Thoracic Ultrasound in Pediatric Intensive Care: A Valuable Tool for Children with Acute Bronchiolitis

INTRODUCTION: Available scoring systems for managing acute bronchiolitis lack accuracy in predicting severity and prognosis. Thoracic ultrasound may help fill this gap. This study evaluated changes in thoracic ultrasound parameters in children with acute bronchiolitis and their association with disease severity. Diaphragmatic ultrasound parameters were also compared between patients with and without invasive mechanical ventilation. METHODS: A prospective observational study included children under 24 months admitted to a Pediatric Intensive Care Unit with acute bronchiolitis. Thoracic ultrasound assessed lung ultrasound score (LUS), diaphragmatic excursion (DE), diaphragmatic thickness (DT), and thickening fraction (DTf) on days one, three, and five. Clinical severity was assessed using the Bronchiolitis Score of Sant Joan de Déu (BROSJOD) and other indicators. RESULTS: Twenty-six patients were enrolled. Lung ultrasound score decreased over time, while DE and DTf increased. On day one, LUS, DE, and DT positively correlated with BROSJOD (rs = 0.586, p = 0.005; rs = 0.599, p = 0.004; rs = 0.534, p = 0.013, respectively); DTf showed an inverse correlation (rs = -0.439, p = 0.047). By day five, only LUS remained significantly associated. LUS and DTf on day one varied with the fraction of inspired oxygen (FiO2) requirements. Lung ultrasound score on day one had an area under the curve of 0.806 for predicting FiO2 ≥ 50%, with a cut-off of 8.5 (sensitivity 63.6%, specificity 93.3%). Lower DT and DTf were consistently seen in patients requiring invasive mechanical ventilation (p < 0.05). CONCLUSION: Lung ultrasound score and DTf correlated with disease severity from the first day in the Pediatric Intensive Care Unit, indicating their potential as early markers of disease worsening. Lower DT and DTf may suggest severe disease and the need for ventilatory support escalation. Thoracic ultrasound is a promising, non-invasive tool for monitoring children with acute bronchiolitis.