Kathleen M. Adelgais
UPPER AIRWAY OBSTRUCTION
EPIDEMIOLOGY
Diseases that cause upper respiratory tract (URT) obstruction account for a significant number of pediatric emergency department visits. While some diseases of the URT are common and benign, others, although rare, can be life threatening.
Most causes of stridor among children younger than 6 months of age are a result of congenital abnormalities while stridor in older children is typically caused by acquired illnesses. Table 71-1 lists the common acquired causes of stridor.
TABLE 71-1 Common Acquired Causes of Stridor
PATHOPHYSIOLOGY
Stridor is the physical sign common to all causes of URT obstruction and can be inspiratory, expiratory, or mixed.
Stridor results from Venturi effects created by airflow through a narrow semicollapsible airway. With inhalation, the relative pressure in the center of the tube becomes greater than at the edges; the pressure differential leads to collapse of airway walls, obstruction, and turbulent airflow creating the sound of stridor.
Resistance is inversely proportion to the fourth power of the airway radius during laminar gas flow and the fifth power during turbulent flow. In the normal pediatric subglottis, 1 mm of edema will reduce its cross-sectional area by 50%.
As air progresses from the supraglottic to the glottic and subglottic areas and finally the trachea, there is an increase in physiologic support structure that decreases the amount of collapse that occurs during inspiration. These structures (eg, tracheal rings) are less developed in young infants.
Expiratory stridor, or wheeze, is common in distal airways since intrathoracic pressure may become much greater than atmospheric pressure during expiration. The pressure differential creates high relative laminar flow through semicollapsible bronchi, resulting in wheezes.
CLINICAL FEATURES
Inspiratory stridor indicates obstruction at or above the larynx (ie, supraglottic). There is often marked inspiratory and expiratory variation.
Glottic and subglottic obstructions commonly cause both inspiratory and expiratory stridor of lesser magnitudes. Obstruction at the level of the trachea and primary bronchi may be associated with inspiratory or expiratory stridor, but usually to a much lesser degree.
Expiratory stridor usually implies obstruction below the carina.
Hypoxia may be present with or without cyanosis, which depends on the hemoglobin level and peripheral circulation. Cyanosis in upper airway obstruction is an ominous sign.
Tachypnea, retractions (subcostal, intercostal, supraclavicular), and nasal flaring or head bobbing, are signs of labored respirations.
Grunting is a valuable diagnostic sign as it localizes disease to the lower respiratory tract and correlates with disease severity.
DIAGNOSIS AND DIFFERENTIAL
The diagnosis of upper airway obstruction is clinical through observation of signs of increased work of breathing and stridor.
The differential diagnosis is aided by considering the age of the patient and duration of symptoms.
Children less than 6 months old with a long duration of symptoms characteristically have a congenital cause of stridor. Common congenital causes of stridor include laryngomalacia, tracheomalacia, vocal cord paralysis, and subglottic stenosis. Less common, but important causes include airway hemangiomas, vascular rings, and slings.
Patients over 6 months of age with a short duration of symptoms characteristically have an acquired cause of stridor such as viral croup, epiglottitis, foreign body aspiration, peritonsillar abscess, or retropharyngeal abscess.
The differential diagnosis and disease severity determine further diagnostic testing, which may include imaging (eg, soft-tissue neck and chest radiography or CT, barium swallow), blood work (eg, CBC, blood cultures), or endoscopy.
STRIDOR IN NEONATES
EPIDEMIOLOGY
Laryngomalacia accounts for 60% of all neonatal laryngeal problems.
After tracheomalacia, vocal cord paralysis is the most common causes of neonatal stridor.
PATHOPHYSIOLOGY
Laryngomalacia is caused by a developmentally weak larynx, which results in airway collapse at the epiglottis, aryepiglottic folds, and arytenoids during inspiration.
Vocal cord paralysis may be congenital or acquired. There may be a history of birth trauma, shoulder dystocia, macrosomia, forceps delivery, or other intrathoracic anomaly.
CLINICAL FEATURES
Stridor from laryngomalacia worsens with crying or agitation and improves with neck extension or when prone.
Laryngomalacia is usually a self-limited disorder that resolves in 90% of cases by 18 months of age.
