Aspiration Syndromes

Cori L. Daines

Pulmonary aspiration is defined as the passage of foreign material or fluid into the lungs during inspiration. Pathologic aspiration events can be divided into 2 main categories: acute and chronic. Acute events include large-volume aspiration of gastric contents, hydrocarbon aspiration, near-drowning, and foreign body aspiration. Chronic events include recurrent, small-volume aspiration of saliva, food, upper airway secretions, or gastroesophageal reflux. Large-volume aspiration events are usually witnessed, but 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).

ACUTE ASPIRATION

ASPIRATION OF FOREIGN BODIES

Airway foreign body aspiration is an important cause of respiratory distress in children, especially those under 3 years of age. 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 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 broncho-scope 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. The details of foreign body aspiration diagnosis, pathogenesis, and management are discussed in detail in Chapter 506.

NEAR-DROWNING

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 leading to pulmonary edema, pneumonia, and sepsis. Most survivors have normal pulmonary function testing in follow up. 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, remains a significant accidental problem, especially in young children (see also Chapter 120). The physiologic effects are dependent on the properties of the hydrocarbon and can consist of central nervous system depression, gastrointestinal irritation with edema or ulceration, cardiac arrhythmias or cardiomyopathy, and pneumonitis. The hydrocarbons with the highest potential of causing aspiration injury are those with low viscosity, low surface tension, and higher volatility. Chest radiograph findings may be present as early as 20 minutes or as late as 24 hours after aspiration. Clinical findings consist of tachypnea, retractions, cough, grunting, and fever.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 as well as treatment of complications as indicated. Most children recover without significant complications, although death does still occur.

LARGE-VOLUME ASPIRATION

PATHOPHYSIOLOGY

The critical volume of aspirate 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 consists of desquamation of the epithelium of the bronchi, bronchioles, and alveoli; edema; and hemorrhage. Repair of the epithelium may require 2 to 3 weeks, but scarring, chronic inflammation with lymphocytes, and even bronchiolitis obliterans may occur.¹⁸

Table 511-1. Risk Factors for Aspiration

CLINICAL MANIFESTATIONS AND DIAGNOSIS

Without a witnessed event, the clinical symptoms on presentation vary depending on the quantity of aspirate and the nature of the aspirate. The symptoms that should raise concern are abrupt dyspnea, fever, cyanosis, hypoxemia and diffuse crackles. Diagnosis is made on the basis of typical symptoms, physical examination, and radiographic findings in an at-risk individual.

TREATMENT

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. Generally, steroids are not recommended.²⁷ Empiric antibiotic use is common, but antibiotics are not helpful unless treating a superimposed bacterial infection. Supplemental chest percussion and postural drainage may be useful if there is atelectasis or pneumonia.

COMPLICATIONS AND OUTCOMES

The most common complication is that of bacterial suprainfection. This complication is seen more frequently in individuals with a predisposing risk factor (Table 511-2). 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. Initial treatment should be with penicillin, ampicillin, and antibiotics geared toward anaerobes. If the aspiration pneumonia has occurred in an individual with significant underlying medical problems, additional treatment with second- or third-generation cephalosporins may be warranted. Mortality rates are about 5% despite best clinical management.

PREVENTION

Prevention revolves around managing the known risk factors. Treatment of gingivitis or tooth decay should occur promptly. 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). Balancing risks and benefits of gastric acid suppression is important because acid suppression may lead to bacterial overgrowth in gastric contents.

Table 511-2. Risk Factors for Superimposed Bacterial Infections in Aspiration

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