Case

A 4 month old male presents with a 3 day history of low grade fever and runny nose. He has now developed a cough and questionable trouble breathing. He has had his first two immunizations and there are no other children in the house. He goes to daycare. On PE temperature was 101 and RR of 50/ min. There are slight retractions. HEENT is negative and there are diffuse wheezes and occasional rales. There is no murmur and he is pink in room air. 

Bronchiolitis is usually seen in infants less than 2 years old and highest incidence in infants less than 6 months old. It is most common in winter and early spring. The majority of cases are caused by respiratory syncitial virus(RSV)) and less often parainfluenza, adenovirus, and Mycoplasma. The infection causes bronchiole obstruction with mucous and edema in the walls of the airways leading to airway resistance and wheezing. It is more severe in infants with history of congenital heart disease, bronchopulmonary dysplasia, and prematurity. 

Usually present with a history of URI symptoms and then develop cough, decreased feeding, and respiratory distress. May have low grade temperature. On physical exam there may be tachypnea, wheezing, rales, respiratory distress, and evidence of dehydration if the patient had poor intake. Xray will demonstrate flattened diaphragms with air trapping and areas of atelectasis. 

Transmission- RSV is transmitted by hand to nasal or hand to conjunctiva. Patients admitted to the hospital should be on strict contact isolation.  The incubation period is 5-8 days and viral shedding lasts about 3-4 days.  In the younger patients the longer the shedding may last.3-4 weeks. 
Children can have RSV infections more than once but subsequent bouts are usually less severe.

Diagnosis

1. Generally a clinical diagnosis and common in Chicago between Dec.-April. 
2. RSV is diagnosed by ELISA or DFA of nasal washings or culture. Rapid assays have excellent sensitivity and specificity .

1. Oxygen if saturation is low and fluids if the child is dehydrated and intake is poor. May need hospitalization if there is oxygen and IV fluid requirements and parents are unable to care for infant. 
2. Bronchodilating drugs are often used but efficacy not proven.  If there is no clinical response after one treatment, use should be stopped. 
3. No role for antibiotics or corticosteroids
4. Ribovarin-may be useful for hospitalized patients at high risk for developing severe infection such as congenital heart disease, BPD, CF, or metabolic and neurologic diseases.  Currently not used often.
5. Prophylactic use of RSV gammaglobulin- may be useful for infants with BPD or history of prematurity.
6. Palivizumab-Synergis.  Monoclonal Antibody that is given monthly during the RSV season.

1. Hypoxemia and need for oxygen
2. Underlying pulmonary (BPD), cardiovascular, or immunologic deficiency syndrome
3. Dehydration and poor oral intake
4. Parental anxiety and poor follow-up

1. Often patients will appear very toxic and need careful observation with blood gas monitoring and administration of oxygen. There is usually a quick improvement afterwards. Rarely associated with mortality unless there is an underlying condition. 
2. Does bronchiolitis lead to asthma? Currently, it has been shown that children with RSV bronchiolitis have a higher incidence of Reactive Airway Disease that usually is not present past the adolescent years. There is also some indications that children with RSV have a higher incidence of pneumonias following RSV bronchiolitis

1. Age of patient
2. time of year and what you are seeing in your office or clinic
3. Asthma often has an acute onset and bronchiolitis often preceded by URI symptoms
4. Family history of allergies and asthma
5. Asthma usually responds more dramatically to bronchodilators

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