Stridor from vocal cord paralysis is typically chronic and may worsen with agitation or secondary viral infection; signs of respiratory distress or cyanosis may be present.
DIAGNOSIS AND DIFFERENTIAL
A presumptive diagnosis can be made clinically, though definitive diagnosis is made by fiberscopic laryngeal examination.
The differential diagnosis includes tracheomalacia, vascular anomalies, foreign body, and infectious causes of stridor.
EMERGENCY DEPARTMENT CARE AND DISPOSITION
Laryngomalacia is usually a self-limiting disease and is only rarely associated with respiratory failure, failure to thrive, apnea, or feeding problems.
Patients with respiratory failure and vocal cord paralysis require cautious airway management: endotracheal intubation can be quite difficult in a child with bilateral cord paralysis. Placing the bevel of the tube parallel to the small remaining glottic opening and rotating the tube one-quarter turn with gentle pressure may facilitate passing the tube. Force should never be applied since this may cause damage to laryngeal structures.
Minimally symptomatic patients with lifelong stridor and no signs of distress or hypoxia can be referred to outpatient pediatric otolaryngology for definitive diagnosis.
Patients with signs of respiratory distress or hypoxia should be admitted to the hospital.
VIRAL CROUP (LARYNGOTRACHEOBRONCHITIS)
EPIDEMIOLOGY
Viral croup is responsible for most cases of stridor after the neonatal period, and is usually a benign, self-limited disease, though it can rarely cause life-threatening airway obstruction.
Children ages 6 months to 3 years are most commonly affected, with a peak at age 12 to 24 months. Croup is rare after 6 years of age but can occur as late as 12 to 15 years of age.
Croup is seasonal and occurs mainly in late fall and early winter in North America.
PATHOPHYSIOLOGY
Croup is caused by a number of viral infections, parainfluenza (I, II, and III) being the most common; influenza, respiratory syncytial virus (RSV), adenovirus, enterovirus, rhinovirus, and metapneumovirus can also cause croup.
Transmission is usually airborne with infection entering the nose and pharynx and spreading to the larynx and trachea.
Inflammation and edema result from viral invasion and cytotoxicity, particularly in the subglottic larynx and trachea around the cricoid cartilage, leading to upper airway obstruction.
Spasmodic croup results from subglottic edema that may be related to allergy or viral infection.
CLINICAL FEATURES
Croup typically begins with a 1- to 5-day prodrome of cough and coryza, which is followed by a 3- to 4-day period of classic barking cough, stridor, and hoarseness. Symptoms peak on days 3 to 4 and then wane.
Spasmodic croup is typically sudden in onset and occurs at night without antecedent symptoms of infection; it may be recurrent.
Croup represents a spectrum of illness from barking cough to stridor at rest with associated labored breathing and hypoxia.
DIAGNOSIS AND DIFFERENTIAL
The diagnosis of croup is clinical.
Physical examination classically reveals a barking cough with or without stridor, which is classically inspiratory but can be biphasic. Stridor may occur with crying or at rest, and may be associated with signs of increased work of breathing.
Laboratory and radiographic studies are not necessary for typical croup, though may aid in the differential diagnosis, which includes epiglottitis, bacterial tracheitis, or foreign body aspiration.
If obtained, a lateral neck and chest radiograph may demonstrate that the normally squared shoulders of the subglottic tracheal air shadow are shaped like a pencil tip, hourglass, or steeple. This “steeple sign” is neither sensitive nor specific for croup.
EMERGENCY DEPARTMENT CARE AND DISPOSITION
Place patients on pulse oximetry and administer oxygen for hypoxia.
Give dexamethasone 0.15 to 0.6 milligram/kg (10 milligrams max) PO or IM. The IV form of dexamethasone may be given orally, is concentrated and thus smaller volume, and is well tolerated. Nebulized budesonide (2 milligrams) may be clinically useful in moderate to severe cases. Even patients with mild croup have been shown to benefit from steroids.
Administer nebulized racemic epinephrine, 0.05 mL/kg/dose up to 0.5 mL of 2.25% solution, for patients with stridor at rest and signs of respiratory distress. Alternatively L-epineprhine (1:1000) 0.5 mL/kg (max 5 mL) can be used. Children with stridor associated only with agitation do not need epinephrine.
