Chapter 511. Aspiration Syndromes

Pulmonary aspiration is defined as the passage of foreign material or fluid into the lungs during inspiration. Although food or gastric contents are considered the main culprits, anything from saliva to plastic toys can be aspirated. Aspiration of saliva and gastric contents can occur in normal individuals silently, especially at night.1,2 The true hazards of aspiration were not reported in the medical literature until 1946 when Mendelson described the clinical and pathologic findings in obstetric patients who aspirated large-volume gastric contents. He described the “asthmalike” symptoms of these patients and then showed in animal models that acidic material, with pH less than 2.5, caused inflammation, damage, and desquamation of the mucosa in the lungs.3 Pathologic aspiration events can be divided into 2 main categories: acute and chronic. The acute events include large-volume aspiration of gastric contents or other fluid, hydrocarbon aspiration, near-drowning, and foreign body aspiration. The chronic events include recurrent, small-volume aspiration of saliva, food, upper airway secretions, or gastroesophageal reflux. Large-volume aspiration events are usually witnessed and can be directly addressed. Recurrent small-volume aspirations are often silent and more difficult to diagnose and manage. It is important to recognize the risk factors to properly diagnose aspiration (Table 511-1).

Aspiration of Foreign Bodies

Airway foreign body aspiration is an important cause of respiratory distress in children, especially those under 3 years of age. It is during this time that children become more mobile and have a tendency to put objects in their mouths. Food is the most common foreign body found in the airways of toddlers, while nonfood items are more common in older children and adolescents.4 Presenting symptoms include cough, wheeze, shortness of breath, and fever, sometimes temporally associated with a witnessed episode of choking. The diagnosis may be confused with pneumonia, asthma, bronchiolitis, or croup. Radiographs may show unilateral hyperinflation, mediastinal shift, atelectasis, or pneumonia, but they may be normal. When the airways are examined, the foreign object is often lodged in the bronchial airways, with the right-sided bronchi being the most common location. The object should be removed with rigid bronchoscopy, which maintains control of the airway and facilitates ventilation. Although fiberoptic bronchoscopy can examine more distal areas of lung, the inability to ventilate and maintain airway patency with a flexible fiberoptic bronchoscope renders this procedure inadequate for foreign body removal. Complications, especially if the object has been present for a long time, may include pneumonia, abscess formation, bronchiectasis, or granulation tissue in the airway. Most cases can be readily treated, but a high index of suspicion is necessary to prevent complications. The details of foreign body aspiration diagnosis, pathogenesis, and management are discussed in detail in Chapter 506.

Near-Drowning

Drowning is an important cause of death in children, with the peak incidences in the 0- to 4-year and 15- to 19-year age ranges.5 Near-drowning is estimated to occur 3 to 10 times more commonly than drowning, and pulmonary sequelae are common.6 Most children with near-drowning aspirate water into their lungs.7 The consequences of this aspiration vary depending on the material aspirated and range from pulmonary edema, the most common consequence, to pneumonia, allergic reactions to particulate matter, and sepsis.8 The tonicity of the fluid aspirated also impacts the pulmonary pathophysiology; hypotonic but not fresh water is the least injurious, most readily absorbed, and least likely to disrupt surfactant function.9 Even though pulmonary function testing in follow up. of adult victims of near-drowning has been normal,10 a small study in children showed a majority with abnormal methacholine challenges and abnormal small airway function.11 The details of near-drowning pathogenesis, management, and outcomes are discussed in Chapter 117.

