Etiology

The recurrent aspiration of small quantities of gastric, nasal, or oral contents can lead to several clinical presentations, including recurrent bronchitis or bronchiolitis; recurrent pneumonia; atelectasis; wheezing; cough; apnea; and/or laryngospasm. Pathologic outcomes include granulomatis inflammation, interstitial inflammation, fibrosis, lipoid pneumonia, and bronchiolitis obliterans. Most cases, although associated with significant morbidity, do not come to pathologic inspection, but clinically manifest as airway inflammation. Underlying disorders that are frequently associated with recurrent aspiration are listed in Table 390-1. Oropharyngeal incoordination is reportedly the most common underlying problem associated with recurrent pneumonias in hospitalized children. In one series of 238 children hospitalized with recurrent pneumonia, 48% were found to have dysphagia as the underlying problem. Lipoid pneumonia may occur after the use of home/folk remedies involving oral or nasal administration of animal or vegetable oils to treat various childhood illnesses. Lipoid pneumonia has been reported as a complication of these practices in the Middle East, Asia, India, Brazil, and Mexico. The initial underlying disease, language barriers, and a belief that these are not “medications” may delay the diagnosis.

Gastroesophageal reflux disease (GERD) is also a common underlying finding that may predispose to recurrent respiratory disease, but it is less frequently associated with recurrent pneumonia than dysphagia. GERD is discussed in Chapter 315.1. Aspiration has also been observed in infants with respiratory symptoms but no other apparent abnormalities. Recurrent microaspiration has been reported in otherwise apparently normal newborns, especially premature infants. Aspiration is also a risk in patients suffering from acute respiratory illness from other causes, especially respiratory syncytial virus infection. These patients, when studied with modified barium swallow and videofluoroscopy, have been seen to have silent aspiration. This finding emphasizes the need for a high degree of clinical suspicion for ongoing aspiration in a child with an acute respiratory illness, being fed enterally, who deteriorates unexpectedly.

Diagnosis

Some underlying predisposing factors (see Table 390-1) are frequently clinically apparent but may require specific further evaluation. Initial assessment begins with a detailed history and physical examination. The caregiver should be asked about spitting, vomiting, arching, or epigastric discomfort in an older child, the timing of symptoms in relation to feedings, positional changes, and nocturnal symptoms such as coughing and wheezing. It is important to remember that coughing or gagging may be minimal or absent in a child with a depressed cough or gag reflex. Observation of a feeding is an essential part of the exam when a diagnosis of recurrent aspiration is being considered. Particular attention should be given to nasopharyngeal reflux, difficulty with sucking or swallowing, and associated coughing and choking. The oral cavity should be inspected for gross abnormalities and stimulated to assess the gag reflex. Drooling or excessive accumulation of secretions in the mouth suggests dysphagia. Lung auscultation may reveal transient crackles or wheezes after feeding, particularly in the dependent lung segments.

The diagnosis of recurrent microaspiration is challenging because of the lack of highly specific and sensitive tests (Table 390-2). A plain chest radiograph is the usual initial study for a child in whom recurrent aspiration is suspected.The classic findings of segmental or lobar infiltrates localized to dependent areas may be found (Fig. 390-1), but there are a wide variety of radiographic findings. These findings include diffuse infiltrates, lobar infiltrates, bronchial wall thickening, hyperinflation, and even no detectable abnormalities. CT scans, though generally not indicated to establish a diagnosis of aspiration, may show infiltrates with decreased attenuation suggestive of lipoid pneumonia (Fig. 390-2). A carefully performed barium esophagram is useful in looking for anatomic abnormalities such as vascular ring, stricture, hiatal hernia, and tracheoesophageal fistula. It also yields qualitative information about esophageal motility and, when extended, of gastric emptying. However, primarily because of the very short viewing time, the esophagram is quite insensitive and nonspecific for aspiration or GERD. A modified barium swallow study with video fluoroscopy (video fluoroscopic swallowing study) is generally considered the gold standard for evaluating the swallowing mechanism. This study is preferably done with the assistance of a pediatric feeding specialist and a caregiver in the attempt to simulate the usual feeding technique of the child. The child is seated in normal eating position, and various consistencies of barium or barium impregnated foods are offered. This study is more sensitive for demonstrating aspiration than bedside assessment or a traditional barium swallow study. The sensitivity of the modified barium swallow study is such that it occasionally detects aspiration in patients without apparent respiratory abnormalities.

