The fluid paradox: dissociation between clinical and ultrasound parameters of fluid overload - results of the INCIVEX exploratory study.

INTRODUCTION

Fluid management in critically ill patients relies on clinical assessment, fluid balance calculations and, increasingly, point-of-care ultrasound. However, the rela-tionships between these assessment modalities remain poorly understood, with conflicting evidence regarding their correlation and clinical utility. The study aimed to eva-luate correlations between clinical indicators of fluid overload, cumulative fluid balance, and comprehensive ultrasound parameters including cardiac function, lung ultrasound, and the venous excess ultrasound (VExUS) protocol in critically ill patients.

MATERIAL AND

METHODS

We conducted a cross-sectional, observational study in a tertiary intensive care unit. Adults admitted for ≥ 72 hours with clinical evidence of fluid overload but haemodynamic stability were eligible. Assessments included focused echocardiography, six-zone lung ultrasound, and comprehensive VExUS. Correlations between cumulative fluid balance, clinical oedema, and ultrasound parameters were analysed.

RESULTS

Of 195 patients screened, 50 were recruited to the study. The study population had a mean age of 59 years. Sepsis and respiratory failure were the most common admission diagnoses. The mean cumulative fluid balance was 7.1 ± 4.8 L at the time of recruitment. Peripheral oedema was present in over 70%. Ultrasound revealed left ventricular dysfunction in 16%, right ventricular dysfunction in 10%, bilateral pleural effusions in 44%, and elevated VExUS scores (> 2) in 20%. Cumulative fluid balance showed no correlation with clinical or ultrasound findings.

CONCLUSIONS

Traditional fluid assessment (cumulative fluid balance and clinical signs of oedema) methods show no correlation with ultrasound parameters in critically ill patients. Future research should focus on ultrasound-guided approaches that provide cardiovascular assessment rather than on cumulative fluid balance calculations or clinical signs alone.