Hydrocarbon Aspiration

Aspiration of hydrocarbons, including solvents, paints, paint removers, turpentine, and petroleum distillates (gasoline, kerosene, mineral seal oils, furniture polish, and lighter fluid), remains a significant accidental problem, especially in young children. As in foreign body aspiration, young children are mobile and likely to orally sample fluids left in accessible spaces in accessible containers. The physiologic effects are dependent on the properties of the hydrocarbon and can consist of central nervous system depression (confusion, weakness, seizure, coma), gastrointestinal irritation with edema or ulceration, cardiac arrhythmias or cardiomyopathy, and, most commonly, pneumonitis. Systemic toxicity, particularly with central nervous system depression, occurs most readily with highly volatile hydrocarbons because they are readily absorbed from the lungs into the circulatory system. The hydrocarbons with the highest potential of causing aspiration injury are those with low viscosity, low surface tension, and higher volatility. This allows for easier penetration of the hydrocarbon deep into the tracheobronchial tree and easier spread over a greater surface area. Hydrocarbons directly injure the respiratory system through aspiration, either on the initial exposure or on subsequent emesis. The pulmonary capillary bed then removes the hydrocarbon.12 Pathology of the lungs can show necrosis of the bronchi, bronchioles, and alveoli with hemorrhagic edema, interstitial inflammation, atelectasis, and hyaline membrane formation.13 Chest radiograph findings may be present as early as 20 minutes or as late as 24 hours after aspiration. Often, there are patchy infiltrates initially, and they become more prominent before improving. Pneumothoraces or pneumatoceles may occur. Clinical findings consist of tachypnea, retractions, cough, grunting, and fever and may be present early or develop over the first 12 hours after aspiration.14 It is important to observe children for at least 6 to 8 hours after a suspected aspiration, to follow serial chest radiographs, and to admit any child with respiratory symptoms or abnormal chest films for observation. There is a risk for secondary aspiration with emesis of material with hydrocarbons, so inducing emesis in these children should be avoided.15 Management is supportive with oxygen or mechanical ventilation as needed as well as treatment of complications of secondary bacterial pneumonia or pneumothorax as indicated. Most children recover without significant complications, although death does still occur. In terms of long-term pulmonary sequelae, one study showed over 80% of children who had had a hydrocarbon aspiration had at least 1 abnormality on subsequent pulmonary function testing.16 The most important management is prevention of accidental ingestion and aspiration by promoting safe storage of hydrocarbons.

Large-Volume Aspiration

These events are acute, generally witnessed aspirations in at-risk individuals. The pathologic changes depend on the nature and volume of material aspirated.

Pathophysiology

Based on animal studies, exposure to acid, of pH less than 2.5, greater than 1.0 mL/kg volume is enough to cause the pneumonitis typical of aspiration.3 The critical volume seems to be 0.8 mL/kg to cause pneumonitis,17 although acidic or caustic materials can cause damage with less volume than more neutral fluids. This pneumonitis is the same as that seen with near drowning and consists of desquamation of the epithelium of the bronchi, bronchioles, and alveoli; edema; and hemorrhage. There is a secondary infiltrate of neutrophils and fibrin around the alveoli with resulting atelectasis. Within 48 to 72 hours, hyaline membranes begin to form, and fibroblasts start to proliferate in an effort to repair. Repair of the epithelium may require 2 to 3 weeks, but scarring, chronic inflammation with lymphocytes, and even bronchiolitis obliterans may occur.18

Clinical Manifestations and Diagnosis

The diagnosis of large-volume aspiration is usually apparent, with a witnessed aspiration event. Without a witnessed event, the clinical symptoms on presentation vary depending on the quantity of aspirate and the nature of the aspirate. Mendelson’s classic description of aspiration pneumonitis can occur and consists of respiratory distress and cyanosis within 2 hours of the event.19 The symptoms that should raise concern are presented in eTable 511.1.20 Diagnosis is made on the basis of typical symptoms, physical examination, and radiographic findings in an at-risk individual. If bronchoscopy is done, it may show erythema of the airway, indicating injury from the aspiration.21

Treatment

If the material aspirated was particulate, flexible or rigid bronchoscopy may be useful to remove the particulate matter; otherwise, the management is largely supportive. Once the aspiration event has occurred, the airway epithelial damage is present, like a burn. There is no way to neutralize the acid to prevent injury.18 If the material aspirated was particulate, flexible or rigid bronchoscopy may be useful to remove the particulate matter; otherwise, the management is largely supportive. Supplemental oxygen for hypoxemia, mechanical ventilation for respiratory failure, and intravenous fluids to support vascular volume are all indicated. The use of systemic corticosteroids in both animal models and human trials of aspiration pneumonitis has had mixed results.22-26 Generally, steroids are not recommended.27 Empiric antibiotic use in aspiration pneumonitis is common but has not been rigorously evaluated. Good outcomes have been reported in patients who did not receive antibiotics,28 but given the reported rates of bacterial suprainfection as high as 50%19 and the difficulty assessing whether infection is a contributing component, antibiotics are commonly used. A general rule is that antibiotics are not necessary until signs or symptoms of superimposed bacterial infection are present. Supplemental chest percussion and postural drainage may be useful if there is atelectasis or pneumonia. Drainage of pleural effusions or empyemas is indicated.

