Point-of-care ultrasound of the diaphragm is a simple, noninvasive, dynamic bedside evaluation of diaphragm function that involves no ionizing radiation, does not require patient transport, and enables the serial evaluation of diaphragmatic function over time. Adverse effects on the diaphragm attributed to ventilator-induced diaphragm dysfunction include longer weaning times, ventilation time and weaning failure. Recent investigations of point-of-care ultrasound evaluating the expiratory muscles of the lateral abdominal wall have found similar adverse effects of mechanical ventilation on these important respiratory muscles resulting in weaning difficulty as well as impaired airway clearance. Children with medical complexity have significant chronic health conditions that may involve multisystem disease (congenital or acquired), high medical fragility, functional and psychosocial impairment, technology dependence (tracheostomies, mechanical ventilation, feeding tubes) and high resource utilization (frequent and/or prolonged hospitalizations). Weaning children dependent on mechanical ventilation is a common rehabilitation goal that has beneficial effects on the quality of life, ease of care, and functionality for transitioning to home care. We present a case of weaning difficulty in a child with medical complexity and the important role of point-of-care ultrasound in the evaluation of the diaphragm and expiratory muscles during a spontaneous breathing trial.