Respiratory Syncytial Virus Bronchiolitis
Cheryl A. Glass and Melissa A. Hall
Definition
A. Respiratory syncytial virus (RSV) is the most frequent cause of viral respiratory tract infection in infants. Most infants develop upper respiratory tract symptoms; 20% to 30% develop lower respiratory tract disease with their first infection. Infection with RSV may produce minimal respiratory symptoms. Most previously healthy infants who develop RSV bronchiolitis do not require hospitalization. Preterm infants with respiratory symptoms with lethargy, irritability, and poor feeding may require admission for treatment. There is no specific treatment for RSV infection.
Incidence
A. RSV is prevalent worldwide and affects all age groups. Infants, the elderly, and adults with chronic heart or lung disease or weakened immune systems are at high risk. Annual epidemics occur in winter and early spring, usually in temperate climates. The peak season in North America is between November and March. Most infants are infected during the first year of life. Peak incidence of occurrence of severe RSV disease is observed at ages of 2 to 8 months. Virtually all children have been infected at least once by their third birthday. Reinfection with RSV throughout life is common.
B. The period of viral shedding usually is 3 to 8 days, but shedding may continue up to 4 weeks. The incubation period ranges from 2 to 8 days.
C. Full recovery from RSV illness occurs in about 1 to 2 weeks.
Pathogenesis
A. RSV is an enveloped, nonsegmented, negative strand RNA virus of the Paramyxoviridae family. Two major strains (Groups A and B) have been identified, and strains of both often circulate concurrently.
B. Humans are the only source of infection. Transmission is by direct or close contact with contaminated secretions. RSV can persist on environmental surfaces for several hours and for a half hour or more on hands.
Predisposing Factors
A. Prematurity
B. Congenital heart disease
C. Chronic lung disease (CLD)
D. Immunodeficiency
E. Child-care centers
F. Two or more siblings younger than 5 years
G. Hospitalization
Common Complaints
A. Pediatrics
1. Fever (less than 101°F); 20% of patients have higher temperatures
2. Decreased appetite
3. Irritability
4. Lethargy
5. Rapid respirations
6. Cough
7. Coryza
8. Decreased activity
9. Wheezing
B. Adults
1. Rhinorrhea
2. Pharyngitis
3. Cough
4. Headache
5. Fatigue
6. Fever
Other Signs and Symptoms
A. Tachypnea or apnea
B. Nasal flaring
C. Retractions
D. Crackles
E. Wheezes
Subjective Data
A. Ask about the onset, duration, and course of illness.
B. Inquire whether the child is having trouble eating or drinking because of breathing problems.
C. Review other symptoms, including fever, nausea, vomiting, or diarrhea.
D. Are there any labored breathing patterns?
E. Calculate the child’s age—how old the baby is and birth date—if palivizumab (Synagis) is prescribed.
F. Was the baby born preterm and at what gestational age?
G. Has the patient ever been diagnosed with any cardiac or lung problems, including cystic fibrosis (CF)?
H. Do the patient’s siblings attend day care?
Physical Examination
A. Record temperature, pulse, respirations, blood pressure, and pulse oximetry.
B. Inspect
1. Observe general appearance.
2. Note respiratory pattern, retractions, nasal flaring, grunting, and circumoral cyanosis.
3. Inspect eyes, ears, nose, and throat. As many as 40% have an associated viral and/or bacterial otitis media.
4. Assess hydration status: Skin turgor, capillary refill, mucous membranes.
C. Auscultate
1. Heart
2. Lungs for crackles and mild to moderate respiratory distress with scattered wheezes
D. Percuss chest.
E. Palpate
1. Lymph nodes for adenopathy
2. Head and fontanelles (if applicable)
Diagnostic Tests
A. Rapid diagnostic assay of nasopharyngeal secretions is reliable in infants and young children.
B. Laboratory studies are frequently not indicated in the infant who is comfortable in room air, is well hydrated, and is feeding adequately. Nonspecific laboratory tests may include complete blood count (CBC), serum electrolytes, and urinalysis.