Complications

The most common complication is that of bacterial suprainfection. Clinically, some children have increased or new fever, worsening respiratory symptoms with cough, wheeze, crackles or respiratory distress, increased leukocytosis, or new findings on chest radiograph. This complication is seen more frequently in individuals with predisposing risk factors (Table 511-2). The source of bacteria is typically the mouth but might also be stomach contents. Organisms vary by age, underlying condition, and prior antibiotic use and are presented in Table 511-3.29-32 Initial treatment should be with penicillin, ampicillin, and antibiotics geared toward anaerobes. Clindamycin and metronidazole may be used in conjunction with penicillin to improve its efficacy.33 If the aspiration pneumonia has occurred in an institutionalized individual or one with significant underlying medical problems, including long-term antibiotic use, additional treatment with second- or third-generation cephalosporins may be warranted. Immunocompromised children may need very broad antibiotic coverage until cultures are able to guide specific therapy.

Outcomes

In Mendelson’s original description of aspiration pneumonitis, the patients generally recovered within a week without significant functional disability.3 Subsequent studies, mainly in the elderly, showed much higher mortality rates of 40% to 80%.34 This difference was likely attributable to the initial observations having been made in young, healthy, pregnant women without comorbid conditions, whereas the subsequent studies were in a more elderly, debilitated population. The most recent studies report a much smaller mortality rate of 5%, probably because of advances in clinical management.28 Survivors who experience acute respiratory distress syndrome are likely to also experience more long-term sequelae from the aspiration event.

Prevention

Prevention of large-volume aspiration events or their complications revolves around managing the known risk factors. Treatment of gingivitis or tooth decay should occur promptly, especially in otherwise high-risk children (institutionalized, neurologically abnormal). In hospitalized patients, endotracheal tubes or enteral feeding tubes should be removed as soon as medically feasible. Maintaining low gastric volumes may help prevent gastroesophageal reflux (GER). Use of acid-suppressing medication will raise the gastric pH and facilitate bacterial growth in the stomach, increasing the potential of injury with aspiration. Unfortunately, many of these children are at risk for peptic or duodenal ulceration, and acid suppression may be warranted. Balancing risks and benefits of gastric acid suppression is important.

Recurrent or chronic pulmonary aspiration (CPA) describes the recurrent passage of food, gastric contents, or saliva into the airway, resulting in symptoms such as cough, wheeze, choking, pneumonia, or lung damage.35-40 CPA may occur only sporadically in some children, when other stressors, such as upper respiratory tract infections, are also present. Often, more than 1 mechanism of CPA is present, complicating diagnosis and management. Because it is known that small amounts of saliva and gastric contents may be aspirated in normal individuals1,2, it is often difficult to determine if CPA is causing lung disease. The 3 main mechanisms of CPA are (1) swallowing dysfunction resulting in the direct aspiration of food, (2) GER and aspiration, and (3) failure to protect the airway from oral secretions, resulting in the aspiration of saliva and oral contents. These mechanisms are discussed separately in terms of their pathophysiology, clinical features, diagnosis, and treatment. Complications and outcomes are addressed globally.

