BACKGROUND: Ventilator-induced lung injury occurs due to exaggerated local stresses, repeated collapse, and opening of terminal air spaces in poorly aerated dependent lung, and increased stretch in nondependent lung. The aim of this study was to quantify the functional behavior of peripheral lung units in whole-lung lavage-induced surfactant depletion, and to assess the effect of positive end-expiratory pressure. METHODS: The authors used synchrotron imaging to measure lung aeration and regional specific ventilation at positive end-expiratory pressure of 3 and 9 cm H2O, before and after whole-lung lavage in rabbits. Respiratory mechanical parameters were measured, and helium-washout was used to assess end-expiratory lung volume. RESULTS: Atelectatic, poorly, normally aerated, hyperinflated, and trapped regions could be identified using the imaging technique used in this study. Surfactant depletion significantly increased atelectasis (6.3±3.3 [mean±SEM]% total lung area; P=0.04 vs. control) and poor aeration in dependent lung. Regional ventilation was distributed to poorly aerated regions with high (16.4±4.4%; P<0.001), normal (20.7±5.9%; P<0.001 vs. control), and low (5.7±1.2%; P<0.05 vs. control) specific ventilation. Significant redistribution of ventilation to normally aerated nondependent lung regions occurred (41.0±9.6%; P=0.03 vs. control). Increasing positive end-expiratory pressure level to 9 cm H2O significantly reduced poor aeration and recruited atelectasis, but ventilation redistribution persisted (39.2±9.5%; P<0.001 vs. control). CONCLUSIONS: Ventilation of poorly aerated dependent lung regions, which can promote the local concentration of mechanical stresses, was the predominant functional behavior in surfactant-depleted lung. Potential tidal recruitment of atelectatic lung regions involved a smaller fraction of the imaged lung. Significant ventilation redistribution to aerated lung regions places these at risk of increased stretch injury.
BACKGROUND: Ventilator-induced lung injury occurs due to exaggerated local stresses, repeated collapse, and opening of terminal air spaces in poorly aerated dependent lung, and increased stretch in nondependent lung. The aim of this study was to quantify the functional behavior of peripheral lung units in whole-lung lavage-induced surfactant depletion, and to assess the effect of positive end-expiratory pressure. METHODS: The authors used synchrotron imaging to measure lung aeration and regional specific ventilation at positive end-expiratory pressure of 3 and 9 cm H2O, before and after whole-lung lavage in rabbits. Respiratory mechanical parameters were measured, and helium-washout was used to assess end-expiratory lung volume. RESULTS: Atelectatic, poorly, normally aerated, hyperinflated, and trapped regions could be identified using the imaging technique used in this study. Surfactant depletion significantly increased atelectasis (6.3±3.3 [mean±SEM]% total lung area; P=0.04 vs. control) and poor aeration in dependent lung. Regional ventilation was distributed to poorly aerated regions with high (16.4±4.4%; P<0.001), normal (20.7±5.9%; P<0.001 vs. control), and low (5.7±1.2%; P<0.05 vs. control) specific ventilation. Significant redistribution of ventilation to normally aerated nondependent lung regions occurred (41.0±9.6%; P=0.03 vs. control). Increasing positive end-expiratory pressure level to 9 cm H2O significantly reduced poor aeration and recruited atelectasis, but ventilation redistribution persisted (39.2±9.5%; P<0.001 vs. control). CONCLUSIONS: Ventilation of poorly aerated dependent lung regions, which can promote the local concentration of mechanical stresses, was the predominant functional behavior in surfactant-depleted lung. Potential tidal recruitment of atelectatic lung regions involved a smaller fraction of the imaged lung. Significant ventilation redistribution to aerated lung regions places these at risk of increased stretch injury.
Authors: Maurizio Cereda; Yi Xin; Hooman Hamedani; Justin Clapp; Stephen Kadlecek; Natalie Meeder; Johnathan Zeng; Harrilla Profka; Brian P Kavanagh; Rahim R Rizi Journal: J Appl Physiol (1985) Date: 2015-12-10
Authors: Luis Felipe Paula; Tyler J Wellman; Tilo Winkler; Peter M Spieth; Andreas Güldner; Jose G Venegas; Marcelo Gama de Abreu; Alysson R Carvalho; Marcos F Vidal Melo Journal: J Appl Physiol (1985) Date: 2016-07-21
Authors: Maurizio Cereda; Yi Xin; Natalie Meeder; Johnathan Zeng; YunQing Jiang; Hooman Hamedani; Harrilla Profka; Stephen Kadlecek; Justin Clapp; Charuhas G Deshpande; Jue Wu; James C Gee; Brian P Kavanagh; Rahim R Rizi Journal: Anesthesiology Date: 2016-01 Impact factor: 7.892
Authors: Jayesh Dhanani; John F Fraser; Hak-Kim Chan; Jordi Rello; Jeremy Cohen; Jason A Roberts Journal: Crit Care Date: 2016-10-07 Impact factor: 9.097
Authors: J B Borges; L Porra; M Pellegrini; A Tannoia; S Derosa; A Larsson; S Bayat; G Perchiazzi; G Hedenstierna Journal: Acta Anaesthesiol Scand Date: 2016-03-21 Impact factor: 2.105