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What is Ventilator-associated lung injury and explain in detail?
Ventilator-associated lung injury (VALI) is an acute lung injury that develops during mechanical ventilation and is termed ventilator-induced lung injury (VILI) if it can be proven that the mechanical ventilation caused the acute lung injury. In contrast, ventilator-associated lung injury (VALI) exists if the cause cannot be proven. VALI is the appropriate term in most situations because it is virtually impossible to prove what actually caused the lung injury in the hospital.

Cause
It is generally regarded, based on animal models and human studies, that volutrauma is the most harmful aspect of mechanical ventilation. This may be regarded as the over-stretching of the airways and alveoli.During mechanical ventilation, the flow of gas into the lung will take the path of least resistance. Areas of the lung that are collapsed (atelectasis) or filled with secretions will be underinflated, while those areas that are relatively normal will be overinflated. These areas will become overdistended and injured. This may be reduced by using smaller tidal volumes.During positive pressure ventilation, atelectatic regions will inflate, however, the alveoli will be unstable and will collapse during the expiratory phase of the breath (atelectotrauma)