Aspiration Due to Swallowing Dysfunction

Normal swallowing is a complex activity that involves a multitude of voluntary and involuntary actions. It can be divided into 3 phases. In the oral phase, food is mixed with saliva and ground to an appropriately sized bolus by the voluntary action of mastication. The tongue must compress the bolus against the hard palate to cause the bolus to pass into the oropharynx. In the pharyngeal phase, the tongue opposes the palate and the soft palate opposes the pharynx to prevent regurgitation of the bolus into the mouth or nose. The larynx elevates and the glottis closes at both the false and true cords to prevent aspiration of the bolus into the airway. The pharyngeal constrictors then contract sequentially and reflexively to propel the bolus into the esophagus. At the cricopharyngeus muscle, there is a short relaxation of the upper esophageal sphincter, due to elevation of the larynx, that allows the bolus to be passed into the esophagus. The subsequent contraction of the cricopharyngeus muscle then serves to propel the bolus into the esophagus, starting the esophageal phase. In this phase, the peristalsis continues down the esophagus, reaching the lower esophageal sphincter. This sphincter relaxes about 2 seconds after the initiation of swallowing and stays relaxed for 8 to 10 seconds. Once the peristaltic wave reaches it, it also contracts and returns to its natural tone after 10 to 15 seconds. Any abnormality in the complex sequence of events can result in aspiration. Swallowing dysfunction occurs most frequently in individuals with neurologic disorders or any of the predisposing factors listed in Table 511-1, but it should be considered in any child with suspicious symptoms.

Pathophysiology and Clinical Manifestations

Typical symptoms of aspiration due to swallowing dysfunction include coughing, wheezing, choking, and gagging that is temporally related to the intake of food. It may be intermittent, occurring only at times of stress such as during upper respiratory tract infections; it may be positional, and it often changes over time with growth and development. Unfortunately, direct aspiration of food can also be silent, especially in neurologically compromised children, so it is important to have a high index of suspicion. Repeated bouts of direct aspiration can lead to significant morbidity from recurrent bronchitis or pneumonia and bronchiectasis as well as chronic hypoxia and dyspnea. Left untreated, children can die from respiratory failure.

The pathophysiology of lung damage arises from the inflammatory cascade triggered by the aspiration. Levels of interleukin-8 and tumor necrosis factor-α are increased, and there is a significant neutrophilic migration to the site of aspiration with subsequent activation and sequestration of the neutrophils. This leads to epithelial damage, increased permeability, decreased compliance, and, over time, scarring.41 There is no difference in the extent of neutrophilic infiltration between acidic (from stomach acid) and neutral (direct aspiration) aspirated food.42

Diagnostic Evaluation

The approach to the evaluation and treatment of children with swallowing dysfunction is discussed in detail in Chapter 31.

Aspiration of Gastroesophageal Reflux

GER occurs occasionally in almost everyone when food mixed with gastric contents moves in a retrograde manner from the stomach through the lower esophageal sphincter into the esophagus. It is common in infants under a year old, but it is rarely pathologically symptomatic (see also Chapter 394). It is also common, often pathologically, in the individuals listed in Table 511-1. Anything that reduces lower esophageal sphincter tension, such as medication, tubes, and anatomic lesions, increases the likelihood of GER. Even direct feeding into the stomach via gastrostomy, especially at night, increases the likelihood of reflux.

Pathophysiology and Clinical Manifestations

Acid is irritating and induces inflammation in the airway.3,18 Even aspiration of materials with a pH higher than 2.5 induces pneumonitis in an animal model.75 This would indicate that when aspiration of gastric contents occurs regularly, pulmonary disease ensues. There is evidence that GER is associated with respiratory symptoms such as cough, wheeze, pneumonia, and apnea.76-78 There is also evidence of an association of GER with lung disease, documented by improvement in pulmonary symptoms with treatment of GER.78 A causal relation between GER and respiratory symptoms due to aspiration is much more difficult to prove.79-81 We know that stimulation of esophageal receptors by GER can cause reflex bronchospasm, cough, and wheeze without actual aspiration of GER.82 Two small studies in adults simultaneously measured pH in the esophagus and the trachea to prove a temporal relation between drop in pH in the esophagus and drop in pH in the trachea and respiratory symptoms, including decreased peak flow measurements.83,84 One documented that laryngeal exposure to acid decreases the sensation of the larynx, diminishing its ability to defend against aspiration, so chronic GER without aspiration may eventually lead to GER with aspiration.85 Our challenge is to determine when GER is pathological and when aspiration in occurring.

Diagnosis

The gold standard for diagnosing GER has been 24-hour esophageal pH monitoring. The upper gastrointestinal series or barium esophagram has also been a test to determine the presence of GER. Neither of these tests determines aspiration. Flexible bronchoscopy with bronchoalveolar lavage or gastroesophageal scintigraphy are often also necessary.

