AUTHOR INFORMATION

Section 1 of 12

Authored by Lonnie King, MD, Consulting Staff, Department of Emergency Medicine, Children's Healthcare of Atlanta at Scottish Rite

Lonnie King, MD, is a member of the following medical societies: Alpha Omega Alpha, American Academy of Emergency Medicine, American Academy of Pediatrics, and American College of Emergency Physicians

Edited by Jerry Balentine, DO, Professor of Emergency Medicine, New York College of Osteopathic Medicine; Medical Director, Saint Barnabas Hospital; Robert Konop, PharmD, Director, Clinical Account Management, Ancillary Care Management, Inc; Wayne Wolfram, MD, MPH, Clinical Associate Professor, Departments of Pediatrics, Children's Hospital and University of Cincinnati; John Halamka, MD, Chief Information Officer, CareGroup Healthcare System, Assistant Professor of Medicine, Department of Emergency Medicine, Beth Israel Deaconess Medical Center; Assistant Professor of Medicine, Harvard Medical School; and Richard G Bachur, MD, Assistant Professor of Pediatrics, Harvard Medical School; Associate Chief and Fellowship Director, Division of Emergency Medicine, Children's Hospital of Boston

Author's Email:	Lonnie King, MD
Editor's Email:	Jerry Balentine, DO

eMedicine Journal, July 27 2006, VOLUME 7, Number 7

INTRODUCTION

Section 2 of 12

Background: Laryngotracheobronchitis (ie, croup) is a viral infection of the upper respiratory tract that causes varying degrees of airway obstruction.

The disease is most often self-limited, but it occasionally is severe and, rarely, fatal. A barking cough, stridor, and fever are characteristic, and it is the most common cause of stridor in children. With aggressive ED treatment, very few cases require admission.

Pathophysiology: This is a disease that mainly affects children. A prodrome of several days of fever and symptoms of mild upper respiratory infection are common.

As the infection extends to the proximal trachea, diffuse inflammation with exudate and edema of the subglottic area causes narrowing of the airway. The cricoid ring of the trachea (in the immediate subglottic area) is the narrowest portion of the airway in a child. A small amount of edema in this region can cause significant airway obstruction. (Remember that the resistance to flow through a tube is inversely proportional to the fourth power of the radius.) Air flowing through this narrowed subglottic area causes stridor. The uncomplicated disease usually wanes in 3-5 days but may persist for as many as 10 days.

Frequency:

• In the US: Laryngotracheobronchitis has a peak incidence of 5 cases per 100 children per year during the second year of life. It is the most common form of airway obstruction or stridor in children aged 6 months to 6 years.

Mortality/Morbidity: The vast majority of children with croup do well. Morbidity is unusual, and mortality is rare.

Sex: Prevalence is higher in males than in females, with a male-to-female ratio of nearly 2:1.

Age: Illness is most common in children aged 3 months to 3 years.

• The mean age of onset is 18 months.

• Laryngotracheobronchitis is uncommon in persons older than 6 years.

CLINICAL

Section 3 of 12

History:

• The patient usually has a few days of a mild upper respiratory illness with low-grade fever, runny nose, and mild cough.

• Typically, between 6 pm and 6 am, the child develops stridor (mainly inspiratory), hoarseness, and a brassy seal-like barking cough.

• Parents may report worsening symptoms on the second night of the illness.

• The child is fatigued.

Physical: The physical examination may range from totally unremarkable on presentation to severe respiratory distress.

• Restless (common); prefers sitting upright in a parent's lap

• Appears nontoxic (common)

• Normal voice or laryngitis

• Mild fever

• Tachycardia

• Tachypnea

• Varying stridor, predominantly inspiratory

• Absence of drooling

• Retractions of the accessory chest muscles

• No change in stridor with positioning

• Nontender larynx

• Worsening disease and possible impending respiratory failure may be indicated by the following:

• Change in mental status (eg, fatigue, listlessness, restlessness)

• Increased retractions

• Decreased breath sounds with decreasing stridor

• Pallor

• Cyanosis

Causes: Croup is most commonly caused by parainfluenza type 1, although parainfluenza type 2 and type 3 also may cause disease. Other etiologies are as follows:

• Paramyxovirus

• Influenza virus type A

• Respiratory syncytial virus (RSV)

• Adenovirus

• Rhinovirus

• Enterovirus

• Coxsackievirus

• Enteric cytopathogenic human orphan virus (ECHO virus)

• Reovirus

• Measles virus

DIFFERENTIALS

Section 4 of 12

Diphtheria
Foreign Bodies, Gastrointestinal
Foreign Bodies, Trachea
Pediatrics, Epiglottitis
Pediatrics, Foreign Body Ingestion

Other Problems to be Considered:

Subglottic stenosis
Retropharyngeal abscess
Subglottic hemangioma

WORKUP

Section 5 of 12

Lab Studies:

• Laboratory testing usually is not needed in well-hydrated patients.

