AUTHOR AND EDITOR INFORMATION

Section 1 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

INTRODUCTION

Section 2 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Background

Human parainfluenza viruses (PIVs) account for a large percentage of pediatric respiratory infections, including upper respiratory tract infections (URTIs), laryngotracheobronchitis (croup), bronchiolitis, and pneumonia. Human PIV is the major cause of croup (type 1 is most frequent, followed by type 3 and type 2). Human PIVs are divided into 4 types, all of which are classified as paramyxoviruses. Infections from types 1 and 3 account for most disease.

Pathophysiology

The virus colonizes the nose and the nasopharynx; then, it invades the epithelium, resulting in cell damage, edema, and loss of cilia. A fibrinous exudate develops with downward spread of cell damage and edema. The resulting airway obstruction and laryngeal muscle spasm account for the typical symptoms of croup. The incubation period is 1-7 days.

Frequency

United States

Outbreaks of parainfluenza disease occur regularly throughout fall and mid winter. Parainfluenza virus type 1 causes biennial epidemics in the United States.

Mortality/Morbidity

• Most children with croup have mild infections that are usually managed on an outpatient basis.
• Approximately 41,000 individuals per year are admitted to the hospital for PIV infections. Only 1-5% of patients admitted to the hospital need artificial airway support.

Age

• Parainfluenza-related laryngotracheobronchitis commonly affects children aged 3 months to 3 years.
• PIV infection can also account for bronchiolitis in infants and children younger than 2 years.

CLINICAL

Section 3 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

History

• Patients typically present with a history of coryza and low-grade fever. They then develop the classic barking cough associated with croup.
• Symptoms of croup include the following:
• • Fever
  • Barking cough
  • Coryza
  • Stridor
  • Retractions
  • Tachypnea (when lower airways become involved)
  • Irritability
• Children with croup are usually more symptomatic at night. Coughing often awakens them from sleep. The reasons for worsening of symptoms at night are unknown.
• Parainfluenza infections can also present as bronchiolitis. The typical presentation includes fever, coryza, tachypnea, coughing, and wheezing.

Physical

• Croup scoring systems have been developed to aid in grading the severity of infection.
• Factors in such scoring systems include stridor, retractions, air entry, color, and level of consciousness.
• Croup scoring systems were developed prior to the advent of pulse oximetry. Pulse oximetry may be beneficial in grading severity of illness, response to management, and disposition.

DIFFERENTIALS

Section 4 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Other Problems to be Considered

Tracheitis
Pneumonia

WORKUP

Section 5 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Lab Studies

• Viral cultures usually require 4-7 days to yield results, which limits their clinical applicability in the acute setting. Cultures can be helpful from an epidemiological standpoint.
• Immunofluorescent and enzyme immunoassay methods can be performed to test nasopharyngeal washings; however, they are not readily available and vary in sensitivity.
• The WBC count on CBC count samples is usually normal; however, lymphocytosis may be noted.

Imaging Studies

• Posteroanterior (PA) radiography of the neck may reveal the classic steeple sign (ie, narrowing of the proximal portion of the trachea, indicative of subglottic edema); however, this finding is absent in approximately 50% of cases.
• Lateral soft tissue films of the neck are normal in most cases. Lateral neck films can be useful if the diagnosis is unclear, especially if conditions such as foreign body aspiration, retropharyngeal abscess, or epiglottitis are in the differential diagnosis.

TREATMENT

Section 6 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical Care

Management of croup depends on the severity of disease.

• Prehospital care
• • Prehospital care includes fever control and attempts to alleviate respiratory symptoms and patient anxiety.
  • Respiratory symptoms commonly improve with benign measures such as sitting in a bathroom with a steaming shower and allowing vapor droplets to soothe inflamed airways. Another option includes exposing the child to the cool night air. Often, the patient's symptoms resolve en route to the hospital. Attempts at calming or distracting the child can be beneficial.
  • Antipyretics may assist with fever control. Moderate or severe croup requires medical evaluation in the office or emergency department.
• Emergency department care
• • Mild croup: Management of mild croup consists of cool blow-by oxygen mist, fever control, and observation to determine whether the airway appears compromised.
  • Moderate croup
  • • Cool oxygen mist and steroids are common therapies. Controlled trials for the palliation of croup symptoms have yielded conflicting results, and routine use of dexamethasone in this disease remains controversial. Dexamethasone was traditionally intramuscularly administered; however, recent studies have documented the use of oral steroids.
    • In patients who fail to improve, administration of racemic epinephrine with a nebulizer has been beneficial. If racemic epinephrine alleviates symptoms, observe the patient for a minimum of 3 hours to ensure the patient's condition does not worsen (eg, due to possible rebound laryngospasm as the racemic epinephrine dose wears off). If asymptomatic at this time, the patient can be discharged with proper follow-up care.
    • In patients with moderate croup, oral intake may be lacking; therefore, evaluate the patient's hydration status. Intravenous fluids may be required.
  • Severe croup
  • • Perform the same measures as in moderate croup. Observe for signs of impending respiratory failure.
    • Repeat racemic epinephrine nebulization may be needed, in addition to intensive care monitoring. Racemic epinephrine nebulizations can be repeated at 1- to 2-hour intervals as needed. Fortunately, fewer than 5% of patients who are admitted require artificial airway support (endotracheal intubation).

MEDICATION

Section 7 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

No specific antiviral agents are available for treating parainfluenza virus (PIV) infections; however, medications are available to treat the respiratory symptoms associated with croup. The medications include corticosteroids and nebulized epinephrine to treat airway inflammation and edema.