Table 390-2 SUMMARY OF DIAGNOSTIC TESTS OF ASPIRATION

HRCT: high-resolution computed tomography; VSS: videofluoroscopic swallow study; FEES: fibreoptic-endoscopic evaluation of swallowing; BAL: bronchoalveolar lavage; CT: computed tomography; GERD, gastroesophageal reflux disease.

From Boesch RP, Daines C, Willging JP, et al: Advances in the diagnosis and management of chronic pulmonary aspiration in children, Eur Respir J 28:847–861, 2006.

Figure 390-1 Chest radiograph of a developmentally delayed 15 yr old with chronic aspiration of oral formula. Note posterior (dependent areas) distribution with sparing of heart borders.

Figure 390-2 Chest CT scan of same patient as in Figure 390-1. Note lung consolidation in dependent region is of similar density to subcutaneous fat.

A gastroesophageal “milk” scintiscan offers theoretical advantages over a barium swallow in being more physiologic and giving a longer window of viewing than the barium esophagram for detecting aspiration and GERD. However, this form of study provides relatively little anatomic detail. Another radionuclide scan termed the “salivagram” may also be useful to assess aspiration of esophageal contents. When this scan is performed by experienced personnel, its sensitivity appears to be comparable to that of the modified barium swallow study. The use of fiberoptic endoscopic evaluation of swallowing (FEES) is useful in pediatric patients to observe swallowing directly without radiation exposure. The child’s reaction to placement of the endoscope may alter the assessment of function, depending on level of comfort and cooperation.

Tracheobronchial aspirates can be examined for numerous entities to evaluate for aspiration. For patients with artificial airways, the use of an oral dye and visual examination of tracheal secretions is useful. However, this test should not be done on a chronic basis, such as in tube feedings, due to possible dye toxicity. In using this test acutely, the best method is to place a few drops of dye on the patient’s tongue and perform subsequent suctioning of the airway over the next several minutes. Quantitation of lipid-laden alveolar macrophages from bronchial aspirates has been shown to be a sensitive test for aspiration in children, but false positive tests occur, especially with endobronchial obstruction, use of intravenous lipids, sepsis, and pulmonary bleeding. Bronchial washings may also be examined for various food substances, including lactose, glucose, food fibers, and milk antigens. Specificity and sensitivity of these tests have not been well studied.

Treatment

If chronic aspiration is associated with another underlying medical condition, treatment should be directed toward that problem. The level of morbidity from respiratory problems should determine the level of intervention. Often milder dysphagia can be treated with alteration of feeding position, limiting texture of foods to those best tolerated on modified barium esophagram (usually thicker foods), or limiting quantity per feeding. Nasogastric tube feedings can be utilized temporarily during periods of transient vocal cord dysfunction or other dysphagia. Post-pyloric feedings may also be helpful, especially if gastroesophageal reflux is present. There are several surgical procedures that may be considered. Tracheostomy, although sometimes predisposing to aspiration, may provide overall benefit from improved bronchial hygiene and the ability to suction aspirated material. Fundoplication with gastrostomy or jejunostomy feeding tube will reduce the probability of gastroesophageal reflux-induced aspiration, but recurrent pneumonias often persist because of dysphagia and presumed aspiration of upper airway secretions. Medical treatment with anticholinergics, such as glycopyrrolate or scopolamine, may significantly reduce morbidity from salivary aspiration but often has side effects. Aggressive surgical intervention with salivary gland excision, ductal ligation, laryngotracheal separation, or esophagogastric disconnection can be considered in severe, unresponsive cases. Although usually reserved for the most severe cases, surgical therapy may significantly improve quality of life and ease of care for some patients.