August 15,2018, Healio 

Women in labor receiving IV remifentanil patient-controlled analgesia were half as likely to need a subsequent epidural than those receiving intramuscular pethidine injection, which is the current standard of care, according to data published in The Lancet.

“Previous studies have shown that at least one in three women given pethidine to manage pain during labor require a subsequent epidural as the drug is not always effective. It also has unwanted side effects such as sedation and nausea for the mother, and it may pass into the baby’s bloodstream through the placenta,” Matthew J.A. Wilson, MD, from the School of Health and Related Research at the University of Sheffield, England, said in a press release.

Remifentanil may be an alternative to pethidine but is not widely used or researched, according to Wilson and colleagues. Therefore, the researchers conducted a trial to investigate whether IV remifentanil patient-controlled analgesia during labor reduces the need for epidural analgesia and subsequent adverse maternal or neonatal events compared with intramuscular pethidine injection.

A total of 400 women aged 16 years or older, beyond 37 weeks’ gestation were randomly assigned to receive either remifentanil (n = 201) or pethidine (n = 199) during labor if they requested opioid pain relief. Patients in the remifentanil group controlled their own IV drip and could receive a 40-g bolus of remifentanil on demand every 2 minutes. Patients in the pethidine group were injected with 100 mg of pethidine every 4 hours for up to 400 mg in a 24-hour period.

All participants were able to request an epidural at any time. If patients received an epidural, the other form of pain relief was discontinued.

The allocated drug was received by 93% of participants in the remifentanil group and 77% of participants in the pethidine group.

The researchers found that 19% of patients in the remifentanil group and 41% of those in the pethidine group had an epidural (RR = 0.48; 95% CI, 0.34–0.66).

Women in the remifentanil group reported that their pain was less severe than those in the pethidine group. The need for forceps and vacuum during labor was less common among women receiving remifentanil than those receiving pethidine (15% vs. 26%).

The incidence of low oxygen levels was twice as likely among women in the remifentanil group than the pethidine group (14% vs. 5%). Additionally, supplementary oxygen was given to more patients in the remifentanil group.

No serious adverse events or drug reactions were observed in either group.

“Our findings challenge the routine use of pethidine for pain relief during labor,” Wilson said in the release. “Remifentanil reduced the need for an epidural by half and there were no lasting problems for the mothers and babies in our trial, although the effect of remifentanil on maternal oxygen levels needs to be clarified in further studies.” – by Alaina Tedesco

Disclosure: The authors report no relevant financial disclosures.