Magnesium therapy in pre-eclampsia prolongs analgesia following spinal anaesthesia with fentanyl and bupivacaine: An observational study

Abstract

Background: Magnesium has anti-nociceptive effects and potenti- ates opioid analgesia following its systemic and neuraxial administra- tion. However, there is no study evaluating the effects of intravenous (IV) magnesium sulphate (MgSO4) therapy on spinal anaesthesia characteristics in severely pre-eclamptic patients. Aims: The aim of this study was to compare spinal anaesthesia char- acteristics in severely pre-eclamptic parturients treated with MgSO4 and healthy preterm parturients undergoing caesarean section. Thus, our primary outcome was regarded as the time to first analgesic re- quest following spinal anaesthesia. Study Design: Case-control Study. Methods: Following approval of Institutional Clinical Research Eth- ics Committee and informed consent of the patients, 44 parturients undergoing caesarean section with spinal anaesthesia were enrolled in the study in two groups: Healthy preterm parturients (Group C) and severely pre-eclamptic parturients with IV MgSO4 therapy (Group Mg). Following blood and cerebrospinal fluid (CSF) sampling, spi- nal anaesthesia was induced with 9 mg hyperbaric bupivacaine and 20 μg fentanyl. Serum and CSF magnesium levels, onset of sensory block at T4 level, highest sensory block level, motor block charac- teristics, time to first analgesic request, maternal haemodynamics as well as side effects were evaluated. Results: Blood and CSF magnesium levels were higher in Group Mg. Sensory block onset at T4 were 257.1±77.5 and 194.5±80.1 sec in Group C and Mg respectively (p=0.015). Time to first postopera- tive analgesic request was significantly prolonged in Group Mg than in Group C (246.1±52.8 and 137.4±30.5 min, respectively, p