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December 26, 1986

Oxygen Prescribing Practices: Measurement of Po2

Author Affiliations

American Thoracic Society Blood Gas Survey Committee New York

JAMA. 1986;256(24):3348-3349. doi:10.1001/jama.1986.03380240038017

To the Editor.—  Dr Skorodin's recent review of current oxygen prescribing practices1 points to the American Thoracic Society Blood Gas Proficiency Testing Program results2 as evidence that measurements of arterial oxygen pressure (Po2) are less precise than measurements of pH and carbon dioxide pressure.It is important to note that the products currently used for blood gas proficiency testing do not behave like fresh whole blood. The particular product we used and reported has very little oxygen buffering capacity and behaves very much like aqueous material. This characteristic contributes to the large variability of the Po2 results. Work by the American Thoracic Society Blood Gas Survey reference laboratories demonstrates that the Clark electrode is both accurate and reproducible when assessed with tonometered fresh whole blood, the best material currently available for assessing the accuracy of Po2 measurements.Proficiency testing results cannot be extrapolated to measurements in