Abstract
<jats:p>The aim – to evaluate and compare the value of cardiac output (CO), determined by different methods (thermodilution, direct and indirect Fick), in patients with pulmonary hypertension (PH).Materials and methods. The study included 57 patients with various forms of PH who underwent right heart catheterization (RHC) according to a standard protocol. A comparative analysis of CO was performed in three stages: comparison of thermodilution (TD) with the indirect Fick method (IF) (n = 45), IF with the direct Fick method (DF) (n = 23), and TD with DF (n = 12). The formed groups were statistically comparable by anthropometric data (height, age, weight, BMI, sex – ANOVA, p > 0.05). Direct oxygen consumption (V̇O2) was determined by indirect respiratory calorimetry. Results. It was established that IF significantly underestimates cardiac output values compared to thermodilution (by 38 %, p < 0.001). Consistency analysis confirmed a critically high percentage error of IF results (88.5–119.9 % according to Critchley). When comparing TD and DF, a statistically significant dependence of the error on the value of cardiac output was revealed (β1 = 0.79; p = 0.029; R2 = 0.392), with an absolute bias of 0.69 L/min and a relative bias of 8.47 ± 43.91 %. At CO values above 7.37 L/min, a rapid increase in discrepancies between methods is observed, indicating limitations in TD accuracy in patients with high cardiac output and the need for data verification.Conclusions. CO values determined by IF significantly differ from the CO values determined by TD or DF methods. If, when evaluating by the TD method, the CO value exceeds the threshold of 7.37 L/min, such patients should undergo CO determination using the direct Fick method to obtain a reliable assessment of hemodynamic status.</jats:p>