The degree of ambient air contamination of blood gas syringes affects Fick cardiac output determination
Year: 2026
Type: article
Abstract: Background: Arterial blood gas (ABG) and mixed venous blood gases (VBGs) are routinely done to assess oxygenation and Fick cardiac output (CO) determination. Little is known on the ABG and VBG effect of variable amounts of air contamination. Contamination of blood with ambient air artificially increases oximetry and hence O 2 content; however, its precise effect on Fick CO measurement remains unexplored. The objective of the study is to test the effect on Fick CO determinations of the introduction of different amounts of ambient air on ABG and VBG syringes. Methods: In this prospective cohort study, we included consecutive patients who underwent invasive cardiopulmonary exercise testing. We collected resting ABG from a radial arterial line and mixed VBG from the pulmonary artery. Preestablished amounts of air were introduced in the blood gas syringes before analysis using co-oximetry. Fick CO was calculated using measured oxygen consumption and O 2 content difference from ABG and VBG determinations with and without air contamination. Results: We included 7 patients in cohort 1 (no air, 100 and 200 mcL of air contamination) and 6 patients in cohort 2 (no air, 25 and 50 mcL of air contamination). The median [interquartile range (IQR)] partial pressure of oxygen (PO 2 ) and oxyhemoglobin (O 2 -Hb) (n=13) in ABG and VBG were 80.0 (74.0, 95.0) mmHg and 95% (94%, 96%), and 40.0 (38.0, 43.0) mmHg and 70% (68%, 74%), respectively. PO 2 was significantly higher in samples contaminated with air, particularly in ABG. However, the increase in O 2 -Hb with air contamination was higher for VBG. Therefore, the increase in O 2 content was more pronounced for the venous rather than arterial blood. True Fick CO (n=13) without air in ABG or VBG syringes was 5.2 (4.8–7.6) L/min. Isolated air contamination in ABG caused a decrease in Fick CO of 3–6%; meanwhile air contamination in VBG produced an increase in Fick CO from 3–42%, depending on the amount of air introduced. Conclusions: Exposure to ambient air in blood gas syringes, predominantly increases the PO 2 in ABG and O 2 -Hb in VBG. Oxygen content increases in both ABG and VBG, but air contamination in VBG introduced a larger error in Fick CO calculation.
Institution: Cleveland Clinic
Language: English
Subfield: Medical Laboratory Technology
Field: Health Professions
Domain: Health Sciences
Open Access status: diamond
OpenAlex ID: W7223258534