The effects of continuous epidural analgesia on Doppler velocimetry of uterine arteries during different periods of labour analgesia

Abstract

Background. The transient effects of epidural bupivacaine 0.25-0.5% on the Doppler velocimetry of umbilical and uterine arteries had been reported, but the effects of continuous lower dose epidural bupivacaine (0.05-0.1%) infusion for labour analgesia have never been reported. In this study, we evaluated the effects of continuous epidural bupivacaine 0.075% on the Doppler velocimetry of uterine arteries. Methods. Twenty pregnant women for labour analgesia received continuous epidural bupivacaine 0.075% infusion. We used a 4-MHz continuous-wave Doppler probe (Multigon 500A) with a 200 Hz thump filter to detect uterine blood flow velocity. We recorded the velocimetry data for uterine relaxation and contraction during five time periods: Pre-epidural insertion, 1, 2, and 4 h post-epidural infusion, and after delivery of fetus. Results. Our data showed that the velocimetric indices of uterine vascular resistance were significantly increased 1, 2, and 4 h after epidural infusion when compared with the pre-epidural level; these returned to the baseline after delivery. Conclusion. Continuous epidural analgesia with bupivacaine 0.075% increases the resistance of uterine artery and therefore possibly reduces the uterine blood flow. © The Board of Management and Trustees of the British Journal of Anaesthesia 2005. All rights reserved.