Morphine versus fentanyl for spinal post-caesarean analgesia: a randomised controlled trial.

BACKGROUND

Finding appropriate analgesics is important for a mother's recovery after a caesarean section. The aim of this study was to compare the analgesic effect of spinal morphine and fentanyl for women undergoing a caesarean section.

METHODS

In this randomised, unmasked, parallel-group, controlled trial, eligible participants were women undergoing caesarean section with spinal anaesthetic at the Al-Helal Al-Emirati Hospital, Rafah, Gaza Strip, occupied Palestinian territory. Using a manually generated allocation sequence that was independently managed by medical staff, we randomly assigned women (1:1) to receive either 0·2 mg preservative-free morphine or 20 μg fentanyl, spinally, combined with 2 mL of 0·5% hyperbaric bupivacaine for spinal anaesthesia. Pain was recorded by visual analogue scales (VAS; range 0-10, where 0 means no pain and 10 means pain is intolerable) at 1 h, 6 h, 12 h, 18 h, and 24 h after the caesarean section. Time and amount of other analgesics needed were recorded (primary outcome). Secondary outcomes were nausea-vomiting scores (NVS 0-3, where 0 means no nausea or vomiting and 3 means severe nausea or vomiting that is unresponsive to antiemetics), and pruritus scores (PS 0-2, where 0 means no pruritus and 2 means severe pruritus). Data were analysed with SPSS. We compared outcomes using Mann-Whitney U-test, student's t-test, OR, or χ test. The study was approved by the ministry of health and the Helsinki Committee, Gaza Strip. Women provided verbal informed consent before participation.

FINDINGS

We enrolled 121 women (mean age 28·43 years [SD 5·62]). 59 women were randomly assigned to the morphine group, and 62 women were randomly assigned to the fentanyl group. Pain was reduced with morphine compared with fentanyl at 1 h (VAS score: 1·81 for morphine vs 2·57 for fentanyl; p<0·039), at 6 h (1·84 vs 5·08; p<0·0001), at 12 h (1·45 vs 3·30; p<0·0001), at 18 h (1·62 vs 3·18; p<0·0001), and at 24 h (1·61 vs 2·68; p=0.0001). The time to needing other analgesic drug was longer in the morphine group than in the fentanyl group (9·03 h vs 2·46 h; p<0·0001). 20 (34%) women in the morphine group did not need analgesics, whereas all (100%) women with fentanyl needed additional analgesics (odds ratio [OR] 2·59, 95% CI 2·03-3·31). Mild nausea and drowsiness were seen more in the morphine group than in the fentanyl group at 6 h and 12 h, respectively (p=0·010). Nine (15%) women in the morphine group had pruritus and needed treatment compared with one (2%) woman in the fentanyl group (OR 10·98, 95% CI 1·35-89·62).

INTERPRETATION

Spinal morphine was more effective than spinal fentanyl for caesarean analgesia. Morphine was associated with more side-effects than fentayl, but these were treatable and did not pose any danger to women.

FUNDING

None.