CAP blood gas survey--1981 and 1982

Area of Science:

• Clinical Chemistry
• Biomedical Engineering
• Medical Diagnostics

Background:

• The College of American Pathologists (CAP) conducts annual surveys to assess laboratory performance.
• Previous surveys utilized aqueous specimens for blood gas analysis.
• The 1982 survey introduced fluorocarbon-based emulsion specimens.

Purpose of the Study:

• To compare the interinstrument and interlaboratory performance of blood gas analysis between the 1981 (aqueous) and 1982 (fluorocarbon emulsion) CAP surveys.
• To evaluate the impact of fluorocarbon-based emulsions on the precision and accuracy of pH, partial pressure of carbon dioxide (PCO2), and partial pressure of oxygen (PO2) measurements.

Main Methods:

• Comparison of results from the 1981 and 1982 CAP Blood Gas Surveys.
• Analysis of interinstrument differences for pH, PCO2, and PO2.
• Assessment of interlaboratory precision for pH and PCO2.
• Evaluation of coefficients of variation for PO2 determination.

Main Results:

• Interinstrument differences were observed for all three analytes (pH, PCO2, PO2) in both surveys.
• Interlaboratory precision for pH and PCO2 showed minimal difference between the two surveys.
• Coefficients of variation for PO2 determination were significantly lower in the 1982 survey compared to 1981.
• The improved PO2 precision in 1982 is attributed to the oxygen buffering capacity of fluorocarbon emulsions.

Conclusions:

• Fluorocarbon-based emulsions may enhance the precision of PO2 measurements in blood gas analysis.
• While precision and interinstrument differences can be assessed, the accuracy of blood gas measurements (pH, PCO2, PO2) cannot be determined without a validated reference method.
• Further investigation into reference methods for blood gas analysis is warranted.