Authors: David G Smithard / Editor: Charlotte Davies / Codes: IC2, RP5, SLO1 / Published: 01/10/2024
Is it time to ditch ‘Aspiration Pneumonia’ and replace it with ‘Frailty Associated Pneumonia’?
Pneumonia was responsible for 2.5 million deaths worldwide in 2019 and remains one of the commonest reasons for admission to hospital, particularly amongst frail older adults. The aetiological cause of the pneumonia is often not considered and when it is, particularly in the most frail older adults, a speculative diagnosis of aspiration pneumonia is made. Speculative in the sense that the diagnosis is often made with little or no objective clinical or radiological evidence either that aspiration has occurred or that it is the aetiology of the infection. In this blog, I will argue that the time has come to reconsider our terminology for pneumonia in frail older adults.
In discussing the aetiology and terminology of pneumonia in frail older adults there are several factors that need to be considered. These include oral, pharyngeal and lung microbiome, the degree of frailty present of the older adult and the immunocompetence of the patient’s immune system.
There are resident bacteria, virus’ and other organisms within the mouth, pharynx and lungs which are important for health and help set the immune tone. The lungs, contrary to popular opinion are not sterile and have their own resident bacteria as well as playing host to transient organisms entering via the mouth which are then cleared by the cough or ciliary staircase or neutralised via macrophages and epithelial cells via the mucus layer.
Frailty is associated with weight loss, reduced muscle mass, poor muscle quality and fatigue. Fatigue and poor muscle function will result in a reduced cough and reduced ability to clear the airways of any foreign body including bacteria. Frail older adults frequently have a compromised immune system for several reasons. Firstly, frailty and many associated co-morbidities, are associated with a proinflammatory internal milieu resulting in the immune system being in a heightened state which then is not only inefficient but overreacts to any infective insult (inflammaging). Not only is the response to any infection inefficient, there is also an over response resulting in increased inflammation and cell damage with reduced ability to ‘kill’ any organism. This is compounded by two factors, an overactivity of the sympathetic nervous system and an ineffective local immunity, including the diurnal production of mucous production, within the lungs. There is therefore an increased propensity for any invading organism to be successful and cause an infection.
Aspiration is a crucial term and is often accepted as a blanket term, and consideration of the type of aspiration is frequently not considered. Aspiration is defined as the entry of liquid or solid into the airway below the level of the vocal cord. This may be a foreign body such as an inhaled object which may well cause choking, obstruction and death; aspiration of acid during a vomiting episode (Mendelson syndrome) which results in a pneumonitis which may present with hypoxia, tachypnoea, cyanosis and fever but no evidence of infection. Again, the outcome may be death. From a pneumonia point of view the commonest cause, particularly in older frail adults is the aspiration of saliva containing bacteria or viruses. The aspiration of saliva (or food/drink) is not necessarily associated with infection. We all aspirate, particularly when asleep. Infection only occurs when either the bacterial load is very high (poor mouth care) and there is a compromised immune response (immunosuppressants or frailty).
The diagnosis of aspiration as a cause of pneumonia is generally made at the ‘whim’ of the admitting doctor without good supporting evidence when it would be better to make a diagnosis of ‘Frailty Associated Pneumonia’ because the infection is more likely to be associated with the presence of frailty rather than any supposed aspiration. This change of approach is not with out precedent. The stroke fraternity, have for a number of years, referred to the presence of pneumonia occurring after stroke as ‘Stroke Associated Pneumonia’ rather than aspiration pneumonia as it has been recognised the complexity associated with pneumonia far exceeds aspiration alone.
Therefore, I would argue the time has come for clinicians to ‘ditch’ Aspiration pneumonia as a diagnosis and switch to Frailty Associated Pneumonia as a more appropriate and accurate clinical term.
What do you think, and will these considerations affect your management? Put your comments below.


2 Comments
A thorough and most efficient presentation of frailty as a key mechanism to compromise of immune mechanisms in the host and cause of infection in the respiratory tract
Good Blog