OBSTETRIC ANESTHESIA--TOCOLYSIS AND HEMORRHAGE

早产是围产儿发病率的主要原因， 美国的死亡率。产科医生经常给贝塔- 拟交感神经药物(如利托君)治疗早产的一种疗法 这叫宫缩。尽管利托君对 β2受体(如子宫平滑肌)、β1受体 刺激也会发生，导致产妇心率增加和 全身血管扩张。硫酸镁(MgSO4)通常作为一种 可供选择的治疗唇裂的药物；许多临床医生认为它产生的费用更少 心血管副作用的风险。产科医生通常避免 利托君用于有出血风险的患者，因为担心严重 低血压。麻醉师经常避免局部麻醉 最近接受利托君或硫酸镁输注的患者。 很少有关于宫缩、出血、 还有麻醉剂。该实验室最近的一项研究表明，硫酸镁 显著恶化了母亲对出血的低血压反应 怀孕的母羊。这项建议的具体目的是：1)止血； 2)确定利托君的心动过速反应是否改变 母儿对出血的血流动力学反应；3)研究 利托君是否会增加低血压风险，如果是，原因是什么？ 硬膜外麻醉；以及4)研究硫酸镁是否增加了 硬膜外麻醉低血压。 方法：研究方法。体外研究将使用悬浮的等长血管环 模特。子宫动脉和肠系膜动脉的收缩反应 有无硫酸镁、血管内皮细胞、 和消炎痛，将被检测。活体研究将长期使用 仪表化妊娠母羊。母体和胎儿动脉导管将 允许连续测量母体和胎儿的体动脉 血压和母体心输出量的间歇性测量。一个 电磁血流探头可以测量子宫血流量。 腰椎硬膜外导管有助于硬膜外诱导 麻醉。 这项提议的长期目标是：1)澄清 宫缩解药、出血和乳酸菌的相互作用机制 麻醉；1)为选择和选择提供客观依据 有出血风险的AS患者的宫缩治疗 以及失败后的麻醉选择和处理 宫缩。

Preterm delivery is the leading cause of perinatal morbidity and mortality in the United States. Obstetricians often give beta- sympathomimetic agents (e.g. ritodrine) to treat preterm labor, a therapy called tocolysis. Although ritodrine is relatively selective for the beta 2 receptor (e.g., uterine smooth muscle), beta 1-receptor stimulation also occurs, resulting in increased maternal heart rate and systemic vasodilation. Magnesium sulfate (MgSO4) is often given as an alternate tocolytic drug; many clinicians believe that it incurs less risk of cardiovascular side effects. Obstetrician usually avoid ritodrine in patients at risk for hemorrhage, for fear of severe hypotension. Anesthesiologists often avoid regional anesthesia in patients recently subjected to infusion of either ritodrine or MgSO4. There are few data regarding interactions between tocolysis, hemorrhage, and anesthesia. A recent study from this laboratory showed that MgSO4 significantly worsened the maternal hypotensive response to hemorrhage in gravid ewes. The specific aims of this proposal are: 1) To hemorrhage; 2) To determine whether the tachycardia response to ritodrine alters maternal and fetal hemodynamic responses to hemorrhage; 3) To study whether, and if so why, ritodrine increases the risk of hypotension with epidural anesthesia; and 4) To study whether MgSO4 increases the risk of hypotension with epidural anesthesia. Methods. In vitro studies will use the suspended isometric vascular ring model. The contractile responses of uterine and mesenteric arterial smooth muscle to various agonists, with and without MgSO4, endothelium, and indomethacin, will be examined. In vivo studies will use chronically instrumented gravid ewes. Maternal and fetal arterial catheters will permit continuous measurement of maternal and fetal systemic arterial pressures, and intermittent measurement of maternal cardiac output. An electromagnetic flow probe will allow measurement of uterine blood flow. A lumbar epidural catheter will facilitate induction of epidural anesthesia. The long-term objectives of this proposal are: 1) To elucidate mechanisms of interaction between tocolytic drugs, hemorrhage, and anesthesia; and 1) To provide an objective basis for the choice and management of tocolytic therapy in patients at risk for hemorrhage, as well as for the choice and management of anesthesia after failed tocolysis.