Chapter 17

Foreign bodies

Sebastian Fernandez-Bussy¹ and Gonzalo Labarca^2,3

¹Interventional Pulmonology Unit, Clinica Alemana-Universidad del Desarrollo, Santiago, Chile. ²School of Medicine, Universidad San Sebastian, Concepcion, Chile. ³Division of Internal Medicine, Complejo Asistencial “Dr Victor Rios Ruiz”, Los Angeles, Chile.

Correspondence: Sebastian Fernandez-Bussy, Interventional Pulmonology Unit, Clinica Alemana-Universidad del Desarrollo, Manquehue Norte 1410, 7650567 Santiago, Chile. E-mail: sfernandezbussy@alemana.cl

The presence of a foreign body in the airway is potentially lethal, particularly in children [1]. All health personnel, notably emergency physicians, pulmonologists, otorhinolaryngologists, surgeons, intensivists and radiologists, should have knowledge and awareness of the signs and symptoms of this condition [2, 3]. Historically, the removal of foreign bodies was the first reference to an endoscopic airway procedure. Towards the end of the 19th century, Gustav Killian used a rigid endoscope to successfully remove a pig bone located in the right bronchus of a patient who presented with asphyxiation [1].

A high index of suspicion, an adequate temporal evaluation from the moment of aspiration to the beginning of the symptoms and timely management are all key to the effectiveness of the therapeutic measures used, the prevention of complications and the survival of these patients [2, 3].

Epidemiology

According to data reported in the literature, the presence of foreign bodies in the airway causes 17 530 hospitalisations per year, with an estimated mortality of 1.2 per 100 000 inhabitants [4]. According to epidemiological reports, foreign body aspiration shows a bimodal distribution, with two higher-incidence age groups clearly described [4, 5]. The first such group falls within childhood, particularly those children aged 1–3 years, and is related to the psychomotor development of children and their interest in exploring objects around them. In a diagnostic series of discharges from a paediatric clinic from 2000 to 2009, an incidence of 6.6 per 10 000 admissions per year was observed, with an associated health expenditure of up to USD486 million per year [4].

The second high-incidence group is late adulthood (particularly those adults aged >75 years) as a result of alterations in swallowing and the neurological regulation of the airway or specific pathologies such as Parkinson’s disease [5, 6].

Pathophysiology

The airways feature a series of defence mechanisms against the aspiration of foreign bodies. These mechanisms include anatomical, immunological and neurological components.

The anatomical components comprise physical barriers such as the nasal passage, oropharynx, larynx and trachea. These mechanical barriers inhibit the passage of large foreign bodies, preventing them from entering the central airway. Trachea size varies, with a typical diameter of 18.5 mm (range 17.5–19.5 mm) for an adult male. At the carina, the trachea divides into two bronchi (left and right bronchi). The length of the right bronchus is ∼2 cm. This bronchus is shorter than the left bronchus. Tracheobronchial angulation is another difference between the right and left bronchi. The right bronchus has an open angle to the carina. At the distal level, the airway is composed of smooth muscle surrounded by a fibrocartilage ring that confers strength and stability to the airway [6, 7].

With regard to immunological defence, the lumen has a secretory epithelium that produces abundant mucus and provides defence mechanisms against the aspiration of small particles along with the features of other sweeping mechanisms (e.g. cilia and flagella) and the increased production of immunoglobulin. These mechanisms are important in mucociliary clearance [7].

Several neurological reflexes of the tracheobronchial tree function to prevent foreign body aspiration, including the reflexes of normal swallowing and coughing. Normal swallowing is the result of a series of interactions between the orobuccal musculature and central mechanisms such as the swallowing reflex. This neurally controlled mechanism allows the passage of the alimentary bolus from the oral cavity towards the oesophagus, while preventing passage of the bolus into the central airway. Other centrally regulated physiological reflexes prevent the entry of foreign bodies into the central airway. For example, the cough reflex is the main component that protects against aspiration [8].

Pathologically, the occurrence of foreign body aspiration is due to an interruption of anatomical barriers. For example, a large diameter foreign body might overcome physiological and anatomical barriers, and become lodged in the central airway, most commonly in the lumen of the right bronchus [8, 9].

Other mechanisms are related to the shape and type of foreign body material, exemplified by certain vegetables or flexible foreign bodies that might migrate and affect the tracheobronchial lumen. Some small size or organic foreign [9] bodies may occlude the lumen at a distal level and cause an asymptomatic obstruction. These cases are usually diagnosed by a complication or because of symptoms related to chronic foreign body aspiration, as discussed later in this chapter.

