This is a 20 month old male who presents to the emergency department with a chief complaint of cough. Two days ago he developed rhinorrhea, fever, a hoarse cry and a progressively worsening, harsh, "barky," cough. Today he developed a "whistling" sound when he breathes, so his parents brought him to the emergency department. His past medical history is unremarkable. His 6 year old brother also has cold symptoms.
Exam: VS T 37.5, P 140, R 36, BP 90/64, oxygen saturation 96% in room air. He is alert, with good eye contact, in mild respiratory distress. He has a dry barking cough and a hoarse cry. He has some clear mucus rhinorrhea but no nasal flaring. His pharynx is slightly injected, but there is no enlargement or asymmetry. His heart is regular without murmurs. His lung exam shows good aeration and slight inspiratory stridor at rest. He has very slight subcostal retractions. No wheeze or rhonchi are noted. His abdomen is flat, soft, and non-tender. His extremities are warm and pink with good perfusion.
He is treated with nebulized racemic epinephrine and his coughing subsides and his stridor resolves. A lateral neck X-ray reveals no prevertebral soft tissue widening or evidence of epiglottitis. The subglottic region is mildly narrowed. He is treated with oral dexamethasone. He is discharged home after one hour of monitoring and his parents were instructed to treat him with humidified mist therapy.
Croup, which is derived from an Anglo-Saxon word meaning "to cry out", is a common respiratory illness in childhood. Croup is also known as laryngotracheitis and laryngotracheobronchitis (LTB). These terms will be used interchangeably in this chapter. The diagnosis describes a disease with some degree of laryngeal inflammation; resulting in hoarseness, a barking cough and varying degrees of respiratory distress over time. There are different etiologies encompassed in the diagnosis of croup, but the most common cause is viral, and this will be the focus of this chapter. The entity known as spasmodic croup is not easily distinguished from viral croup except that spasmodic croup has a greater tendency to recur. The treatment and evaluation are similar. When evaluating a child with croup, it is important to rule out epiglottitis, so this will be discussed as well.
Croup occurs most commonly between the ages of 1 and 6 years, with a peak incidence being around 18 months of age and the majority of cases below 3 years of age. It is more common in boys than girls. In temperate climates, it is most common during the late fall and winter, although cases can occur throughout the year.
Parainfluenza viruses are the most frequent cause of croup, accounting for more than 60% of cases. Less frequently associated with croup are influenza A and B, respiratory syncytial virus, adenovirus and measles. Bacterial superinfection can occur in cases of laryngotracheobronchtitis and laryngotracheobronchopneumonitis.
Like most respiratory infections, the initial site of infection is thought to be the nasopharynx with subsequent spread to the larynx and trachea. The respiratory epithelium becomes diffusely inflamed and edematous, resulting in airway narrowing and stridor. Reduced mobility of the vocal cords results in a hoarse voice or cry.
Laryngotracheitis generally starts with several days of rhinorrhea, pharyngitis, low-grade fevers and a mild cough. Over the next 12 to 48 hours, a progressively worsening "barky" cough, hoarseness and inspiratory stridor are noted, secondary to some degree of upper airway obstruction and laryngeal inflammation. The speed of progression and degree of airway obstruction can vary widely. The onset is often rapid and typically in the early morning hours (e.g., 2:00 am). Croup symptoms appear to subside during the day (possibly because of positioning), only to recur the following night. Thus, a child with significant stridor presenting during daylight, may be more seriously affected. On examination, the child will be noted to have coryza, a hoarse voice, and varying degrees of pharyngeal inflammation, tachypnea, and stridor. More severe cases may involve nasal flaring, moderate tachypnea, retractions and cyanosis. Some children with croup may not be able to maintain adequate oral intake of fluids. Alveolar gas exchange is usually normal, with hypoxia seen only in severe cases. Symptoms of croup usually normalize over 3-7 days, although in severely affected children, this may take 7-14 days.
The diagnosis is usually made on clinical grounds. Laboratory studies add little to the diagnosis of croup if bacterial infection is not suspected. White blood cell counts may be elevated above 10,000 with a predominance of polymorphonuclear cells. White blood cell counts greater than 20,0000 with bandemia may suggest bacterial superinfection. Chest radiographs may show subglottic narrowing (in 50% of children with croup), but this can also be seen in normal patients. Lateral neck radiographs are often obtained, not as much to confirm the diagnosis of croup, but to rule out other causes of stridor such as soft tissue densities in the trachea, a retropharyngeal abscess and epiglottitis.
The most important diagnostic consideration is distinguishing acute epiglottitis from acute laryngotracheitis. Epiglottitis describes a bacterial infection of the epiglottis. It is most commonly caused by H. influenzae type B, and occasionally by S. pneumoniae and group A Streptococcus. The prevalence of epiglottitis has decreased markedly (almost non-existent) since the widespread use of H. influenzae B vaccine.
