Definition:

The aspiration of oropharyngeal/gastrointestinal contents into the lungs causing inflammation and subsequent bacterial infection.

Cause:

Micro-aspiration is believed to occur in many healthy adults without resulting in infection. However, when the swallow or cough reflex is compromised an increased volume of aspirate may lead to inflammation and damage to lung tissue. This allows infection to occur through colonised oropharyngeal organisms such as Staphylococcus Aureus, Streptococcus Pneumoniae, Klebsiella pneumoniae (more common in alcohol misuse), and enterobacteria (in hospital settings). Infection is more prevalent in nursing home residents and ITU patients.

Risk factors:

• Age- Increased age or residency in a care facility
• Sedation- Medications including opiates and anaesthetics, alcohol excess
• Neurological disease- Acute stroke, Parkinson’s disease, Dementia, Multiple Sclerosis, Motor Neuron Disease, Cerebral Palsy
• Instrumentation- Tracheal intubation, Endoscopy, Enteral feeding
• Learning disability

Clinical features:

Aspiration can be difficult to diagnose as it is often unwitnessed or inconspicuous to the observer. In elderly patients the immune response may be dampened, and resultant pneumonia can present atypically with symptoms such as fatigue, confusion/delirium, and reduced mobility. Symptoms are otherwise representative of those in Community Acquired Pneumonia (CAP) and can include cough, shortness of breath, fever, and chest pain.

Severe infection may lead to sepsis and complications including empyema, lung abscess, and death.

Diagnosis:

A thorough history and Speech and Language Therapy (SLT) assessment should be undertaken in all at-risk groups. Clinical diagnosis of infection follows a similar course to those presenting with features of CAP. Other investigations may include:

1. Chest X-ray: In an upright patient the basal segment of the lower lobe is more likely to be affected. In supine patients the apical segment of the lower lobe is more commonly affected. Infiltrates can be unilateral or bilateral, but the right lung is more commonly affected.
2. Videofluoroscopy (modified barium swallow): This is an X-ray investigation of the mouth, pharynx, and oesophagus after ingesting a harmless barium drink, and carries low risk of complications. They may prove difficult to perform in patients who are unable to stand/sit up or are confused or agitated.
3. Fibre-optic endoscopic evaluation of swallow (FEES): This allows a camera to be passed through the nose to directly visualise the oropharynx and larynx during swallowing and is a valuable addition to the SLT assessment if tolerated.

Prevention and Management:

All at-risk patient groups should have their swallow assessed and managed by an SLT team. Interventions may include changes in the posture of patients, the introduction of thickened fluids, and the provision of feeding support at mealtimes.

Cough adequacy can also be evaluated through Peak Cough Flow (PCF) and cough techniques demonstrated.

Broad-spectrum antibiotics should be prescribed for hospitalised patients with aspiration pneumonia and advice sought from microbiology on local antibiotic choice and resistance.

Learning points:

• In older patients consider Aspiration Pneumonia as a possible cause of delirium, falls, and reduced mobility.
• A proportion of CAP is caused by aspiration and an SLT assessment should be made in all at-risk groups or in those with a history suggestive of aspiration.
• Treatment should be guided by local microbial resistance data.

Author: Stephanie Radoja -Assistant Resuscitation Officer

Date: 7th July 2022

Further reading:

• British Thoracic Society statement on Aspiration Pneumonia 2022
• NICE guidelines: Pneumonia in adults
• BMJ Best Practice: Aspiration Pneumonia