Guo Feng-mei, Ding Jing-jing, Su Xin, Xu Hui-ying, Shi Yi
Department of Respiratory Diseases, Nanjing General Hospital of Nanjing Military Command, PLA, School of Medicine, Nanjing University, Nanjing, Jiangsu 210002, China.
Chin Med J (Engl). 2008 Nov 20;121(22):2218-23.
It is still controversial as to the implementation of higher positive end-expiratory pressure (PEEP) in patients with acute respiratory distress syndrome (ARDS). This study was conducted to compare the lower and higher PEEP in patients with ARDS ventilated with low tidal volume, to investigate the relationship between the recruited lung volume by higher PEEP and relevant independent variables and to provide a bedside estimate of the percentage of potentially recruitable lung by higher PEEP.
Twenty-four patients with ARDS were studied. A lung recruiting maneuver was performed, then each patient was ventilated with PEEP of 8 cmH(2)O for 4 hours and subsequently with PEEP of 16 cmH(2)O for 4 hours. At the end of each PEEP level period, gas exchange, hemodynamic data, lung mechanics, stress index "b" of the dynamic pressure-time curve, intrinsic PEEP and recruited volume by PEEP were measured.
Fourteen patients were recruiters whose alveolar recruited volumes induced by PEEP 16 cmH(2)O were (425 +/- 65) ml and 10 patients were non-recruiters. Compared with the PEEP 8 cmH(2)O period, after the application of the PEEP 16 cmH(2)O, the PaO(2)/FiO(2) ratio and static lung compliance both remained unchanged in non-recruiters, whereas they increased significantly in recruiters. Changes in PaO(2)/FiO(2) and static lung compliance after PEEP increase were independently associated with the alveolar recruitment. Analyzing the relationship between recruiting maneuver (RM)-induced change in end-expiratory lung volume and the alveolar recruitment induced by PEEP, we found a notable correlation.
The results of this study indicated that the potential for alveolar recruitment might vary among the ARDS population and the higher PEEP levels should be limited to recruiters. Improving in PaO(2)/FiO(2), static lung compliance after PEEP increase and the shape of the pressure-time curve could be helpful for PEEP application.
对于急性呼吸窘迫综合征（ARDS）患者实施较高水平的呼气末正压（PEEP）仍存在争议。本研究旨在比较低潮气量通气的ARDS患者采用较低和较高水平PEEP的情况，探讨较高水平PEEP引起的肺复张容积与相关独立变量之间的关系，并提供较高水平PEEP下潜在可复张肺组织百分比的床旁评估方法。
对24例ARDS患者进行研究。先进行肺复张手法，然后每位患者先以8 cmH₂O的PEEP通气4小时，随后以16 cmH₂O的PEEP通气4小时。在每个PEEP水平阶段结束时，测量气体交换、血流动力学数据、肺力学、动态压力 - 时间曲线的应力指数“b”、内源性PEEP以及PEEP引起的复张容积。
14例患者为复张者，16 cmH₂O的PEEP诱导的肺泡复张容积为（425±65）ml，10例患者为非复张者。与8 cmH₂O的PEEP阶段相比，应用16 cmH₂O的PEEP后，非复张者的PaO₂/FiO₂比值和静态肺顺应性均未改变，而复张者则显著增加。PEEP增加后PaO₂/FiO₂和静态肺顺应性的变化与肺泡复张独立相关。分析肺复张手法（RM）引起的呼气末肺容积变化与PEEP诱导的肺泡复张之间的关系，发现存在显著相关性。
本研究结果表明，ARDS患者群体中肺泡复张的潜力可能存在差异，较高水平的PEEP应仅限于复张者。PEEP增加后PaO₂/FiO₂、静态肺顺应性的改善以及压力 - 时间曲线的形态有助于指导PEEP的应用。
