Bronchiolitis is a major public health problem and the leading cause of paediatric intensive care unit admission in infants. Hypophosphatemia is common in adult intensive care units and was associated with an increase of the duration of mechanical ventilation and the length of stay. Our hypothesis is that hypophosphatemia is common in bronchiolitis and could be a marker of severity.

Inclusion Criteria:

• Age > 7 days and < 3 months of life
• Admission to the pediatric intensive care unit from 01/11/2016 to 31/03/2020
• With a diagnosis of moderate to severe bronchiolitis according to HAS 2019 criteria

Exclusion Criteria:

• Renal Failure and tubulopathy
• Previous disorder of phospho-calcium balance
• Malignant pathology
• Lenght of stay less than 24 hours
• History of cardiac, aortic or hepatic surgery

Infant less than 3 months with severe bronchiolitis admitted in a pediatric intensive care unit