ARDS and Dysphagia (Part 2): A Vicious Cycle
By George Barnes, Dr. James Coyle, and Kelsey Day
The pronoun “I” and “me” will often be used during this series, but the words represent the work and knowledge of all three authors.
Missed Part 1? Check it out here to get caught up.
COVID-19 has been receiving A LOT of attention. It’s novel. It’s different. It’s COMING! We, as SLPs, are curious. So we ask questions. What’s different about COVID? Which new management strategies should I use? How do I combat this strange alien life form (ok, maybe that last one’s just me)? Though well-intentioned, these types of questions have created an echo chamber of fear and confusion. Especially since most of them have already been answered long before COVID.
The most unique part of COVID is that it has made so many people sick at the same time, ultimately suffocating the medical team’s time and resources. This goes for SLPs as well. Many of us have been thrown into the mix without warning; managing complex cases we were not prepared for. But this has only strengthened our skills, our position on the critical care team, and our resolve to improve and protect life. We have proven that our expertise in managing dysphagia and our understanding of the risk factors that lead to pneumonia is essential to providing comprehensive, effective care.
It’s not COVID you fear, it’s ARDS
The scariest part of COVID is that it may lead to ARDS. ARDS can be defined by the insufficiency of the pulmonary system to perform gas exchange in the absence of heart failure, leading to hypoxemia, and in severe cases, death (Rawal et al., 2018). It is typically managed with mechanical ventilation or other high levels of respiratory support to prevent intubation. It’s a combination of the causes, effects, and treatment of ARDS that negatively impacts pulmonary function and the ability to swallow. In order to manage dysphagia in ARDS, we must understand these factors.
ARDS raises the stakes
Pneumonia and aspiration are listed as two of the top four precipitating factors of ARDS. Further, the likelihood of survival after ARDS is directly related to the quality of supportive care (Matthay et al., 2012). This raises the stakes for us. By controlling the risk factors associated with aspiration pneumonia, we can manage the risks of developing ARDS and improve the chances of recovery.
Aspiration is a major risk factor for pneumonia and pneumonitis (McGinnis et al., 2019). However, aspiration by itself is arguably harmless. 50% of us aspirate every day without any impact on our health (Kollmeier & Keenaghan, 2020). Depending on the volume and the contents of the aspirate, healthy lungs will either clear or absorb it without incident (See part one for a recap on this phenomenon). On the other hand, the medically complex or immunocompromised person has a higher risk of infection and respiratory decline from aspiration. Therefore, in the setting of certain risk factors, aspiration may play an important role in the pathophysiology of both pneumonia and ARDS. In other words, this is our time to shine.
Cherry-picking patients
Knowing and understanding the specific medical history of patients and how this correlates with the overall risk of ARDS would make it possible for SLPs to successfully determine the patients for whom dysphagia management is crucial; as well as for those with lower risk profiles who may not benefit from aggressive management of dysphagia (See post on Aspiration Pneumonia: The Whole Story for further details on this topic). Think about it this way: People with peanut allergies avoid peanuts. People without them, don’t. A doctor wouldn’t prohibit her patient from eating peanuts on the off chance of an allergic reaction without good reason. We don’t treat every patient the same: we triage. Triage is not only crucial during a pandemic when resources are limited, but is always the right approach to providing efficient, effective, and appropriate care.
Look for the red flags
In order to discover the patients who will need our services the most, we need to look for the red flags that indicate they are at higher risk for aspiration pneumonia. Overall debility, for example, has been found to increase the likeliness of aspiration pneumonia and may come in the form of reduced physical mobility and feeding dependence (Bock et al., 2017; Langmore et al, 1998; Momosaki, 2017). The takeaway? The weaker the patient is, the more susceptible they are to overall infection and decline. Another red flag is poor oral hygiene which when coupled with dysphagia was found to increase the risk of nursing home acquired pneumonia (Quagliarello, 2005). This makes sense, the more bacteria we bring into the airway from the mouth, the more likely an infection is to occur.
