Yasuda Shun, Kyozuka Hyo, Nomura Yasuhisa, Fujimori Keiya
Department of Obstetrics and Gynecology, Fukushima Medical University, Fukushima, Japan.
Department of Obstetrics and Gynecology, Ohta Nishinouchi Hospital, Koriyama, Japan.
J Obstet Gynaecol Res. 2020 Jul;46(7):1035-1043. doi: 10.1111/jog.14274. Epub 2020 May 27.
To investigate the effects of magnesium sulfate on fetal baroreflex in normoxemia or acute fetal hypoxemia.
Fetal baroreflex response was elicited using phenylephrine (30 μg) in saline and magnesium sulfate in 8 chronically treated and instrumented fetal sheep. Hypoxemia was induced using nitrogen gas inflow for 30 min. Baroreflex, calculated as the ratio of the fetal heart rate change to the mean arterial pressure, was monitored after magnesium sulfate administration and in rapid and nonrapid eye movement (NREM) sleep states. Baroreflex was assessed in response to hypoxemia in control groups in both the rapid and NREM sleep states.
Baroreflex was not significantly affected by saline, magnesium sulfate and rapid or NREM sleep states in normoxemic sheep. Hypoxemia increased the baroreflex in the saline-treated group (hypoxemic vs normoxemic rapid eye movement sleep: 4.37 ± 2.48 vs 2.72 ± 0.83; P < 0.05; hypoxemic vs normoxemic NREM sleep: 4.30 ± 1.47 vs 3.15 ± 0.83; P < 0.001). Magnesium sulfate decreased the baroreflex in the hypoxemic fetuses (magnesium sulfate hypoxemic vs. control normoxemic fetuses: 1.42 ± 0.92 vs 3.15 ± 0.83, P < 0.05).
The hypoxemic fetal sheep, from the ewes that were receiving magnesium sulfate, showed a significantly reduced in the baroreflex response. In clinical practice, baroreflex-related decelerations in hypoxemic fetuses of mothers receiving magnesium sulfate should be carefully interpreted.
研究硫酸镁对正常氧合或急性胎儿低氧血症时胎儿压力反射的影响。
在8只经长期处理并植入仪器的胎羊中，使用生理盐水和硫酸镁中的去氧肾上腺素（30μg）引发胎儿压力反射反应。通过通入氮气30分钟诱导低氧血症。在给予硫酸镁后以及快速眼动睡眠和非快速眼动睡眠状态下监测压力反射，压力反射以胎儿心率变化与平均动脉压的比值计算。在快速眼动睡眠和非快速眼动睡眠状态下的对照组中评估对低氧血症的压力反射。
在正常氧合的绵羊中，生理盐水、硫酸镁以及快速眼动睡眠或非快速眼动睡眠状态对压力反射均无显著影响。低氧血症使生理盐水处理组的压力反射增加（低氧血症组与正常氧合快速眼动睡眠组：4.37±2.48对2.72±0.83；P<0.05；低氧血症组与正常氧合非快速眼动睡眠组：4.30±1.47对3.15±0.83；P<0.001）。硫酸镁降低了低氧血症胎儿的压力反射（硫酸镁低氧血症胎儿与对照正常氧合胎儿：1.42±0.92对3.15±0.83，P<0.05）。
接受硫酸镁的母羊所产的低氧血症胎羊，其压力反射反应显著降低。在临床实践中，对于接受硫酸镁治疗的母亲的低氧血症胎儿中与压力反射相关的减速应谨慎解读。
