Introduction
Aspiration is the inhalation of liquid or solid particles, particularly food, into the airways beyond the vocal cords. It can be categorised as:
Aspiration Pneumonitis
Chemical injury after aspiration of gastric contents
Aspiration Pneumonia
Infectious process secondary to aspiration of orogastric contents colonised with bacteria
Risk Factors
Pulmonary aspiration usually occurs in patients with altered level of consciousness, dysphagia, or impaired cough reflex.
High Risk Groups
- Patients with oropharyngeal dysphagia (especially post-stroke or cervical spine surgery)
- Older patients (>70 years)
- Patients taking sedative medications
- Patients being fed by gastric tube
- Patients dependent on others for feeding
- Current smokers
- Patients taking >8 medications
- Pregnant women
Prevention in Anaesthesia
- Identify patients susceptible to vomiting/reflux
- Minimise gastric contents before surgery
- Minimise emetic stimuli
- Avoid complete loss of protective reflexes from over-sedation
Clinical Features
Diagnostic Approach
- Primarily based on history and risk factors
- Confirmed by imaging when necessary
Key Symptoms
- Sudden onset of fever, cough, dyspnoea
- Wheezing or cyanosis in at-risk patients
- Bronchospasm in anaesthesia/ICU settings
- May be silent in some cases
Physical Findings
- Crackles on auscultation (72% of cases)
- Respiratory failure from non-cardiogenic pulmonary oedema
- Tachypnoea, hypoxia, confusion
Investigations
Chest X-ray
- Patchy, bilateral airspace consolidations
- Perihilar and basilar distribution
- Right lung more frequently involved
- Pneumonitis: develops within 2 hours, may resolve quickly
- Pneumonia: develops days later, takes weeks to resolve
CT Chest
- Indicated if foreign body aspiration suspected
- Needed if patient fails to improve with initial therapy
- Rules out empyema or lung abscess
Bronchoscopy
- Indicated for particulate aspiration or lobar collapse
- Can clear airway obstruction
- Collects cultures to guide antibiotic therapy
- Particularly useful for non-responders to empirical treatment
Management
Immediate Actions
- Place patient semi-prone with 30° head-down tilt
- Gently suction oropharynx (avoid gag reflex)
- Endotracheal intubation if:
- Risk of further aspiration
- Unable to protect airway (regurgitation, poor cough)
- Respiratory failure present
- Insert NG tube to empty stomach
- Position at 45° head-up after airway secured
Bronchoscopy
Indicated if substantial aspiration (>20-25mL in adults) to:
- Remove gastric fluid/solid material
- Reduce inflammatory reaction
- Prevent lung collapse
- Lessen infection risk
Antibiotic Therapy
- Not recommended initially for pneumonitis (gastric contents sterile at low pH)
- Start empirical broad-spectrum antibiotics if:
- No resolution after 48 hours
- Persistent leukocytosis, fever, infiltrates
- Obtain cultures (sputum/BAL/blood) to guide therapy
- Repeat CXR if non-resolution suspected
Monitoring
- Observe for at least 48 hours (reduced consciousness common)
- Hospital or care facility monitoring required
- Watch for development of bacterial pneumonia