Subglottic positive end-expiratory pressure in extubated patients recovering from acute lung injury

Background In acute lung injury positive end-expiratory pressure (PEEP) and recruitment maneuver are proposed to optimize arterial oxygenation. The aim of the study was to evaluate the impact of such a strategy on lung histological inflammation and hyperinflation in pigs with acid aspiration-induced lung injury. Methods Forty-seven pigs were randomly allocated in seven groups: (1) controls spontaneously breathing; (2) without lung injury, PEEP 5 cm H2O; (3) without lung injury, PEEP titration; (4) without lung injury, PEEP titration + recruitment maneuver; (5) with lung injury, PEEP 5 cm H2O; (6) with lung injury, PEEP titration; and (7) with lung injury, PEEP titration + recruitment maneuver. Acute lung injury was induced by intratracheal instillation of hydrochloric acid. PEEP titration was performed by incremental and decremental PEEP from 5 to 20 cm H2O for optimizing arterial oxygenation. Three recruitment maneuvers (pressure of 40 cm H2O maintained for 20 s) were applied to the assigned groups at each PEEP level. Proportion of lung inflammation, hemorrhage, edema, and alveolar wall disruption were recorded on each histological field. Mean alveolar area was measured in the aerated lung regions. Results Acid aspiration increased mean alveolar area and produced alveolar wall disruption, lung edema, alveolar hemorrhage, and lung inflammation. PEEP titration significantly improved arterial oxygenation but simultaneously increased lung inflammation in juxta-diaphragmatic lung regions. Recruitment maneuver during PEEP titration did not induce additional increase in lung inflammation and alveolar hyperinflation. Conclusion In a porcine model of acid aspiration-induced lung injury, PEEP titration aimed at optimizing arterial oxygenation, substantially increased lung inflammation. Recruitment maneuvers further improved arterial oxygenation without additional effects on inflammation and hyperinflation.

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Effects of recruitment maneuvers in patients with acute lung injury and acute respiratory distress syndrome ventilated with high positive end-expiratory pressure*

Critical Care Medicine ◽

10.1097/01.ccm.0000090001.91640.45 ◽

2003 ◽

Vol 31 (11) ◽

pp. 2592-2597 ◽

Cited By ~ 110

Author(s):

Keyword(s):

Acute Respiratory Distress Syndrome ◽

Acute Lung Injury ◽

Lung Injury ◽

Respiratory Distress Syndrome ◽

Respiratory Distress ◽

Distress Syndrome ◽

Positive End Expiratory Pressure ◽

Recruitment Maneuvers

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Dynamic mechanical consequences of deep inflation in mice depend on type and degree of lung injury

Journal of Applied Physiology ◽

10.1152/japplphysiol.00270.2003 ◽

2004 ◽

Vol 96 (1) ◽

pp. 293-300 ◽

Cited By ~ 50

Author(s):

Gilman Allen ◽

Jason H. T. Bates

Keyword(s):

Acute Lung Injury ◽

Lung Injury ◽

Bronchoalveolar Lavage ◽

Bronchoalveolar Lavage Fluid ◽

Fluid Pressure ◽

Lavage Fluid ◽

Forced Oscillations ◽

Positive End Expiratory Pressure ◽

Reduced Pressure ◽

Volume Curve

In a previous study (Allen G, Lundblad LK, Parsons P, and Bates JH. J Appl Physiol 93: 1709-1715 , 2002), our laboratory used deep inflations (DI) in mice to show that recruitment of closed lung units can be a very transient phenomenon in lung injury. The purpose of this study was to investigate how this transience of lung recruitment depends on the nature and degree of acute lung injury. Mice were administered 50 μl of either saline ( n = 8), 0.01 M ( n = 9) or 0.025 M ( n = 8) hydrochloric acid, or 50 μg ( n = 10) or 150 μg ( n = 6) of LPS and were mechanically ventilated 24-48 h later. At various levels of positive end-expiratory pressure, two DIs were delivered, and forced oscillations were used to obtain a measure of lung stiffness ( H) periodically over 7 min. After LPS exposure, pressure-volume curve hysteresis and recovery in H after DI were no different from saline-exposed controls despite 500 times more neutrophils in bronchoalveolar lavage fluid. Pressure-volume hysteresis and recovery in H were increased in acid-exposed mice ( P < 0.001) and were correlated with bronchoalveolar lavage fluid protein content ( R = 0.81). Positive end-expiratory pressure reduced recovery in H in all groups ( P < 0.01) but reduced pressure-volume hysteresis in the acid-injured groups only ( P < 0.001). We conclude that the effects of DIs in acute lung injury depend on the degree of lung injury but only to the extent that this injury reflects a disruption of the air-liquid interface.

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