Department of Anesthesiology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
Int J Obstet Anesth. 2012 Jul;21(3):212-6. doi: 10.1016/j.ijoa.2012.01.006. Epub 2012 May 24.
Magnesium has been reported to augment the analgesic effects of opioids when co-administered into the cerebrospinal fluid. The purpose of this study was to determine the influence of intravenous magnesium therapy administered for preeclampsia on the duration of intrathecal fentanyl analgesia for labor.
Thirty-four nulliparous parturients having labor induced for preeclampsia and receiving intravenous magnesium therapy were recruited. Thirty-four nulliparous patients having labor induced for elective or medical reasons were recruited as controls. At request for analgesia, baseline serum magnesium levels were obtained and combined spinal-epidural analgesia was initiated with intrathecal fentanyl 25μg. Before injection of fentanyl, a sample of cerebrospinal fluid was obtained for magnesium assay. An epidural catheter was sited but no additional medications were administered until the second request for analgesia. The primary outcome was duration of intrathecal fentanyl analgesia.
There was no difference in the median duration of analgesia between the magnesium [79min (95% CI 76 to 82)] and control groups [69min (95% CI 56 to 82)] (difference between medians: 10min (95% CI -4 to 21min; P=0.16). There was neither a relationship between the serum and cerebrospinal fluid magnesium concentrations nor the cerebrospinal magnesium concentration and duration of intrathecal fentanyl analgesia.
Intravenous magnesium therapy at doses typically used for seizure prophylaxis in preeclampsia did not influence the duration of intrathecal fentanyl labor analgesia. However, this study may have been underpowered to detect a difference and future study is warranted.
有报道称，将镁与阿片类药物同时注入脑脊液中，可增强其镇痛效果。本研究旨在确定子痫前期患者静脉内给予镁治疗对分娩时鞘内芬太尼镇痛持续时间的影响。
招募了 34 名因子痫前期而接受引产的初产妇，并给予静脉内镁治疗。招募了 34 名因选择性或医学原因接受引产的初产妇作为对照。在要求镇痛时，获得基线血清镁水平，并在鞘内给予芬太尼 25μg 开始脊髓-硬膜外联合镇痛。在注射芬太尼之前，抽取脑脊液样本进行镁测定。放置硬膜外导管，但在第二次要求镇痛之前不给予其他药物。主要结局是鞘内芬太尼镇痛的持续时间。
镁组[79 分钟（95%置信区间 76 至 82）]和对照组[69 分钟（95%置信区间 56 至 82）]的镇痛持续时间中位数无差异（中位数差异：10 分钟（95%置信区间 -4 至 21 分钟；P=0.16）。血清和脑脊液镁浓度之间以及脑脊液镁浓度与鞘内芬太尼镇痛持续时间之间均无相关性。
子痫前期中常用的预防惊厥剂量的静脉内镁治疗并未影响鞘内芬太尼分娩镇痛的持续时间。然而，本研究可能没有足够的效力来检测到差异，需要进一步研究。