C. Chest radiograph (CXR) may show hyperexpansion, atelectasis, and/or infiltrates in a specific nonlobar (bacterial) viral pattern.
D. Arterial blood gases (ABGs) or pulse oximetry may show hypoxemia.
Differential Diagnoses
A. Viral or bacterial pneumonia
B. Asthma
C. Croup
D. Influenza
E. Neonatal sepsis
F. Foreign body aspiration
Plan
A. General interventions
1. Most infants require only supportive care, such as nasal suctioning.
2. Infants should never be exposed to cigarette smoke.
3. Hydration is important.
4. Contact precautions are recommended for the duration of RSV- associated illness among infants and young children. Adhere to appropriate hand-hygiene practices.
5. Prevention includes limiting, when feasible, exposure to contagious settings (e.g., child-care centers).
B. Patient teaching: See Section III: Patient Teaching Guide for this chapter, “Respiratory Syncytial Virus.”
C. Dietary management
1. Tell caregiver to offer juice, water, and other fluids frequently and to dilute juice for younger infants.
2. Suggest offering small, frequent feedings.
D. Pharmacological therapy
1. Ribavirin is an antiviral drug that may be delivered by means of aerosol, but it is reserved for severely ill children or those at high risk.
2. The use of bronchodilators and corticosteroids is controversial, but they may be indicated for hospitalized patients.
3. Antibiotics are not indicated for RSV bronchiolitis or pneumonia unless there is a secondary bacterial infection.
4. Palivizumab (Synagis) immunoprophylaxis is extremely costly and should be limited to infants at risk of hospitalization related to RSV. Dosing: Palivizumab 15 mg/kg intramuscularly every 30 days. Immunizations are given from 3 to 5 months depending on the gestational age, risk factors, and month that prophylaxis is started. The 2012 AAP eligibility criteria for palivizumab prophylaxis criteria includes:
a. Infants with CLD younger than 24 months who receive supplemental oxygen and bronchodilator, diuretic, or chronic corticosteroids. A maximum of five doses is recommended for this category.
b. Infants born before 32 weeks gestation (31 weeks + 6 days or less). A maximum of five monthly doses is recommended depending on gestational age and chronological age at the start of RSV season.
c. Infants born at 32 to younger than 35 weeks gestation (32 weeks + 0 days through 34 weeks + 6 days): Palivizumab prophylaxis should be limited to infants at greatest risk, younger than 3 months of age at the start of RSV season.
d. Infants with congenital abnormalities of the airway or neuromuscular disease may be considered for immunoprophylaxis. A maximum of five doses of palivizumab during the first year of life is recommended.
e. Infants and children with congenital heart disease who are 24 months of age or younger with hemodynamically significant acyanotic congenital heart disease may benefit from immunoprophylaxis. The decision to treat should be based on the degree of physiological cardiovascular compromise.
f. Immunocompromised children with severe immunodeficiency or advanced AIDS may benefit from prophylaxis.
g. There is insufficient data to determine the efficacy of palivizumab with patients with CF.
Follow-Up
A. Call the patient’s caregiver in 12 to 24 hours to assess feeding and respiratory status.
Consultation/Referral
A. Refer the patient to a physician or emergency room if the infant is in moderate respiratory distress, is dehydrated, is hypoxemic, or is less than 6 months of age.
B. Admit hypoxemic infants to the hospital for hydration, oxygen therapy, and, possibly, mechanical ventilation.
C. Age is a significant factor in the severity of infection: The younger the patient is, the more severe the infection/hypoxemia tends to be. Infants younger than 6 months are most severely affected secondary to their smaller, more easily obstructed airways and their decreased ability to clear secretions.
Individual Considerations
A. Adults: Palivizumab (Synagis) is not approved for adults.
B. Pediatrics
1. All high-risk infants 6 months of age and older and their contacts should be administered the influenza vaccine as well as other recommended age-appropriate immunizations.
2. Palivizumab does not interfere with response to vaccines.
C. Pregnancy: Ribavirin is contraindicated during pregnancy. A negative pregnancy test and assurance of contraception should be obtained before prescribing.