CHAPTER 69 Chronic Aspiration
The three major functions of the larynx—respiration, phonation, and airway protection—are intimately related. Impairment of laryngeal protective function can result in aspiration, the laryngeal penetration of secretions such as saliva, ingested liquids or solids, or refluxed gastric contents below the level of the true vocal cords.
A certain amount of aspiration is known to occur normally. Scintigraphic evaluation of healthy persons during sleep reveals aspiration in nearly 50%.1 A certain amount of aspiration may be tolerated without complications, provided that tracheobronchial clearance is normal and defense mechanisms are intact. Contamination of the respiratory tract associated with aspiration can result in a spectrum of bronchopulmonary complications. The severity of complications depends on the volume and the character (e.g., pH) of the aspirated material. Respiratory complications of aspiration include bronchospasm, airway obstruction, tracheitis, bronchitis, pneumonia, pulmonary abscess, sepsis, and death.2–4 Significant aspiration results in a high mortality rate.5
Aspiration may be an isolated event related to temporary impairment of normal swallowing mechanisms and airway protection. Typically, isolated aspiration occurs secondary to neurologic dysfunction. This dysfunction may in turn be secondary to a depressed state of consciousness related to drugs, alcohol, or metabolic derangement. In addition, seizure, injury, or infection may cause isolated aspiration. Elderly patients are more likely to experience aspiration, presumably in relation to physiologic and neurologic changes associated with age.6–8 Patients with dentures experience impaired swallowing with decreased oral sensation and oral control, which may contribute to aspiration.
Chronic or intractable aspiration entails repeated episodes of aspiration. Patients with chronic aspiration require evaluation and effective management to prevent life-threatening complications. This chapter discusses the evaluation and management of patients with chronic aspiration and emphasizes surgical management.
Chronic aspiration usually results from a severe loss of laryngeal protective function related to impaired motor activity or sensory loss. Chronic aspiration can occur, despite healthy laryngeal function, if dysfunctional swallowing is significant.
Box 69-1 lists causes of chronic aspiration. The most common origin is associated with cerebrovascular accidents, particularly those involving the brainstem with bilateral cranial nerve (CN) deficits.9 In addition, degenerative neurologic diseases are frequently associated with chronic aspiration. Peripheral nerve disorders, particularly those involving the cranial nerves, as well as neuromuscular diseases and muscular disorders, can cause recurrent aspiration. Diffuse neurologic dysfunction from head injury, anoxic brain injury, infection, or drug toxicity can cause severe dysfunction and chronic aspiration.10–12 Chronic aspiration also can result from disorders of the pharynx and the esophagus, including neoplasms, postoperative and postirradiation dysfunction, Zenker’s diverticulum, stricture, and severe gastroesophageal reflux.13
Box 69-1 Causes of Chronic Aspiration
Chronic aspiration can occur in pediatric patients, in whom it is usually related to severe neurologic dysfunction resulting from cerebral palsy, anoxic encephalopathy, sequelae of neurologic trauma or surgery, tracheoesophageal fistula, or other severe congenital or acquired neurologic disorders.14
Patients may be aware of recurrent aspiration and describe episodes of coughing or choking during swallowing. Some patients, however, may experience silent aspiration, whereby cough does not occur after laryngeal penetration.15–17 Fever and respiratory symptoms such as productive cough with purulent sputum may occur, indicating an infectious complication. Patients may have weight loss, dysphonia, pain, dysphagia, odynophagia, or other symptoms, depending on the cause of the underlying disorder.9 Frequently, patients are severely ill because of their disease and secondary infectious complications.
In the evaluation of a patient with chronic aspiration, a detailed medical history is important. Frequently, the cause of aspiration is apparent from the history. The medical history and history of prior surgery or injury should be thoroughly investigated.
