This prospective observational study aims to evaluate the utility of vena cava ultrasound in predicting systemic venous congestion in critically ill invasively ventilated patients admitted to a mixed medical-surgical ICU Traditional markers like central venous pressure have limitations and while the VEXUS (Venous Excess Ultrasound) grading system has shown promise in cardiac surgical patients its applicability in non-cardiac ICU patients remains unclear

The primary objective is to assess the predictive ability of the maximum anteroposterior diameter of the inferior vena cava (IVCAP) for venous congestion, defined by at least mild abnormalities in hepatic portal or renal venous Doppler

 Secondary objectives include comparing diagnostic accuracy between IVCAP lateral diameter IVCLat their ratio IVCAP Lat and IVC distensibility index along with evaluating their correlation with acute kidney injury AKI

Adult patients m ore than18 years expected to remain ventilated for more than 48 hours will undergo serial ultrasound evaluations over 5 days Venous Doppler studies and IVC measurements will be performed with standardized protocols using B-mode and Doppler imaging  AKI will be assessed as per KDIGO criteria and correlated with ultrasound findings using logistic regression and ROC analysis

The study will enroll 64 patients as determined by sample size calculations based on expected AUC values Results aim to establish optimal IVC diameter cutoffs and validate vena cava ultrasound as a non-invasive diagnostic tool for venous congestion and its association with AKI in the ICU setting