Ultrasound-guided management of reversible diaphragmatic dysfunction after extubation in an infant with transient pectus excavatum: a case report

Abstract Background : Diaphragmatic dysfunction is a clinically relevant complication of invasive mechanical ventilation (IMV) in infants, associated with respiratory biomechanical immaturity and reduced muscle activation related to sedation and prolonged ventilatory support. Diaphragmatic ultrasonography has emerged as a noninvasive bedside tool for real-time functional assessment and may support clinical decision-making during ventilator weaning and rehabilitation. Case presentation : We report the case of a previously healthy 1-month-old infant admitted with respiratory syncytial virus bronchiolitis complicated by pneumonia, requiring IMV for 7 days. Following extubation to high-flow nasal cannula (HFNC), the patient developed persistent moderate-to-severe inspiratory effort, requiring noninvasive ventilation (NIV) for 6 days. After withdrawal of positive pressure support, progressive pectus excavatum, subcostal and intercostal retractions, axial hypotonia, a globular abdomen, and radiographic hypoventilation were observed. Diaphragmatic ultrasonography demonstrated reduced inspiratory thickness (13.5 mm) and a low diaphragmatic thickening fraction (DTF, 17%), consistent with diaphragmatic weakness. An individualized physiotherapy program was initiated, including sensorimotor stimulation, abdominal muscle strengthening, and the use of an abdominal support band, while HFNC was maintained. After 72 hours, repeat ultrasonography showed improvement (DTF 33%, thickness 16 mm), accompanied by better thoracoabdominal synchrony, regression of chest wall deformity, and improved lung aeration. HFNC was subsequently discontinued, and the patient was discharged with clinical improvement. Conclusions : Diaphragmatic ultrasonography enabled early identification of diaphragmatic dysfunction, differentiation from inspiratory overload, and avoidance of unnecessary reintroduction of positive pressure support. Serial assessment supported targeted rehabilitation and demonstrated short-term reversibility of diaphragmatic dysfunction, highlighting its potential role in pediatric critical care. Clinical trial number : not applicable