A multidisciplinary approach to patients with chronic aspiration is important.18 Frequently, an otolaryngologist–head and neck surgeon is consulted after complications of chronic aspiration have occurred. Once chronic aspiration has been identified, consultation with specialists in speech-language pathology, neurology, internal medicine, rehabilitation medicine, radiology, gastroenterology, thoracic surgery, and psychiatry may be beneficial. A cooperative effort in which each specialist provides special expertise ensures optimal care for the patient.
Physical examination should be thorough, with careful examination of the head and neck, including cranial nerve evaluation. Examination of the hypopharynx and larynx is performed with indirect mirror examination or fiberoptic nasopharyngoscopy. If these structures are not adequately visualized by these methods (e.g., in an endotracheally intubated patient), direct laryngoscopy is recommended. Esophagoscopy is performed if an esophageal abnormality is suspected. Pulmonary function tests help assess pulmonary function and reserve.
Radiography provides important diagnostic information and should include chest radiography and swallowing evaluation. A videofluoroscopic swallowing study reliably provides information about the precise physiologic nature of aspiration and swallowing disturbance and about the severity of aspiration.19,20 Logemann21 described a modified barium swallow study in which small amounts of barium are used because of the risk of aspiration. Different consistencies of contrast material are used to assess whether consistency alteration has any effect on aspiration reduction. A videofluoroscopic swallowing study performed in conjunction with a speech-language pathologist allows radiographic assessment of the effects of swallowing therapy and maneuvers on control of aspiration.22,23
Functional endoscopic evaluation of swallowing (FEES) was proposed by Langmore and associates24 in 1988 as an alternative to videofluoroscopy for the evaluation of dysphagia. In this study, dyed pudding and liquids are swallowed by the patient during nasopharyngeal fiberoptic observation. The swallow is recorded and reviewed for evidence of oral leakage, pharyngeal stasis, laryngeal penetration, and aspiration. Evaluation of FEES suggests that it is similar in sensitivity and specificity to videofluoroscopic examination with the advantages of lower cost, decreased radiation exposure, and bedside availability.25–29 In general, the choice between videofluoroscopy and FEES depends on multiple factors, including physician and speech-language pathologist preferences and hospital availability.
Scintigraphy may help quantify the magnitude of aspiration30,31 but in general adds little information, beyond that obtained from a FEES or a videofluoroscopic swallowing study, for the management of aspiration. Other imaging studies that may provide important information are computed tomography (CT) or magnetic resonance imaging (MRI) of the head and neck, and soft tissue radiography of the neck.
Comprehensive evaluation of the patient with aspiration ideally determines the cause of the underlying disorder or disorders causing the aspiration. A thorough search for any correctable cause of aspiration (e.g., obstructing lesion, Zenker’s diverticulum, cricopharyngeal muscle dysfunction, esophageal motility disorder) is important to management.
Frequently, progressive functional deterioration can be anticipated for certain degenerative neurologic diseases and malignant neoplasms. It can be extremely difficult, however, to predict the time course of improvement and recovery for cerebrovascular accidents, head injuries, anoxic brain injuries, postoperative dysfunction, and other disorders. Multispecialty input is helpful in planning management for these difficult cases.
Initial management of the patient with chronic aspiration should include appropriate antibiotics for any infectious complications. Aggressive pulmonary therapy is instituted. All oral intake is discontinued, and an alternative route of alimentation is provided. Enteral routes of alimentation include small, soft nasogastric feeding tubes, cervical esophagotomy, piriform sinusotomy, gastrostomy, and jejunostomy. Gastrostomy can easily be performed percutaneously with minimal morbidity. Patients with significant reflux may benefit from a tube passed through a gastrostomy into the small intestine or jejunostomy.
