What is VExUS actually measuring? A new multicentre study provides a useful answer. D’Alto and colleagues studied 187 patients referred for pulmonary hypertension assessment across 7 centres. VExUS was performed within one hour of right-heart catheterisation, allowing direct comparison with invasively measured right atrial pressure (RAP). The relationship was striking: VExUS 0: mean RAP 3.9 mmHg VExUS 1: 8.4 mmHg VExUS 2: 13.5 mmHg VExUS 3: 15.8 mmHg For identifying RAP >12 mmHg, VExUS had an AUC of 0.97. The association held across patients with precapillary pulmonary hypertension, postcapillary pulmonary hypertension and those without pulmonary hypertension. What does this tell us? VExUS is often discussed as a tool for assessing “volume status” or “venous congestion”. But these data reinforce a more precise interpretation: VExUS is primarily a marker of the venous pressure environment, especially right atrial pressure and its transmission into the systemic veins. High RAP is not the same thing as excess intravascular volume. RAP may be elevated because of: • RV dysfunction or RV–pulmonary arterial uncoupling • severe tricuspid regurgitation • pericardial constraint • raised intrathoracic pressure • pulmonary hypertension • excess circulating volume • or a combination of these So an abnormal VExUS score tells us that systemic venous pressures are high. It does not, by itself, tell us why they are high and it does not automatically mean the patient needs diuresis or fluid removal. The key takeaway: VExUS appears to be an excellent non-invasive marker of elevated RAP. Use it to identify an adverse venous pressure state. Then work out the mechanism @ThinkingCC @NephroP journal.chestnet.org/article…