Epiglottitis

Etiology

The cause of epiglottitis is most commonly infectious, whether bacterial, viral, or fungal in origin. In children, Haemophilus influenzae type B (HIB) is still the most common cause. However, this has decreased dramatically since the widespread availability of immunizations. Other agents such as Streptococcus pyogenes, S pneumoniae, and S aureus have been implicated. In patients who are immunocompromised, Pseudomonas aeruginosa and Candida have been named. Noninfectious causes can be traumatic such as thermal, caustic, or foreign body ingestion.[2][3][4]

While viruses do not cause epiglottitis, a prior viral infection may allow bacterial superinfection to develop. Viruses that may allow a superinfection include varicella-zoster, herpes simplex, and Epstein-Barr virus.

Epidemiology

Since the addition of the HIB vaccine to the infant immunization schedule in many countries worldwide, the annual incidence of epiglottitis in children has decreased overall. However, the incidence in adults has remained stable. Additionally, the age of children who have had epiglottitis has increased from three years old to six to twelve years old in the post-vaccine era.[5] While in the past epiglottitis was thought to be primarily a disease of young children, it is now much more likely practitioners will encounter epiglottitis/supraglottitis in adults as well.

Pathophysiology

The airway in the pediatric population is markedly different compared to that of an adult (see Image. The Muscles of the Larynx). In a young child, the epiglottis is located more superiorly and anteriorly than in an adult. There is also a more oblique angle with the trachea. The narrowest portion of the infant and pediatric airway is the subglottis, while in adults it is the glottis. Furthermore, the infant epiglottis is comprised of cartilage that is far more pliant when compared to that of an adult, whose epiglottis is more rigid (this is the natural progression of cartilage maturation, and explains why laryngomalacia is more prevalent in very young children). It is not surprising, then, that an infectious process that leads to edema and increase in weight and mass of the epiglottis is more likely to cause symptoms in a child - the pliancy of the cartilage allows a ball-valve effect, where each inspiration pulls an edematous epiglottis over the laryngeal airway, causing symptoms. In adults, whose cartilages are stiffer, an isolated epiglottic infection and the resultant increase in epiglottic mass may be resisted by the more rigid laryngeal/epiglottic cartilage; but an infection that encompasses more of the tissues of the supraglottis, leading to edema, can lead to symptoms and an unstable airway.

H. influenzae and other, infections of the epiglottis can lead to marked edema and swelling 0f the epiglottis and supraglottis of patients of any age. This edema can rapidly spread to adjacent structures leading to the rapid development of airway obstruction symptoms. While H. influenzae remains the most common pathogen in both adults and children, other organisms such as S. Pneumoniae, S. aureus, and beta-hemolytic Streptococcus sp. are important pathogens also in both adults and children. In immunocompromised patients, the list of potential causes is much longer and must include Mycobacterium tuberculosis, as well as a litany of others, though the relative frequencies remain the same.

Toxicokinetics

Other complications of epiglottitis include:

• Cervical adenitis
• Empyema
• Epiglottic abscess
• Meningitis
• Pneumonia
• Pneumothorax
• Sepsis
• Septic arthritis
• Septic shock
• Vocal cord granuloma
• Ludwig angina-type submental infection

History and Physical

The history will often reveal an antecedent URI, though not always. Symptoms may be very mild for a period of hours to days, until they dramatically worsen, mimicking a sudden onset. This will usually have occurred within the past 24 hours, or sometimes the last 12 hours. The patient will appear very uncomfortable, and possibly overtly toxic. Most children have no prodromal symptoms. In the emergency department, the child will likely be sitting upright with the mouth open in a tripod position and possibly have a muffled voice. Adults may be minimizing symptoms, but will likely be reluctant to lie flat or be uncomfortable when doing so. Drooling, dysphagia, and distress, or anxiety may be present (especially in children, but also in adults). These are often referred to as the 3 Ds. Swelling of the upper airway results in turbulent airflow during inspiration or stridor. Signs of severe upper airway obstruction such as intercostal or suprasternal retractions, tachypnea, and cyanosis are concerning for impending respiratory failure and should signal the provider to act quickly. Avoid an exam of the throat with a tongue blade or a flexible laryngoscope, as it may result in the loss of the airway.

Anterior examination of the neck may reveal lymphadenopathy. If cyanosis is present, it is indicative of advanced infection and poor prognosis.

