Sladen R N, Klamerus K J, Swafford M W, Prough D S, Mann H J, Leslie J B, Goldberg J S, Levitsky S, Molina J E, Mills S A
Anesthesiology Service, Durham Veterans Administration Medical Center, NC 27705.
J Cardiothorac Anesth. 1990 Apr;4(2):210-21. doi: 10.1016/0888-6296(90)90240-g.
In a multicenter study, the efficacy and safety of intravenous (IV) labetalol for the control of elevated blood pressure were studied in the intensive care unit (ICU) in 65 patients within 4 hours following coronary artery bypass grafting (CABG). Patients with pre-existing ventricular dysfunction, bradycardia, bronchospastic disease, or postoperative complications were excluded. All patients were monitored with a thermodilution pulmonary artery catheter. Entry criteria were a systolic blood pressure (SBP) greater than 140 mm Hg or diastolic blood pressure (DBP) greater than 90 mm Hg for at least five minutes. Intravenous labetalol was loaded incrementally (5, 10, 20, and 40 mg at 10-minute intervals) to a maximum cumulative dose of 75 mg, until either SBP decreased 10% or DBP decreased 10% and was less than 90 mm Hg. Responders were entered into a 6-hour maintenance period, and received 5 to 40 mg of IV labetalol every 10 minutes as needed for blood pressure control. Hemodynamic data and temperature were recorded at baseline, just before each dose of labetalol during the loading period, and at the end of the maintenance period. Alternative therapy was given in the case of nonresponse or adverse events. Intravenous labetalol successfully controlled post-CABG hypertension in 55 of 65 patients (85%); of these, 46 responded to 35 mg or less. Although 28 patients required no further labetalol in the maintenance period, in the others dosage varied from 5 to 400 mg. Reductions in SBP and DBP were associated with moderate reductions in pulse pressure (SBP-DBP) and heart rate (HR). Cardiac index decreased by 18.5%, with a 12.5% decrease in stroke index and 8.1% decrease in HR. Systemic vascular resistance did not increase significantly. Four patients (6%) developed hypotension related to IV labetalol. There was one death due to perioperative myocardial infarction, which was unrelated to labetalol use. The mechanism of action of IV labetalol in controlling hypertension after CABG surgery seems to be moderate negative inotropy and chronotropy. Its alpha-blocking effects seem to be important in preventing reflex vasoconstriction. This is directly opposite to the primary vasodilator effect found when IV labetalol is used to control nonsurgical hypertension. Because of these actions, labetalol should be avoided or used with caution in patients with preoperative and postoperative cardiac dysfunction. In patients with normal left ventricular function, IV labetalol appears to be a safe, effective agent in controlling post-CABG hypertension, with the added potential benefit of enhanced myocardial oxygen balance.
在一项多中心研究中，对65例冠状动脉搭桥术（CABG）后4小时内入住重症监护病房（ICU）的患者，研究了静脉注射拉贝洛尔控制血压升高的疗效和安全性。排除已有心室功能障碍、心动过缓、支气管痉挛性疾病或术后并发症的患者。所有患者均使用热稀释肺动脉导管进行监测。入选标准为收缩压（SBP）大于140 mmHg或舒张压（DBP）大于90 mmHg至少持续5分钟。静脉注射拉贝洛尔以递增方式给药（每隔10分钟分别给予5、10、20和40 mg），最大累积剂量为75 mg，直至SBP下降10%或DBP下降10%且低于90 mmHg。有反应者进入6小时维持期，根据血压控制需要每隔10分钟静脉注射5至40 mg拉贝洛尔。在基线、负荷期每次注射拉贝洛尔前以及维持期末记录血流动力学数据和体温。无反应或出现不良事件时给予替代治疗。静脉注射拉贝洛尔成功控制了65例患者中55例（85%）CABG术后的高血压；其中，46例对35 mg或更低剂量有反应。尽管28例患者在维持期无需进一步使用拉贝洛尔，但其他患者的剂量从5至400 mg不等。SBP和DBP的降低与脉压（SBP - DBP）和心率（HR）的适度降低相关。心脏指数下降了18.5%，每搏输出量指数下降了12.5%，HR下降了8.1%。全身血管阻力没有显著增加。4例患者（6%）出现与静脉注射拉贝洛尔相关的低血压。有1例因围手术期心肌梗死死亡，与拉贝洛尔的使用无关。静脉注射拉贝洛尔在控制CABG术后高血压方面的作用机制似乎是适度的负性肌力和负性变时作用。其α受体阻滞作用在预防反射性血管收缩方面似乎很重要。这与静脉注射拉贝洛尔用于控制非手术性高血压时发现的主要血管扩张作用正好相反。由于这些作用，术前和术后有心脏功能障碍的患者应避免使用或谨慎使用拉贝洛尔。对于左心室功能正常的患者，静脉注射拉贝洛尔似乎是控制CABG术后高血压的一种安全、有效的药物，还可能具有增强心肌氧平衡的潜在益处。
