The RESPITE trial: remifentanil intravenous patient controlled analgesia (PCA) versus intramuscular pethidine for pain relief in labour: study protocol for a randomised controlled trial

Background The commonest opioid used for pain relief in labour is pethidine (meperidine), however its effectiveness has long been challenged and the drug has known side effectsincluding maternal sedation, nausea and potential transfer across the placenta to the foetus.Over a third of women receiving pethidine require an epidural due to inadequate pain relief. Epidural analgesia increases the risk of an instrumental vaginal delivery and its associated effects. Therefore there is a clear need for a safe, effective, alternative analgesic to pethidine.Evidence suggests that remifentanil patient controlled analgesia reduces epidural conversion rates compared to pethidine, however no trial has yet investigated this as a primary end point. We are therefore comparing intramuscular pethidine to remifentanil PCA in a randomised controlled trial. Methods/Design Women in established labour, requesting systemic opioid pain relief, will be randomised to either intravenous remifentanil PCA (intervention) or pethidine intramuscular injection (control) in an unblinded, 1:1 individual randomised trial. Following informed consent, 400 women in established labour requesting systemic opioid pain relief from NHS Trusts across England will undergo a minimised randomisation by a computer or automated telephone system to either pethidine or remifentanil. In order to balance the groups this minimisation is based on four parameters; parity (nulliparous vs multiparous), maternal age (<20, 20-<30, 30-<40, 40+), ethnicity (South Asian (Pakistani/Indian/Bangladeshi) vs Other) and induced vs spontaneous labour. The effectiveness of pain relief provided by each technique will be recorded every 30 minutes after time zero, until epidural placement, delivery or transfer to theatre, quantified by Visual Analogue Scale. Incidence of maternal side effects including sedation, delivery mode, foetal distress requiring delivery, neonatal status at delivery and rate of initiation of breast feeding within the first hour of birth will also be recorded. Maternal satisfaction with childbirth experience will be determined by a postpartum questionnaire prior to discharge from the delivery ward. Discussion The RESPITE trial’s primary outcome is the proportion of women who have an epidural placed for pain relief in labour in each arm. Trial Registration Current Controlled Trials registration number: ISRCTN29654603, registered on 23rd July 2013