C72-05 Assessment of Diaphragmatic Dysfunction With Point-Of-Care Ultrasound in Patients With Prolonged Mechanical Ventilation in Medical Intensive Care Unit

Rationale Prolonged mechanical ventilation is frequently complicated by diaphragmatic dysfunction. Point of care ultrasound (POCUS) offers a feasible bedside method to track diaphragmatic function, but longitudinal data remains limited. This study aimed to characterize serial changes in diaphragmatic excursion (DE) using POCUS in patients requiring prolonged mechanical ventilation in a tertiary Medical Intensive Care Unit (MICU). Methods Adult MICU patients who remained mechanically ventilated for ≥7 days between January and April 2025 underwent serial diaphragmatic ultrasound. DE was measured with standard M-mode ultrasound using a phased array transducer during spontaneous breathing trials at pre-defined intervals: days 7-10, 14-17, 21-24, and 28-31 of mechanical ventilation. Thirty patients were enrolled; ten had ≥2 ultrasound assessments and were included in the longitudinal analysis. Clinical data, including demographics, indication for intubation, tracheostomy placement, and clinical outcomes, were collected. Trends in DE were analyzed using first-derivative analysis. Results Among the ten patients with longitudinal data, mean age was 61 years, six were female, and six had prior intubation within the past year. Indications for intubation included acute hypoxemic respiratory failure (n = 5), altered mental status requiring airway protection (n = 3), combined hypoxemic hypercarbic respiratory failure (n = 1), and cardiac arrest (n = 1). Tracheostomy was performed in seven patients.Serial ultrasound revealed heterogeneous diaphragmatic trends. Two patients improved in DE with favorable outcomes: one was extubated, and the other was discharged to a facility on minimal ventilator support. Five showed overall decline; four died during the study period, and one remained ventilator-dependent at six weeks post-intubation. One patient initially worsened but was later liberated from the ventilator, another showed no overall change and remained ventilator-dependent, and one had transient post-tracheostomy improvement before subsequent decline. Variability in timing and frequency of assessments limited formal pattern modeling. Conclusions In patients requiring prolonged mechanical ventilation, serial diaphragmatic ultrasound revealed heterogeneous but clinically meaningful trajectories of muscle function. Improvement in DE was associated with successful weaning, while decline or persistently low function paralleled poor outcomes. These findings suggest that bedside ultrasound may serve as a practical, noninvasive marker of respiratory muscle health in critical illness. By capturing trends in recovery or decline, it could complement traditional parameters in guiding ventilator weaning, tracheostomy timing, and goals-of-care discussions. Larger prospective studies are warranted to validate these observations and to define how ultrasound-derived metrics can be integrated into research and clinical protocols to improve patient-centered outcomes.