Acute lung injury

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

• acute onset of bilateral pulmonary infiltrates
  • with hypoxemia
  • without evidence of hydrostatic pulmonary edema
• 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.

Pathology

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.