MECHANISM BY WHICH THE PRONE POSITION IMPROVES OXYGENATION IN ACUTE LUNG INJURY

被引:303
作者
LAMM, WJE
GRAHAM, MM
ALBERT, RK
机构
[1] UNIV WASHINGTON,MED CTR,DEPT MED,SEATTLE,WA 98195
[2] UNIV WASHINGTON,DEPT RADIOL,SEATTLE,WA 98195
关键词
D O I
10.1164/ajrccm.150.1.8025748
中图分类号
R4 [临床医学];
学科分类号
1002 ; 100602 ;
摘要
The mechanism by which oxygenation improves when patients with ARDS are turned from supine to prone position is not known. From results of our previous studies we reasoned that (1) when supine, in the setting of lung injury, transpulmonary pressure will be less than airway opening pressure and (2) atelectasis will develop preferentially in dorsal lung areas, and (3) both ventilation and ventilation/perfusion ratios would improve in these regions on turning prone. To study this directly, we measured regional ventilation and perfusion using Kr-81m and Tc-99m-MAA, respectively, and single photon emission computed tomography, both prone and supine, in four control animals and four given oleic acid. After oleic acid, the prone position improved (1) oxygenation (mean +/- SD Pa-O2 = 140 +/- 112 versus 453 +/- 54 mm Hg), (2) median ventilation/ perfusion ratios (0.77 versus 0.95), (3) ventilation/perfusion heterogeneity (coefficient of variation 86 +/- 15 versus 61 +/- 6), and (4) the gravitational ventilation/perfusion gradient (dependent to non-dependent slopes of 0.22 versus -0.02, all p < 0.05). The prone position generates a transpulmonary pressure sufficient to exceed airway opening pressure in dorsal lung regions, i.e., in regions where atelectasis, shunt, and ventilation/perfusion heterogeneity are most severe, without adversely affecting ventral lung regions.
引用
收藏
页码:184 / 193
页数:10
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