Esophageal pH or Impedance Monitoring

Esophageal pH monitoring is considered the gold standard for detecting GER. Most studies are done with 2 pH channels, one just above the lower esophageal sphincter and the other in the posterior pharynx. It detects drops in pH, indicating the presence of acid from the stomach at those 2 levels. Done over 24 hours, it is a reasonable test of GER of acid. It cannot, however, detect nonacid reflux or acid reflux events that occur after a pH drop but before pH normalization. Because of its limitations, it must be performed in individuals who are not on acid suppressive medication.86,87

Multichannel intraluminal impedance with pH monitoring (MII-pH) is a newer technique that has certain advantages of traditional pH monitoring. It can measure the change in electrical impedance along the length of the esophagus. It can track the movement of gas or liquid boluses, both anterograde and retrograde; detect both acid and nonacid liquid boluses; determine if the bolus is being swallowed or refluxed; and determine how high along the esophagus the bolus moves.88 It is better able than pH monitoring to detect pharyngeal-level reflux,89-91 and in one study in infants, it detected a large number of events that correlated with respiratory symptoms on sleep study, only 12% of which were acid.89 Unfortunately, MII-pH is not yet widely available due to startup costs and technical support for the procedure.

Both studies will diagnose GER, but neither study, even with pharyngeal channels, can detect aspiration. These studies must be used in conjunction with direct evidence of aspiration.

Upper Gastrointestinal Series/Barium Esophagram

This simple test detects the presence of reflux of swallowed barium. Its advantages are that it is simple, inexpensive, and quick. It also detects certain anatomic lesions such as vascular rings and malrotation. Unfortunately, it captures GER only if GER happens to occur during the study, and it cannot quantify GER. Once again, it can detect GER, not aspiration, and must be used in conjunction with direct evidence of aspiration.

Flexible Bronchoscopy with Bronchoalveolar Lavage

As mentioned previously, the use of LLMI obtained during bronchoscopy is used most often as evidence of aspiration due to GER. Finding lipid, however, in the lower airways does not help determine whether the lipid came from GER or from direct aspiration due to swallowing dysfunction. Using alternative markers of GER aspiration is a topic of significant research. In recent years, pepsin has been studied and found to have good correlation with respiratory symptoms when found in the airways.92-95 Having a marker specific to GER versus food would help distinguish between direct aspiration and aspiration of GER. Currently, bronchoscopy results must be used together with other evidence of GER, absence of swallowing issues and clinical findings to formally diagnose aspiration of GER.

Gastroesophageal Scintigraphy/“Milk Scan”

This study has been used as a physiologic means of determining aspiration of GER.96 Technetium Tc99 is mixed with a child’s milk or food and the child is allowed to eat. Serial radiologic images are then captured to detect tracer in the lungs. Unfortunately, this test does not clearly distinguish between aspiration from swallowing and aspiration from GER. It also seems to have a low sensitivity.96-99 In one study, positive scans were found in only 6% of children with cerebral palsy, a group of children who have a much higher prevalence of aspiration, based on VSS and salivagrams. This test, however, is much less invasive than bronchoscopy and does not require a great deal of radiation, allowing multiple uses if necessary. In children with a gastrostomy, it can distinguish between GER and swallowing dysfunction if the radiotracer is given via tube.

Dye Studies

In the case of aspiration of GER, dye studies are only helpful if the child has a gastrostomy or jejunostomy and a tracheostomy tube. Dye can be mixed with tube feedings and detected with tracheal suctioning. If aspiration is seen, it is accurate and helpful. If not, it may be falsely negative.

Treatment

Medical treatment of GER is the first line of treatment. This includes the use of thickened feeds, which has been shown to decrease nonacid reflux events by MII-pH.100 Pharmaceuticals include histamine blockers, such as ranitidine and famotidine, and proton pump inhibitors, such as omeprazole. Acid blockade makes gastric contents more neutral, decreasing their toxicity to the airway if aspirated, but it does not prevent aspiration of GER. Prokinetic agents are also used, but choices in the United States are limited, and effectiveness is questionable. Metoclopramide has not had widely proven efficacy and has side effects that may limit its use.101 Erythromycin is also used, at both antimicrobial and low-dose options mainly in infants, with mixed results but without significant side effects.102-105 It has had some efficacy on antral gastric motility.106 Domperidone is available as a promotility agent outside of the United States, but it also has not been demonstrated to be clearly effective against GER.107 No pharmacological agents have been tested specifically against aspiration.

