Pulmonary ultrasound provides a more accurate assessment of pulmonary congestion than wet/dry lung weight in rats

Pulmonary congestion is a common complication in critically ill patients, but its quantification remains challenging. The wet-to-dry (W/D) lung weight ratio, widely used in experimental models, is a terminal and semi-quantitative method. Lung ultrasonography (LU) may offer a non-invasive and reproducible alternative for assessing pulmonary edema. To evaluate the accuracy and reproducibility of LU compared with the W/D ratio in a rat model of oleic acid-induced lung injury. Thirty Wistar-Kyoto rats were randomized into injury (oleic acid, n = 15) and control (saline, n = 15) groups. Echocardiography and LU were performed at baseline and 1 h after infusion. B-line scoring was independently analyzed by two echocardiographers, with reproducibility assessed by Bland-Altman plots. Evans blue dye evaluated vascular permeability. Oleic acid-treated rats showed significantly higher LU scores, B-line counts, W/D ratios, and Evans blue levels than controls. LU demonstrated good diagnostic performance in detecting lung edema in this experimental model, with excellent inter- and intraobserver agreement confirming strong reproducibility. LU proved accurate, reproducible, and non-terminal for detecting pulmonary congestion in rats, showing good agreement with traditional gravimetric measures and supporting its use for longitudinal assessment of pulmonary edema in experimental research.