Getman C E, Goetzman B W, Bennett S
Department of Pediatrics, University of California, Davis 95616.
Pediatr Res. 1991 Apr;29(4 Pt 1):329-33.
Vasodilators and cardiotonic agents are frequently used in hypoxemic newborn infants with persistent pulmonary hypertension. We studied the effects of sodium nitroprusside and dopamine on hypoxia-induced pulmonary hypertension in seven newborn (0-3 d) and seven young (10-14 d) lambs under chloralose anesthesia. Pulmonary blood flow, pulmonary arterial pressure, systemic arterial pressure, and left atrial pressure were measured during the experimental states of hypoxia, hypoxia plus nitroprusside, and hypoxia plus both nitroprusside and dopamine. Pulmonary and systemic arterial pressure and cardiac output all decreased significantly when hypoxemic newborn lambs were given nitroprusside; in contrast, when hypoxemic young lambs were given nitroprusside, cardiac output did not change, whereas both pulmonary and systemic arterial pressure decreased significantly. Calculated pulmonary vascular resistance was unchanged in the newborn lambs but fell in the young lambs, implying that active pulmonary vasodilation by nitroprusside occurred only in the latter group. Systemic vascular resistance was not significantly affected by nitroprusside in either group. The addition of dopamine resulted in qualitatively similar changes in both groups of lambs, with increased pulmonary blood flow and no significant change in pulmonary or systemic arterial pressures. Maturation in vascular smooth muscle responsiveness to nitrovasodilators may explain the age-related differences that we found in lambs, and could also account for the variable clinical responses to vasodilators observed in hypoxemic human infants.
血管扩张剂和强心剂常用于患有持续性肺动脉高压的低氧血症新生儿。我们在水合氯醛麻醉下，研究了硝普钠和多巴胺对7只新生（0 - 3日龄）和7只幼年（10 - 14日龄）羔羊缺氧诱导的肺动脉高压的影响。在缺氧、缺氧加硝普钠、缺氧加硝普钠和多巴胺的实验状态下，测量肺血流量、肺动脉压、体动脉压和左心房压。给低氧血症新生羔羊使用硝普钠时，肺和体动脉压以及心输出量均显著降低；相反，给低氧血症幼年羔羊使用硝普钠时，心输出量未改变，而肺和体动脉压均显著降低。计算得出的肺血管阻力在新生羔羊中未改变，但在幼年羔羊中下降，这意味着硝普钠的活性肺血管舒张仅发生在后一组。两组中硝普钠对体血管阻力均无显著影响。添加多巴胺后，两组羔羊出现了定性相似的变化，肺血流量增加，肺或体动脉压无显著变化。血管平滑肌对硝血管扩张剂反应性的成熟可能解释了我们在羔羊中发现的与年龄相关的差异，也可能解释了在低氧血症人类婴儿中观察到的对血管扩张剂的不同临床反应。
