Reliability of Arterial Blood Gas Analyzer for Electrolyte and Hemoglobin Measurement: A Method Comparison Study

Area of Science:

• Clinical Chemistry
• Point-of-Care Testing
• Laboratory Medicine

Background:

• Accurate electrolyte and hemoglobin assessment is vital in critical care settings.
• Arterial blood gas (ABG) analyzers are common point-of-care devices, but their accuracy compared to central labs is debated.
• Methodological differences between ABG analyzers and central autoanalyzers necessitate reliability studies.

Purpose of the Study:

• To evaluate the reliability of sodium, potassium, chloride, and hemoglobin from ABG analyzers against central laboratory autoanalyzers.
• To assess the analytical acceptability of ABG results using US Clinical Laboratory Improvement Amendments (CLIA) 2025 error limits.

Main Methods:

• Prospective observational study of 200 paired arterial and venous samples.
• Arterial samples analyzed on ABG analyzer (direct ISE); venous serum electrolytes on central autoanalyzer (indirect ISE).
• Hemoglobin measured on a hematology analyzer; statistical analysis included Wilcoxon, Spearman, and Bland-Altman.

Main Results:

• ABG-derived sodium and potassium were lower; chloride and hemoglobin were higher than venous lab values (p < 0.001).
• Acceptable agreement within CLIA limits for sodium (bias -2.8 mmol/L) and potassium (bias -0.2 mmol/L).
• Chloride (total error 6.43%) and hemoglobin (total error 15.15%) showed unacceptable analytical error.

Conclusions:

• ABG-derived sodium and potassium show acceptable agreement for rapid emergency decision-making.
• Chloride and hemoglobin ABG values are not interchangeable with central lab results without validation.
• Institution-specific validation and correction equations are needed for ABG chloride and hemoglobin.