Differences in Arterial Oxygen Saturation Measurements Between Two Co-Oximeters From Different Manufacturers

Area of Science:

• Clinical Chemistry
• Medical Instrumentation
• Respiratory Physiology

Background:

• Functional arterial hemoglobin oxygen saturation (sO2) is crucial for pulse oximeter accuracy verification.
• Variability in co-oximeter performance complicates research and regulatory interpretations.
• This study addresses systematic differences between widely used co-oximeter brands.

Purpose of the Study:

• To quantify systematic measurement differences between same-model co-oximeters from two major brands (GEM and Radiometer ABL).
• To assess the impact of these differences on functional arterial oxygen saturation (sO2) measurements.
• To inform accuracy standards for pulse oximeter verification studies.

Main Methods:

• Controlled hypoxemia experiments in healthy volunteers measuring sO2 and S মনো_pO2.
• Analysis of 31 arterial blood samples across multiple GEM Premier 5000 and Radiometer ABL90 Flex analyzers.
• Statistical analysis including paired differences, mixed-effects modeling, and variance analysis.

Main Results:

• GEM analyzers measured sO2 2.3% higher on average than ABL analyzers (P < .001).
• Differences were more pronounced at lower saturations (3.2% vs 1.4%).
• Despite high correlation (r=0.999), 96.8% of samples differed by >1% and 61.3% by >2%.

Conclusions:

• Clinically significant systematic sO2 measurement differences exist between GEM and ABL co-oximeters.
• These discrepancies have implications for patient care and pulse oximeter verification.
• Further research with more brands and blood tonometry is recommended; current standards should specify co-oximeter manufacturer.