Ultrasound-based assessment of the correlation between pleural effusion volume, peripheral edema and pitting edema in intensive care patients

Background: Pleural effusion volume and peripheral edema are important markers of systemic fluid overload in critically ill patients. The aim of this study was to investigate the relationship between ultrasound-measured pleural effusion volume, ultrasonographic pretibial edema thickness, and clinically assessed pitting edema in hypoalbuminemic intensive care patients, and to determine whether peripheral edema can serve as a quantitative indicator of systemic fluid overload. Material and Methods: This prospective observational study included 40 intubated and hypoalbuminemic adults followed in a tertiary intensive care unit. Pleural effusion volume was calculated using an ultrasound-based volumetric formula. Pretibial edema thickness was measured at the mid-tibial level with a linear probe. Pitting edema was assessed clinically. Clinical, laboratory, and ultrasound data were analyzed using correlation and multivariate regression. Results: Pretibial edema was present in 77.5% of patients, and mean pleural effusion volume indicated marked fluid accumulation. Pretibial edema thickness showed a significant positive correlation with pleural effusion volume (p=0.012). Despite low albumin levels, no significant relationship was found between albumin and either effusion volume or peripheral edema. In multivariate analysis, pretibial edema thickness emerged as the only independent predictor of pleural effusion volume (p=0.013). Clinically assessed pitting edema showed no significant association with effusion volume. Conclusion: Ultrasound-measured pretibial edema thickness is a reliable, non-invasive and quantitative indicator of systemic fluid overload, demonstrating a strong association with pleural effusion volume. Its independent predictive value suggests that peripheral edema ultrasonography may serve as an integrable biomarker for fluid management in intensive care. The combined use of lung and peripheral edema ultrasonography may enhance early detection of fluid accumulation and support personalized therapeutic decisions.