Croup: ED-focused Highlights
- Feb 15th, 2017
- James Costakis
Authors: James Costakis, MD (EM Resident Physician, UW/Harborview, Seattle, WA), Siobhan Thomas-Smith, MD (Pediatrics Resident Physician, Seattle Children’s Hospital, Seattle, WA), and Rebekah Burns, MD (Pediatric Emergency Attending Physician, Seattle Children’s Hospital, Seattle, WA) // Edited by: Alex Koyfman, MD (@EMHighAK, EM Attending Physician, UTSW / Parkland Memorial Hospital) and Brit Long, MD (@long_brit)
A 2-year-old boy presents with sudden onset of cough and difficulty breathing that woke him from sleep. Parents thought his breathing was labored and brought him to the ED. He has a history of reactive airway disease but has never been hospitalized.
Vitals in the ED:
Temperature 100F, heart rate 110, blood pressure 90/60, respiratory rate 30, oxygen saturation 98% on room air.
Exam is remarkable for a fatigued boy who refuses to speak. He has stridor at rest, tracheal tug, and moderate intercostal retractions. You do not appreciate wheezing on exam. He has a mild scattered erythematous rash on his chest and arms.
A 10-year-old boy presents with fever and vomiting. Parents report two days of fever up to 104F, associated with myalgias, nausea, and mild cough. Vomiting was prominent today, and parents are worried that he is dehydrated. For the past day, his voice has become slightly hoarse, and his breathing audible.
Vitals in the ED:
Temperature 103F, heart rate 120, blood pressure 110/70, respiratory rate 26, oxygen saturation 91% on room air.
Exam is remarkable for suprasternal and supraclavicular retractions, as well as audible stridor at rest.
Physiology of Croup
Croup is a spectrum of illness characterized by varying degrees of inflammation in the upper respiratory tract, with possible involvement of the lower respiratory tract. Patients may have laryngotracheitis, laryngotracheobronchitis, or laryngotracheobronchopneumonitis. In 75% of cases, parainfluenza virus is responsible . Otherwise, RSV, metapneumovirus, influenza, adenovirus, coronavirus, or even mycoplasma can cause a similar syndrome [6,8]. Some patients have recurrent bouts of upper airway edema causing a croup-like syndrome, which is referred to as spasmodic croup. This is thought to be potentially related to hypersensitivity to viral antigens.
Croup primarily affects children from 6 months to 3 years of age, with a peak incidence of 5% per year in 2-year-olds . Boys are 1.4 times more likely than girls to develop croup . Typically, it occurs in the late fall or early winter . Patients may or may not complain of a short prodromal upper respiratory infection. The acute phase of illness is characterized by stridor, barky cough, hoarseness, and sometimes fever. Symptoms often come on abruptly at night. Within 48 hours, most patients have recovered, but they may have lingering upper respiratory symptoms for about a week [4,9].
Diagnosis of Croup
Croup is diagnosed clinically. Chest X-ray and respiratory viral panel are sometimes used when one is considering an alternative diagnosis, but otherwise do not meaningfully affect the patient’s clinical course and are not recommended in uncomplicated croup .
The differential diagnosis of croup includes other causes of upper airway obstruction, gastroesophageal reflux, and allergic syndromes such as angioedema or spasmodic croup.
Other causes of upper airway obstruction include:
- Bacterial tracheitis
- Vascular rings
- Epiglottitis (unlikely if vaccinated)
- Foreign body aspiration
- Peritonsillar abscess
- Retropharyngeal abscess
- Tracheo-esophageal fistula
A high index of suspicion for these alternative diagnoses is critical, particularly in patients who are presumptively diagnosed with croup but fail to follow the expected clinical course. Some red flags include:
- Failure to respond to racemic epinephrine after 30 minutes
- Trouble handling secretions
- Oxygen requirement
How to Identify Sick Patients
Croup is common, accounting for 15% of ED visits by children with respiratory complaints and for 5% of ED admissions in children under 6 years of age [4,5]. Luckily, croup is usually a mild syndrome requiring minimal intervention – about 85% of children presenting to the ED have mild croup . Only 1 to 3% of children with croup are intubated, and even then the mortality rate of children intubated for croup is only 0.5% . Even so, early identification and aggressive treatment are critical in this subgroup of very sick children in order to maintain this low mortality rate.
How can we quickly identify patients who are in more severe respiratory distress? The Westley croup score has been around since the 1970’s and might help predict which patients need racemic epinephrine . The score stratifies patients based on level of consciousness, cyanosis, stridor, air entry, and retractions. However, the score is typically used in research studies to quantify the efficacy of an intervention, and it has not been prospectively validated to predict mortality, intubation, or hospital admission.
At Seattle Children’s Hospital, a child is considered to have “severe” croup when they have stridor at rest, plus one of the following :
- Moderate intercostal retractions
- Agitation or restlessness
- Difficulty speaking or feeding
These patients warrant racemic epinephrine, as discussed below. Notably, decreasing stridor can be an ominous sign, just as decreasing wheezing can suggest impending respiratory failure in asthmatics. Be on the lookout for lethargy, increasing fatigue, and worsening mental status. In the lethargic patient with decreasing stridor, decreased level of alertness, and hypoxemia, intubation may be required.
Historically, cool mist or humidified air was used to treat croup, but they are no longer recommended as studies have consistently failed to show clinical improvement with these interventions [13-15]. The primary adjuncts to support of airway, breathing, and circulation are dexamethasone and racemic epinephrine.
Dexamethasone has been found to improve the Westley score at 6 and 12 hours (but not at 24 hours), with a NNT of 5 to improve the score . Patients typically require less epinephrine, spend less time in the ED or hospital (by about 12 hours), and have fewer return visits or readmissions (RR of return or readmission 0.5) when treated early with dexamethasone .
