A closer look at the “3 Pillars of Pneumonia”
At this point , all of us are probably familiar with the 3 pillars of pneumonia: 3 factors that need to be considered together when assessing risk for developing aspiration pneumonia in our patients with dysphagia.
According to this theory, which is now widely accepted within and outside of our field, and heavily supported by the literature, aspiration pneumonia occurs only within the context of a serious illness. That is, aspiration alone, does not cause aspiration pneumonia, except in cases in which “the resident immune defenses are insufficient to meet the challenge of bacterial or viral pathogens entering and colonizing the lower respiratory system” (Ashford, 2005).
Furthermore “Whether pneumonia develops from one or more episodes of aspiration depends on the volume of aspirated material, the characteristics of the aspirate (e.g., bacterial load, liquid versus particulate matter, pH level), the frequency of aspiration events, and the integrity of the immune system”
Namely the 3 factors that comprise the 3 pillars of pneumonia are:
- Oral health status: This can be assessed via clinical exam. The use of an oral health screen such as the OHAT is recommended.
- Presence of aspiration: Assessed via VFSS or FEES, as clinical methods are known to be inaccurate and unable to reliably identify aspiration.
- Health Status: Now things get complicated. Determining a patient’s health status requires understanding and knowledge of the patients comorbidities, current, state of health, presence of acute or chronic illness, functional status, medications, etc. As SLPs in the acute care setting, consultation with members of the medical team and/or through review of the patient’s chart (imaging, lab values, etc) are necessary to fully understand the patient’s level of illness and how this can impact their susceptibility to infections.
Effect of Illness on overall health: In the article Pneumonia: Factors Beyond Aspiration, Dr. J. Ashford explains how acute or chronic illness can decrease the host’s ability to fight infection. For instance, in response to severe acute illness, such as CVA, surgery, or trauma (cited in other articles) there is a systemic stress response that leads to changes in HR, O2 intake, glandular secretion, and peripheral blood vessels. Blood flow is directed towards vital organs (i.e. fight or flight response). This also drives changes in the oral and pharyngeal cavities and lower airway that increase colonization of bacteria and impair normal pulmonary clearance. Pulmonary clearance is especially compromised in patients who smoke, leading to decreased ability to clear pathogens from the lower airway.
As a way to re-establish homeostasis the body secretes stress hormones, such as cortisol, which lessen the stress response but also dampen the immune system.
Severe Illness also results in the release of increased numbers of WBC, especially neutrophils, which act as phagocytes in the bloodstream, identifying and destroying bacteria. An increased number of neutrophils would therefore be consistent with infection. If the pt also shows evidence of aspiration, this particular patient is at high risk for developing aspiration pneumonia.
Why? The patient shows evidence of aspiration + has compromised immune system + has poor oral health status due to acute/severe illness.
Effect on muscle function: Acute illness results in weakness of slow and fast twitch muscle fibers. In prolonged illness there is also reduction of muscle mass, protein deficiency, and systemic debility. These patients tend to have poor wound healing, and may present with lethargy and generalized weakness.
Complicated? Yes. But the more we are aware of changes brought on by illness, the better we can help out patients make educated decisions related to feeding and nutrition.