DataSheet1_Mechanical power is associated with cardiac output and pulmonary blood flow in an experimental acute respiratory distress syndrome in pigs.pdf

BackgroundDespite being essential in patients with acute respiratory distress syndrome (ARDS), mechanical ventilation (MV) may cause lung injury and hemodynamic instability. Mechanical power (MP) may describe the net injurious effects of MV, but whether it reflects the hemodynamic effects of MV is currently unclear. We hypothesized that MP is also associated with cardiac output (CO) and pulmonary blood flow (PBF).Methods24 anesthetized pigs with experimental acute lung injury were ventilated for 18 h according to one of three strategies: 1) Open lung approach (OLA), 2) ARDS Network high-PEEP/FIO2 strategy (HighPEEP), or 3) low-PEEP/FIO2 strategy (LowPEEP). Total MP was assessed as the sum of energy dissipated to overcome airway resistance and energy temporarily stored in the elastic lung tissue per minute. The distribution of pulmonary perfusion was determined by positron emission tomography. Regional PBF and MP, assessed in three iso-gravitational regions of interest (ROI) with equal lung mass (ventral, middle, and dorsal ROI), were compared between groups.ResultsMP was higher in the LowPEEP than in the OLA group, while CO did not differ between groups. After 18 h, regional PBF did not differ between groups. During LowPEEP, regional MP was higher in the ventral ROI compared to OLA and HighPEEP groups (2.5 ± 0.3 vs. 1.4 ± 0.4 and 1.6 ± 0.3 J/min, respectively, P < 0.001 each), and higher in the middle ROI compared to the OLA group (2.5 ± 0.4 vs. 1.6 ± 0.5 J/min, P = 0.04). MP in the dorsal ROI did not differ between groups (1.4 ± 0.9 vs. 1.4 ± 0.5 vs. 1.3 ± 0.8 J/min, P = 0.916). Total MP was independently associated with CO [0.34 (0.09, 0.59), P = 0.020]. Regional MP was positively associated with PBF irrespective of the regions [0.52 (0.14, 0.76), P = 0.01; 0.49 (0.10, 0.74), P = 0.016; 0.64 (0.32, 0.83), P = 0.001 for ventral, middle, and dorsal ROI, respectively]. Subgroup analysis revealed a significant association of MP and CO only in the OLA group as well as a significant association between MP with regional PBF only in the HighPEEP group.ConclusionIn this model of acute lung injury in pigs ventilated with either open lung approach, high, or low PEEP tables recommended by the ARDS network, MP correlated positively with CO and regional PBF, whereby these clinically relevant lung-protective ventilation strategies influenced the associations.

尽管机械通气（MV）对于急性呼吸窘迫综合征（ARDS）患者至关重要，但机械通气可能引发肺损伤及血流动力学不稳定。机械功率（MP）或许能够描述MV的净损伤效应，然而，其是否反映MV的血流动力学效应目前尚不明确。本研究假设MP亦与心输出量（CO）及肺血流量（PBF）相关联。研究方法：对24只实验性急性肺损伤的麻醉猪进行了18小时的通气，采用以下三种策略之一：1）开肺途径（OLA），2）ARDS网络高-肺复张压/吸入氧浓度策略（HighPEEP），或3）低-肺复张压/吸入氧浓度策略（LowPEEP）。总MP被评估为每分钟克服气道阻力所消耗的能量与暂时存储在弹性肺组织中的能量之和。通过正电子发射断层扫描确定肺灌注分布。在三个等重量的感兴趣区域（ROI）（腹部、中部和背部ROI）中，对区域PBF和MP进行评估，并比较各组之间的差异。结果：与OLA组相比，LowPEEP组的MP更高，而各组之间的CO并无显著差异。经过18小时后，各组之间的区域PBF无显著差异。在LowPEEP期间，与OLA和HighPEEP组相比，腹部ROI的区域MP更高（分别为2.5 ± 0.3 vs. 1.4 ± 0.4 和 1.6 ± 0.3 J/min，P < 0.001）；与OLA组相比，中部ROI的区域MP更高（2.5 ± 0.4 vs. 1.6 ± 0.5 J/min，P = 0.04）。背部ROI的MP在各组间无显著差异（1.4 ± 0.9 vs. 1.4 ± 0.5 vs. 1.3 ± 0.8 J/min，P = 0.916）。总MP与CO呈独立相关[0.34 (0.09, 0.59)，P = 0.020]。无论区域如何，区域MP与PBF均呈正相关[腹部ROI：0.52 (0.14, 0.76)，P = 0.01；中部ROI：0.49 (0.10, 0.74)，P = 0.016；背部ROI：0.64 (0.32, 0.83)，P = 0.001]。亚组分析表明，MP与CO仅在OLA组中显著相关，而MP与区域PBF仅在HighPEEP组中显著相关。结论：在本研究中，针对猪的急性肺损伤模型，通过开放肺途径、高或低PEEP策略（由ARDS网络推荐）进行通气，MP与CO和区域PBF呈正相关，表明这些具有临床相关性的肺保护性通气策略影响了这些相关性。