Wright J W, Seelig C B, Ridgway L E
Department of Obstetrics and Gynecology, University of Texas Health Science Center at San Antonio.
J Am Coll Nutr. 1994 Oct;13(5):499-501. doi: 10.1080/07315724.1994.10718442.
To measure the apparent volume of distribution (AVOD) for magnesium (Mg) in preeclampsia and preterm labor and determine if a standard 4 gm loading dose of magnesium sulfate (MgSO4) is sufficient to attain therapeutic levels.
Twenty-five patients with preeclampsia and 25 with preterm labor received 4 g of MgSO4 intravenously over 15 minutes. Serum Mg levels were determined before and one minute after loading and the AVOD for Mg was calculated. Stepwise linear regression with AVOD as the dependent variable was performed and comparisons between the groups were made.
Preeclamptics were heavier, had greater surface areas, and presented at a later stage of pregnancy than did patients with preterm labor. Despite these differences AVOD did not differ between the groups. Predose magnesium levels were slightly higher in the preeclamptic group (p = .04). Post-loading levels were nearly identical due to similar AVOD's and, because of the lower levels required for seizure prevention as opposed to tocolysis, were therapeutic 88% of the time in preeclampsia but only 12% of the time in preterm labor (p < .001). Multivariate analysis revealed that only ideal body weight, degree of underweight, and current therapy with betamimetics were significantly related to AVOD.
AVOD was found to be similar in preeclamptic and preterm labor patients. A 4 g loading dose of MgSO4 is usually adequate to achieve therapeutic levels in preeclampsia but not in preterm labor.
测量子痫前期和早产患者中镁（Mg）的表观分布容积（AVOD），并确定标准的4克硫酸镁（MgSO4）负荷剂量是否足以达到治疗水平。
25例子痫前期患者和25例早产患者在15分钟内静脉输注4克MgSO4。在负荷前和负荷后1分钟测定血清镁水平，并计算镁的AVOD。以AVOD为因变量进行逐步线性回归，并对两组进行比较。
子痫前期患者比早产患者体重更重，体表面积更大，且就诊时孕周更大。尽管存在这些差异，但两组的AVOD并无差异。子痫前期组的负荷前镁水平略高（p = 0.04）。由于AVOD相似，负荷后水平几乎相同，并且由于预防子痫所需的水平低于抑制宫缩所需的水平，子痫前期患者88%的时间达到治疗水平，而早产患者仅12%的时间达到治疗水平（p < 0.001）。多变量分析显示，只有理想体重、体重不足程度和当前使用β-拟交感神经药治疗与AVOD显著相关。
子痫前期和早产患者的AVOD相似。4克MgSO4负荷剂量通常足以在子痫前期达到治疗水平，但在早产中则不然。
