Variability in Resting Oxygen Consumption Estimation in Adult Patients After Fontan Operation
Year: 2026
Type: preprint
Study design: Observational Study
Abstract: The hemodynamics in patients after Fontan operation are commonly evaluated through cardiac catheterization, where accurate assessment depends on reliable estimation of the resting oxygen consumption (rVO₂). In clinical practice, rVO₂ is frequently estimated using predictive equations rather than measured directly. In this prospective observational study, we compared rVO₂ measured by indirect calorimetry with rVO₂ measured during pre-exercise rest phase on routine cardiopulmonary exercise testing (CPET) or estimated using commonly applied predictive equations. To illustrate the potential consequences of rVO₂ variability on hemodynamic calculations, pulmonary vascular resistance (PVR) was modeled using a hypothetical patient scenario. Twenty-six clinically stable adult patients after Fontan operation were included (mean age 26.6 ± 5.8 years, 46% female, 73% extracardiac conduit, 42% open fenestration). Substantial variability in rVO₂ was observed depending on the method used. Measured rVO₂ by indirect calorimetry (246.2 ± 45.1 ml/min) differed significantly from that acquired by CPET (n = 22; 355.5 ± 74.4 ml/min) or calculated using predictive equations (n = 26 for all; LaFarge: 146.0 ± 31.9ml/min; Dehmer: 229.3 ± 28.1 ml/min; Bergstra: 264.6 ± 38.8 ml/min; p < 0.05 for all comparisons against indirect calorimetry). The Dehmer and Bergstra equations showed the smallest systematic differences and strongest correlations with measured rVO₂. Modeled PVR varied markedly and inversely with the rVO₂ estimation method used, reflecting its direct mathematical derivation from the rVO₂ values. Given the observed limitations of predictive equations and CPET-derived estimates in this population, direct measurement of rVO₂ by indirect calorimetry should be the preferred method for hemodynamic calculations in adult patients after Fontan operation.
Source: Research Square
Institution: Ljubljana University Medical Centre
Language: English
Subfield: Cardiology and Cardiovascular Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W7221594635