Evaluation of the correlation between the difference of arterial and venous carbon dioxide tension and cardiac index

Abstract

Background: One study showed that the difference (DCO₂) between central venous (PvCO₂) and arterial carbon dioxide tension (PaCO₂) inversely and strongly correlated with cardiac index (CI). We carried out to determine whether DCO₂ was alternative for CI. Methods: Twenty patients with central venous catheter were included for the study. On the next day after admission to ICU, we sampled the arterial blood and central venous blood for measurement of DCO₂. Simultaneously, we measured cardiac output (CO) by dye dilution method and calculated CI. We evaluated the correlation between DCO₂ and CI. Result: The correlation (r² = 0.509, P = 0.03) was significant in the only low CI patients (CI < 2.5 l·min⁻¹·m⁻¹), but not in normal CI patients. Conclusion: The present results suggested that DCO₂ might not be the alternative method for CI.