Despite the mechanism of obstruction, acute foreign body aspiration and luminal retention lead to decreased ventilation, which diminishes the gas exchange surface area and causes hypoxaemia. Occasionally, foreign body retention may result in a “ball valve” effect, which develops when air inflow circumvents the foreign body during inspiration but cannot exit during expiration, thereby leading to air trapping distal to the foreign body with the risk of cardiorespiratory compromise and collapse [1–4, 9].

Risk factors

The factors associated with an increased risk of foreign body aspiration in adults include alterations in the mechanisms that regulate swallowing, such as alterations in consciousness, alcoholism, loss of teeth, swallowing disorders, trauma and use of drugs (e.g. benzodiazepines and hypnotics) [3]. Other associated factors are related to degenerative neurological disorders, such as dementia, Parkinson’s disease, mental retardation, stroke sequelae, central nervous system tumours and seizures [5, 6, 10].

Risk factors are similar for the paediatric population; however, this group is more vulnerable to foreign body aspiration because children commonly laugh, talk, cry or play with organic or inorganic objects in their mouths [2, 5].

Among the existing scenarios related to foreign body aspiration are general anaesthesia-related iatrogenic complications via the use of a laryngeal mask or orotracheal tube, which might displace a tooth into the distal airway, and during conscious sedation in dental procedures [3, 6, 9].

Types of foreign body

A foreign body may be classified according to its origin into organic (e.g. peanuts, nuts, fruits, vegetables), inorganic (e.g. pills, coins, plastics), mineral (e.g. dental pieces, bones), endogenous (e.g. broncholithiasis) and miscellaneous [9–13].

Clinical signs and symptoms

The clinical manifestations of foreign body aspiration are varied and may range from asymptomatic to fulminant [1]. An acute episode of foreign body aspiration (potentially a life-threatening sudden event) should be distinguished from a chronic foreign body aspiration that might lead to persistent cough, persistent or recurrent pneumonia, or atelectasis, but not to an acute life-threatening presentation [9–11].

Acute foreign body aspiration

A detailed history obtained from the patient and their relatives is important to determine the type of foreign body aspirated, the timing of the event and the severity of the condition [10]. During the initial examination, it is crucial to identify acute episodes of aspiration with life-threatening risk secondary to obstruction of the central airway, which may provoke an episode of asphyxia and dyspnoea that could lead to acute hypoxaemic respiratory failure and cardiorespiratory arrest [3, 4].

Factors that are important to evaluate upon physical examination are haemodynamic stability, oxygenation, ventilation, state of consciousness, use of accessory muscles, thoracic asymmetry, abolition of pulmonary murmur, unilateral wheezing, auscultation of crepitus, stridor and loose teeth (table 1) [4, 9–12].

Another form of presentation, i.e. subacute, manifests as a result of the complications sustained from foreign body aspiration. These cases may present clinically with chest pain, dyspnoea, pneumothorax, pneumomediastinum, atelectasis or post-obstructive pneumonia [12–14].

Chronic foreign body aspiration

Familiarity with associated comorbidities such as the presence of the mental alterations that contribute to aspiration is important. The most frequently reported symptoms are cough (66%), followed by asphyxia (27%), dyspnoea (26%), fever (22%) and nonmassive haemoptysis (17%) [10, 15, 16]. For episodes of a longer duration or prolonged evolution, the presence of recurrent pneumonia or pneumonia complicated by pulmonary abscess might be reported. However, MCGUIRT et al. [15] found that up to 39% of presentations could be asymptomatic.

Paediatric foreign body aspiration

Special consideration should be given to paediatric patients because the diagnosis of foreign body aspiration is delayed in up to 25% of these patients [2]. Importantly, these patients may present with episodes of asthma, recurrent pneumonia, recurrent laryngitis or croup [2, 5]. As the clinical presentation of foreign body aspiration is less categorical in this population, clinical prediction rules have been designed to guide physicians when evaluating these patients. JANAHI et al. [17] published a scale that included clinical presentation, physical examination, and radiological and ventilatory variables with an area under the curve of 0.76 (95% CI 0.70–0.82; p<0.05) (table 2). In that study, a cut-off of ≥2 points denoted a sensitivity of 89% and a specificity of 45%, whereas a cut-off of ≥3 points denoted a sensitivity of 75% and a specificity of 65%. In those with a score ≥2 points, a flexible bronchoscopy should be performed to inspect the airway. For those with a score ≥5 points, the more appropriate diagnostic and therapeutic procedure is early rigid bronchoscopy [17].

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