CAP blood gas survey--first year's experience.

Area of Science:

• Clinical Chemistry
• Pathology
• Medical Laboratory Science

Background:

• Clinical laboratories perform vital diagnostic tests, including blood gas analysis.
• Interlaboratory variability in blood gas measurements can impact patient care.
• Standardized surveys are crucial for assessing analytical performance.

Purpose of the Study:

• To assess the interlaboratory precision and accuracy of blood gas analysis (pH, PO2, PCO2).
• To identify sources of variability in blood gas measurements among participating laboratories.
• To evaluate the performance of different analytical instruments in a survey setting.

Main Methods:

• Over 500 clinical chemistry/pathology laboratories participated in the survey.
• Participants analyzed provided survey specimens containing pH, PO2, and PCO2.
• Interlaboratory precision was assessed, and interinstrument differences were analyzed using all-methods results.

Main Results:

• pH demonstrated the best interlaboratory precision, while PO2 exhibited the lowest.
• Accuracy evaluation was limited by the absence of an accepted reference method.
• Interinstrument differences were observed and were more attributable to individual instruments than manufacturers.
• Survey specimens, being buffered aqueous solutions, may not fully represent blood characteristics, potentially creating artifacts, especially for PO2.

Conclusions:

• The study highlights variability in blood gas analysis, particularly for PO2, among clinical laboratories.
• Instrument-specific factors contribute more to measurement differences than manufacturer.
• Caution is advised when interpreting survey results due to the limitations of the aqueous survey material.
• Further development of reference methods is needed for accurate assessment of blood gas analysis performance.