Appendix C: Outcomes for intravenous remifentanil patient-controlled analgesia (PCA) compared with intramuscular pethidine

Guidance

**Table C1 Outcomes that were more or less likely for women using intravenous remifentanil PCA compared with intramuscular pethidine**
Outcome	Intravenous remifentanil patient-controlled analgesia (PCA)	Intramuscular pethidine	Risk difference
Request for epidural analgesia	About 194 per 1,000 women would be expected to request epidural analgesia (so 806 would not)	About 407 per 1,000 women would be expected to request epidural analgesia (so 593 would not)	About 213 per 1,000 fewer women would be expected to request epidural analgesia with intravenous remifentanil PCA, so for 787 there would be no difference
Spontaneous vaginal birth	About 647 per 1,000 women would be expected to have a spontaneous vaginal birth (so 353 would not)	About 536 per 1,000 women would be expected to have a spontaneous vaginal birth (so 464 would not)	About 111 per 1,000 more women would be expected to have a spontaneous vaginal birth with intravenous remifentanil PCA, so for 889 there would be no difference
Birth with forceps or ventouse	About 145 per 1,000 women would be expected to have a birth with forceps or ventouse (so 856 would not)	About 245 per 1,000 women would be expected to have a birth with forceps or ventouse (so 756 would not)	About 100 per 1,000 fewer women would be expected to have a birth with forceps or ventouse with intravenous remifentanil PCA, so for 900 there would be no difference
Requirement for supplemental oxygen	About 461 per 1,000 women would be expected to need supplemental oxygen (so 539 would not)	About 13 women per 1,000 women would be expected to need supplemental oxygen (so 987 would not)	About 448 per 1,000 more women would be expected to need supplemental oxygen with intravenous remifentanil PCA, so for 552 there would be no difference
Maternal reduced oxygen saturation (less than 94% SpO₂)	About 138 per 1,000 women would be expected to have reduced oxygen saturation (so 862 would not)	About 52 per 1,000 women would be expected to have reduced oxygen saturation (so 948 would not)	About 86 per 1,000 more women would be expected to have reduced oxygen saturation with intravenous remifentanil PCA, so for 914, there would be no difference

For more details, see evidence review D: remifentanil patient-controlled analgesia.

**Table C2 Outcomes that were similar regardless of the intervention for women using intravenous remifentanil PCA compared with women using intramuscular pethidine**
Outcome
Maternal respiratory rate less than 8 breaths per minute
Caesarean birth
Pain in labour (based on a visual analogue scale)
Maternal satisfaction
Breastfeeding within first hour of birth