From the Research
Hemolyzed venous blood gas (VBG) or arterial blood gas (ABG) samples typically show falsely elevated carbon dioxide (CO2) levels, as evidenced by a study published in 2013 1, which found a significant increase in pCO2 (+4.1%) in hemolyzed blood. However, a more recent study from 2022 2 found that hemolysis led to a significant decrease in pCO2 (-7.0%), which contradicts the previous finding. Despite this discrepancy, the most recent and highest quality study from 2025 3 did not specifically address the effect of hemolysis on CO2 levels, but it did evaluate the congruency of venous and calculated blood gas values to arterial values in critically ill patients. Considering the potential for hemolysis to affect blood gas analysis, it is crucial for healthcare providers to inspect blood gas samples for visible hemolysis and consider rejecting severely hemolyzed specimens for analysis. Some key points to consider when interpreting blood gas results in the context of hemolysis include:
- The degree of elevation in CO2 levels correlates with the severity of hemolysis
- Hemolysis can lead to incorrect interpretation of a patient's acid-base status and respiratory function
- Repeat non-hemolyzed samples should be obtained for accurate assessment whenever possible
- The presence of spurious hemolysis should be suspected whenever test results do not reflect the clinical presentation of the patient, as noted in a study from 2013 1. In clinical practice, the priority should always be to prioritize morbidity, mortality, and quality of life outcomes, and to use the most recent and highest quality evidence available to guide decision-making, such as the study from 2025 3.