Gattinoni L, Pesenti A, Bombino M, Baglioni S, Rivolta M, Rossi F, Rossi G, Fumagalli R, Marcolin R, Mascheroni D
Istituto di Anestesiologia e Rianimazione, Università degli Studi di Milano, Italy.
Anesthesiology. 1988 Dec;69(6):824-32. doi: 10.1097/00000542-198812000-00005.
Twenty-two patients with acute respiratory failure underwent lung computed tomography (CT) and physiological measurements at 5, 10, and 15 cm H2O positive end-expiratory pressure (PEEP) to investigate the relationship between morphology and function. Lung densities were primarily concentrated in the dependent regions. From the frequency distribution of CT numbers (difference in x-ray attenuation between water and lung) and lung gas volume measurements the authors obtained a quantitative estimate of normally inflated, poorly inflated, and non-inflated lung tissue weight. This estimated average lung weight was increased twofold above normal and excess lung weight correlated with the mean pulmonary artery pressure (P less than 0.01). Venous admixture correlated with the non-inflated tissue mass (P less than 0.01). Increasing PEEP caused progressive clearing of radiographic densities and increased the mass of normally inflated tissue (anatomic recruitment), while reducing venous admixture. The cardiac index decreased after increasing PEEP while oxygen delivery was unchanged. The authors conclude that CT scan lung density and oxygen exchange efficiency are correlated; the main effect of augmenting PEEP is to recruit perfused alveolar units that were previously collapsed.
22例急性呼吸衰竭患者在呼气末正压（PEEP）分别为5、10和15 cm H₂O时接受了肺部计算机断层扫描（CT）及生理学测量，以研究形态与功能之间的关系。肺密度主要集中在下垂部位。通过CT值（水与肺之间X线衰减差异）的频率分布及肺气体容积测量，作者获得了正常充气、充气不良及未充气肺组织重量的定量估计值。该估计的平均肺重量比正常增加了两倍，且肺重量增加与平均肺动脉压相关（P<0.01）。静脉血掺杂与未充气组织量相关（P<0.01）。增加PEEP可使影像学密度逐渐消退，并增加正常充气组织的重量（解剖学上的肺复张），同时减少静脉血掺杂。增加PEEP后心脏指数下降，而氧输送不变。作者得出结论，CT扫描肺密度与氧交换效率相关；增加PEEP的主要作用是使先前萎陷的灌注肺泡单位复张。
