Approach
Patients that aspirate will often have a reduced level of consciousness and require close observation for at least 48 hours, either in the hospital or in another care facility. Although some patients may have dramatic signs and symptoms, many are asymptomatic, and infectious complications and acute respiratory distress syndrome (ARDS) can be delayed.[2] A high index of suspicion and prompt action are required if optimum outcomes are to be obtained.
Aspiration pneumonitis
Aspiration of gastric contents
Patients with recent suspected or witnessed aspiration of gastric contents should, whenever possible, be immediately placed semi-prone and tilted to a 30° head-down position. This positions the larynx at a higher level than the oropharynx and allows the gastric content to drain externally. The oropharynx should be gently suctioned, taking care to avoid initiating a gag reflex that may worsen aspiration.[2]
Once the oropharynx has been suctioned, the airway should be secured by endotracheal intubation after rapid sequence induction with cricoid pressure if the patient is deemed to be at risk of further aspiration, is unable to protect their own airway (regurgitation, poor cough reflex), or shows signs of respiratory failure (tachypnea, dyspnea, confusion, cyanosis).[62][63] Once the airway is secured, a nasogastric tube should be inserted to empty the stomach, and where possible the patient can be tilted to a 45° head-up position to help prevent further aspiration.
If a substantial amount of gastric content (>20-25 mL in an adult) is likely to have been aspirated, prompt (within a few hours) bronchoscopy and suctioning can remove aspirated gastric fluid and solid material from the central airways, thereby helping reduce inflammatory reaction, prevent lung collapse, and lessen the risk of subsequent infection.[98] A volume of gastric aspirate >0.3 mL per kilogram of body weight (i.e., 20-25 mL in adults) with a pH <2.5 is believed necessary for the development of aspiration pneumonitis, although aspiration of particulate food matter can cause severe pulmonary damage, even if the pH of the aspirate is above 2.5.[2][99] Animal studies have shown a biphasic pattern to injury, with an initial peak at 1-2 hours after aspiration (direct burn effects) and a second peak at 4-6 hours (related to neutrophil infiltration).[1][2]
Gastric aspirate is sterile under normal conditions due to the low pH, so bacterial infection does not have an important role in the early stages of acute lung injury.[2] Consequently, immediate routine antibiotic therapy is not recommended for aspiration pneumonitis.[2] Even if a patient has fever, leukocytosis, or pulmonary infiltrates, immediate use of antibiotics may be unnecessary and may select resistant organisms in an uncomplicated case of chemical pneumonitis.
The empiric use of antibiotics should, however, be considered depending on the clinical situation (e.g., severe respiratory involvement; severe preexisting lung pathology such as advanced COPD or interstitial lung disease; immunocompromise, including corticosteroid or immunomodulator use, post-transplant immunosuppression, chemotherapy, neutropenia; poor dentition; or the development of lung abscess, necrotizing pneumonia, or empyema).[100] In the context of small bowel obstruction, where there is a high risk of bacterial translocation, bacterial contamination of gastric juice, and sepsis, the initiation of antibiotics should be considered up front and should be adjusted when pathogens are identified.[2] See Small bowel obstruction and Sepsis in adults.
In practice, antibiotics should be initiated based on clinical concern and if the patient is not responding to supportive care. Local microbiology, resistance patterns, and risks for anaerobic infection should be considered when choosing the antibiotic regimen. Culture and sensitivities of samples obtained via bronchoscopy with bronchoalveolar lavage or protected brush specimens, thoracentesis, or blood taken for culture should guide antimicrobial management.[101] Empiric therapy with broad-spectrum antibiotics is recommended if the pneumonitis does not resolve 48 hours after aspiration.[2][102] Antibiotics should be stopped if concern for infection drops and narrowed quickly if a specific pathogen is identified. See Aspiration pneumonia, Community-acquired pneumonia, and Hospital-acquired pneumonia.
Computed tomography (CT) imaging can identify related pathologies indicating a need for antibiotic therapy (e.g., empyema, abscess, necrosis). See Lung abscess, Empyema, Pleural effusion, and Sepsis in adults.
Positive-pressure ventilation with positive end-expiratory pressure can be used in patients who are intubated for airway protection or respiratory failure. However, positive pressure ventilation without a secure endotracheal tube is generally contraindicated in patients with known or suspected aspiration causing respiratory failure. Positive pressure helps to prevent atelectasis and improve the ventilation-perfusion ratio in patients who have aspirated gastric content.[37] However, it is essential that endotracheal suctioning, and if needed, post-intubation bronchoscopy, is performed before positive-pressure ventilation is employed, to avoid forcing aspirated material deeper into the lungs.[35][37] Mechanical ventilatory support should follow lung-protective strategies as per ARDS guidelines. See Acute respiratory distress syndrome.
Respiratory cultures should be obtained from patients on mechanical ventilation, and antibiotics should be initiated immediately because of a high risk of developing ventilator-associated pneumonia.[1] See Hospital-acquired pneumonia.
Aspiration of barium
This usually occurs in the context of upper gastrointestinal radiologic studies.[Figure caption and citation for the preceding image starts]: Bronchoscopy showing barium aspiration in a lung transplant patient in the right mainstem bronchus after a barium swallow studyFrom the collection of Dr Kamran Mahmood [Citation ends].
Bronchoscopy with suctioning, if considered, should be done immediately post-aspiration with the aim to remove any residual barium from the proximal airway and to reduce hypoxemia. Care should be taken to minimize potential spread of barium to unaffected areas from washing or lavage techniques. Owing to the inert nature of barium sulfate, usually no severe long-term harm is to be expected; however, severe pneumonitis and death has been reported in infants, and in older or debilitated patients.[4][24] Infants, older adult patients, and those of any age with significant symptoms, should be admitted for observation if not already hospitalized.
There is no evidence for routinely prescribing antibiotics after barium aspiration, but antibiotics for possible pneumonia are usually considered if infiltrates do not resolve 48 hours post-aspiration.[70] See Aspiration pneumonia.
Corticosteroids
Human studies have shown no improvement in mortality, and the rate of gram-negative pneumonia 5 days after aspiration was higher in patients receiving corticosteroids.[103] Although the infiltrates improve more quickly in the patients given corticosteroids than in those given placebo, patients given corticosteroids might have a longer intensive care unit (ICU) stay.[104][105]
Overall, because of the increased risk for gram-negative bacterial pneumonia and a prolonged stay in the ICU, together with the lack of any mortality benefit, corticosteroids are not indicated in the initial or empiric management of aspiration pneumonitis. They are also not indicated with aspiration pneumonitis that is complicated by acute respiratory distress syndrome.[2] However, corticosteroids may be considered if other indications develop such as in select patients with severe ARDS.[106][107] See Acute respiratory distress syndrome.
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