Upper Airway Obstruction

Louisa S. Canham and Jonathan Fisher

Upper airway obstruction occurs from a variety of causes including foreign-body obstruction, infection, swelling, and bleeding. Airway obstruction from choking on a piece of food can occur rapidly, although conditions such as epiglottitis may occur more insidiously. Early recognition and treatment of impending complete airway obstruction is essential to avoid catastrophic results. Evaluation, differential diagnosis, and emergency intervention all must occur simultaneously. Although not every patient with upper airway obstruction will require emergency airway management, for a subset of patients there is only a small window of opportunity to intervene before the airway is completely lost.

The major determinant of airway resistance is the radius of the airway, resistance being proportional to the fourth power of the radius. Therefore, a small decrease in diameter can have an extreme impact on the airway. Identification of high-risk presentations and clinical situations is the key to successful outcomes.

CLINICAL PRESENTATION

Nontraumatic airway obstruction can occur rapidly in a manner of seconds or through a period of days to months. The process may progress gradually or suddenly with little warning. The emergency physician must understand the disease processes at work and be prepared to intervene quickly.

The site of the obstruction, the size of the obstructing agent, and associated spasm and edema are important determinants of the presentation. Historical factors may aid in arriving at the diagnosis. Physical findings may be nonspecific but can help to separate patients into a category of obstruction.

Increasing airway obstruction is first evidenced by subjective complaints of respiratory distress by the patient. Patients may complain of a sensation of “throat closing” or “something stuck in their throat.” Objective findings include the presence of respiratory sounds such as stridor or wheezing. Inspiratory noises tend to indicate an upper airway source of obstruction. In general, stridor is produced in large, upper airways during inspiration, while wheezing occurs in smaller, lower airways during expiration. However, the distinction may not always be so clear. Inability to swallow or handle one’s secretions can be an ominous finding. The patient’s positioning is important to note. An upright posture with the neck extended in the sniffing position is characteristic of the patient with supraglottic obstruction, such as epiglottitis. Forcing the patient to become supine can cause complete airway obstruction.

Although airway obstruction by a foreign body, such as food, occurs suddenly, obstruction by an expanding mass effect within the upper airway is more insidious. Abscesses may obstruct the airway by their location or can rupture into the airway, causing acute obstruction. Expanding hematomas behave similarly. Edema and soft tissue swelling owing to infection or allergy have a more diffuse mass effect.

DIFFERENTIAL DIAGNOSIS

Foreign-body obstruction, infection, hypersensitivity, hemorrhagic disorders, extrinsic mass, and neoplasia all may result in the syndrome of upper airway obstruction. Paradoxical vocal cord motion is a psychogenic form of stridor that mimics true airway obstruction. It is a diagnosis of exclusion, but it is an important entity to recognize to avoid harmful unnecessary interventions, such as intubation (1).

Foreign-Body Obstruction

The classic example of upper airway obstruction by a foreign body is the “cafe coronary” (2). Food that causes an obstruction has often been poorly masticated. The victim may have painful or poorly fitting dentures or otherwise poor dentition that hampers chewing. Alcohol consumption has been associated with an increased risk of choking. This type of obstruction is usually supraglottic and responds to the maneuvers prescribed by the American Heart Association, such as abdominal thrusts (3).

Aspirated toys or smaller pieces of food may pass the vocal cords and produce obstruction in the subglottic area. These obstructions may be intermittent and aggravated by the head-down position, which allows the object to move an obstructing position. Back blows and the head-down position may actually worsen these obstructions. The clinical presentation of a subglottic foreign body may be one of localized wheezing and atelectasis as the foreign body becomes lodged in a bronchus (4).

Infection

Infection of the upper airway structures may produce airway compromise within hours. Patients often present with fever, pain, hoarseness, and decreased ability to open the mouth or move the neck. Ludwig angina (cellulitis of the sublingual space) can quickly obstruct the airway. The condition is a true otolaryngologic emergency that requires airway maintenance and antibiotic therapy (5). Retropharyngeal or parapharyngeal abscess can cause gradual obstruction as it expands and then catastrophic deterioration if it suddenly ruptures into the airway (6). Epiglottitis may produce sufficient swelling to produce airway obstruction in the adult or child.

Hypersensitivity

Anaphylaxis presents suddenly after exposure to an antigenic stimulus. When there is laryngeal edema, prompt intervention is needed (see Chapter 175), and a delay in the initiation of medical therapy may make immediate surgical intervention necessary. Food, drug, and insect sting allergies are the commonly encountered causes of anaphylactic airway emergencies. Severely ill patients may not be able to speak and therefore unable to relate a history of exposure.

