Barrington K J, Singh A J, Etches P C, Finer N N
Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada.
Am J Respir Crit Care Med. 1999 Dec;160(6):1922-7. doi: 10.1164/ajrccm.160.6.9812068.
The object of this study was to determine the effects of partial liquid ventilation (PLV) with and without inhaled nitric oxide (NO) over a 4-h period on lung mechanics, gas exchange, and hemodynamics in an animal model of meconium aspiration syndrome (MAS). Twenty-four fentanyl-anesthetized piglets were instrumented and administered a slurry of human meconium to create a model with hypoxia, hypercarbia, acidosis, and pulmonary hypertension. They were then randomly assigned to conventional ventilation, conventional ventilation plus inhaled NO at 40 ppm, PLV using perfluorodecalin, or PLV plus inhaled NO. The perfluorocarbon was added until a meniscus was visible in the endotracheal tube during expiration. Hemodynamics, lung mechanics, and gas exchange were monitored for 4 h, and then the animals were killed. The conventionally ventilated animals continued to deteriorate, and three of the six died prior to 4 h. All the animals in the remaining groups survived. Oxygenation improved significantly immediately with the start of inhaled NO (from 43.8 SD 10.3 to 62.6 SD 11.7 mm Hg after 30 min) and stayed elevated compared with the control group for the remainder of the study (62.4 SD 21.8 mm Hg at 4 h compared with 44.9 SD 1.6 mm Hg for the control group, p < 0.05). Oxygenation improved more slowly in the PLV alone group, being slightly less than control at 30 min (p = NS) but increasing to 104 SD 34.9 after 4 h (p < 0.01 compared with the control group), at which time it was also greater than inhaled NO alone (p < 0.05). The combined group had an acute increase in oxygenation indistinguishable from the NO alone group and maintained this until the end of the study. Lung compliance was unaffected in the inhaled NO group. In both the liquid ventilation groups the lung compliance improved with the instillation of perfluorodecalin (from 0.46 SD 0.18 to 0.62 SD 0.09 ml/cm H(2)O/kg in the PLV alone group at 1 h, p < 0.05 compared with the control group) and remained stable for the remainder of the study. Cardiac output and pulmonary vascular resistance were not significantly affected by any of the treatments. It was concluded that in this animal model of MAS, inhaled NO led to an acute improvement in gas exchange and prolonged survival compared with conventional therapy. PLV improved lung mechanics, which was maintained over the course of the study. The combination of PLV and inhaled NO produced both effects, acutely improving both gas exchange and lung mechanics. Combined therapy with PLV and inhaled NO may have benefits in the MAS.
本研究的目的是确定在4小时内，在胎粪吸入综合征（MAS）动物模型中，有或没有吸入一氧化氮（NO）的部分液体通气（PLV）对肺力学、气体交换和血流动力学的影响。24只经芬太尼麻醉的仔猪被插管并给予人胎粪混悬液，以建立一个伴有低氧血症、高碳酸血症、酸中毒和肺动脉高压的模型。然后将它们随机分为常规通气组、常规通气加40 ppm吸入NO组、使用全氟萘烷的PLV组或PLV加吸入NO组。添加全氟碳化合物，直到呼气时气管导管中可见弯月面。监测血流动力学、肺力学和气体交换4小时，然后处死动物。常规通气的动物病情持续恶化，6只中有3只在4小时前死亡。其余组的所有动物均存活。吸入NO开始后，氧合立即显著改善（30分钟后从43.8±10.3升至62.6±11.7 mmHg），并且在研究的剩余时间内与对照组相比一直保持升高（4小时时为62.4±21.8 mmHg，而对照组为44.9±1.6 mmHg，p<0.05）。单独PLV组的氧合改善较慢，30分钟时略低于对照组（p=无显著性差异），但4小时后升至104±34.9（与对照组相比p<0.01），此时也高于单独吸入NO组（p<0.05）。联合组的氧合急性增加与单独吸入NO组无差异，并一直维持到研究结束。吸入NO组的肺顺应性未受影响。在两个液体通气组中，随着全氟萘烷的滴注，肺顺应性均得到改善（单独PLV组在1小时时从0.46±0.18升至0.62±0.09 ml/cm H₂O/kg，与对照组相比p<0.05），并在研究的剩余时间内保持稳定。任何一种治疗对心输出量和肺血管阻力均无显著影响。得出的结论是，在这个MAS动物模型中，与传统治疗相比，吸入NO可使气体交换急性改善并延长生存期。PLV改善了肺力学，并在研究过程中得以维持。PLV和吸入NO联合使用产生了两种效果，急性改善了气体交换和肺力学。PLV和吸入NO联合治疗可能对MAS有益。