For children who have failed medical therapy, fundoplication is the surgical option of choice. Generally, fundoplications are successful with good outcomes, but surgical complications are still possible. When fundoplications are too tight, they can impede movement of food, liquid, and saliva into the stomach, leaving it in the distal esophagus and increasing the likelihood of aspiration. Improvement of pulmonary symptoms with fundoplication occurs in 48% to 92% of children.108-111 Recurrence of GER occurs in approximately 10%, but in most cases, repeat fundoplication can be performed successfully.110−115 Children with neurologic disorders have a higher rate of failure of fundoplication, approximately 25%.108,110,112 These are the same children who are at higher risk for from aspiration, so reevaluation for GER is warranted if symptoms persist. Evaluation for complicating pathology, including dysmotility and eosinophilic esophagitis, should be performed before fundoplication because these children are most likely to have complications such as retching and failure to improve from surgery.

In children who have failed fundoplication, or who have contraindications to fundoplication, another option is feedings into the jejunum.116,117 Placement of a surgical jejunostomy will allow for full feeds with reduced risk of GER and aspiration. Aspiration of gastric secretions is still possible. If temporary feeding into the jejunum is necessary, placement of a nasojejunal tube or gastrojejunal tube is possible, but these tubes obstruct the pylorus and/or lower esophageal sphincter, impeding passage through these openings. They are also prone to displacement, requiring radiologically guided replacement. All jejunal feedings must be done as a continuous drip, and jejunal tubes carry the risk of inducing intussusception.

A final option in extreme cases where other options have all failed is esophagogastric separation with permanent gastrostomy tube for feeding and esophageal drainage into the jejunum.118,119 Unfortunately, even with this procedure, there seem to be complications because a high number of these children appear to mishandle their oral secretions, aspirating these instead of gastric contents.

Salivary Aspiration

Aspiration of saliva is the most insidious type of aspiration. Some nocturnal aspiration of saliva can occur in healthy individuals,2 so understanding when aspiration of saliva is pathological is key to prevention of complications. Recognizing symptoms and having a high index of suspicion, especially in high-risk children (Table 511-1), will help prevent poor outcomes.

Pathophysiology and Clinical Manifestations

The clinical symptoms of aspiration of oral secretions include choking and gagging as well as chronic or intermittent cough and wheeze and recurrent pneumonia. Additionally, these children often have sialorrhea with drooling and pooling of saliva in the mouth. They often have overt choking on their saliva and may improve when positioned so saliva runs out of the mouth. Many of these children are developmentally delayed, although cranial nerve palsies, vocal cord paralysis, laryngoesophageal cleft, and craniofacial abnormalities also lead to inability to handle saliva appropriately. In these children, their swallowing is severely dysfunctional, not allowing them to swallow saliva appropriately, and their laryngeal sensation is abnormal, not allowing them to protect their airway adequately.120 Saliva contains bacteria and yeast that are potentially pathological to the lungs if aspirated in large enough quantities or frequently. Recurrent pneumonia or even pulmonary abscesses are possible.31 Aspiration of oral secretions, not inflammation due to food or gastric acid, is the main source of lung damage. Unfortunately, children who aspirate oral secretions are likely to also aspirate food and to have pathologic GER. Evaluation for salivary aspiration may need to occur simultaneously with evaluation for other types of aspiration.

Diagnosis

In children with suspected aspiration and either treated or absent GER, who are being fed parenterally, these diagnostic tests are essential. In children with potentially confounding causes of aspiration, these tests may be necessary or should be performed concomitantly with others to rule out other forms of aspiration.