Hereditary angioedema (HAE) is an autosomal dominant inherited condition that is manifested by sudden edema of the face, hands, abdominal viscera, and airway. Airway obstruction is the most dramatic and life-threatening complication of the disease (7). Episodes may be triggered by minor trauma, emotional distress, or surgery. There is no race or sex predilection. Despite the inherited nature of the disease (see Chapter 176), there is often no known family history.

Angiotensin-converting enzyme (ACE) inhibitor agents have also been associated with the development of angioedema (8,9). Moderate to complete airway obstruction may occur. It is important to note that this reaction may occur even in patients who have been taking ACE inhibitors for years.

Hemorrhagic Disorders

The widespread use of anticoagulants for the treatment of cardiac and cerebrovascular disease has increased the population who are at risk for the development of spontaneous hematoma. These hematomas may develop anywhere in the body, but when the pharynx, tongue, or soft tissues surrounding these structures are involved, airway compromise is a predictable consequence.

Airway compromise has been reported because of hematoma of the sublingual space, retropharynx, and hypopharynx (10,11). There is rapid, unexpected deterioration of a patient who, in most cases, was previously healthy. Pain is often noted early, frequently preceding other symptoms. Signs of airway obstruction may develop before the examiner’s eyes. Physical examination often reveals an area of swelling, with or without ecchymosis. Close observation is essential to avoid an adverse outcome from unrecognized abrupt deterioration.

Extrinsic Mass

Airway obstruction owing to an extrinsic mass is occasionally seen. An example is the development of an obstruction in the esophagus caused by achalasia (12). The distended esophagus impinges on the airway in the neck and produces recurrent airway obstruction that resolves when the esophageal obstruction is cleared. Cystic lesions of various types may produce a similar syndrome that may require temporary airway support until the lesion is removed.

Neoplasia

Tumors located anywhere along the airway may cause respiratory distress via extrinsic compression or internal infiltration of the airway. Common culprits include mediastinal tumors, lung cancer, and Kaposi sarcoma. Patients present with dyspnea and noisy respirations, and may be misdiagnosed as having asthma or an airway infection. Some clues to the diagnosis of neoplastic etiology include hemoptysis and worsening of symptoms with lying flat (13,14).

Congenital tumors of the oropharynx or neck may present immediate and unexpected airway emergencies at birth. These conditions require the immediate availability of neonatal resuscitation capabilities and surgical resources (15).

ED EVALUATION

Regardless of the cause of the obstruction, the emergency physician must first gauge its severity by quickly placing the patient in one of four categories:

1. Stable airway, deterioration risk low

2. Stable airway, deterioration risk high

3. Compromised airway and respiration

4. Obstructed airway and agonal respirations

The evaluation and therapy process can then proceed with the appropriate degree of urgency.

The history should include questions about previous allergic reactions, medications, cancer, fever, pain with swallowing, and hoarse voice. The vital signs, presence or absence of stridor, and degree of respiratory distress should be quickly assessed. The neck should be palpated for masses and lymphadenopathy, and the larynx and trachea should be moved from side to side to check if this “tracheal rock” elicits pain with gentle movement. Examination of the throat may reveal a partial view of a supraglottic foreign body, an abscess, or swelling of the tongue or pharynx.

A patient placed in the stable category with low risk of deterioration is in some ways the most hazardous for the emergency physician. It implies that the patient can be evaluated at a leisurely pace with a minimal degree of observation. However, airway obstructing lesions can deteriorate quickly and unexpectedly.

The second category reflects the appropriate degree of concern during the initial evaluation of any patient in whom airway obstruction is suspected. The risk of deterioration calls for constant observation and readiness to intervene if necessary. Measures intended to correct the underlying obstructive process should be instituted as soon as possible. Laboratory studies may be helpful in confirming an infectious or hemorrhagic etiology. A lateral cervical spine radiograph may reveal a thick epiglottis or signs of a retropharyngeal abscess, such as prevertebral thickening or gas. Computed tomography (CT) scan may further delineate a mass or abscess impinging upon the airway but must be used carefully in the patient who may not tolerate the time and positioning necessary to obtain this study.

The third category, with established airway compromise, calls for immediate decisions regarding airway intervention. The emergency physician must quickly assess the likelihood of success with a medical approach before intubation or surgical intervention is required. The decision to intubate is a clinical one. An arterial blood–gas analysis may add more supporting data, but such testing usually only delays needed therapy, with potentially catastrophic results.

The last category, with the patient in an agonal state, represents the most straightforward situation. The airway must be established emergently.