This study aims to examine the effect of nebulized 3% hypertonic saline in the treatment of viral bronchiolitis. The investigators hypothesize that nebulized 3% saline will decrease rate of hospital admission, decrease clinical severity scores, and decrease length of stay.

Bronchiolitis is the most common viral respiratory infection in young children and infants. It is responsible for hundreds of thousands of outpatient visits and hospitalizations every year. Hypertonic saline may decrease swelling in the lung tissue, improve the patient's ability to clear secretions, and decrease nasal congestion. Hypertonic saline nebulizations have already been used effectively in patients with cystic fibrosis and in a few small trials on infants with bronchiolitis. Patients who come to the emergency department or inpatient ward of two urban free-standing pediatric hospitals in California between December and April and are diagnosed with bronchiolitis will be randomized into two groups- the control group will receive nebulized 0.9% normal saline, while the study group will receive nebulized 3% hypertonic saline. Nebulizations will be pretreated with albuterol, to prevent the theoretical risk of increased wheezing in patients with undiagnosed underlying asthma. Patients will be given up to 3 nebulizations in the emergency department, after which time the attending physician will decide whether admission to the hospital is required. Patients who are admitted will continue to receive the same nebulized treatment every 8 hours until discharged. Additional interventions such as epinephrine treatments and antibiotics can be ordered as indicated by the patient care team.

Investigators will measure symptom severity before and after treatments using the respiratory distress assessment instrument (RDAI). The investigators will compare rates of being admitted to the hospital in each group. The investigators will also compare RDAI scores, average length of stay, number of additional respiratory treatments needed, number of hours requiring oxygen, amount of IV fluid needed, and frequency of adverse effects. The investigators hypothesize that nebulized hypertonic saline will be a safe, cost-effective, and efficacious therapy which can be utilized in the outpatient setting to prevent hospital admission, as well as decrease length of stay for patients who require admission. Given the significant disease burden of viral bronchiolitis, the potential impact is substantial.

Inclusion Criteria:

• clinical diagnosis of viral bronchiolitis
• between November and April

Exclusion Criteria:

• prematurity < 34 weeks
• chronic lung disease
• congenital heart disease
• history of wheezing, asthma or albuterol use
• tracheostomy status
• need for intensive care of assisted ventilation

Patient enrollment through duration of hospitalization (average 3.5 days)

The number of participants at risk is different from the number started because one patient randomized to the normal saline group received hypertonic saline.

• Albuterol administered before each study treatment
• Did not reach subject accrual goals
• Number of patients recruited from inpatient unit too small to analyze separately