• If laboratory tests are needed, they should be deferred while the patient is in distress.

• Approximately 80% of admitted patients are hypoxic.

• A pulse oximetry measurement is indicated in all but the mildest cases.

• In the usual case, hypoxia is caused by pulmonary involvement.

• With severe airway obstruction, respiratory failure may occur.

• Complete blood count

• Leukopenia in early stage of illness

• Leukocytosis in later stage of patients with severe disease

Imaging Studies:

• Imaging tests are not required in mild cases with typical history that respond appropriately to treatment.

• An anteroposterior (AP) soft tissue neck x-ray may show subglottic narrowing.

• The usual squared-shoulder appearance of the subglottic area is replaced by cone shaped narrowing just distal to the vocal cords. This is called the steeple or pencil-point sign.

• Monitor patients during imaging because progression of airway obstruction may be rapid.

Other Tests:

• Rapid antigen tests are available in some centers but usually are not needed.

Procedures:

• Direct laryngoscopy if the child in not in acute distress

• Fiberoptic laryngoscopy

• Bronchoscopy

TREATMENT

Section 6 of 12

Prehospital Care:

• Try to avoid actions that may agitate the child in distress and increase the work of breathing.

• Transport the child in a parent's lap and give oxygen as tolerated, usually via a "blow by" technique.

Emergency Department Care: Goals of emergency department care are to reduce any respiratory distress, monitor for worsening condition, and consider, or evaluate for, other etiologies of stridor.

• Make the child as comfortable as possible.

• Avoid agitating the child with unnecessary procedures and examinations.

• Humidified air or mist therapy may be used, but both have unproven efficacy.

• Provide oxygen (humidified) to all hypoxic patients.

• L-epinephrine (1:1000) is as effective as racemic epinephrine. Epinephrine therapy does not indicate the need for admission.

• Dexamethasone has been shown to reduce symptoms in patients with moderate-to-severe croup. (0.6 mg/kg IM, not to exceed 10 mg)

• Nebulized budesonide (2 mg) has been shown in several studies to be equivalent to oral dexamethasone. Inhaled Decadron also is used when budesonide is unavailable.

Consultations: Consultation with ORL and anesthesia prior to RSI may be necessary if patient is exhibiting rapid deterioration that might suggest an alternative diagnosis.

MEDICATION

Section 7 of 12

The goal of pharmacotherapy is to reduce morbidity and prevent complications.

Drug Category: Adrenergic agonist -- Alpha-agonist effects include increased peripheral vascular resistance, reversed peripheral vasodilatation, systemic hypotension, and vascular permeability. Beta-agonist effects include bronchodilatation, chronotropic cardiac activity, and positive inotropic effects.

Drug Name	Epinephrine (Adrenaline) -- Inhalation of racemic epinephrine is the cornerstone of symptomatic relief during exacerbations of croup. Alpha-receptor stimulation causes mucosal vasoconstriction, leading to decreased edema of the subglottic region of the larynx. Beta2-receptor stimulation may provide additional benefit by causing bronchial smooth muscle relaxation.
Pediatric Dose	Nebulizer: 0.25-0.5 mL of 2.25% solution diluted in 3 mL of isotonic sodium chloride solution or sterile water; may be repeated 3 times
Contraindications	Documented hypersensitivity; cardiac arrhythmias, obstructed ventricular outflow, or angle-closure glaucoma; local anesthesia in areas such as fingers or toes because vasoconstriction may produce sloughing of tissue; do not use during labor (may delay second stage of labor)
Interactions	Increases toxicity of beta- and alpha-blocking agents and that of halogenated inhalational anesthetics
Pregnancy	C - Safety for use during pregnancy has not been established.
Precautions	Caution or discontinue if heart rate >200; short duration of action and relapse may occur; caution in elderly persons, prostatic hypertrophy, hypertension, cardiovascular disease, patients with diabetes mellitus, hyperthyroidism, and cerebrovascular insufficiency; rapid IV infusions may cause death from cerebrovascular hemorrhage or cardiac arrhythmias

Drug Category: Corticosteroids -- Steroids are used to decrease subglottic edema by suppressing local inflammatory process. The effectiveness of steroids in croup has been much debated, and, although no clear-cut information proves that steroids are beneficial, meta-analysis has shown that they decrease symptoms within 24 hours and may reduce the need for endotracheal intubations.