Drug Category: Glucocorticoids

These agents have anti-inflammatory properties and cause profound and varied metabolic effects. They modify the body's immune response to diverse stimuli. Anti-inflammatory drugs (specifically dexamethasone) help reduce the inflammation and subglottic edema of croup. Despite delayed onset of action, the high potency and prolonged intramuscular half-life of dexamethasone make it the preferred corticosteroid for croup.

Drug Category: Bronchodilators

When delivered by air or oxygen-powered devices, epinephrine is directly delivered to respiratory mucosal surfaces and smooth muscle. Because nebulizers deliver the medication directly to the target organ, fewer systemic adverse effects are encountered in comparison with oral or parenteral administration.

FOLLOW-UP

Section 8 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Further Inpatient Care

Indications for hospitalization include the following:

• Stridor or retractions present at rest despite therapy
• Need for repeated doses of racemic epinephrine
• Rebound laryngospasm in patients who receive racemic epinephrine
• Signs of respiratory distress
• Inadequate oral intake or dehydration

Further Outpatient Care

• Use cool mist vaporizers.
• Administer acetaminophen or ibuprofen for fever.
• Increase oral fluid intake.

Deterrence/Prevention

No vaccine is currently available for parainfluenza virus (PIV). Passively acquired maternal antibodies from breast feeding may be protective in the first few months of life. Handwashing and contact precautions can limit the spread of disease to others.

Complications

Posttransplant PIV is a cause of serious lower respiratory tract involvement in both adults and children who undergo bone marrow transplantation. Long-term ribavirin therapy has been helpful in case reports.¹

Prognosis

• Patients with parainfluenza infections generally do well, with resolution of symptoms in 7-10 days.
• On occasion, the infection spreads to the lower respiratory tract, causing bronchiolitis or viral pneumonia.
• Denudation of respiratory epithelium places patients at a slightly increased risk of bacterial superinfection. Evaluate any patient recovering from croup who deteriorates suddenly for possible bacterial tracheitis.

Patient Education

• For excellent patient education resources, visit eMedicine's Lung and Airway Center. Also, see eMedicine's patient education article Croup.

MISCELLANEOUS

Section 9 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical/Legal Pitfalls

• A common occurrence in pediatric emergency department charts concerns varied assessment of the patient. All notes on the chart (eg, triage, nursing, resident) should be examined. If the assessments differ from the physician's assessment, the physician should address said differences in his or her notes. At discharge, ensure that proper discharge instructions, both written and oral, are given to the patient.
• Document an examination at time of discharge. For example, "Patient is breathing comfortably, is alert, consolable, without tachypnea, stridor, or retractions." A pulse oximetry reading can also be included if available.
• If the patient has a pediatrician or other primary care provider, attempt to contact them to ensure proper follow-up care. The pediatrician can also be consulted on management issues if the physician has concerns or doubts.
• For any concerns about stability for discharge, always err on the side of admission.

REFERENCES

Section 10 of 10

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

1. Stankova J, Carret AS, Moore D, et al. Long-term therapy with aerosolized ribavirin for parainfluenza 3 virus respiratory tract infection in an infant with severe combined immunodeficiency. Pediatr Transplant. Mar 2007;11(2):209-13. [Medline].
2. Barkin RM. Respiratory disorders. In: Pediatric Emergency Medicine Concepts Clinical Practice. 1993.
3. Cressman WR, Myer CM 3rd. Diagnosis and management of croup and epiglottitis. Pediatr Clin North Am. Apr 1994;41(2):265-76. [Medline].
4. Cruz MN, Stewart G, Rosenberg N. Use of dexamethasone in the outpatient management of acute laryngotracheitis. Pediatrics. Aug 1995;96(2 Pt 1):220-3. [Medline].
5. Custer JR. Croup and related disorders. Pediatr Rev. Jan 1993;14(1):19-29. [Medline].
6. Donaldson D, Poleski D, Knipple E, et al. Intramuscular versus oral dexamethasone for the treatment of moderate-to-severe croup: a randomized, double-blind trial. Acad Emerg Med. Jan 2003;10(1):16-21. [Medline].
7. Kairys SW, Olmstead EM, O'Connor GT. Steroid treatment of laryngotracheitis: a meta-analysis of the evidence from randomized trials. Pediatrics. May 1989;83(5):683-93. [Medline].
8. Klassen TP, Watters LK, Feldman ME, et al. The efficacy of nebulized budesonide in dexamethasone-treated outpatients with croup. Pediatrics. Apr 1996;97(4):463-6. [Medline].
9. Prendergast M, Jones JS, Hartman D. Racemic epinephrine in the treatment of laryngotracheitis: can we identify children for outpatient therapy?. Am J Emerg Med. Nov 1994;12(6):613-6. [Medline].
10. Rittichier KK, Ledwith CA. Outpatient treatment of moderate croup with dexamethasone: intramuscular versus oral dosing. Pediatrics. Dec 2000;106(6):1344-8. [Medline].
11. Rudy. Croup: Has management changed?. Contemp Pediatr. 1993;10:21-32.
12. Vega R. Rapid viral testing in the evaluation of the febrile infant and child. Curr Opin Pediatr. Jun 2005;17(3):363-7. [Medline].
13. Wendt CH, Weisdorf DJ, Jordan MC, Balfour HH Jr, Hertz MI. Parainfluenza virus respiratory infection after bone marrow transplantation. N Engl J Med. Apr 2 1992;326(14):921-6. [Medline].
14. Williams JV. The clinical presentation and outcomes of children infected with newly identified respiratory tract viruses. Infect Dis Clin North Am. Sep 2005;19(3):569-84. [Medline].

Article Last Updated: Sep 24, 2007