Overview
Aspiration is the inhalation of liquid or solids into the airways. This can be gastric contents or foreign bodies. Aspiration pneumonia most commonly affects the right middle and lower lobes due to the right main bronchus being more vertical.
Aspiration can lead to:
- Obstruction of the respiratory tract
- Chemical irritation of the lungs which may cause acute respiratory distress syndrome
- Bacterial infection
Epidemiology
- More common with advancing age
- Relatively common in hospital
Pathogens
Pathogens seen in aspiration pneumonia are often part of the normal flora of the oropharynx:
- Streptococcus pneumonia
- Staphylococcus aureus
- Haemophilus influenzae
- Klebsiella pneumoniae – more common in alcohol abuse
Risk Factors
- Impaired swallowing e.g. stroke, dementia, multiple sclerosis, Parkinson’s disease, motor neurone disease, epilepsy
- Impaired consciousness
- Substance misuse
- During general anaesthesia
- Hiatus hernia
- Pregnancy
- Obesity
- Gastroparesis
- Head and neck trauma
Presentation
Any patient with a sudden onset of fever and respiratory systems in the presence of risk factors should have aspiration pneumonia considered as a differential diagnosis.
- Systemic upset (fever, nausea and vomiting, headache, anorexia, myalgia)
- Intractable cough
- Dyspnoea
- Pleuritic chest pain
- Purulent sputum
- If severe: hypoxia and septic shock
Signs on examination
Features of sepsis may be present:
- Tachycardia
- Tachypnoea
- Fever
- Decreased breath sounds
- Wheeze
- Dullness to percussion
- Cyanosis
Investigations
Overview
- Chest x-ray:
- This may show consolidation
- X-ray changes may not be present as the aspiration may not yet have led to pneumonia
- Full blood count (FBC) and differential:
- May show leukocytosis suggesting infection
- C-reactive protein (CRP):
- May be raised
- Blood cultures:
- If sepsis suspected
- Chest CT:
- If the patient does not improve with initial treatment
Management
- 1st-line: immediate postural drainage:
- They should be leaning forward with the head tilted slightly down
- Consider suctioning of the oropharynx
- This must be done carefully as stimulating the gag reflex may worsen aspiration
- Consider oxygen should be given if saturations drop
- Consider antibiotics and/or endotracheal intubation and ventilation
- If at-risk may need alternate means of nutrition e.g. nasogastric feeding.
Patient Advice
- To avoid aspiration of gastric contents in patients undergoing general anaesthesia, the following advice is given:
- Clear fluids up to 2 hours preoperatively
- Clear fluids are generally liquids that do not have pulp or suspended particles
- Light meals up to 5 hours preoperatively
- Clear fluids up to 2 hours preoperatively
Complications
- Pneumonia
- Acute respiratory distress syndrome
- Lung fibrosis
Prognosis
- Prognosis depends on the general health of the patient, whether complications are present or not, how quickly the diagnosis is made, and how effective treatment is.