So the past medical and social history of each patient should be studied carefully to determine the health of the pulmonary and immune systems. Another red flag we should look out for is a history of smoking, which appears to increase the susceptibility and severity of both ARDS and pneumonia (Langmore et al., 1998; Matthay et al., 2012). Smoking can cause inflammation and may lead to significant damages to the barriers that separate and protect the alveoli and the blood vessels (the capillary endothelium and the alveolar epithelium, or the “blood-gas barrier”) (Matthay et al., 2012). Smoking is just one of many factors of lung health we need to look for when assessing overall risk (Take a look at the studies mentioned in this section if you want a more detailed look at all of the risk factors).
How our body changes with ARDS:
Similar to smoking, it is the inflammation in ARDS and infection that causes traumatic changes to the permeability of the blood-gas barrier. With infection, the barrier becomes less of a great wall and more like a measly fence. That’s because its permeability increases with the inflammation, cell death, leukocyte infiltration, and hypercoagulation associated with infection and the immune response (Gerlach, 2001; Herrero et al., 2018; Lucas et al., 2009). This extra “stuff” in the blood vessels and lungs alters the balance of pressure that maintains the blood-gas barrier (See vascular-to-extravascular hydrostatic pressure gradient to learn more). Without an effective boundary, these contents will arrive in the alveoli like that uncle on holidays who never gets the hint. These additional contents will alter the ability to clear out other unwanted guests too (think aspiration) and will inhibit oxygen exchange (Gerlach, 2001; Herrero et al., 2018; Lucas et al., 2009).
Unless cleared, this extra “stuff” in our lungs will result in alveolar edema (obstructive lung disease) and interstitial edema (restrictive lung disease). Edema is so dangerous because the respiratory membrane will have less surface area for gas exchange (Matthay et al., 2012). This can result in increased minute volume (more inspiratory air volume per minute as compensation)--> increasing the respiratory rate--> increasing the risk of aspiration--> increasing further damage to the lung--> increasing the respiratory rate (see where this is going?). Aspiration makes ARDS worse. ARDS makes aspiration worse. This means aspiration can be both the cause and effect of ARDS (if your brain didn’t explode yet, please read on).
Next week:
Are you in the mood for some good news? Me too. There is still work to be done and words to be read. In our next post, we will discuss the SLP’s role in ARDS management. Spoiler alert: There’s a lot we can do to improve outcomes and change lives.
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Bios:
Dr. Coyle PhD, CCC-SLP, BCS-S is a Professor of Communication Science and Disorders and Otolaryngology at the University of Pittsburgh where he teaches undergraduate, Master’s and doctoral SLP students both in the classrooms and clinics and has an active clinical caseload in the University of Pittsburgh Medical Center. His current research focuses on development of noninvasive sensor-based dysphagia screening and diagnostic systems for dysphagia screening and automated diagnostic annotations. He teaches nationally and internationally about the medical aspects of our profession. He is a Board Certified Specialist in Swallowing Disorders, and an ASHA Fellow.
Affiliations: Department of Communication Science and Disorders, Department of Otolaryngology, University of Pittsburgh.
Kelsey Day, M.S., CCC-SLP is an acute care Speech-Language Pathologist (SLP) who specializes in dysphagia management for the medically complex, critically ill, and tracheostomy dependent populations. She now serves as the Lead SLP at California Hospital Medical Center, a trauma and stroke center in downtown Los Angeles, where she supervises a team of nine SLPs. Kelsey demonstrates her commitment to the education of new medical SLPs through her mentorship for the Medical SLP Collective and supervision of graduate student clinicians and Clinical Fellows in the acute care setting. She is a guest lecturer at several graduate level SLP programs, invited keynote speaker at national and international conferences, course creator and presenter of “Clinical Writing for Dysphagia Diagnostics”, and special guest on the “Swallow Your Pride” and “Speech Uncensored” podcasts.
Affiliations: Department of Rehabilitation, California Hospital Medical Center
