Pressure support improves oxygenation and lung protection compared to pressure-controlled ventilation and is further improved by random variation of pressure support.
OBJECTIVE
To explore whether 1) conventional pressure support ventilation improves lung function and attenuates the pulmonary inflammatory response compared to pressure-controlled ventilation and 2) random variation of pressure support levels (noisy pressure support ventilation) adds further beneficial effects to pressure support ventilation.


METHODS
Three-arm, randomized, experimental study.


METHODS
University hospital research facility.


METHODS
Twenty-four juvenile pigs.


METHODS
Acute lung injury was induced by surfactant depletion. Animals were randomly assigned to 6 hrs of mechanical ventilation (n = 8 per group) with either 1) pressure-controlled ventilation, 2) pressure support ventilation, or 3) noisy pressure support ventilation. During noisy pressure support ventilation, the pressure support varied randomly, with values following a normal distribution. In all groups, the driving pressures were set to achieve a mean tidal volume of 6 mL/kg. At the end of experiments, animals were killed and lungs extracted for histologic and biochemical analysis.


RESULTS
Respiratory, gas-exchange, and hemodynamics variables were assessed hourly. The diffuse alveolar damage and the inflammatory response of lungs were quantified. Pressure support ventilation and noisy pressure support ventilation improved gas exchange and were associated with reduced histologic damage and interleukin-6 concentrations in lung tissue compared to pressure-controlled ventilation. Noisy pressure support ventilation further improved gas exchange and decreased the inspiratory effort while reducing alveolar edema and inflammatory infiltration compared to pressure support ventilation.


CONCLUSIONS
In this model of acute lung injury, pressure support ventilation and noisy pressure support ventilation attenuated pulmonary inflammatory response and improved gas exchange as compared to pressure-controlled ventilation. Noisy pressure support ventilation further improved gas exchange, reduced the inspiratory effort, and attenuated alveolar edema and inflammatory infiltration as compared to conventional pressure support ventilation.
Department of Anesthesiology and Intensive Care Therapy, Pulmonary Engineering Group, University Hospital Carl Gustav Carus, Dresden, Germany.
Peter M
PM
Spieth
Alysson R
AR
Carvalho
Andreas
A
Güldner
Michael
M
Kasper
René
R
Schubert
Nadja C
NC
Carvalho
Alessandro
A
Beda
Constanze
C
Dassow
Stefan
S
Uhlig
Thea
T
Koch
Paolo
P
Pelosi
Marcelo
M
Gama de Abreu
D055371:Acute Lung Injury / Q000517:prevention & control / Q000628:therapy*; D000818:Animals; D001794:Blood Pressure; D002302:Cardiac Output; D005260:Female; D006439:Hemodynamics; D007385:Intermittent Positive-Pressure Ventilation / Q000379:methods*; D008168:Lung / Q000503:physiopathology; D011175:Positive-Pressure Respiration / Q000379:methods*; D011659:Pulmonary Gas Exchange; D011663:Pulmonary Surfactants / Q000378:metabolism; D012121:Respiration, Artificial / Q000379:methods*; D013552:Swine
D011663:Pulmonary Surfactants