美索比妥透过灌注人胎盘的转运

Herman N L, Li A T, Van Decar T K, Johnson R F, Bjoraker R W, Downing J W, Jones D

Department of Anesthesiology, New York Presbyterian Hospital-Weill Medical College of Cornell University, NY 10021, USA.

J Clin Anesth. 2000 Feb;12(1):25-30. doi: 10.1016/s0952-8180(99)00130-0.

STUDY OBJECTIVES

To evaluate the transfer properties of methohexital and the influence of protein binding using the in vitro human placental perfusion model.

DESIGN

Fresh term human placentae from healthy parturients were perfused bidirectionally via a cannulated fetal chorionic artery and vein and needles placed into the maternal intervillous space. Maternal-to-fetal (M-->F) and fetal-to-maternal (F-->M) transfer and ultimate distribution of methohexital was investigated using a closed (recirculating) placental perfusion model.

SETTING

Obstetric anesthesia laboratories of two university medical centers.

PATIENTS

No patient participation occurred as placentae were obtained after delivery.

INTERVENTION

M-->F and F-->M transfer of methohexital was compared in vitro in perfusates with equal protein concentrations (2 g/100 mL in both perfusates) or albumin-simulated physiologic protein binding concentrations (maternal 8 g/100 mL; fetal 4 g/100 mL).

MEASUREMENTS AND MAIN RESULTS

Data obtained consisted of measurements of methohexital and antipyrine concentrations by high-performance liquid chromatography. Glucose and lactate concentrations and perfusate loss were measured to assess placental viability. Methohexital protein binding was assessed at 2, 4, and 8 g/100 mL of albumin by equilibrium dialysis. The transfer index of 0.83 +/- 0.11 for the M-->F perfusions was significantly greater (p < or = 0.05) than in the F-->M direction (0.61 +/- 0.04) when albumin concentration was equal in both perfusates. This transfer asymmetry disappeared when albumin concentrations simulating maternal (8 g/100 mL) versus fetal (4 g/100 mL) protein concentrations in the perfusate were used (M-->F 0.87 +/- 0.12 and F-->M 0.95 +/- 0.11).

CONCLUSION

Methohexital readily crosses the placenta in both directions. Protein binding has significant effects on the degree of transfer of methohexital at any time when compared with antipyrine and its ultimate fetal/maternal distribution.

研究目的

使用体外人胎盘灌注模型评估甲己炔巴比妥的转运特性及蛋白结合的影响。

设计

通过插管至胎儿绒毛膜动脉和静脉以及置于母体绒毛间隙的针头，对来自健康产妇的足月新鲜人胎盘进行双向灌注。使用封闭（循环）胎盘灌注模型研究甲己炔巴比妥的母胎（M→F）和胎母（F→M）转运及最终分布。

地点

两个大学医学中心的产科麻醉实验室。

患者

由于胎盘是在分娩后获得的，所以没有患者参与。

干预

在灌注液中蛋白浓度相等（两种灌注液均为2 g/100 mL）或白蛋白模拟生理蛋白结合浓度（母体8 g/100 mL；胎儿4 g/100 mL）的情况下，体外比较甲己炔巴比妥的M→F和F→M转运。

测量和主要结果

通过高效液相色谱法测量甲己炔巴比妥和安替比林浓度获得数据。测量葡萄糖和乳酸浓度以及灌注液损失以评估胎盘活力。通过平衡透析在2、4和8 g/100 mL白蛋白浓度下评估甲己炔巴比妥的蛋白结合。当两种灌注液中的白蛋白浓度相等时，M→F灌注的转运指数为0.83±0.11，显著高于F→M方向（0.61±0.04）（p≤0.05）。当使用模拟灌注液中母体（8 g/100 mL）与胎儿（4 g/100 mL）蛋白浓度时，这种转运不对称消失（M→F 0.87±0.12和F→M 0.95±0.11）。