RSV bronchiolitis in the pediatric intensive care unit Searching for a new flow

Respiratory syncytial virus (RSV) bronchiolitis is a major cause of disease in infants worldwide. In severe cases, RSV bronchiolitis can lead to respiratory failure, necessitating admission to a pediatric intensive care unit (PICU) for respiratory support. PICU admissions are associated with a high patient and societal burden. The first part of this thesis studies the (inter)national admission burden of RSV bronchiolitis in the PICU and relates the increase of this burden with the introduction of High-Flow Nasal Cannula (HFNC) to the pediatric intensive care unit and general ward.
The second part of this thesis studies airway mucus obstruction in invasively ventilated children, with an emphasis on mucus obstruction in children with severe RSV bronchiolitis. The pathophysiology of RSV bronchiolitis is characterized by airway epithelial injury and inflammation, increased mucus production, impaired mucociliary clearance and neutrophilic influx. This neutrophilic influx, and especially the formation of neutrophil extracellular traps (NETs), is associated with the emergence of mucus plugs obstructing the lower. We studied NETs in the context of mucus viscoelasticity as well as airway epithelial injury. Last, mucus retention in the lower airways is a frequently encountered problem in children who are invasively ventilated for various kinds of illnesses. Aiming to ultimately improve our care for invasively ventilated children, we performed a pilot study for the use of bedside mucus rheology as a tool to identify patients at risk for mucus obstruction or to monitor treatment effect in the PICU.