Helium plus oxygen (Heliox) in a 70:30 mixture may prevent the need for intubation in children with severe croup. Heliox is only effective to a maximum concentration of oxygen of 40%, and is therefore not useful in patients requiring additional oxygen for hypoxia.
Although intubation should be performed whenever clinically indicated, when treated aggressively, less than 1% of admitted patients require intubation. When necessary, consider using smaller endotracheal tubes than recommended to avoid trauma to inflamed mucosa.
Most patients can be safely discharged to home if they meet criteria listed in Table 71-2.
Children with persistent stridor at rest, tachypnea, retractions, and hypoxia or those who require more than two treatments of epinephrine should be admitted to the hospital.
TABLE 71-2 Criteria for Discharge from ED in Patients with Croup
EPIGLOTTITIS
EPIDEMIOLOGY
Epiglottitis is life threatening and can occur at any age. Since the introduction of Haemophilus influenzae vaccine the incidence and demographics have changed remarkably, with less than 25% of cases caused by Haemophilus, and a median age of presentation shifting to older children and adults.
In immunized children, most cases are caused by gram-positive organisms, including Streptococcus pyogenes, Staphylococcus aureus, and Streptococcus pneumoniae.
In immunocompromised children, herpes, Candida, and varicella can cause epiglottitis.
CLINICAL FEATURES
Classically there is abrupt onset of high fever, sore throat, and drooling. Symptoms may rapidly progress to stridor and respiratory distress. Cough may be absent.
Patients usually appear toxic and may assume a tripod or sniffing position to maintain their airway.
Symptoms in older children and adults may be subtle; severe sore throat, with or without stridor may be the primary complaint.
DIAGNOSIS AND DIFFERENTIAL
The diagnosis is clinical and suggested by severe sore throat, a normal-appearing oropharynx, and tenderness with gentle movement of the hyoid.
Radiographs are usually unnecessary in patients with a classic presentation.
When the diagnosis is uncertain, lateral neck radiographs should be obtained with the neck extended during inspiration. The normal epiglottis is tall and thin, but appears swollen, squat, and flat like a thumb-print when inflamed (Fig. 71-1).
False-negative radiographs can occur, and if clinical suspicion exists, direct visualization of the epiglottis, preferably in the operating room with anesthesiology and otolaryngology present.
Blood cultures are positive in up to 90% of patients, while cultures from the epiglottis are less sensitive.
A CBC may reveal leukocytosis and left shift.
FIG. 71-1. Lateral neck view of a child with epiglottitis. (Courtesy of W. McAlister, MD, Washington University School of Medicine, St. Louis, MO.)
EMERGENCY DEPARTMENT CARE AND DISPOSITION
Anticipation of airway loss is of primary importance in epiglottitis, and preparation for emergent advanced airway management (medical and surgical) should take place early; patients should be accompanied by a physician if moved to a radiograph suite.
Keep patients seated and upright. Provide oxygen and administer nebulized racemic or L-epinephrine. Consider heliox if available.
If total airway obstruction or apnea occurs, children with epiglottitis sometimes can be effectively ventilated with a bag-valve-mask device.
The most experienced individual should perform intubation as soon as the diagnosis is made. Ensure that multiple endotracheal tube sizes are immediately available. Use of paralytics in the patient who is able to maintain their airway must be accompanied by the certainty that intubation will be successful or that a surgical airway can immediately be performed if unsuccessful.
Only after airway management should intravenous (IV) antibiotics be considered. Empiric broad-spectrum antibiotic choices include cefuroxime 50 milligrams/kg IV per dose, cefotaxime 50 milligrams/kg IV per dose, or ceftriaxone 50 milligrams/kg IV per dose. In regions with increased cephalosporin resistance, add vancomycin 10 milligrams/kg/dose.
Administer methylprednisolone 1 milligram/kg IV every 6 hours or dexamethasone 0.15 to 0.6 milligram/kg IV.
All patients with epiglottitis require hospitalization, typically in intensive care.
BACTERIAL TRACHEITIS
EPIDEMIOLOGY
Bacterial tracheitis (membranous laryngotracheobronchitis) is rare and caused by bacterial infection of the trachea, often following viral upper respiratory infection.
Tracheitis is more common in children under 3, but can occur in children 3 months to 13 years of age.
