Croup: What It Is and How to Treat It

US Pharm. 2013;38(7):47-50.

ABSTRACT: Croup results from a narrowing of the subglottic airway secondary to inflammation associated with certain viral respiratory tract infections and is represented by the sudden onset of a barking cough. Croup is an acute or chronic disease associated with very young children. Treatment consists of corticosteroids and sometimes nebulized racemic epinephrine, depending upon the severity of symptoms. OTC medications, including cough suppressants, offer no relief from the symptoms of croup. The role of the pharmacist lies in triaging patients with croup to a higher level of care and discouraging the use of OTC medications that provide no benefit.

The mention of croup may evoke images of a crying child with a cough like the bark of a seal or of a mother pacing inside a steamy bathroom with a “barking” infant in her arms. Certainly, the abrupt onset, nighttime worsening, and severity of symptoms can be quite frightening for parents, who may seek advice from their trusted pharmacist. This article seeks to bring these images into focus with a clear understanding of what croup is and how it is treated, including recommendations that the community pharmacist may have for children with croup.

Clinical Features and Diagnosis

Croup is a nonspecific term denoting a respiratory tract infection that causes inflammation and narrowing of the larynx and trachea.¹ The formal term for croup is laryngotracheitis. In this condition, the narrowing of the subglottic space causes the trademark barklike cough. Croup may be either acute or chronic. Some children may experience recurrent episodes of croup, a condition known as spasmodic or allergic croup. This type of croup is thought to be associated with reflux or with an allergen. For the purposes of this article, the word “croup” will refer to the viral form.

One of the most common respiratory diseases in children, croup typically occurs between the ages of 6 months and 3 years, with a peak in the second year of life.² It is believed that croup does not manifest in older children because of the increase in airway diameter as children grow.

Croup is diagnosed primarily by its rapid onset and its characteristic barking cough.³ Other symptoms of croup include hoarseness and inspiratory stridor. The cough associated with croup is nonproductive.

No laboratory tests or cultures are required for the diagnosis of croup.³ Some physicians may order radiographs; however, these are not necessary for diagnosis, and they incur costs for the patient’s family and cause unnecessary radiation exposure in the patient. Furthermore, any unnecessary testing of the child may lead to increased agitation and crying, which will then worsen symptoms.¹ Keeping the child calm and comfortable is more beneficial than the anticipated yield of any diagnostic test.

Differential Diagnosis

Since foreign-body obstruction of the airway can mimic the symptoms of croup, aspiration of a foreign body must be ruled out before a diagnosis of croup can be made.^1-3 Generally, an interview with the child’s parents or caregivers can help rule out this diagnosis. Epiglottitis—a medical emergency—also must be considered in children presenting with signs and symptoms of croup. Epiglottitis is distinguished from croup by high fever and toxic appearance of the child.¹ Children with epiglottitis will have a sore throat and often will drool and sit or lean forward.³ These symptoms warrant urgent medical attention. Of note, the incidence of epiglottitis has markedly diminished since the development of the Haemophilus influenzae vaccine.¹

Bacterial tracheitis also must be eliminated as a potential diagnosis.^1-3 This disorder usually presents as an abrupt deterioration following a moderate illness. Unlike croup, bacterial tracheitis does not respond to racemic epinephrine and instead requires treatment with antibiotics.

Pathophysiology and Epidemiology

Historically, croup has been associated with diphtheria and rubella infections.² Since the development of diphtheria and rubella vaccinations, these causes of croup have all but faded into history in the United States. In nonimmunized children, these organisms may still need to be considered as potential pathogens.

The most common causes of croup today are the parainfluenza viruses; therefore, clinicians should expect a rise in cases during peak months of parainfluenza activity.^1-3 In North America, this peak occurs in late autumn. Owing to the increased prevalence of parainfluenza type 1 in odd-numbered years, the incidence of croup is 50% greater during those years than in even-numbered years.¹ Although respiratory syncytial virus also is common in young children, it rarely causes croup. Rhinovirus coinfection is common. Other viruses associated with croup are listed in TABLE 1.¹

Treatment

In the early 19th century, treatments for croup included bleeding of patients and the use of leeches.⁴ Tracheotomy also was performed in the years before a method of endotracheal intubation was developed. Given the advent of current treatment, intubation is rarely required in the management of croup.

Croup treatment is based upon disease severity.¹ Croup can be mild in nature and may even resolve without medical attention; however, if left untreated, severe cases can eventually lead to respiratory failure. With proper treatment, even the most severe cases of croup rarely result in hospitalization.

Although many scoring systems for croup have been studied, the most familiar one is the Westley Croup Score.⁵ Used more for research than for clinical purposes, the Westley Croup Score assigns points based on the severity of croup symptoms. A score of 2 or less is designated mild disease. A score of 3 to 7 constitutes moderate croup. A score of 8 or more is considered severe croup, with a score above 12 indicating a risk of imminent respiratory failure. The Westley Croup Score appears in TABLE 2, and TABLE 3 describes the gradations of croup severity and corresponding treatment recommendations.^1,5

Corticosteroids: Corticosteroids are the mainstay of treatment for croup and are indicated for all severity levels.² The anti-inflammatory properties of corticosteroids are thought to decrease the degree of inflammation and swelling in the airway.⁶ This results in easier breathing for the patient.

