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KEY POINTS
Mechanical ventilation, though lifesaving, can worsen morbidity and mortality by causing ventilator-induced lung injury (VILI).
VILI primarily results from the mechanical and hemodynamic effects of excess tidal stress and strain on the injured lung.
Pulmonary injury and inflammation resulting from VILI decompartmentalizes through the systemic circulation to mediate multiorgan failure.
Lung-protective ventilation strategies aim to minimize stress and strain applied to the lung by limiting global and regional lung-distending pressure to safe levels.
Lung-protective ventilation strategies involve limiting tidal volume and driving pressure and by recruiting atelectatic lung with higher PEEP and prone positioning.
Adjuvant therapies to facilitate lung-protective ventilation in carefully selected cases include neuromuscular blockade, extracorporeal life support, and high-frequency oscillation.
There is growing awareness that patient respiratory muscle effort may also result in excessive and injurious lung-distending pressures (spontaneous breathing-associated lung injury).
Monitoring and controlling excessive respiratory effort represent an important future area for development of the lung-protective approach to the management of hypoxemic respiratory failure.
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Consistent clinical and experimental evidence, developed over the past four decades, demonstrates that mechanical ventilation can cause functional and structural alterations in the lung, which has been defined as ventilator-induced lung injury (VILI). By causing or perpetuating lung injury, VILI contributes to both the morbidity and mortality of mechanically ventilated patients, and in particular those with acute respiratory distress syndrome (ARDS). There is an increasing body of investigation aiming to define and refine strategies to optimally protect the lung, thereby improving patient outcome.
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The objectives of this chapter are to review current concepts of VILI and to provide the rationale for lung-protective ventilation strategies. Since most studies evaluating VILI have focused on ARDS, the relevant features of ARDS as it pertains to VILI will be reviewed first. The concept of lung-protective ventilation will then be discussed, and pertinent studies evaluating lung-protective ventilation strategies will be presented. This field involves a range of technical terms that are defined in Table 51-1. Recommendations based on current clinical evidence, and when this is lacking best experimental evidence, will also be presented.
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