Key result
Continuous thermodilution cardiac index linked to ~37% lower ITU mortality, outperforming indirect Fick estimates.
Why the study?
Continuous thermodilution and indirect Fick-derived cardiac index are frequently used interchangeably to guide haemodynamic management in critically ill cardiac patients, although their relative prognostic value for ITU mortality is uncertain.
Does continuous thermodilution cardiac index improve prediction of ITU mortality compared to indirect Fick-derived cardiac index in critically ill cardiac ITU patients?
Observational (n=1,045)
No
Does continuous thermodilution cardiac index improve prediction of ITU mortality compared to indirect Fick-derived cardiac index in critically ill cardiac ITU patients?
In critically ill cardiac ITU patients, continuous thermodilution and indirect Fick-derived cardiac index are not interchangeable, and only continuous thermodilution independently predicts mortality.
Answers are grounded in this paper and cite their sources.
Continuous thermodilution CI was associated with ITU mortality prediction in cardiac ICU; leaves open superiority over indirect Fick pending prospective validation.
Background Cardiac index (CI) guides haemodynamic management in critically ill patients with cardiogenic shock or advanced cardiac failure. Continuous thermodilution and indirect Fick-derived CI are frequently used interchangeably, although their relative prognostic value is uncertain. Purpose To compare the prognostic performance of continuous thermodilution and indirect Fick-derived CI for ITU mortality. Methods We retrospectively analysed 1,045 consecutive critically ill cardiac patients admitted to a quaternary ITU undergoing invasive hemodynamic monitoring (mean age 58.9±16.2 years; 67% male; 65% on inotropes; mortality 24.9%). CI was assessed simultaneously by continuous thermodilution and indirect Fick method using estimated oxygen consumption (VO2). Multivariable models included both CI measurements and were adjusted for age, sex, inotrope use, mechanical ventilation, and renal ultrafiltration. Results Agreement analysis showed minimal mean bias (0.11 L/min/m²) but wide limits (−1.83 to +2.07) and percent error of 64%, well above accepted interchangeability thresholds. Both CI measurements demonstrated strong physiological coherence, showing robust associations with SvO2 (R²=0.60, p<0.001). In univariable analysis, continuous thermodilution predicted ITU mortality (OR 0.63, 95% CI 0.52–0.76, p<0.001), whereas indirect Fick-derived CI did not (OR 1.13, p=0.156). Continuous thermodilution showed moderate discrimination (AUC 0.71), while indirect Fick-derived CI showed poor discrimination (AUC <0.6). In multivariable analysis including both measurements and clinical confounders, only continuous thermodilution retained independent prognostic significance. Prognostic value was stronger in patients receiving inotropes (OR 0.59). A CI threshold of 2.35 L/min/m² identified high-risk patients for mortality with high specificity (81.5%). Conclusions Continuous thermodilution and indirect Fick-derived CI are not clinically interchangeable. Although both methods are positively associated with SvO2, only continuous thermodilution provides independent prognostic information for mortality, supporting its preferential use for invasive risk stratification in high-risk critically ill cardiac ITU patients.
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Cesani et al. (2026) conducted an observational in Critically ill cardiac patients (cardiogenic shock or advanced cardiac failure) (n=1,045). Continuous thermodilution cardiac index vs. Indirect Fick-derived cardiac index was evaluated on ITU mortality (OR 0.63, 95% CI 0.52–0.76, p=<0.001). Continuous thermodilution cardiac index independently predicted ITU mortality (OR 0.63, 95% CI 0.52–0.76, p<0.001), whereas indirect Fick-derived cardiac index did not (OR 1.13, p=0.156).
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