Karmrodt Jens, David Matthias, Yuan Shying, Markstaller Klaus
Department of Anesthesiology, Johannes Gutenberg-University, Langenbeckstrasse 1, D-55101 Mainz, Germany.
Crit Care. 2006;10(5):R138. doi: 10.1186/cc5052.
The objective was to study the effects of a novel lung volume optimization procedure (LVOP) using high-frequency oscillatory ventilation (HFOV) upon gas exchange, the transpulmonary pressure (TPP), and hemodynamics in a porcine model of surfactant depletion.
With institutional review board approval, the hemodynamics, blood gas analysis, TPP, and pulmonary shunt fraction were obtained in six anesthetized pigs before and after saline lung lavage. Measurements were acquired during pressure-controlled ventilation (PCV) prior to and after lung damage, and during a LVOP with HFOV. The LVOP comprised a recruitment maneuver with a continuous distending pressure (CDP) of 45 mbar for 2.5 minutes, and a stepwise decrease of the CDP (5 mbar every 5 minute) from 45 to 20 mbar. The TPP level was identified during the decrease in CDP, which assured a change of the PaO2/FIO2 ratio < 25% compared with maximum lung recruitment at CDP of 45 mbar (CDP45). Data are presented as the median (25th-75th percentile); differences between measurements are determined by Friedman repeated-measures analysis on ranks and multiple comparisons (Tukey's test). The level of significance was set at P < 0.05.
The PaO2/FiO2 ratio increased from 99.1 (56.2-128) Torr at PCV post-lavage to 621 (619.4-660.3) Torr at CDP45 (CDP45) (P < 0.031). The pulmonary shunt fraction decreased from 51.8% (49-55%) at PCV post-lavage to 1.03% (0.4-3%) at CDP45 (P < 0.05). The cardiac output and stroke volume decreased at CDP45 (P < 0.05) compared with PCV, whereas the heart rate, mean arterial pressure, and intrathoracic blood volume remained unchanged. A TPP of 25.5 (17-32) mbar was required to preserve a difference in PaO2/FIO2 ratio < 25% related to CDP45; this TPP was achieved at a CDP of 35 (25-40) mbar.
This HFOV protocol is easy to perform, and allows a fast determination of an adequate TPP level that preserves oxygenation. Systemic hemodynamics, as a measure of safety, showed no relevant deterioration throughout the procedure.
目的是研究一种使用高频振荡通气（HFOV）的新型肺容积优化程序（LVOP）对表面活性剂耗竭猪模型的气体交换、跨肺压（TPP）和血流动力学的影响。
经机构审查委员会批准，在六只麻醉猪进行生理盐水肺灌洗前后获取血流动力学、血气分析、TPP和肺分流分数。在肺损伤前后的压力控制通气（PCV）期间以及HFOV的LVOP期间进行测量。LVOP包括以45 mbar的持续扩张压力（CDP）进行2.5分钟的复张操作，以及将CDP从45 mbar逐步降低（每5分钟降低5 mbar）至20 mbar。在CDP降低期间确定TPP水平，这确保与45 mbar的CDP（CDP45）时的最大肺复张相比，动脉血氧分压/吸入氧分数值（PaO2/FIO2）比值的变化<25%。数据以中位数（第25 - 75百分位数）表示；测量值之间的差异通过Friedman秩次重复测量分析和多重比较（Tukey检验）确定。显著性水平设定为P < 0.05。
PaO2/FiO2比值从灌洗后PCV时的99.1（56.2 - 128）Torr增加到CDP45时的621（619.4 - 660.3）Torr（P < 0.031）。肺分流分数从灌洗后PCV时的51.8%（49 - 55%）降至CDP45时的1.03%（0.4 - 3%）（P < 0.05）。与PCV相比，CDP45时心输出量和每搏输出量降低（P < 0.05），而心率、平均动脉压和胸腔内血容量保持不变。需要25.5（17 - 32）mbar的TPP来维持与CDP45相关的PaO2/FIO2比值差异<25%；在35（25 - 40）mbar的CDP时达到该TPP。
该HFOV方案易于实施，并能快速确定维持氧合的合适TPP水平。作为安全性指标的全身血流动力学在整个过程中未显示出相关恶化。
