Foreign-Body Aspiration: A Guide to Early Detection, Optimal Therapy

Foreign-body aspiration is a relatively common occurrence in children. It may present as a life-threatening event that necessitates prompt removal of the aspirated material. However, the diagnosis may be delayed when the history is atypical, when parents fail to appreciate the significance of symptoms, or when clinical and radiologic findings are misleading or overlooked by the physician.

Aspiration of organic matter causes severe airway mucosal inflammation. If the organic matter is not promptly removed, chronic inflammation leads to the development of granulation tissue around the foreign body, which may ultimately present as a lung infection. In this setting, it is not uncommon to treat patients for secondary complications, such as persistent fever, “asthma,” or recurrent pneumonia for long periods.

Here we review the incidence of foreign-body aspiration, its various clinical guises, its management, and measures that can prevent future aspirations.

UPPER AIRWAY OBSTRUCTION
Upper airway obstruction is one of the leading causes of pediatric emergencies. According to the National Safety Council, mechanical suffocation accounted for 5% of all unintentional deaths among children younger than 4 years in 1995 in the United States.¹ Most of these deaths involved children younger than 12 months (10% of all unintentional deaths occurred in this age group).²

Pathogenesis. A foreign body in the posterior pharynx causes irritation and discomfort that causes the child to cry or cough. Vigorous inspiration causes the foreign body to become impacted within the airway;there is increased resistance to inspiratory and expiratory flow as a result. The impacted foreign body in the intrathoracic airway creates a valvelike effect that causes more airflow obstruction during expiration than during inspiration; the result is generalized or asymmetric gas trapping. Surface sensory receptors of the respiratory tract adapt to the prolonged pressure caused by the foreign body. Consequently, the child will not experience further coughing until other sensory receptors are stimulated by dislodgment of the foreign body or by secretions. Thus the patient may be asymptomatic for some time (ie, hours to months or even longer).

Epidemiology. Foreign-body aspiration accounts for more than 300 deaths annually in this country.3 Approximately 80% of episodes of foreign-body aspiration occur in those younger than 3 years.4 Most children of this age are learning to explore their world via the oral route and tend to put everything in theirmouth. The absence of the molars makes them unable to chew adequately, however. These factors increase the risk of foreign-body aspiration. Other predisposing factors include older siblings who may place food or objects in the mouth of infants or toddlers; neurologic disorders, such as cerebral palsy; loss of consciousness; and wallowing dysfunction.

During infancy, the incidence of foreign-body aspiration episodes is equal in boys and girls. After infancy, however, boys are more likely to experience aspiration than girls: the male-to-female ratio varies from 1.5:1 to 2.4:1.^4,5
 
Food items (nuts, seeds, food particles) have been implicated in 70% to 90% cases involving infants and toddlers.⁶ Various types of nuts top the list of  aspirated foreign bodies: peanuts are the most common (36% to 55%).^5,7 Melon and sunflower seeds are also commonly aspirated.⁸

Older children tend to aspirate non-food items, such as paper clips, coins, balls, marbles, and pins.⁶ Balloon aspiration is frequently fatal.⁹ Balloons can pass through the vocal cords and lodge in the carina; they prevent air passage through to the lungs. As a result, balloons have been banned in many day-care centers and schools.

CLINICAL PRESENTATION
A foreign body may become lodged in the larynx, trachea, or bronchus. The right bronchus is more commonly affected than the left because of the lesser angle of divergence relative to the left bronchus and because of its greater diameter.^7,10 Larger foreign bodies may become lodged in the larynx. Laryngotracheal foreign bodies are associated with increased morbidity and mortality.¹¹

Signs and symptoms associated with foreign body aspiration occur in 3 phases.

Stage 1. Choking, coughing, gasping, and respiratory distress develop because of airway obstruction. Choking lasts for a few seconds to several minutes after the episode and may be self-limited.

Stage 2. Acute symptoms may be followed by a temporary quiescent phase in which the patient may not have any symptoms.

Stage 3. During the last phase, symptoms of complications such as infection may develop.

The clinical presentation depends on the child’s age, the type of object that has been aspirated, the time elapsed since the event, and the location of the foreign body. Only 50% to 75% of children present to a health facility within 24 hours of the initial aspiration.5,7 A review of 400 cases of foreign-body aspiration showed that almost 71% children presented within 1 week of aspiration.¹⁰

The most common symptoms of foreign-body aspiration are coughing, choking, and wheezing.^5,7,12 Fever, stridor, chest pain, and throat or sternal discomfort occur less frequently. Laryngotracheal foreign bodies present with cough, stridor, hoarseness, and increased respiratory effort. Foreign bodies in the larynx may also manifest with symptoms related to the esophagus, such as dysphagia, gagging, or throat discomfort. Lower airway foreign bodies present as cough, wheezing, and shortness of breath; examination reveals decreased breath sounds on one side.¹³

Affected patients may experience little acute distress after an initial phase of choking episode. A history of choking in a previously healthy child can be elicited in 80% to 90% of patients who have aspirated a foreign body.^7,12 Physical examination results may be normal or nonspecific  in up to 30% patients.¹⁰ Others may have generalized or localized wheezing and decreased air entry.

Because foreign-body aspiration can mimic other respiratory conditions, a high index of suspicion is  necessary in all patients with pneumonia, atelectasis, or wheezing with an atypical course—especially in patients who are unresponsive to medical therapy (see Box). This helps in the early diagnosis of foreign-body aspiration, especially in the absence of a history of choking.

Foreign-body aspiration can closely mimic an acute asthma exacerbation.¹⁴ However, the absence of atopy, the acute onset of symptoms, and unilateral physical findings may suggest foreign-body aspiration. Moreover, patients who have inhaled a foreign body fail to improve with conventional bronchodilators. Thus, clinical suspicion is crucial in the diagnostic process.