The dose of dexamethasone is 0.6 mg/kg, rounded to the nearest 2mg, up to a maximum dose of 16mg. Lower doses may be as effective, but some studies have seen more patients improved at 12 hours with the higher dose . At Seattle Children’s Hospital, all children with croup of any severity receive dexamethasone. Repeat doses are rarely given .
Racemic epinephrine may help by causing mucosal vasoconstriction and decrease subglottic edema. It has been found to improve symptoms at 30 minutes, but the effect is normally gone by 2 hours .
The dose of racemic epinephrine is 0.5 mL of nebulized 2.25% solution, diluted in 3 mL of normal saline. At Seattle Children’s, this is given as soon as possible to children with “severe” croup, and can be re-dosed every 2 hours up to 3 times . Further doses are typically given as an inpatient, and failure to improve after 3 doses suggests a possible alternative or concomitant diagnosis. This medication is most commonly given to those with stridor at rest.
There is conflicting data on whether heliox can be beneficial in croup. Most studies assessing heliox have looked at children with moderate to severe croup . Heliox may improve the croup score, even compared to racemic epinephrine, starting at 90 minutes and lasting up to 4 hours, but no difference was found after 4 hours . Overall, the data are conflicting, and at this point it is impossible to make a strong recommendation on administration of heliox. Currently, it may be considered as an adjunct therapy in a patient with severe croup with only partial response to racemic epinephrine.
Patients may have stridor with activity and still do well at home. However, stridor at rest warrants further intervention. Children should be able to talk and feed with minimal retractions. At Seattle Children’s, patients must be on room air and must not have received racemic epinephrine in the 2 hours prior to discharge .
Patients not meeting discharge criteria within 2 hours of dexamethasone are likely to require admission. Respiratory distress despite multiple doses of racemic epinephrine suggests likely need for ICU care and consideration of ENT consultation for direct laryngoscopy.
This patient may have classic laryngotracheitis from parainfluenza. The viral exanthem is non-specific. However, if you are concerned about anaphylaxis, it would not be wrong to administer intramuscular epinephrine. Otherwise, his stridor at rest and moderate intercostal retractions warrant racemic epinephrine in addition to dexamethasone.
This patient is older than most patients with classic croup. Given his fever, age, and poor oxygenation, he requires consideration of a broad differential. Chest X-ray and viral panel are reasonable. He may have influenza causing a croup-like syndrome with stridor and respiratory distress, and may benefit from racemic epinephrine to decrease upper airway inflammation.
Pearls & Takeaways
- Do not routinely obtain chest X-ray or respiratory viral panel in children with uncomplicated croup.
- In patients who fail to respond to racemic epinephrine, or who are in significant respiratory distress, the differential must be initially very broad, with particular concern for bacterial tracheitis.
- All patients with croup of any severity can benefit from dexamethasone.
- Racemic epinephrine can help for a short time, and if it doesn’t, broaden your differential.
References / Further Reading
- Bjornson C, Russell K, Vandermeer B, Klassen TP, Johnson DW. Nebulized epinephrine for croup in children. Cochrane Database of Systematic Reviews 2013, Issue 10. Art. No.: CD006619.
- Russell KF, Liang Y, O’Gorman K, Johnson DW, Klassen TP. Glucocorticoids for croup. Cochrane Database of Systematic Reviews 2011, Issue 1. Art. No.: CD001955.
- Westley CR, Cotton EK, Brooks JG. Nebulized racemic epinephrine by IPPB for the treatment of croup: a double-blind study. Am J Dis Child. 1978 May;132(5):484-7.
- Johnson DW. Croup. BMJ Clin Evid. 2009; 2009: 0321.
- Cherry JD. Clinical practice. Croup. N Engl J Med. 2008;358(4):384–391.
- Rihkanen H, Rönkkö E, Nieminen T, et al. Respiratory viruses in laryngeal croup of young children [published correction appears in J Pediatr. 2008;153(1):151]. J Pediatr. 2008;152(5):661–665.
- Mazza D, Wilkinson F, Turner T, Harris C. Evidence based guideline for the management of croup. Aust Fam Physician. 2008 Jun;37(6 Spec No):14-20.
- Denny FW, Murphy TF, Clyde WA Jr, Collier AM, Henderson FW. Croup: an 11-year study in a pediatric practice. Pediatrics. 1983;71(6):871–876.
- Bjornson CL, Johnson DW. Croup. 2008;371(9609):329–339.
- Bjornson CL, Johnson DW. Croup-treatment update. Pediatr Emerg Care. 2005;21(12):863–870.
- Chan A, Langley J, Leblanc J. Interobserver variability of croup scoring in clinical practice. Paediatr Child Health. 2001;6(6):347–351.
- Swingler GH, Zwarenstein M. Chest radiograph in acute respiratory infections. Cochrane Database Syst Rev. 2008;(1):CD001268.
- Scolnik D, Coates AL, Stephens D, Da Silva Z, Lavine E, Schuh S. Controlled delivery of high vs low humidity vs mist therapy for croup in emergency departments. JAMA. 2006;295(11):1274–1280.
- Moore M, Little P. Humidified air inhalation for treating croup. Cochrane Database Syst Rev. 2010;(9):CD002870.
- Moore M, Little P. Humidified air inhalation for treating croup. Fam Pract. 2007;24(4):295–301.
- Kairys SW, Olmstead EM, O’Connor GT. Steroid treatment of laryngotracheitis: a meta-analysis of the evidence from randomized trials. Pediatrics. 1989;83(5):683–693.
- Moraa I, Sturman N, McGuire T, van Driel ML. Cochrane Database Syst Rev. 2013 Dec 7;(12):CD006822.