Evaluation

An oropharyngeal exam is usually not performed to evaluate a suspected case of epiglottitis because manipulation of the oral cavity may lead to disaster, such as respiratory arrest. This diagnosis is primarily one of clinical suspicion. A lateral neck radiograph will show swelling of the epiglottis, also referred to as the “thumb sign.” See Image. Lateral X-ray, Epiglottitis. It is not necessary to make the diagnosis but can be used to narrow down the provider’s differential diagnosis. This should only be performed in the most stable, comfortable, and cooperative of patients. A flexible fiberoptic laryngoscopy can be performed theoretically, but only in a very controlled setting such as the operating room due to the risk of inducing laryngospasm. This is almost always never done. If clinical suspicion for acute epiglottitis exists, the patient should be taken emergently to the operating room for airway examination under the most optimal conditions possible.

Ultrasonography has been mentioned as another way to evaluate these patients, revealing an “alphabet P sign” in a longitudinal view. This must also be weighed against the clinical condition and may be ill-advised in children. A complete blood count with differential, a blood culture, and an epiglottal culture should only be obtained in patients with a secured endotracheal tube.[6]

CT scan of the neck is rarely needed and can precipitate disaster.  Placing the patient in a supine position can trigger respiratory crises. If this diagnosis is yielded unexpectedly on a CT scan, the child (or adult) should not be left alone in the radiology suite and should be transported emergently to the operating room for airway evaluation and intubation.

The chest x-ray may reveal concomitant pneumonia in 10-15% of patients. A lateral neck X-ray can be obtained in select cooperative patients as detailed previously (with great caution). A standard portable P-A X-ray may also suggest the diagnosis via a narrowing of the laryngotracheal area easily confused with the "steeple sign" of laryngotracheal bronchitis (croup). Therefore, this remains a purely clinical diagnosis.[7]

Treatment / Management

The singular, most important, aspect of treatment is to secure the airway. Experienced providers should intubate these patients since their airways are regarded as difficult. An individual capable of performing a tracheotomy should be available if needed. This likely involves an inhalation induction of general anesthesia and subsequent intubation, though this varies from patient to patient. The patient should be admitted to the intensive care unit after the airway is secured, and culture swabs should be sent at the time of intubation after the tube is placed. The use of corticosteroids to reduce edema has been cited, with an overall shorter intensive care unit stay for these patients. Empiric antimicrobials should be initiated. Once culture and sensitivity results are available, the regimen should be adjusted. Once a leak around the endotracheal tube can be demonstrated with the cuff deflated, extubation can be entertained.[8][9](B2)

All non-intubated patients must be admitted for observation and a tracheostomy tray must be available at the bedside. The ENT surgeon and the anesthesiologist must be notified of the admission in case an emergency airway is required. Nurses should be warned not to place the child in a supine position. In reality, this is rare - patients with a high suspicion of epiglottitis should be intubated as soon as possible.

If an emergency airway is needed, it should ideally be obtained in the operating room. The airway should be visualized with a laryngoscope first. if endotracheal intubation is not an option, then a tracheostomy should be performed.

Antibiotics usually administered should cover common respiratory and oral cavity flora, and can include cefuroxime, ceftriaxone, and cefotaxime.

Differential Diagnosis

Because of the availability of the HIB vaccine, acute epiglottitis due to H. influenzae is less common (though this is sporadically increasing due to public misconception regarding vaccination), though still remains the single most common pathogen responsible for the condition in both adults and children. Thus, most health care providers may have less insight into the disorder. This lack often leads to delays in starting antibiotics. Acute epiglottitis can result in sudden airway obstruction. It is never wise to send the patient anywhere without proper monitoring and resuscitative equipment if this diagnosis is remotely suspected.

Other conditions that can mimic the presentation include an airway obstruction from a foreign object, acute angioedema, caustic ingestion causing airway compromise, diphtheria, or peritonsillar and retropharyngeal abscesses.

Prognosis

For most patients with epiglottitis, the prognosis is good when the diagnosis and treatment are prompt. Even those who require intubation are usually extubated in a few days without any residual sequelae. However, when the diagnosis is delayed in children, airway compromise can occur, and death is possible.

The cause of death is usually due to sudden upper airway obstruction and difficulty intubating the patient, with extensive swelling of the laryngeal structures. Thus, every patient admitted with a diagnosis of acute epiglottitis must be seen by an ear, nose, and throat surgeon or anesthesiologist, and a tracheostomy tray must be made available at the bedside. Globally, a mortality rate of 3% to 7% has been reported in patients with unstable airways.

Complications

Complications of epiglottitis include the following:

• Cellulitis
• Cervical adenitis
• Death
• Empyema
• Epiglottic abscess
• Meningitis
• Pneumonia
• Pulmonary edema
• Respiratory failure
• Septic shock
• Hypoxia
• Prolonged ventilation
• Tracheostomy
• Death