Acute lung injury

Last revised by Henry Knipe on 14 Oct 2022

Acute lung injury (ALI) refers to a rather broad clinical syndrome defined by a constellation of clinical criteria:

  • acute onset of bilateral pulmonary infiltrates

  • pulmonary wedge pressures of usually 18 mmHg or less

It encompasses and also carries some overlap with the term acute respiratory distress syndrome (ARDS) with some publications stating a PaO2/FiO2 of:

  • ≤300 for ALI 1

  • ≤200 for ARDS 1 

Some publications state ARDS as a more severe form of ALI.


Histologically, it is represented by diffuse alveolar damage in most cases but can also be uncommonly represented by acute eosinophilic pneumonia (AEP) and acute fibrinous and organizing pneumonia (AFOP) 6. It can be precipitated by numerous agents.

Treatment and prognosis

Treatment is primarily supportive through supplemental oxygen with mechanical ventilation provided if necessary. The prognosis is variable.

ADVERTISEMENT: Supporters see fewer/no ads

Updating… Please wait.

 Unable to process the form. Check for errors and try again.

 Thank you for updating your details.