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SOURCE

Source: Blackford MG, Glover ML, Reed MD. Lower respiratory tract infections. In: DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM, eds. Pharmacotherapy: A Pathophysiologic Approach. 10th ed. New York, NY: McGraw-Hill; 2017. http://accesspharmacy.mhmedical.com/content.aspx?bookid=1861&sectionid=146071234. Accessed July 12, 2012.

DEFINITION

  • Acute viral infection of lower respiratory tract of infants that affects ~50% of children during first year of life and 100% by 3 years.

ETIOLOGY

  • Most common cause: respiratory syncytial virus (RSV)

  • Other: parainfluenza viruses.

  • Bacteria are secondary pathogens in minority of cases.

PATHOPHYSIOLOGY

  • Viral or bacterial invasion of lung parenchyma.

EPIDEMIOLOGY

  • Occurrence peaks during winter months and persists through early spring.

  • Major reason for hospital admission during first year of life.

  • More common in males than females.

PREVENTION AND SCREENING

  • RSV prophylaxis in infants with underlying pulmonary or cardiovascular disease.

  • Monthly administration during RSV season.

    • RSV immune globulin.

    • Palivizumab.

RISK FACTORS

  • Age <1 year.

  • Male gender.

CLINICAL PRESENTATION

  • Prodrome suggesting an upper respiratory tract infection, usually lasting 2–8 days, precedes onset of clinical symptoms.

SIGNS AND SYMPTOMS

  • Prodrome with irritability, restlessness, and mild fever.

  • Cough.

  • Coryza.

  • Vomiting.

  • Diarrhea.

  • Noisy breathing.

  • Increase in respiratory rate.

  • Labored breathing with retractions of chest wall, nasal flaring, and grunting.

  • Dehydration.

DIAGNOSIS

MEANS OF CONFIRMATION AND DIAGNOSIS

  • History and physical exam.

    • Tachycardia and increased respiratory rate.

    • Wheezing and inspiratory rales.

    • Mild conjunctivitis in one-third of patients.

    • Otitis media in 5–10% of patients.

LABORATORY TESTS

  • Complete blood count (CBC): White blood cell (WBC) count normal or slightly elevated.

  • Arterial blood gases.

    • Hypoxemia.

    • Culture of respiratory secretions: Establishes presumptive diagnosis of infectious bronchiolitis.

IMAGING

  • Chest radiograph to distinguish between illnesses characterized by wheezing.

DIFFERENTIAL DIAGNOSIS

DESIRED OUTCOMES

  • Resolution of signs and symptoms.

TREATMENT: GENERAL APPROACH

  • Self-limiting illness usually requiring no therapy unless infant hypoxic or dehydrated.

TREATMENT: NONPHARMACOLOGIC THERAPY

  • Otherwise healthy infants:

    • Antipyretics.

    • Fluids.

  • Severe cases:

    • Oxygen therapy.

    • IV fluids.

TREATMENT: PHARMACOLOGIC THERAPY

  • Antibiotics not routinely administered, but may be used until culture results available.

  • Ribavirin if caused by RSV in patients with underlying pulmonary or cardiac disease, or with severe acute infection.

TREATMENT: SPECIAL CONSIDERATIONS

  • Infants with underlying pulmonary or cardiovascular disease.

    • RSV prophylaxis.

      • Monthly administration during RSV ...

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