 +/- 0.17 for fentanyl 50 mug, lockout three-minute groups. We found no significant differences among the four groups with respect to using delivery/demand ratio as a measure of pain relief. Morphine had the highest rate of side effects compared to fentanyl. There was strong evidence of differences among groups with regard to patient satisfaction and expected pain, and moderate evidence of differences in the delivery and labour pain scores. Conclusion: This study found PCA fentanyl 50 mug with a lockout period of six minutes provided satisfactory analgesia for second trimester labour.