Acute Lung Injury Ratio
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FIO2
unit % Fraction
PaO2 (mmHg)
R e s u l t s
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ALI Ratio
 
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Acute Lung Injury Ratio

Acute lung injury (ALI) and its more severe counterpart acute respiratory distress syndrome (ARDS) can occur due to various processes which causes direct or indirect injury to the lung. Manifestations include non-cardiogenic pulmonary edema, respiratory distress and hypoxemia.

ALI/ARDS are defined by radiographic and physiological changes which characterize patients with acute lung failure. Radiographical criteria consist of bilateral lung field infiltrates while physiological criteria include ratio of arterial oxygen pressure (PaO 2 ) and the inspiratory oxygen concentration ( F iO2 ). Criteria for ALI are PaO 2 /FiO 2 ratio of <=300 mmHg while for ARDS it is <=200 mmHg.

Formula used:

ALI ratio = PaO 2 /FiO 2 ,
where,

  • PaO 2 = arterial oxygen pressure
  • FiO 2 = inspiratory oxygen concentration

Data the user will need:

  • PaO 2 in mmHg
  • FiO 2 in % or fraction

References:

  1. Luh SP, Chiang CH. Acute lung injury/acute respiratory distress syndrome (ALI/ARDS): the mechanism, present strategies and future perspectives of therapies. J Zhejiang UnivSci B . 2007;8(1):60-9.
  2. Proudfoot AG, Hind M, Griffiths MJ. Biomarkers of acute lung injury: worth their salt?. BMC Med . 2011;9:132.