Children with mild cases of croup are half as likely to return for medical care if they are treated with corticosteroids.² Children who have severe croup with threatened respiratory failure are five times less likely to need intubation if they are treated with corticosteroids.²

Considerations in the use of corticosteroids include route of administration, selection of steroid, and dosing. Intramuscular administration and oral administration are acceptable for the treatment of croup.² Both routes of administration have been demonstrated to be superior to inhaled steroids for this indication. Oral administration offers the advantage of ease of use without the discomfort of an injection. The intramuscular form is preferable for children who are unable to tolerate an oral dose because of vomiting or other gastrointestinal symptoms.

Dexamethasone is considered the glucocorticoid of choice, although some physicians still successfully treat patients with prednisolone.³ Advantages of dexamethasone include fivefold to sixfold greater anti-inflammatory activity compared with prednisolone, and a longer half-life. With a half-life of 36 to 72 hours and a speculated duration of anti-inflammatory activity of 2 to 4 days, one dose of dexamethasone will cover the 72-hour period during which most croup symptoms persist.⁷

The generally accepted dosage of dexamethasone for the management of croup is 0.6 mg/kg administered as a single dose.⁷ Dosages of 0.15 mg/kg and 0.3 mg/kg appear to be sufficient for most cases of croup. There is some evidence that the 0.6-mg/kg dosage may be necessary for the treatment of severe croup.³

An improvement in croup symptoms following corticosteroid administration is anticipated to occur within 4 to 6 hours.² Although there is the potential for numerous adverse effects, corticosteroids are generally considered safe for the treatment of croup.

Racemic Epinephrine: The use of nebulized racemic epinephrine has been demonstrated to improve symptoms of croup within 10 to 15 minutes of administration.² By dilating the airway, racemic epinephrine greatly reduces the need for intubation or tracheotomy in severe cases of croup. The recommended dosage of racemic epinephrine 2.25% is 0.05 mL/kg (maximum dose = 0.5 mL).³ The most common adverse events associated with racemic epinephrine are tachycardia and pallor.

The effects of racemic epinephrine do not last long; the treatment is expected to provide relief for no more than 2 hours. Fortunately, when they return, the symptoms are no worse—or may even be better—than they were prior to treatment. The quick onset of symptom relief with racemic epinephrine and the later onset of symptom relief with corticosteroids render a combination approach appealing.³

Antibiotics: Since the causative organism in croup is always viral, antibiotics are generally not warranted. Children may present with bacterial superinfections such as pharyngitis or pneumonia, which do require antibiotic treatment. Since cases of superinfection are rare, antibiotic prophylaxis is not indicated.²

Antipyretics/Analgesics: Antipyretics/analgesics may help make the child more comfortable if he or she has fever or discomfort associated with the viral infection; however, these agents will provide no relief from the croup itself. If the use of such an agent is necessary, acetaminophen is preferable, at a dosage of 15 mg/kg every 4 hours as needed and not to exceed five doses in 24 hours.⁸

Cough Suppressants: Cough suppressants are not effective against croup. These products should not be recommended for the treatment of croup.²

Humidity: For years, humidity was considered a mainstay of therapy for croup. Clinical trials have demonstrated no benefit to this practice, and it is no longer recommended.^2,3 In fact, equipment that increases humidity can have potentially harmful effects (e.g., scald injuries from hot humidified air, or dispersal of mold from mist tents or humidifiers that have not been properly cleaned). In addition, the use of humidity often comes at the expense of the child’s comfort, since the process by which humidity is applied may keep the child from his or her parents’ arms or his or her bed. The pharmacist should actively discourage the use of such equipment for the relief of croup.

Heliox: Heliox, a mixture of helium and oxygen, has practical limitations to its use. This agent cannot be recommended for the general treatment of croup.³

Conclusion

The role of the pharmacist in the treatment of croup is multifactorial. First, it is essential to recognize croup and to refer the patient for medical treatment. Additionally, an understanding of the importance of corticosteroid treatment in improving croup and an awareness of the futility of cough suppressants and humidity therapy in treating this condition can potentially lead to a speedier recovery for the patient.

REFERENCES

1. Hall CB, McBride JT. Acute laryngotracheobronchitis (croup). In: Mandell GL, Bennett JE, Dolin R, eds. Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, PA: Elsevier; 2010:825-829.
2. Bjornson CL, Johnson DW. Croup. Lancet. 2008;371:329-339.
3. Zoorob R, Sidani M, Murray J. Croup: an overview. Am Fam Physician. 2011;83:1067-1073.
4. Stool SE. Croup syndrome: historical perspective. Pediatr Infect Dis J. 1988;7(suppl 11):S157-S161.
5. Pitluk JD, Uman H, Safranek S. What’s best for croup? J Fam Pract. 2011;60:680-681.
6. Russell KF, Liang Y, O’Gorman K, et al. Glucocorticoids for croup. Cochrane Database Syst Rev. 2011;(1):CD001955.
7. Sparrow A, Geelhoed G. Prednisolone versus dexamethasone in croup: a randomised equivalence trial. Arch Dis Child. 2006;91:580-583.
8. Taketomo CK, Hodding JH, Kraus DM. Pediatric & Neonatal Dosage Handbook. 18th ed. Hudson, OH: Lexicomp; 2012.

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