Common pathogens include S. aureus, S. pneumoniae, or β-lactamase-producing gram-negative organisms (H. influenzae and Moraxella catarrhalis).
CLINICAL FEATURES
Symptoms of tracheitis resemble severe croup or epiglottitis.
Patients often appear toxic, and may have cough, stridor (inspiratory and expiratory), hoarseness, and occasionally thick sputum production.
Dysphagia is uncommon with tracheitis.
DIAGNOSIS AND DIFFERENTIAL
Radiographs of the lateral neck and chest usually demonstrate subglottic narrowing of the trachea, and an irregular “shaggy” boarder (Fig. 71-2).
Bacterial cultures of tracheal secretions and blood may identify a pathogen and antibiotic sensitivities; a CBC may reveal leukocytosis.
FIG. 71-2. Lateral neck view of patient with bacterial tracheitis. Note presence of irregular tracheal margins (arrows). (Courtesy of W. McAlister, MD, Washington University School of Medicine, St. Louis, MO.)
EMERGENCY DEPARTMENT CARE AND DISPOSITION
Management is similar to that of epiglottitis, with primary attention to airway and anticipation of airway loss. Greater than 85% of patients ultimately require intubation. As with epiglottitis, ideal intubating conditions include an operating room for sedation, paralysis, intubation, and bronchoscopy. The emergency department physician must be prepared to perform emergent intubation and should prepare multiple endotracheal tube sizes.
Initial antibiotic choices include ampicillin/sulbactam 50 milligrams/kg/dose IV, or the combination of a third-generation cephalosporin such as ceftriaxone 50 milligrams/kg IV per dose and clindamycin 10 milligrams/kg/dose. In areas with increasing S. aureus resistance, consider vancomycin 10 milligrams/kg IV every 6 hours.
RETROPHARYNGEAL ABSCESS
EPIDEMIOLOGY
Retropharyngeal abscesses, although rare, are the second most common deep neck infection, usually occurring in children aged 6 months to 6 years of age.
Infection in the retropharyngeal space can be caused by aerobic organisms (eg, β-hemolytic streptococci and S. aureus) anaerobes (eg, Bacteroides), and gram-negative organisms (eg, Haemophilus).
The incidence of retropharyngeal abscess appears to be increasing in the United States in recent years.
CLINICAL FEATURES
Patients usually present with fever, sore throat, neck pain, drooling, dysphagia/odynophagia. Dysphagia and refusal to feed occur before significant respiratory distress.
Patients typically appear toxic and neck swelling or torticollis may be noted on examination along with drooling.
Rapidly fatal airway obstruction from sudden rupture of the abscess pocket can occur.
Aspiration pneumonia, empyema, mediastinitis, and erosion into the jugular vein and carotid artery have been reported.
DIAGNOSIS AND DIFFERENTIAL
Physical examination of the pharynx may demonstrate posterior pharyngeal fullness. Additional examination findings include nuchal rigidity or torticollis, cervical adenopathy, drooling, and fever.
Plain radiographs of the lateral neck during inspiration may show a widened retropharyngeal space; the diagnosis is suggested when the retropharyngeal space at C2 is twice the diameter of the vertebral body or greater than one-half the width of C4.
CT of the neck with IV contrast is thought to be near 100% sensitive and is the diagnostic study of choice.
Blood tests are rarely helpful for diagnosis or acute management.
EMERGENCY DEPARTMENT CARE AND DISPOSITION
Immediate airway stabilization is the first priority. Unstable patients should be intubated before performing imaging.
Empiric antibiotic choice is controversial since most retropharyngeal abscesses contain mixed flora. Consider broad-spectrum coverage with ampicillin-sulbactam, 200 milligrams/kg/d divided every 6 hours, and/or clindamycin 25 to 40 milligrams/kg IV divided every 6 hours. In penicillin-allergic patients, clindamycin and a third-generation cephalosporin are recommended.
Steroids may reduce airway inflammation and prevent progression of cellulitis to abscess.
Consult otolaryngology for operative incision and drainage; although cellulitis and some very small abscesses may improve with antibiotics alone, most require surgery.
PERITONSILLAR ABSCESS
EPIDEMIOLOGY
Peritonsillar abscesses occur most frequently in adolescents and young adults.