The peak incidence of epiglottitis is between the ages of 3 and 7 years, with cases described in infants and adults as well. It occurs throughout the year, but is more common in winter months. Children with epiglottitis do NOT have a "croupy" cough. They appear more toxic, stridorous, apprehensive, have higher fever (e.g., 40 degrees C, 104 degrees F) and will often be drooling. Patients will often be tachycardic and tachypneic. The child with epiglottitis may prefer to adopt a position of sitting up, leaning forward, with their chin pushed forward and they may refuse to lie down. They will have a very inflamed, swollen epiglottis. Lateral neck radiographs may be helpful in making the diagnosis. X-rays are usually deferred if this diagnosis is suspected, owing to the critical clinical condition of the patient. The three characteristic findings on lateral neck X-ray are: a swollen epiglottis (thumb sign), thickened aryepiglottic folds and obliteration of the vallecula (pre-epiglottic space). Lab work is usually not done, but if done generally reveals elevated white blood cell counts with a left shift and blood cultures are positive in 80-90% of cases.
Other entities on the differential include bacterial laryngotracheobronchitis and laryngotracheobronchopneumonitis, which will have signs of lower respiratory involvement such as, wheezing and/or changes on chest x-ray. Often they will have hypoxia secondary to the lower airway disease. Retropharyngeal or peritonsillar abscess can cause upper airway obstruction, with soft tissue swelling evident on lateral neck x-ray (widening of the prevertebral soft tissue) or physical exam respectively. These children will often have high fever, drooling and be more toxic in appearance. Laryngitis can be seen in older children and adults, with a similar prodrome and cough, but lacking the inspiratory stridor. Foreign body aspiration should be considered in cases of sudden onset stridor without cough or fever. Acute angioneurotic edema, can cause acute swelling of the upper airway, but usually presents with external evidence of swelling of the face and neck. Laryngeal diphtheria (sometimes presents with a croup like syndrome known as membranous croup), although rare, should be considered and is another reason to assess the immunization record.
Once the diagnosis of croup is made, mist therapy, corticosteroids and epinephrine are the usual treatments. Since croup is chiefly viral in etiology, antibiotics play no role. Historically, mist therapy has been the mainstay of croup therapy, yet in small empiric trials, mist therapy has shown little benefit. Mist therapy (warm or cool) is thought to reduce the severity of croup by moistening the mucosa and reducing the viscosity of exudates, making coughing more productive. For patients with mild symptoms, mist therapy may be all that is required and can be provided at home.
For more severe cases, further intervention may be required. Oxygen should be provided to patients with hypoxemia. Racemic epinephrine, given by nebulizer, is thought to stimulate alpha-adrenergic receptors with subsequent constriction of arterioles and decreased laryngeal edema. Nebulized epinephrine may have marked effect to decrease inspiratory stridor and the work of breathing. Adverse effects include tachycardia and hypertension. The effects of this medication last less than two hours and children need to be monitored (not necessarily in the hospital) serially for the return of symptoms. Racemic epinephrine is a mixture of 50% biologically active epinephrine and 50% inactive epinephrine. The usual dose is 0.5cc of the 2.25% concentration diluted with 2cc of saline. 0.5cc of the 2.25% is equal to 11 mg of racemic epinephrine or 5.5 mg of plain epinephrine (0.5 cc of 2.25 gm/100cc = 11 mg). Thus, 5cc of 1:1000 epinephrine solution is pharmacologically similar and can also be used for inhalation therapy with a nebulizer if racemic epinephrine is not available.
Corticosteroids provide benefit for children with viral croup by reducing the severity and shortening the course of the symptoms. Dexamethasone is the most commonly used, with the dose being 0.6 mg/kg (maximum 10 mg) by mouth or intramuscularly. Clinical improvement from corticosteroids is usually not apparent until 6 hours after treatment. More recent studies have shown high dose nebulized budesonide to be as effective as dexamethasone, with more rapid onset of effect.
Endotracheal intubation is reserved for children with severe symptoms who do not respond to the previous therapies. This decision should be based on criteria such as hypercarbia, impending respiratory failure and changes in mental status.
