What is aspiration pneumonia?

It is important to distinguish aspiration pneumonia from aspiration events and aspiration pneumonitis because antibiotic therapy is only needed for aspiration pneumonia. Definitions of aspiration-related terms defines aspiration-related terms and Management of a patient who has had an aspiration event explains the management of patients who have had an aspiration event.

Table 1. Definitions of aspiration-related termsMandell, 2019

Term

Definition

aspiration

The inhalation of foreign material (eg food, vomit, blood, saliva) into the lungs. Impaired consciousness (eg due to trauma, stroke, general anaesthetic, alcohol or drug intoxication) increases the risk of aspiration by compromising the swallowing reflex.

Recurrent aspiration can occur in patients with impaired swallowing or a neurological disorder.

aspiration event

A clear or witnessed episode of aspiration (eg aspiration of vomit during a seizure).

aspiration pneumonitisMetlay, 2019

Acute chemical injury to the lung parenchyma after aspiration of acidic stomach contents (also known as chemical pneumonitis or Mendelson syndrome).

Clinical features can be difficult to distinguish from aspiration pneumonia and diagnostic imaging (eg chest X-ray) can appear similar to pneumonia. However, symptom onset is rapid (usually within hours of aspiration) and improves within 24 to 48 hours, which is the key difference from aspiration pneumonia.

Severity ranges from mild symptoms such as cough or wheeze to severe ARDS.

aspiration pneumoniaSimpson, 2023

A bacterial infection caused by aspiration of bacteria from the oropharynx into the lungs and is more likely to occur in patients with swallowing difficulties (which may not be apparent).

It is common in people with advanced age, a learning disability or a neurological or upper gastrointestinal condition.

It can follow aspiration pneumonitis, particularly in patients taking gastric acid suppression therapy (eg a proton pump inhibitor [PPI]) or with bowel obstruction.

Clinical features suggestive of pneumonia include tachypnoea at rest, tachycardia, persistent fever, rigors, hypoxaemia or crepitations (crackles) on auscultation that do not clear with coughing.

Note:

ARDS = acute respiratory distress syndrome; PPI = proton pump inhibitor

Figure 1. Management of a patient who has had an aspiration event
Prevention of aspiration pneumoniaDefinitions of aspiration-related termsDefinitions of aspiration-related termsCommunity-acquired pneumonia (CAP) in adultsChoosing the right empirical regimen for residents of an aged-care facility with community-acquired pneumonia (CAP)Community-acquired pneumonia (CAP) in children 2 months or olderHospital-acquired pneumoniaPrevention of aspiration pneumoniaInitial management of aspiration pneumoniaManagement of aspiration pneumonia in patients who are not improving on empirical therapy for CAP or HAP
Note:

CAP = community-acquired pneumonia; HAP = hospital-acquired pneumonia

NB1: Aspiration is the inhalation of foreign material (eg food, vomit, blood, saliva) into the lungs. Impaired consciousness (eg due to trauma, stroke, general anaesthetic, alcohol or drug intoxication) increases the risk of aspiration by compromising the swallowing reflex.

NB2: Clinical features of aspiration pneumonitis can be difficult to distinguish from aspiration pneumonia and diagnostic imaging (eg chest X-ray) can appear similar to pneumonia – the key difference from aspiration pneumonia is rapid symptom onset and improvement within 24 to 48 hours. If unable to differentiate aspiration pneumonitis from aspiration pneumonia, see Initial management of aspiration pneumonia.

NB3: For information on aspiration pneumonitis in cases of poisoning (overdose), see Aspiration pneumonitis due to poisoning.

NB4: Empirical therapy (eg doxycycline, azithromycin, clarithromycin) used for its activity against atypical pathogens (eg Mycoplasma pneumoniae, Chlamydophila [Chlamydia] pneumoniae, Legionella species) is only required for aspiration pneumonia in adults if the patient has high-severity CAPSimpson, 2023Neill, 2019.