The equipment to be used for the study was inoperable and not repairable.

The fraction of exhaled nitric oxide (FeNO) in expired air is a reliable measure of airway inflammation and has been used as a marker in asthma and other respiratory illnesses such as primary ciliary dyskinesia, bronchopulmonary dysplasia (BPD), liver cirrhosis, chronic obstructive pulmonary disease (COPD), cystic fibrosis (CF). Although, some exquisite bench research experiments have demonstrated stimulation of nitric oxide production in respiratory epithelial cells infected with RSV, there is a paucity of clinical data regarding levels of feNO in viral respiratory illness and specifically RSV.

The investigators conducted a pilot study from the fall of 2007 until October of 2009, looking at FeNO levels in RSV infected patients and compared it to non-RSV viral infections. The investigators recruited a total of 28 RSV positive and 1 RSV negative subjects, as well as 4 control subjects. The investigators found FeNO values not statistically significant between the study group (the two-tailed p=0.09, considered not quite significant), but there was a trend of higher FeNO values in the non-RSV group when compared to the RSV group. A larger sample may detect a statistically significance between these 2 groups.

Objectives:

i. To determine if the fraction of exhaled nitric oxide (feNO) is elevated in hospitalized pediatric patients with viral lower respiratory illness when compared with normal subjects without respiratory symptoms.

ii. To determine if there is a difference in feNO level between RSV and non-RSV infection in hospitalized pediatric patients with viral lower respiratory illness.

Method of feNO measurement utilized the offline options for preschool children & infants appropriate for age as described in the 2005 Joint Statement of the American Thoracic Society & the European Respiratory Society when discussing tidal breathing techniques with uncontrolled flow rate.

The investigators plan that our sample sizes for the RSV+ and control groups will be, by design, three times as large as the RSV- group. In order to achieve 80% power, the investigators will then require 45 control and 45 RSV+ patients, and 15 RSV- patients

Inclusion Criteria:

• Consecutive children admitted to WUH with a diagnosis of bronchiolitis, viral pneumonia or other significant respiratory viral infection
• The control group will include patient within the same age range as the study group who comes to the pediatric office for a well child visit and has none of the exclusion criteria listed below

Exclusion Criteria:

• Subjects who do not meet the diagnosis for bronchiolitis, viral pneumonia or other significant respiratory viral infection; all patients with underlying diagnosis of asthma/RAD, recurrent wheezing, "recurrent bronchiolitis", allergic rhinitis, atopy, any chronic lung disease, hypertension, heart failure, kidney failure receiving or not dialysis, pulmonary hypertension, primary ciliary dyskinesia, bronchiectasis, alveolitis, lung transplant rejection, pulmonary sarcoidosis, chronic cough (i.e. greater four weeks), systemic sclerosis, hypersensitivity, cystic fibrosis, HIV, sickle cell anemia, cardiac pulmonary bypass, liver cirrhosis, alpha-1 anti-trypsin disease and interstitial lung.

Children admitted to Winthrop University Hospital with lower respiratory tract viral illness, bronchiolitis or pneumonia.

The control group will include children in the same age range without respiratory conditions and who are well enough to perform the test from the out patient setting