EFFICACY OF ULTRASOUND GUIDED EXTRA-VASCULAR LUNG WATER INDEX MEASUREMENT IN PREDICTING DURATION OF MECHANICAL VENTILATION IN CRITICAL CARE UNIT –A PROSPECTIVE OBSERVATIONAL STUDY

Abstract

Background: Extravascular lung water (EVLW) contributes to respiratory dysfunction and poor outcomes in critically ill patients requiring mechanical ventilation. Lung ultrasound (LUS) is a rapid, non-invasive bedside tool for assessing pulmonary fluid burden using the Total Lung Score (TLS). This study evaluated the utility of LUS-derived TLS in predicting the duration of mechanical ventilation, weaning outcomes, and intensive care unit (ICU) length of stay. Methods: This prospective observational study included 136 mechanically ventilated adult patients admitted to a tertiary care ICU. Lung ultrasound was performed serially from Day 1 to Day 8 using a standardized four-zone protocol. Total Lung Score and pulmonary fluid burden were categorized as low, moderate, or high. Correlation analysis, one-way ANOVA, multivariable regression, logistic regression, and receiver operating characteristic (ROC) analysis were performed to evaluate the association of baseline TLS with duration of mechanical ventilation, prolonged weaning (>7 days), and ICU length of stay. Results: The mean age was 46 ± 13 years, and 57% of patients were male. The mean Day 1 TLS was 13.76 ± 3.84, with 69.9% having moderate pulmonary fluid burden. TLS progressively declined to 2.70 ± 3.09 by Day 8, indicating improvement in pulmonary aeration. Day 1 TLS showed weak, non-significant correlations with duration of mechanical ventilation (r = 0.131, p = 0.13) and ICU stay (r = 0.157, p = 0.069). Patients with high pulmonary fluid burden required significantly longer mechanical ventilation (5.78 ± 0.97 days) than those with moderate (4.35 ± 1.79 days) or low burden (4.16 ± 1.74 days) (p = 0.045). Baseline TLS was not an independent predictor of mechanical ventilation duration, prolonged weaning, or ICU stay. ROC analysis showed poor predictive accuracy for prolonged weaning (AUC = 0.45). Conclusion: Serial lung ultrasound effectively monitored changes in pulmonary fluid burden during ICU stay. Although higher pulmonary fluid burden was associated with longer mechanical ventilation, baseline Total Lung Score alone was not an independent predictor of mechanical ventilation duration, prolonged weaning, or ICU length of stay. LUS is therefore a valuable bedside monitoring tool when interpreted alongside clinical assessment.