If epiglottitis is suspected, the most serious complication is sudden airway obstruction. Because of this, airway management becomes the most important consideration. Visualization of the epiglottis should not be attempted, unless clinical suspicion is low or respiratory failure occurs. Assistance from a surgeon, intensivist, anesthesiologist, etc. (more than one is better), should be sought immediately since patients with epiglottitis may arrest at any time. Intubation is difficult so preparation should be made for intubation or tracheostomy. If the child is stable, it may be possible to start at intravenous line and obtain radiographic studies. Once the airway is secure, IV antibiotic therapy with either ceftriaxone or cefotaxime should be initiated. In the event of a respiratory arrest, mask ventilation with 100% FiO2 should be attempted using a two-person technique with one person ensuring a tight mask fit and the other squeezing the ventilation bag hard enough to drive air through the narrowed airway. Placing the patient prone (instead of the usual supine position) may improve ventilation by utilizing gravity to lift the epiglottitis off the larynx.
Most children with croup do extremely well and do not require hospitalization. Most children can be discharged from the emergency department after receiving dexamethasone and epinephrine therapy if they have no stridor at rest, normal color, aeration and level of consciousness and have been monitored for a period of time. 3-4 hours of observation is often recommended, but this is rarely followed in actual practice since most families are reluctant to remain in the emergency department during the early morning hours if their child is now sleeping comfortably.
1. Which of the following viruses are most commonly associated with viral croup?
. . . . . a. Adenovirus.
. . . . . b. Human papilloma virus
. . . . . c. Varicella virus
. . . . . d. Parainfluenza viruses
. . . . . e. RSV
2. True/False: An acutely ill child presents to the emergency department with the signs and symptoms of acute epiglottitis. The diagnosis should be confirmed with direct visualization of the epiglottis?
3. Which of the following is/are true?
. . . . . a. There is good evidence from randomized controlled trials that mist therapy is effective for the treatment of croup.
. . . . . b. Antibiotics are indicated in the treatment of croup.
. . . . . c. Nebulized albuterol is effective in the treatment of croup.
. . . . . d. Dexamethasone has been shown to be effective in the treatment of croup.
4. Which of the following is/are true?
. . . . . a. Croup affects more girls than boys.
. . . . . b. Croup shows no seasonal prevalence.
. . . . . c. Most cases occur in teenagers.
. . . . . d. It is a common respiratory infection in children.
5. True/False: Once a child with croup has been given corticosteroid treatment and racemic epinephrine, they may safely be discharged home after 20-30 minutes of monitoring.
Comparison of croup, epiglottitis and retropharyngeal abscess: Boychuk RB. Drooling, Stridor, and a Barking Cough: Croup?? In: Yamamoto LG, Inaba AS, DiMauro R. Radiology Cases In Pediatric Emergency Medicine, 1994, volume 1, case 10. Available online at: www.hawaii.edu/medicine/pediatrics/pemxray/v1c10.html
Series of lateral neck radiographs, some of which are retropharyngeal abscesses: Yamamoto LG. Test Your Skill In Reading Pediatric Lateral Necks. Yamamoto LG, Inaba AS, DiMauro R. Radiology Cases In Pediatric Emergency Medicine, 1995, volume 2, case 20. Available online at: www.hawaii.edu/medicine/pediatrics/pemxray/v2c20.html
Membranous croup case: Yamamoto LG. Membranous Croup. In: Yamamoto LG, Inaba AS, DiMauro R. Radiology Cases In Pediatric Emergency Medicine, 1996, volume 5, case 20. Available online at: www.hawaii.edu/medicine/pediatrics/pemxray/v5c20.html
1. Malhotra A, Krilov LR. Viral Croup. Pediatr Rev 2001;22(1):5-12.
2. Cherry JD. Chapter 22 - Croup. In: Feigin RD, Cherry JD (eds). Textbook of Pediatric Infectious Disease, 4th edition. 1998, Philadelphia: WB Saunders, pp. 228-241.
3. Klassen TP. Croup: A Current Perspective. Pediatr Clinics North Am 1999;46(6):1167-1178.
4. Cherry JD. Chapter 21 - Epiglottitis. In: Feigin RD, Cherry JD (eds). Textbook of Pediatric Infectious Disease, 4th edition. 1998, Philadelphia: WB Saunders, pp. 228-241.
5. Fleisher GR. Chapter 84 - Infectious Disease Emergencies. In: Fleisher GR, Ludwig S (eds). Textbook of Pediatric Emergency Medicine, fourth edition. 2000, Baltimore: William & Wilkins, pp. 745-750.
Answers to questions
2. False. Routine airway visualization is stressful and may precipitate respiratory arrest. If epiglottitis is unlikely, then airway visualization appears to be safe. In the event of respiratory arrest, laryngoscopy will be necessary for tracheal intubation.
3. d is the best answer. c is also correct in that nebulized albuterol does have some efficacy in croup, but nebulized epinephrine is better.
5. Most textbooks would suggest that this is false in that a longer observation period is generally recommended. However, most patients are low risk and can be discharged soon after dexamethasone and epinephrine are administered. Severe patients or those who do not respond as well should be observed for longer periods of time.