Ventilator-induced lung injury

Lung injury comes from a variety of causes.  There are many causes, but let’s boil it down to the basics: oxygen.

Too much = ventilator-induced lung injury

Too little = hypoxemia

Tidal volumes

In the past, large tidal volumes were used to prevent collapse of the alveoli and to deliver more oxygen.  Volumes as large at 10-15 ml/kg ideal body weight were used.  But, these caused stress fractures in the alveolar-capillary interface.  These days lower tidal volumes of 6-8 ml/kg of ideal body weight are used for lung protection.

Oxygen free radicals

Large amounts of oxygen is bad due to its status as a free radical.  It is reduced in a series of one electron reactions.  The intermediates are free radicals that are highly reactive.

Types of trauma in ventilator-induced lung injury

Barotrauma — alveolar fractures from high pressure

Volutrauma — alveolar fractures from high volumes

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