Drug Name	Dexamethasone (Decadron) -- DOC. Decreases inflammation by suppressing migration of polymorphonuclear leukocytes and reducing capillary permeability.
Pediatric Dose	0.6 mg/kg PO/IM once; some repeat the dose in 6 h
Contraindications	Documented hypersensitivity; active bacterial or fungal infection
Interactions	Effects decrease with coadministration of barbiturates, phenytoin, and rifampin; decreases effect of salicylates and vaccines used for immunization
Pregnancy	C - Safety for use during pregnancy has not been established.
Precautions	Increases risk of multiple complications, including severe infections; monitor adrenal insufficiency when tapering drug; abrupt discontinuation of glucocorticoids may cause adrenal crisis; hyperglycemia, edema, osteonecrosis, myopathy, peptic ulcer disease, hypokalemia, osteoporosis, euphoria, psychosis, myasthenia gravis, growth suppression, and infections are possible complications of glucocorticoid use

Drug Name	Prednisone (Deltasone) -- May decrease inflammation by reversing increased capillary permeability and suppressing PMN activity.
Pediatric Dose	Prednisone in equivalent doses may be substituted if given over 5 d
Contraindications	Documented hypersensitivity; viral infection, peptic ulcer disease, hepatic dysfunction, connective tissue infections, and fungal or tubercular skin infections; GI disease
Interactions	Coadministration with estrogens may decrease clearance; concurrent use with digoxin, may cause digitalis toxicity secondary to hypokalemia; phenobarbital, phenytoin, and rifampin may increase metabolism of glucocorticoids (consider increasing maintenance dose); monitor for hypokalemia with coadministration of diuretics
Pregnancy	B - Usually safe but benefits must outweigh the risks.
Precautions	Abrupt discontinuation of glucocorticoids may cause adrenal crisis; hyperglycemia, edema, osteonecrosis, myopathy, peptic ulcer disease, hypokalemia, osteoporosis, euphoria, psychosis, myasthenia gravis, growth suppression, and infections may occur with glucocorticoid use

Drug Name	Budesonide (Pulmicort Turbuhaler) -- Has been shown in several studies to be equivalent to oral dexamethasone.
Pediatric Dose	2 mg (2 mL) of solution via nebulizer
Contraindications	Documented hypersensitivity; active bacterial or fungal infection
Interactions	None reported
Pregnancy	C - Safety for use during pregnancy has not been established.
Precautions	Prolonged use may increase systemic absorption of corticosteroids and may cause Cushing syndrome, reversible HPA axis suppression, hyperglycemia, and glycosuria

FOLLOW-UP

Section 8 of 12

Further Inpatient Care:

• Perform frequent or continuous monitoring of respiratory status.

• Obtain a continuous pulse oximetry measurement.

• Provide a humidified environment, which may include use of the following:

• Mist therapy

• A croup tent (still used but generally not recommended unless no alternative therapy is available)

• A vaporizer at bedside

• Give intravenous fluids to dehydrated children not tolerating oral fluids.

Further Outpatient Care:

• Parents must provide a humidified environment at night, which may include use of the following:

• A cool mist vaporizer

• A steamed bathroom environment, which may relieve mild exacerbation

• Exposure to cool night air, which may relieve mild exacerbation, especially if a spasmodic component is present

• Tobacco smoke and other irritants should not be allowed to come in contact with the child.

In/Out Patient Meds:

• Inhalation of racemic epinephrine is the cornerstone of symptomatic relief during exacerbations of croup.

• Some authorities recommend a repeat dose of dexamethasone in 6 hours.

Complications:

• Intubation (required in as many as 2% of patients)

• Subglottic stenosis in intubated patients

• Bacterial tracheitis

• Cardiopulmonary arrest

• Pneumonia

Prognosis:

• Recovery is usually complete.

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 12

Medical/Legal Pitfalls:

• Rebound stridor after epinephrine therapy has been described, but it appears to be less of a problem if corticosteroid therapy is initiated early in the ED course.

• Failure to treat patients with steroids can be a pitfall.

• Always consider other causes of stridor, such as foreign bodies, bacterial tracheitis, and epiglottitis.

• Failure to observe patients for an adequate period before ED discharge and failure to document satisfactory pulse oximetry.

TEST QUESTIONS

Section 10 of 12

CME Question 1: A 2-year-old boy presents with a 2-day history of upper respiratory infection (URI) symptoms and 2 hours of stridor. He is experiencing mild respiratory distress. Which of the following is the most common etiology for his stridor?

A: Streptococcus pyogenes
B: Mycoplasma pneumoniae
C: Parainfluenza type 1
D: Respiratory syncytial virus (RSV)
E: None of the above

The correct answer is C: Parainfluenza type 1 virus is the most common cause of croup, which is the most common cause of stridor in children of this age group.

CME Question 2: A child presents to the ED with severe and prolonged stridor. Respiratory therapy is occupied in a code elsewhere and cannot respond. Racemic epinephrine is not available to you. Which of the following is the most appropriate action?

