The CR-AZI Study will assess the immunomodulatory effects of Azithromycin for pediatric Critical Asthma.

Azithromycin (AZI), a macrolide antibiotic, has been applied for adult and pediatric respiratory pathology to alter immune system response.1 For pediatric critical asthma (CA), a term used to describe a critically ill child hospitalized with an asthma exacerbation requiring an intensive care unit (PICU) hospitalization, the investigator's prior research has revealed 1 in 10 will receive AZI.2 Yet, the application of AZI in this setting is poorly studied nor is clear if, and to what degree AZI alters the immune response in conjunction with systemic corticosteroids traditionally applied in CA.

In this proposal, the investigators aim to characterize a respiratory epithelial inflammatory biomarker, periostin, among children with CA with and without exposure to AZI. The investigators hypothesize children receiving AZI will have lower periostin levels. As a secondary analysis, the investigators will describe the rates of adverse events related to AZI (previously not done) and explore differences in clinical and physiologic CA efficacy markers.

Inclusion criteria

• Age 3-17 years
• Admission to the PICU
• Primary diagnosis of critical asthma
• Prescription for continuous inhaled beta-agonist therapy and/or intravenous (IV) beta-agonist therapy
• Prescription for intravenous systemic corticosteroids

Exclusion criteria

• Critical Congenital Heart Disease Unrepaired
• Tracheostomy Dependence at Admission
• Ongoing Exposure to Azithromycin or Macrolide Antibiotics for any indication
• Past Medical History of Prolonged QT Syndrome or Arrhythmias
• Concomitant respiratory pathology including Acute Chest Syndrome, Interstitial Lung Disease, Cystic Fibrosis, and pulmonary hypertension

No plan to share with other researchers.