What did they do?

Wilson et al randomized 401 laboring women across multiple centers to either remifentanil PCA or pethidine/meperidine IM, then compared the progression of these women to labour epidural.

On the surface... this might appear disingenuous, as it compares remifentanil PCA to widely-shown-to-be-ineffective parenteral pethidine – rather than to the gold standard labour epidural. But it's also a study of how the technique might practically be used in the real world.

What they found

Women with remifentanil PCA progressed half as often to require epidural analgesia than those receiving pethidine (19% vs 41%).

Though it's one of the secondary findings that is most interesting: the remifentanil group were less likely to need instrumental delivery (15% vs 26%).

But don't get carried away

Despite the demonstrated superiority of remi PCA to pethidine, the technique is not without it's issues:

• Safety concerns regarding respiratory depression cannot be ignored, and because managing this relies upon staff vigilance, increased PCA use may conversely lead to a normalisation of risk and institutional complacency, rather than safety improvement.
• Analgesia is still inferior to epidural, even if maternal satisfaction is comparable.
• Technique acceptability might not be as good in communities with high pre-existing epidural use.

And finally... why are we so eager to do away with the labour epidural? Serious complications are very uncommon to rare, the technique is widely acceptable to women, and it is more effective than any other modality.

Is this change driven by the needs of pregnant women, or the health system's limited resources?

summary

• WilsonMatthew J AMJASchool of Health and Related Research, University of Sheffield, Sheffield, UK. Electronic address: m.j.wilson@sheffield.ac.uk., Christine MacArthur, Catherine A Hewitt, Kelly Handley, Fang Gao, Leanne Beeson, Jane Daniels, and RESPITE Trial Collaborative Group.
• School of Health and Related Research, University of Sheffield, Sheffield, UK. Electronic address: m.j.wilson@sheffield.ac.uk.
• Lancet. 2018 Aug 25; 392 (10148): 662-672.

BackgroundAbout a third of women receiving pethidine for labour pain subsequently require an epidural, which provides effective pain relief but increases the risk of instrumental vaginal delivery. Remifentanil patient-controlled analgesia (PCA) in labour is an alternative to pethidine, but is not widely used. We aimed to evaluate epidural analgesia progression among women using remifentanil PCA compared with pethidine.MethodsWe did an open-label, multicentre, randomised controlled trial in 14 UK maternity units. We included women aged 16 years or older, beyond 37 weeks' gestation, in labour with a singleton cephalic presentation, and who requested opioid pain relief. We randomly assigned eligible participants (1:1) to either the intravenous remifentanil PCA group (40 μg bolus on demand with a 2 min lockout) or the intramuscular pethidine group (100 mg every 4 h, up to 400 mg in 24 h), using a web-based or telephone randomisation service with a minimisation algorithm for parity, maternal age, ethnicity, and mode of labour onset. Because of the differences in routes of drug administration, study participants and health-care providers were not masked to the group allocation. The primary outcome was the proportion of women who received epidural analgesia after enrolment for pain relief in labour. Primary analyses were unadjusted and analysed by the intention-to-treat principle. This study is registered with the ISRCTN registry, number ISRCTN29654603.FindingsBetween May 13, 2014, and Sept 2, 2016, 201 women were randomly assigned to the remifentanil PCA group and 200 to the pethidine group. One participant in the pethidine group withdrew consent, leaving 199 for analyses. The proportions of epidural conversion were 19% (39 of 201) in the remifentanil PCA group and 41% (81 of 199) in the pethidine group (risk ratio 0·48, 95% CI 0·34-0·66; p<0·0001). There were no serious adverse events or drug reactions directly attributable to either analgesic during the study.InterpretationIntravenous remifentanil PCA halved the proportion of epidural conversions compared with intramuscular pethidine. This finding challenges routine pethidine use as standard of care in labour.FundingNational Institute for Health Research Clinician Scientist Award.Copyright © 2018 Elsevier Ltd. All rights reserved.

This article appears in the collection: Is remifentanil for labour analgesia safe and effective?.

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