Most are unilateral, with <10% becoming bilateral.
CLINICAL FEATURES
Symptoms include fever, sore throat (often unilateral), dysphagia, odynophagia, and neck pain.
Patients usually appear acutely ill with fever, and may have trismus, drooling, and a muffled “hot potato” voice. The uvula is displaced away from the affected side. As a rule the affected tonsil is anteriorly and medially displaced.
DIAGNOSIS AND DIFFERENTIAL
Careful visualization of the oral cavity can reliably confirm or exclude peritonsillar abscess in most cases The presence of uvular deviation, soft palate displacement, trismus, airway compromise, or localized areas of fluctuance are sufficient for diagnosis and no imaging is required.
For ambiguous cases computed tomography (CT) or ultrasound (US) of the neck may be helpful.
EMERGENCY DEPARTMENT CARE AND DISPOSITION
The majority of cases can be safely treated in the ED with needle drainage followed by outpatient antibiotics and analgesics.
Formal incision and drainage in the operating room is sometimes necessary, especially in young or uncooperative patients.
Parenteral antibiotic choices include clindamycin 10 milligrams/kg IV or ampicillin-sulbactam 50 milligrams/kg; oral options include amoxicillin/clavulanate 45 milligrams/kg/d divided twice a day or clindamycin 10 to 20 milligrams/kg/d divided every 6 to 8 hours.
Close outpatient follow-up is essential for all discharged patients.
FOREIGN BODY ASPIRATION
EPIDEMIOLOGY
Foreign body (FB) aspirations cause over 3000 deaths each year, and have a peak incidence between ages 1 and 3 years. In children under 6 months of age, the cause is usually secondary to a feeding by a well-meaning sibling.
Commonly aspirated foreign bodies include foods and toys.
CLINICAL PRESENTATION
Clinical symptoms and signs depend on the size and location of the aspirated foreign body and range from mild coughing to acute airway obstruction and respiratory failure. Many patients are completely asymptomatic.
Classic teaching is that an FB in the laryngotracheal area causes stridor, whereas a bronchial FB causes wheezing. There is significant overlap in symptoms, however, and wheeze is present in 30% of laryngotracheal FB aspirations, and stridor in up to 10% of bronchial aspirations.
DIAGNOSIS AND DIFFERENTIAL
A high index of suspicion is required to diagnose FB aspiration. Since as many as one-third of the aspirations are not witnessed or remembered by the parent, FB aspirations should be considered in all children with unilateral wheezing or persistent symptoms that do not respond to standard bronchodilator therapy.
Plain chest radiograph can be normal: >50% of tracheal FB, 25% of bronchial FB, and more than 75% of FB in children < 3 years of age are radiolucent. In cases of complete obstruction, atelectasis may be found. In partial obstructions, air trapping with asymmetric hyperinflation of the obstructed lung may occasionally be seen. There is little additional value to expiratory or decubitus views.
Definitive diagnosis requires laryngoscopy or bronchoscopy in the operating room, which should be considered in any patient with a history of choking, asymmetric breath sounds, or suggestive findings on chest radiograph.
The differential diagnosis of upper airway foreign body includes esophageal foreign body: radiographically, flat foreign bodies such as coins are usually oriented in the sagittal plane when located in the trachea (ie, appears as a thick line in an antero-posterior chest radiograph) and in the coronal plane when in the esophagus (ie, appears round on an anteroposterior chest radiograph).
EMERGENCY DEPARTMENT CARE AND DISPOSITION
If FB aspiration or airway obstruction is clearly present, BLS procedures to relieve airway obstruction should be implemented immediately.
If BLS maneuvers fail, perform direct laryngoscopy and attempt to remove the FB with Magill forceps. If the FB cannot be seen, orotracheal intubation with distal displacement of the FB into a bronchus may be lifesaving.
Consider racemic epinephrine or Heliox for patients with stridor and respiratory distress as a temporizing measure.
Definitive treatment usually requires rigid laryngoscopy or bronchoscopy under general anesthesia.
Foreign bodies in the proximal airways require immediate treatment while distal foreign bodies may be removed in the outpatient setting after consultation with subspecialists when reliable follow-up can be ensured.
For further reading in Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 7th ed., see Chapter 119, “Stridor and Drooling,” by Joseph D. Gunn III.