Thomas et al defined acute lung injury and acute respiratory distress in critically-ill pediatric patients using various measures of oxygenation. The authors are from Penn State Hershey Children's Hospital, Pennsylvania State University, University of Virginia, Stanford University, Children's Hospital Boston, University of Pennsylvania and the VA Cooperative Studies Program in Mountain View, California.


Patient selection: patients in a pediatric ICU (with ages up to 20 years)


A goal was to define critical lung disease using the oxygen saturation rather than PaO2, which requires an arterial blood gas sample.



(1) PaO2 to FIO2 ratio

(2) oxygen saturation to FIO2 ratio

(3) oxygenation index (see section 08.07)

(4) oxygen saturation index (see section 08.07)


Acute Lung Injury (ALI)

Acute Respiratory Distress Syndrome (ARDS)

PaO2 to FIO2 ratio

201 to 300

<= 200

oxygen saturation to FIO2 ratio

213 to 253

<= 212

oxygen index

5.3 to 8.0

>= 8.1

oxygen saturation index

6.5 to 7.7

>= 7.8



• The oxygen saturation to FIO2 ratio is comparable to the PaO2 to FIO2 ratio.


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