Comparative study of labour analgesia onset with injection of loading dose through epidural needle versus catheter

Abstract

BACKGROUND Rapid onset of epidural analgesia is an important concern for the parturient. Commonly, the local anaesthetic mixture is administered through the epidural catheter. Drugs administered through the epidural needle might decrease the onset time and enhance the spread of medication within the epidural space. OBJECTIVES The primary aim of this study was to compare the onset time of analgesia when a loading dose of dilute local anaesthetic opioid mixture was injected through either the Tuohy needle or a single end-hole epidural catheter. DESIGN A prospective, double-blinded, randomised clinical trial. SETTING Single university hospital, from November 2022 to August 2023. PARTICIPANTS A total of 200 healthy nulliparous women who requested epidural analgesia for labour were randomly allocated to the needle group (n = 100) or the catheter group (n = 100). INTERVENTIONS In the needle group, after identification of the epidural space, a test dose of 3 ml 0.1% ropivacaine with 0.3 μg ml−1 sufentanil was injected through the Tuohy needle followed 3 min later by a 15 ml loading dose of the same mixture over 30 s. Then the catheter was inserted into the epidural space. In the catheter group, after identification of the epidural space, a catheter was advanced into the epidural space and the ropivacaine/sufentanil mixture was injected in an identical manner though the catheter. MAIN OUTCOME MEARSURES The primary outcome was the onset time of labour analgesia (defined as the time from drug administration to adequate analgesia). Adequate analgesia was defined as a visual analogue score 10 mm or less during uterine contractions. RESULTS Median [IQR] onset time of labour analgesia did not differ significantly between the two groups (needle group: 20 [16 to 30] minutes; catheter group: 20 [15 to 25] minutes, P = 0.232). CONCLUSION Compared with bolus injection though a single end-hole epidural catheter, injection through the epidural needle did not shorten the analgesia onset time for adequate labour analgesia. TRIAL REGISTRATION ClinicalTrials.gov (NCT05594771).