Radionuclide Salivagram/“Spit Scan”

This test is often considered the gold standard for detection of salivary aspiration. Its accuracy, however, has not been evaluated. Similar to gastroesophageal scintigraphy, this test involves using a small amount of radiotracer placed on the tongue, in the buccal pouch or as a continuous infusion.121,122 Subsequent detection in the lower airways or lungs can diagnose aspiration of the oral secretions. The test is usually readily available and often used because of its simplicity, noninvasive nature, nonreliance on oral feeding, and low radiation exposure.

Studies have shown positive salivagrams in 26% to 28% of children suspected of aspirating oral secretion, but none of these studies had any confirmatory tests, most being done prior to use of FEES.123-125 This test also has poor agreement with VSS and milk scan,99 but it has been used successfully in one case to titrate nocturnal tracheal positive pressure.126 There is no doubt that the salivagram can detect salivary aspiration. It appears, however, that many children who might, at least intermittently, aspirate their saliva are missed with this test.

Fees with Sensory Testing (Feest)

As mentioned previously, FEES allows direct visualization of the larynx with observation of the swallowing mechanism without feeding. Pooling of secretions and penetration or aspiration of oral secretions can be seen with a small amount of dye added to the secretions. Sensory testing involves graduated puffs of air delivered to the larynx to determine the threshold necessary to induce protective laryngeal reflexes and can help distinguish those at risk for aspiration. There is good evidence that this testing can predict the tendency toward aspiration without giving the child a feeding.46,127-130

Dye Studies

In assessing salivary aspiration in a child with a tracheostomy, dye is placed on a child’s tongue and detected by suctioning stained secretions from the tracheostomy. Its sensitivities and specificities are similar to those when dye is mixed with oral or tube feedings; if aspiration is seen, it is accurate, but false negatives occur regularly.

Treatment

The first line of therapy for aspiration of saliva is pharmacological to reduce salivary flow. Some studies have evaluated behavioral modification to control drooling, with positive results, but none of these actually decrease salivary flow.131,132 Salivary flow reduction can be accomplished by anticholinergics. Glycopyrrolate administered orally at a dose of 0.04 to 0.1 mg/kg/dose will reduce saliva but may have diminishing effects, the longer a child takes it.133 Glycopyrrolate is also associated with anticholinergic side effects such as flushing, urinary retention, constipation, behavior changes, and mucus plugging that may make some children stop taking it.133-135 Mucus plugging is the most concerning because it may cause respiratory distress or even be life threatening. Using antihistamines such as cetirizine for drooling has had anecdotal success. Scopolamine patches tend to be more successful than antihistamines, with few side effects.136,137 Because treatment is usually accomplished with a patch, titration can be difficult. Generally, a single patch is applied every 72 hours, although partial patches have also been tried. No studies have shown that medical treatment actually prevents aspiration or resultant lung damage even though it reduces salivary flow.

Botulinum toxin injection into the salivary glands can paralyze the glands and reduce saliva production. All studies of this therapy have demonstrated improvement of sialorrhea, but length of response varies.138-140 There does seem to be a need for repeat therapy as the toxin wears off; no long-term studies of efficacy of repeated doses have been done. There has not been any study of the impact of botulinum toxin injection on aspiration or lung disease.

Surgical options include ligation of salivary ducts or removal of certain salivary glands. This therapy can serve to permanently decrease salivary flow. Ligation of the ducts of the parotid and submandibular glands or excision of the submandibular glands and ligation of the parotid ducts has been used with good success in children.141-144 Two studies have also shown a reduction in hospitalizations and lower respiratory tract infections in children who have undergone the procedures.141,143 Prospective studies and comparisons with other techniques such as botulinum injection still need to be assessed.

Another option is insertion of a tracheostomy tube. This alone does not decrease salivation and cannot prevent aspiration. It does allow for suctioning of aspirated saliva to hopefully prevent pneumonia. Some children who aspirate saliva require tracheostomy for upper airway obstruction and other reasons. There is evidence that swallowing is affected in children with tracheostomy,145,146 which may make children more prone to aspiration. If a child is placed on positive pressure ventilation, aspiration may be less likely because of the positive pressure in the lower airway impeding passive influx of saliva.

