Labor Analgesia Initiation With Dural Puncture Epidural Versus Conventional Epidural Techniques: A Randomized Biased-Coin Sequential Allocation Trial to Determine the Effective Dose for 90% of Patients of Bupivacaine

Abstract

BACKGROUND: The dural puncture epidural (DPE) technique has a faster onset, better sacral spread, and improved bilateral coverage when compared to the conventional epidural (EPL) technique. Whether these qualities translate into a lower bupivacaine dose to provide initial analgesia is unknown. We sought to determine the effective dose of bupivacaine to achieve initial (first 30 minutes) labor analgesia in 90% of patients (ED90) with the DPE and EPL techniques, using a biased-coin, sequential allocation method. METHODS: A total of 100 women of mixed parity with term, singleton gestation at ≤5 cm dilation with no major comorbidities were randomized to receive a DPE or an EPL technique. An experienced anesthesiologist performed these techniques and administered an allocated dose of plain bupivacaine diluted with isotonic sterile 0.9% saline to a total volume of 20 mL via the EPL catheter. Bupivacaine doses for each subject were determined by the response of the previous subject, using a biased-coin sequential allocation method, with success defined by a numeric rating scale (NRS) < 3 at 30 minutes. Outcome assessments were performed by an investigator blinded to the technique and bupivacaine dose. Sensory and motor blockade and maternal or fetal side effects were recorded every 5 minutes for the first 30 minutes. The ED90 of bupivacaine with each technique was estimated using centered isotonic regression. RESULTS: A total of 95 women were included in the final analysis. The ED90 of bupivacaine was estimated at 29.30 mg (90% confidence interval [CI], 28.55–31.56) with a DPE technique and 45.25 mg (90% CI, 42.80–52.03) with an EPL technique. CONCLUSIONS: Using a biased-coin, sequential allocation method, the DPE technique requires less bupivacaine to achieve effective initial analgesia (ED90) when compared to the EPL technique.

The 50% effective dose of hydromorphone and morphine for epidural analgesia in the hemorrhoidectomy: a double-blind, sequential dose-finding study

“…If no rescue analgesia was required or if the NRS pain score was ≤ 3 any time point within 24 h (6, 12 and 24 h) after CSEA treatment, analgesia was considered “effective”. To estimate the ED50, doses for future patients were modified using the a sequential allocation biased-coin design technique according to the references [ 14 – 16 ].…”

“…According to sample size termination criteria of the biased-coin sequential allocation method, literature and preliminary experiment research studies implied that using 20 to 40 patients would yield stable estimates of the target estimate of ED50 and ED90 [ 7 , 14 – 16 , 18 , 19 ]. The purpose of this study is to observe the ED50 of epidural morphine and hydromorphone analgesia in patients undergoing hemorrhoidectomy.…”