Depending on the cause of aspiration, alimentation by nasogastric feeding tube decreases but does not eliminate the risk of aspiration.32 Some researchers believe that nasogastric feeding tubes may actually predispose to aspiration.33,34 In addition, nasogastric feeding tubes can be uncomfortable and aesthetically displeasing when used for long periods. Gastrostomy alone has been shown not to reduce aspiration in neurologically impaired patients. 35,36 Some patients may be candidates for parenteral hyperalimentation if gastrointestinal function is impaired (e.g., patients with acute severe brain injury).37
Proper nursing care includes special positioning of the patient, such as elevation of the head of the bed for patients with severe reflux. However, one study showed no significant difference in aspiration with respect to patient position in the patient with endotracheal intubation.34 Frequent suctioning of the oral cavity and oropharynx is also important.
A tracheotomy tube with a low-pressure cuff provides comfortable airway control for patients requiring intubation and facilitates pulmonary toilet in patients with copious secretions. Tracheotomy also effectively reduces the pulmonary dead space. Despite these advantages, tracheotomy cannot be relied upon to eliminate aspiration.38,39 In addition, tracheotomy has been implicated as a causative factor in aspiration. The proposed mechanisms include esophageal compression via inflated tracheotomy cuff,40 desensitization of the larynx from diversion of airflow through the tracheotomy,41 impairment of laryngeal elevation through tethering of the larynx by the tracheotomy tube,42 disruption of the normally closed aerodigestive system,43 disorder of laryngeal reflexes due to chronic upper airway bypass,1,44,45 reduced effectiveness of cough to clear secretions from the upper airway,43,46 and the inability to generate subglottic air pressure.47,48 Despite these proposed mechanisms, no clear causal relationship between tracheotomy and aspiration exists. In a study of 20 patients evaluated with FEES before and after tracheotomy (within 1 month), no causal relationship between tracheotomy and aspiration was demonstrated.49
The use of a tracheotomy tube for aspiration control requires close attention and skilled care, particularly for the debilitated patient. Several studies have examined the effect of endotracheal and tracheotomy tube cuffs on the prevention of aspiration. Although low-pressure, high-compliance cuffs are the most effective in minimizing cuff leak, they do not prevent aspiration.50–52
Vocal cord paralysis can result in chronic aspiration, particularly when combined with a laryngeal sensory deficit (e.g., a high vagal lesion). Vocal cord injection with materials such as collagen derivatives or hydroxyapatite can be performed endoscopically or transcervically to achieve vocal cord medialization and may prevent aspiration related to vocal cord paralysis.53–55 Bilateral vocal cord injection with permanent materials such as polytetrafluoroethylene, however, has been shown to be an unreliable method for the prevention of chronic aspiration.56
Alteration of the laryngeal framework by medialization laryngoplasty using an implant is another excellent technique for vocal cord medialization.57,58 Carrau and associates59 reported that 94% of patients with high vagal lesions experienced improved swallowing after medialization thyroplasty with or without arytenoid adduction. In the same study 79% of patients who presented with tracheotomies underwent successful decannulation following laryngeal framework surgery.
Sometimes a correctable cause of chronic aspiration is not identified, and nonsurgical and minor surgical procedures (e.g., tracheotomy, vocal cord medialization) do not prevent chronic aspiration. In these cases, surgical separation of the upper digestive tract from the upper respiratory tract is necessary to prevent the morbidity and mortality of recurrent respiratory tract soilage. A reasonable probability and duration of survival are necessary prerequisites for this surgery.
Clinical judgment should be used to determine the likelihood of recovery of laryngeal protective function and to identify patients who require prompt surgical intervention to separate the upper digestive and respiratory tracts to prevent death. The patient’s general medical and mental status, severity of illness, and potential quality of life should be addressed.60 Patients may have to sacrifice normal phonation and laryngeal respiration to ensure restoration of airway protection. This difficult issue requires thorough discussions of management options and sequelae with the patient and family members.
The ideal surgical procedure for chronic aspiration would be uniformly effective in preventing aspiration, be simply achieved, and have few complications and low morbidity. This procedure could be performed with local anesthesia for debilitated patients. In addition, the ideal procedure would allow phonation and deglutition and would be reversible if the underlying cause of aspiration were to improve. Many surgical options have been described for the management of chronic aspiration (Box 69-2).