The definitive treatment for salivary aspiration is physical separation of the upper airway from the lower airway.147-150 This is accomplished by a separation of the larynx from the trachea with the trachea diverted to a permanent stoma. A complete laryngectomy may also be performed. This surgery will prevent aspiration of saliva and may allow for oral feedings, but it will prevent phonationand may not be reversible. It should be considered in children with intractable aspiration who are experiencing progressive lung damage or life-threatening pneumonias.

Radiographic Diagnosis of Recurrent Aspiration

Radiographic testing is not diagnostic of recurrent pulmonary aspiration and cannot distinguish among the types of aspiration. It can, however, give evidence of pulmonary inflammation or damage and help us to assess the pulmonary impact of the aspiration.

Chest Radiograph

Often, baseline radiographs from children who aspirate are nonspecific. They may show peribronchial thickening, atelectasis, scattered infiltrates, or hyperinflation. In advanced cases, bronchiectasis may also be present. Radiographs obtained during acute aspiration pneumonia are more likely to show active disease with segmental or lobar infiltrate, especially in dependent areas of the lung (Fig. 511-1).

High-Resolution Computed Tomography of the Chest

High-resolution computed tomography (HRCT) scanning gives more precise information about lung damage than do plain radiographs (Fig. 511-2). These scans demonstrate the detail of bronchiectasis, “tree-in-bud” opacities, and air trapping more clearly.151-153 These findings are often seen in children who aspirate, especially in dependent portions of the lung. Findings may be present before clinical symptoms of chronic lung disease are present, so obtaining an HRCT should be considered in most children with potential CPA. Any single HRCT is a single point in time. Serial HRCT can follow progression or resolution of lung damage with time and interventions. High-resolution technique is preferred because it provides more detail.

Treatment of Acute Small Volume Aspiration

As in large-volume aspirations, small-volume aspirations of gastric material and food, although irritating, are sterile and do not require antibiotics. Aspiration must be treated acutely when symptoms are present. As in large-volume aspirations, small-volume aspirations of gastric material and food, although irritating, are sterile and do not require antibiotics. The children may require supportive care, such as suctioning, oxygen, or bronchodilators, to treat bronchospasm for hours to days after the event. These aspirations may be witnessed and involve vomiting or choking on food. Close monitoring is warranted to ensure a secondary bacterial infection does not occur, especially in children with bronchiectasis or tracheostomies or with other risk factors, who may have lower airway colonization with bacteria (Table 511-2).

Aspiration of oral contents may, instead, result in aspiration pneumonia from aspiration of pathogenic bacteria from the upper airway. These may include anaerobes, common mouth flora, or secretions from the nose, ears, and sinuses containing common upper respiratory pathogens. Children with true aspiration pneumonia may have fever, persistent cough, and wheeze in addition to acute respiratory distress. Treatment should be supportive, as described previously, but also should include antibiotics to cover common upper respiratory pathogens (Table 511-3).

Complications of Recurrent Aspiration

The long-term complications of aspiration include chronic disabling symptoms associated with airway inflammation such as chronic cough and wheeze. Recurrent bacterial pneumonias occur in the inflamed airway that has altered host defenses. Pneumonias can lead to lung damage and bronchiectasis. Bronchiectasis manifests as dilated, chronically inflamed airways characterized by impaired mucus clearance. Subsequent infections in these airways lead to pulmonary fibrosis and scarring with respiratory insufficiency. The ultimate complication is death from overwhelming aspiration pneumonia. Potential complications from therapy include inadequate nutritional intake and malnutrition, intolerance to tube feeds, or worsening of GER with subsequent aspiration. Growth and development must be carefully monitored in children who cannot consume all calories orally. Medications and surgeries also have potential complications, so no therapy should be instituted without considering the risks versus the benefits, as well as the impact on the child’s quality of life.

Outcomes of Recurrent Aspiration

Outcomes are dependent on the successful, early institution of therapy. If aspiration of food, liquid, and saliva is prevented, the symptoms of airway inflammation and lung damage can also be prevented. Airway inflammation is reversible, and some bronchiectasis may also be reversible, significantly reducing the morbidity and mortality. Alternatively, when aspiration is allowed to continue, the outcome is usually progressive lung damage, respiratory insufficiency and disability (chronic oxygen dependency), and occasionally death from overwhelming pneumonia.