A: Call anesthesia to perform emergent intubation.
B: Give 0.6 mg/kg of intramuscular dexamethasone.
C: Intubate the patient.
D: Give 5 mL of nebulized epinephrine.
E: Provide a cool mist and oxygen, if tolerated.

The correct answer is D: Inhalation of racemic epinephrine is the cornerstone of symptomatic relief during exacerbations of croup; however, plain epinephrine may be substituted for racemic epinephrine if unavailable.

Pearl Question 1 (T/F): A lateral neck radiograph is indicated in the initial diagnosis of croup.

The correct answer is False: Rarely, if ever, does the lateral neck x-ray influence the management of typical croup. An anteroposterior AP x-ray often may show a steeple sign of laryngeal narrowing consistent with croup, but it still is unlikely to change management in the ED. A lateral neck is helpful if concerned for early epiglottitis, foreign body, or retropharyngeal abscess.

Pearl Question 2 (T/F): Croup is the most common form of airway obstruction in children aged 6 months to 6 years.

The correct answer is True: It has a peak incidence of 5 cases per 100 children per year during the second year of life.

Pearl Question 3 (T/F): Haemophilus influenzae is the most common cause of croup.

The correct answer is False: Parainfluenza type 1 is the most common cause, although parainfluenza type 2 and 3 also may cause disease.

Pearl Question 4 (T/F): A steeple sign is usually a normal x-ray finding.

The correct answer is False: This finding is a cone shaped narrowing of the trachea in the subglottic area observed in the anteroposterior (AP) neck radiograph and is quite specific for croup.

PICTURES

Section 11 of 12

Caption: Picture 1. Child with croup. Note the steeple or pencil sign of the proximal trachea evident on this anteroposterior film. Courtesy of Dr. Kelly Marshall, CHOA at Scottish Rite.
	View Full Size Image
	eMedicine Zoom View (Interactive!)
Picture Type: X-RAY

BIBLIOGRAPHY

Section 12 of 12

• Bjornson CL, Klassen TP, Williamson J, et al: A randomized trial of a single dose of oral dexamethasone for mild croup. N Engl J Med 2004 Sep 23; 351(13): 1306-13[Medline].
• Connors K, Gavula D, Terndrup T: The use of corticosteroids in croup: a survey. Pediatr Emerg Care 1994 Aug; 10(4): 197-9[Medline].
• Dawson KP, Steinberg A, Capaldi N: The lateral radiograph of neck in laryngo-tracheo-bronchitis (croup). J Qual Clin Pract 1994 Mar; 14(1): 39-43[Medline].
• Eitzen EM: Croup, epiglottis, and bacterial tracheitis. In: Rosen ed. Emergency Medicine: Concepts and Clinical Practice. 4th ed. 1998:1123.
• Geelhoed GC, Macdonald WB: Oral and inhaled steroids in croup: a randomized, placebo-controlled trial. Pediatr Pulmonol 1995 Dec; 20(6): 355-61[Medline].
• Geelhoed GC, Macdonald WB: Oral dexamethasone in the treatment of croup: 0.15 mg/kg versus 0.3 mg/kg versus 0.6 mg/kg. Pediatr Pulmonol 1995 Dec; 20(6): 362-8[Medline].
• Johnson DW, Schuh S, Koren G, Jaffee DM: Outpatient treatment of croup with nebulized dexamethasone. Arch Pediatr Adolesc Med 1996 Apr; 150(4): 349-55[Medline].
• Kelley PB, Simon JE: Racemic epinephrine use in croup and disposition. Am J Emerg Med 1992 May; 10(3): 181-3[Medline].
• Klassen TP, Rowe PC: Outpatient management of croup. Curr Opin Pediatr 1996 Oct; 8(5): 449-52[Medline].
• Kunkel NC, Baker MD: Use of racemic epinephrine, dexamethasone, and mist in the outpatient management of croup. Pediatr Emerg Care 1996 Jun; 12(3): 156-9[Medline].
• Leung AK, Kellner JD, Johnson DW: Viral croup: a current perspective. J Pediatr Health Care 2004 Nov-Dec; 18(6): 297-301[Medline].
• Orenstein DM: Acute inflammatory upper airway obstruction. In: Behman ed. Nelson Textbook of Pediatrics. 15th ed. 1996:1201.
• Rittichier KK, Ledwith CA: Outpatient treatment of moderate croup with dexamethasone: intramuscular versus oral dosing. Pediatrics 2000 Dec; 106(6): 1344-8[Medline].

eMedicine Journals > Emergency Medicine > Pediatric > Pediatrics, Croup or Laryngotracheobronchitis

Please email us with any comments you have on our new chapter format.

Author Information | Introduction | Clinical | Differentials | Workup | Treatment | Medication | Follow-up | Miscellaneous | Test Questions | Pictures | Bibliography