Aortic volume determines global end-diastolic volume measured by transpulmonary thermodilution

• Published in: Intensive care medicine experimental Vol. 8; no. 1; pp. 1 - 13
• Main Authors: Akohov, Aleksej, Barner, Christoph, Grimmer, Steffen, Francis, Roland CE, Wolf, Stefan
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 02.01.2020; Springer Nature B.V; SpringerOpen
• Subjects: Aorta; Aortic volume; Cardiac function; Coronary vessels; Critical Care Medicine; GEDV; GEDVI; Global end-diastolic volume; Hemodynamics; Intensive; Intensive care; Medicine; Medicine & Public Health; Monitoring systems; Transpulmonary thermodilution; Vital signs; GEDV; GEDVI; Aortic volume; Transpulmonary thermodilution; Aorta; Global end-diastolic volume; Vena cava; Vena cava volume
• ISSN: 2197-425X; 2197-425X
• DOI: 10.1186/s40635-019-0284-8

Background Global end-diastolic volume (GEDV) measured by transpulmonary thermodilution is regarded as indicator of cardiac preload. A bolus of cold saline injected in a central vein travels through the heart and lung, but also the aorta until detection in a femoral artery. While it is well accepted that injection in the inferior vena cava results in higher values, the impact of the aortic volume on GEDV is unknown. In this study, we hypothesized that a larger aortic volume directly translates to a numerically higher GEDV measurement. Methods We retrospectively analyzed data from 88 critically ill patients with thermodilution monitoring and who did require a contrast-enhanced thoraco-abdominal computed tomography scan. Aortic volumes derived from imaging were compared with GEDV measurements in temporal proximity. Results Median aortic volume was 194 ml (interquartile range 147 to 249 ml). Per milliliter increase of the aortic volume, we found a GEDV increase by 3.0 ml (95% CI 2.0 to 4.1 ml, p < 0.001). In case a femoral central venous line was used for saline bolus injection, GEDV raised additionally by 2.1 ml (95% CI 0.5 to 3.7 ml, p = 0.01) per ml volume of the vena cava inferior. Aortic volume explained 59.3% of the variance of thermodilution-derived GEDV. When aortic volume was included in multivariate regression, GEDV variance was unaffected by sex, age, body height, and weight. Conclusions Our results suggest that the aortic volume is a substantial confounding variable for GEDV measurements performed with transpulmonary thermodilution. As the aorta is anatomically located after the heart, GEDV should not be considered to reflect cardiac preload. Guiding volume management by raw or indexed reference ranges of GEDV may be misleading.