• Yi Xin, Maurizio Cereda, Hooman Hamedani, Mehrdad Pourfathi, Sarmad Siddiqui, Natalie Meeder, Stephen Kadlecek, Ian Duncan, Harrilla Profka, Jennia Rajaei, Nicholas J Tustison, James C Gee, Brian P Kavanagh, and Rahim R Rizi.
• 1 Department of Radiology and.
• Am. J. Respir. Crit. Care Med. 2018 Jul 15; 198 (2): 197207197-207.

RationaleIt remains unclear how prone positioning improves survival in acute respiratory distress syndrome. Using serial computed tomography (CT), we previously reported that "unstable" inflation (i.e., partial aeration with large tidal density swings, indicating increased local strain) is associated with injury progression.ObjectivesWe prospectively tested whether prone position contains the early propagation of experimental lung injury by stabilizing inflation.MethodsInjury was induced by tracheal hydrochloric acid in rats; after randomization to supine or prone position, injurious ventilation was commenced using high tidal volume and low positive end-expiratory pressure. Paired end-inspiratory (EI) and end-expiratory (EE) CT scans were acquired at baseline and hourly up to 3 hours. Each sequential pair (EI, EE) of CT images was superimposed in parametric response maps to analyze inflation. Unstable inflation was then measured in each voxel in both dependent and nondependent lung. In addition, five pigs were imaged (EI and EE) prone versus supine, before and (1 hour) after hydrochloric acid aspiration.Measurements And Main ResultsIn rats, prone position limited lung injury propagation and increased survival (11/12 vs. 7/12 supine; P = 0.01). EI-EE densities, respiratory mechanics, and blood gases deteriorated more in supine versus prone rats. At baseline, more voxels with unstable inflation occurred in dependent versus nondependent regions when supine (41 ± 6% vs. 18 ± 7%; P < 0.01) but not when prone. In supine pigs, unstable inflation predominated in dorsal regions and was attenuated by prone positioning.ConclusionsProne position limits the radiologic progression of early lung injury. Minimizing unstable inflation in this setting may alleviate the burden of acute respiratory distress syndrome.

31 keywords...

hide…