First Aid, Chapter 7 Hypersensitivity Disorders, Bronchiolitis and Croup

Question 1

What are causes of pediatric bronchiolitis?

Answer 1

• RSV
• Rhinovirus
• Parainfluenza virus
• Human metapneumovirus
• Influenza

Question 2

What are the causes of adult bronchiolitis?

Answer 2

• Inhalational injury
• Infection (mycoplasma pneumonia)
• Drug reaction
• Hypersensitivity pneumonitis
• Connective tissue disease

Question 3

Who is most prone to get bronchiolitis? At what time of year?

Answer 3

Infants 3–6 months of age are the most prone to symptoms during peak RSV season, from October through May.

Question 4

What percentage of infants have been infected with RSV during their first year? by 2 years?

Answer 4

Approximately 50–65% infants have been infected with RSV during their first year, and nearly 100% infants have been infected by 2 years of age.

Question 5

What is the pathophysiology of bronchiolitis?

Answer 5

Necrosis of respiratory epithelium occurs along with ciliary disruption and peribronchiolar lymphocytic infiltration. Obstruction of the small airways is caused by excessive mucus and edema.

Question 6

When do bronchiolitis symptoms peak? When do they resolve? What are symptoms? What are severe symptoms?

Answer 6

Symptoms typically peak at 3–5 days and resolve in 2 weeks, although wheezing can persist.

Symptoms: cough, wheezing, fever, rhinorrhea, nasal congestion, dehydration.

Severe symptoms: hypoxia, tachypnea, and apnea.

Question 7

Who is at higher risk for severe disease with bronchiolitis?

Answer 7

Infants at higher risk for severe disease include those with:

• Congenital heart disease
• Immunodeficiency
• Bronchopulmonary dysplasia
• Prematurity

Question 8

How is bronchiolitis diagnosed?

Answer 8

Bronchiolitis is a clinical diagnosis. Virologic tests and radiographs can be used to support the diagnosis, but they rarely alter management or outcomes and are not routinely required.

Question 9

What is the treatment of bronchiolitis? When should patients be hospitalized? What medication should be given as an inpatient?

Answer 9

Bronchiolitis is usually a self-limited, mild disease, and treatment is primarily supportive. Patients in moderate-to-severe respiratory distress may require hospitalization. In the inpatient setting a trial of albuterol is appropriate with assessment for bronchodilator response.

Question 10

What medication should be given for severely ill infants with bronchiolitis or those at risk for complication?

Answer 10

Ribavirin can be considered for severely ill infants or those at risk for complications.

Question 11

What medication should be given to high-risk infants under age 2 for prevention of bronchiolitis?

Answer 11

Palivizumab is a monoclonal antibody directed against an epitope of the RSV virus and can be given monthly to high-risk infants younger than 2 years of age as a preventive measure (bronchopulmonary dysplasia, cyanotic congenital heart disease, and prematurity).

Question 12

What is the incidence of recurrent wheezing in the first year of life?

Answer 12

40%

Question 13

Until what age is RSV bronchiolitis considered an independent risk factor for development of frequent wheezing?

Answer 13

until age 10

Question 14

What are possible contributing factors to frequent wheezing in children?

Answer 14

RSV bronchiolitis, genetic disposition, gender, lung size, tobacco exposure, or immune response.

Question 15

What is croup? What is it characterized by?

Answer 15

Laryngotracheitis (croup) is a respiratory illness that results in inflammation of the larynx and subglottic airway. It is characterized by a barking cough.

Question 16

What is the most common cause of stridor in a febrile child?

Answer 16

croup

Question 17

Define laryngitis and laryngotracheobronchitis.

Answer 17

• Laryngitis: Inflammation limited to the larynx; manifests itself as hoarseness; usually occurs in older children and adults; and is frequently caused by viral infections.
• Laryngotracheobronchitis: Inflammation extending into the lower airways; symptoms include wheezing, rales, air trapping, and tachypnea.

Question 18

Define bacterial tracheitis.

