Croup Syndrome

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Croup Syndrome

Laryngotracheobronchitis and Acute Epiglottitis

Chapter Objectives

After reading this chapter, you will be able to:

• List the anatomic alterations of the lungs associated with croup syndrome.

• Describe the causes of croup syndrome.

• List the cardiopulmonary clinical manifestations associated with croup syndrome.

• Describe the general management of croup syndrome.

• Describe the clinical strategies and rationales of the SOAPs presented in the case studies.

• Define key terms and complete self-assessment questions at the end of the chapter and on Evolve.

FIGURE 39-1 Laryngotracheobronchitis and acute epiglottitis. A, Acute epiglottitis. B, Laryngotracheobronchitis. NEP, Normal epiglottis; SEP, swollen epiglottis; STT, swollen tracheal tissue; TR, trachea. VC, vocal cords.

The word croup is a general term used to describe the inspiratory, barking or brassy sound associated with a partial upper airway obstruction. In other words, croup is actually a clinical sign (objective data) or a clinical manifestation—that is, the “barking or brassy sound” associated with a partial upper airway obstruction. Clinically, the inspiratory barking sound heard in a patient with a partial upper airway obstruction is called inspiratory stridor.

Most experts treat laryngotracheobronchitis (LTB)—which is a subglottic airway obstruction—and the term croup interchangeably, and acute epiglottitis—which is a supraglottic airway obstruction—as two entirely separate disease entities (see Figure 39-1). Historically, this is likely a result, in part, of the fact that the inspiratory stridor (i.e., the croup sound) associated with a patient with LTB is usually a loud and high-pitched brassy sound, whereas the inspiratory stridor associated with a patient with acute epiglottis is often lower in pitch or muffled, or even absent.

In addition, some sources refer to LTB as a subglottic croup and to acute epiglottis as a supraglottic croup. In essence, these phrases (subglottic croup versus supraglottic croup) simply mean that the inspiratory stridor sound originates from either the subglottic area (i.e., in LTB) or the supraglottic area (i.e., in acute epiglottis).

Thus, in view of the confusing nature of the term croup and the two types of partial upper airway disorders—LTB and acute epiglottis—the phrase inspiratory stridor will always be used in place of the term croup throughout this chapter to enhance the clarity of the subject matter.

Anatomic Alterations of the Upper Airway

Laryngotracheobronchitis

Because laryngotracheobronchitis can affect the lower laryngeal area, trachea, and occasionally the bronchi, the term laryngotracheobronchitis is used as a synonym for “classic” subglottic croup. Pathologically, LTB is an inflammatory process that causes edema and swelling of the mucous membranes. Although the laryngeal mucosa and submucosa are vascular, the distribution of the lymphatic capillaries is uneven or absent in this region. Consequently, when edema develops in the upper airway, fluid spreads and accumulates quickly throughout the connective tissues, which causes the mucosa to swell and the airway lumen to narrow. The inflammation also causes the mucous glands to increase their production of mucus and the cilia to lose their effectiveness as a mucociliary transport mechanism.

Because the subglottic area is the narrowest region of the larynx in an infant or small child, even a slight degree of edema can cause a significant reduction in cross-sectional area of the airway. The edema in this area is further aggravated by the rigid cricoid cartilage, which surrounds the mucous membrane and prevents external swelling as fluid engorges the laryngeal tissues. The edema and swelling in the subglottic region decrease the ability of the vocal cords to abduct (move apart) during inspiration. This further reduces the cross-sectional area of airway in this region.

Acute Epiglottitis

Acute epiglottitis is a life-threatening emergency. In contrast to LTB, epiglottitis is an inflammation of the supraglottic region, which includes the epiglottis, aryepiglottic folds, and false vocal cords (see Figure 39-1). Epiglottitis does not involve the pharynx, trachea, or other subglottic structures. As the edema in the epiglottis increases, the lateral borders curl and the tip of the epiglottis protrudes posteriorly and inferiorly. During inspiration the swollen epiglottis is pulled (or sucked) over the laryngeal inlet. In severe cases, this may completely block the laryngeal opening. Clinically, the classic finding is a swollen, cherry-red epiglottis.

The major pathologic or structural changes associated with croup are as follows:

• LTB—Airway obstruction caused by tissue swelling just below the vocal cords

• Epiglottitis—Airway obstruction caused by tissue swelling just above the vocal cords

Etiology and Epidemiology

Laryngotracheobronchitis

The parainfluenza viruses cause most cases of LTB, with type 1 being the most common type, type 3 less common, and type 2 infrequent. LTB also may be caused by influenza A and B, respiratory syncytial virus (RSV), herpes simplex virus, Mycoplasma pneumoniae, rhinovirus, and adenoviruses. LTB is primarily seen in children 6 months to 5 years of age, with peak prevalence in the second year of life. Boys are affected slightly more often than girls. The onset of LTB is slow (i.e., symptoms progressively increase over 24 to 48 hours), and it is most common during the fall and winter. A brassy or barking cough is commonly present. The child’s voice is hoarse, and the inspiratory stridor is typically loud and high in pitch. The patient usually does not have a fever, drooling, swallowing difficulties, or a toxic appearance.

Acute Epiglottitis *

Acute epiglottitis is a bacterial infection that is almost always caused by Haemophilus influenzae type B. It is transmitted via aerosol droplets. Since 1985, when vaccinations with H. influenzae type B vaccine became widespread, the number of reported cases of epiglottitis has decreased by over 95%. H. influenzae type B, however, is still responsible for 75% of the epiglottitis cases. Other causes of epiglottitis include aspiration of hot liquid and trauma from repeated intubation attempts.

Epiglottitis has no clear-cut geographic or seasonal incidence. Although acute epiglottitis may develop in all age groups (neonatal to adulthood), it most often occurs in children 2 to 6 years of age. Boys are affected more often than girls. The onset of epiglottitis is usually abrupt. Although the initial clinical manifestations are usually mild, they progress rapidly over a 2- to 4-hour period. A common scenario includes a sore throat or mild upper respiratory problem that quickly progresses to a high fever, lethargy, and difficulty in swallowing and handling secretions. The child usually appears pale. As the supraglottic area becomes swollen, breathing becomes noisy, the tongue is often thrust forward during inspiration, and the child may drool. Compared with LTB, the inspiratory stridor is usually softer and lower in pitch. A cough is usually not associated with acute epiglottis. The voice and cry are usually muffled rather than hoarse. Older children commonly complain of a sore throat during swallowing. A cough is usually absent in patients with epiglottitis. Acute epiglottitis in adults is typically seen in patients with neck trauma (e.g., blunt force neck injury or aspiration of hot liquid), in those who have been intubated repeatedly, and in drug abuse (crack cocaine) cases.

The general history and physical findings of LTB and epiglottitis are compared and contrasted in Table 39-1.

TABLE 39-1

General History and Physical Findings of Laryngotracheobronchitis (LTB) and Epiglottitis

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	LTB	Epiglottitis
Age	6 months-5 years (with the peak prevalence in the second year)	2-6 years
Onset	Usually slow or gradual (24-48 hours)	Abrupt (2-4 hours)
Fever	Absent	Present
Drooling	Absent

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