Answer 18

Bacterial infection of the subglottic trachea; thick and purulent exudates; symptoms of upper-airway obstruction; and may occur as a complication of viral respiratory infections or as a primary bacterial infection.

Question 19

Define spasmodic croup.

Answer 19

Sudden onset of inspiratory stridor at night often associated with mild URI. Symptoms last several hours with sudden cessation and condition is recurrent. There is evidence that spasmodic croup may be more common in atopic children and is often referred to as “allergic croup.”

Question 20

What is the most common viral cause of croup? What are the other viral causes of croup?

Answer 20

Approximately 80% of croup is secondary to parainfluenza virus infection (type one most common).

• RSV
• Adenovirus
• Rhinovirus
• Influenza virus
• Measles

Question 21

What are the most common seconadry bacterial pathogens in croup?

Answer 21

The most common secondary bacterial pathogens include Staphylococcus aureus, Streptococcus pyogenes, and Streptococcus pneumoniae.

Question 22

Do viruses or bacteria more commonly cause croup?

Answer 22

Croup is most often caused by viruses with bacterial infections occurring secondarily.

Question 23

What virus causes more severe disease in croup?

Answer 23

Influenza A is associated with more severe disease and seen in those with respiratory compromise

Question 24

What age is croup most common in? What time of year?

Answer 24

Croup is most common between 6–36 months of age. Most common in late fall and early winter.

Question 25

What is the pathogenesis of croup?

Answer 25

Viral infection leads to inflammation and edema of the subglottic larynx and trachea, especially near the cricoid cartilage (i.e., narrowest part of the pediatric airway). Narrowing results in the turbulent airflow, stridor, and chest retractions. Decreased mobility of the vocal cords due to edema leads to the associated hoarseness.

Question 26

What size tracheal tube should be used for severe respiratory distress in croup?

Answer 26

In cases of severe respiratory distress, a tracheal tube that is 0.5– 1 mm smaller than would typically be used may be required secondary to laryngeal edema.

Question 27

What is the presentation of croup?

Answer 27

The onset of symptoms of croup is usually gradual, beginning with nasal irritation, congestion, and coryza. Symptoms generally progress over 12–48 hours to include fever, hoarseness, barking cough, and stridor. Symptoms can persist for 3–7 days. Identifying patients with severe respiratory distress and/or impending respiratory failure is paramount.

Question 28

What are symptoms of signficant upper-airway obstruction in croup?

Answer 28

• Stridor at rest
• Retractions
• Diminished breath sounds -Hypoxia and cyanosis

Question 29

How do infants and young children present vs. older children and adults with croup?

Answer 29

Infants and young children will frequently present with a barking cough, whereas older children and adults will present with hoarseness.

Question 30

What does imaging reveal in croup?

Answer 30

Imaging—Posteroanterior chest radiograph reveals subglottic narrowing; commonly called the “steeple sign.”

Question 31

What does CBC with croup reveal?

Answer 31

CBC is usually nonspecific. WBC and differential may reveal a viral pattern with leukocytosis and lymphocytosis.

Question 32

What other conditions are in the differential of croup?

Answer 32

• Epiglottitis
• Foreign body aspiration
• Peritonsillar/retropharyngeal abscesses
• Upper-airway injury
• Congenital anomalies of upper airway

Question 33

How is diagnosis of croup made?

Answer 33

Clinical diagnosis of croup is based on symptoms, specifically barking cough and stridor, and is more common during an epidemic. Radiographs and laboratory tests are not necessary to make the diagnosis. Viral culture of secretions from the nasopharynx or throat can be obtained if etiologic diagnosis is desired, antiviral therapy is indicated, or in patients being admitted, whether isolation is required.

Question 34

What is the treatment of croup?

Answer 34

• reassurance
• single dose of PO or IM dex 0.6mg/kg (max dose 10mg)
• nebulized epinephrine for rapid clinical improvement
• exposure to cold air and humidified air mist therapy have mixed results