ICU

★ ICU-Acquired Swallowing Disorders

Every month a group of #SLPeeps blogs about research. You can find out more about it here.

My last post for Research Tuesday was about cognitive dysfunction in ICU patients. That post emphasized some long-term effects of severe illness. This post will shift gears and focus on something more short-term: swallowing dysfunction resulting from ICU-level illness. Though the article I chose isn't itself a research article, it is a nice overview of swallowing and the role of SLPs in intensive care units. Also, the article was published in a medical journal, which is an exciting place for SLPs to get exposure and to hopefully increase awareness of how we can be assets to patient care.

What I enjoyed most about the article was how well the authors broke down different reasons why patients might have swallowing difficulty. There was also a nice overview of swallowing physiology, despite the authors' use of the cringe-worthy term swallow reflex.

The Numbers

The article shared some interesting numbers regarding ICU patients.

  • There are over 700,000 patients who develop acute respiratory failure requiring mechanical ventilation in the US.
  • Of those, over 400,000 patients survive to be extubated. (There's a 35% mortality rate.)
  • A "significant portion" of those 400,000 patients have post-extubation swallowing dysfunction. Why no proper estimate? The article cites the wide variety of diagnoses that accompany swallowing dysfunction, in addition to the likelihood that many cases are overlooked. The "guesstimate" they offer, taking into account biases and heterogenous patient populations? Something between 3% and 62% of patients recovering from critical illness have swallowing dysfunction.

Mechanisms of Swallowing Dysfunction

I like that the article uses the term "ICU-acquired" as a general term; I find it helpful because it frees one up to the idea that swallowing dysfunction is complex, and can occur for a variety of reasons. The authors go further to describe "postextubation dysphagia (PED)", which is exactly what it sounds like. From a critical care standpoint, the others describe six different mechanisms in which ICU patients can develop swallowing dysfunction.

  1. Endotracheal tubes and tracheostomy tubes. These can can cause trauma to normal anatomic structures. Ulceration can develop from the constant contact of a tube with various structures, including the vocal folds, the arytenoids, the epiglottis, and the base of the tongue. Chronic inflammation can lead to granulation tissue and potentially to scarring. There are implications for swallowing function as well as respiratory function. Commonly, there is concern for vocal fold paresis or paralysis following intubation. The authors note that "the recurrent laryngeal nerve can be copressed (usually by the endotracheal tube cuff)" (2398).
  2. Neuromyopathy resulting in muscle weakness. Classic "use it or lose it". This can result from both prolonged intubation as well as the use of paralytics. Longer intubation time means not only weaker lungs, but weaker muscles along the entire aerodigestive tract.
  3. Dysfunctional oropharyngeal and laryngeal sensation. This can result from polyneuropathy (reduced nerve function) or local edema. In either case, afferent input is reduced.
  4. Impaired sensorium. Call it what you like: altered mental status, confusion, or delirium. The cause can range from the illness itself, infections peripheral to the illness, or even heavy sedatives. As SLPs from every setting can attest, the ability to participate is one of our #1 needs for effective intervention. Interestingly, I've found in my own experience that this concept is possibly the hardest; many times, I've assessed patients who I'm told "swallow fine" who present with significant amounts of food pocketed in their cheeks or caked on the palate. Sometimes we have to advocate not only from the "aspiration risk" perspective, but also from the perspective of adequate nutrition. What helps here? An interdisciplinary team approach. Dietitians can be an SLP's best friend, especially in an ICU.
  5. Gastroesphageal reflux. ICU patients are commonly on prophylactic medication for reflux. Why is that? The authors note that reflux is a concern during intubation in addition to after extubation. They cite three reasons for this: (a) supine positioning, (b), higher levels of sedation, and (c) the use of paralytics. Gastric motility is commonly impacted. Some ICUs prefer to have feeding tubes placed post-pyloric in order to reduce the potential for reflux (the thought being that there are two valves, the pyloris and the lower esophageal sphincter, and two valves can protect better than one). However, the presence of a feeding tube alone puts one at increased risk for reflux.
  6. Dyssyncronous breathing and swallowing. We don't think of it this way enough, especially when it comes to patient and family education, but swallowing is an act of fine-tuned coordination. I love the recent trend for describing the aerodigestive tract, because it's the most apt for describing how closely linked breathing and swallowing really are. Though the authors describe the imporantance of the coordination of the "apneic" period and its role for aspiration prevention, I wish they had gone further. I've noticed that tachypnea (rapid breathing) impacts the oral preparatory phase as well (specifically, bolus preparation and cohesion); patients who are struggling to breathe have a tendency to try to take in more air, and in doing so may be opening their mouth more than usual when breathing. We're taught from a young age to chew with our mouths closed, but it does serve a purpose: to better control a bolus, for one, and to act as the first pressure point in a series of pressure-driven events that is the swallow. If we think of reserve lung volume, it makes sense that we can manage to breathe gently through our noses while chewing; a patient who is critically ill likely does not have this same reserve volume, so this process requires considerably more effort, which leads to something else: fatigue.

Risk Factors and Screening

The usual suspects are mentioned, such as neurological injury and neuromuscular disease. The authors note the use of screening tools for dysphagia among stroke patients. Stroke protocols today require screening stroke patients for potential swallowing dysfunction. The authors note that there is no similar requirement for critically ill patients, but 41% of hospitals surveyed did, in fact, have routine screens established. Though I'm not sure if my own hospital was part of that survey, I am pleased to be part of an institution which has taken up more universal screening. Though the department I work in is nicely staffed, it would be impossible for us to see every patient admitted. I work a lot in the ICU, though, and have found that the added bonus to seeing more patients who present with some level of dysphagia is that I can also assess for cognition. I consider this a bonus because mild cognitive impairment is often so easily overlooked.

Clinical Dysphagia Evaluation (CDE) vs. Diagnostic

The authors describe clinical, videofluoroscopic, and endoscopic evaluations of swallowing. When it comes to ICU patients, the clinical dysphagia evaluation is typically my go-to. I like it because I can take my time to meet patients, get a sense for their cognitive status, and also see how they perform with real foods (not to mention it's much easier to push their limits and assess for fatigue). There are some patients with histories that clearly indicate the need for more objective assessments, but for most patients a clinical exam is sufficient to get started.

There's a fine balance, especially for ICU patients, given that the acute nature is such that they can make gains with just as much speed as they can decline. It's a balancing act, really, and requires persistent follow-up to see if any change, either progressive or regressive, is occurring. My initial and early subsequent follow-ups look closely at whether a patient may need an instrumental exam. Challenges for attaining such exams can include medical status (is the patient stable enough to leave the ICU, or to tolerate an endoscopic procerdure?), acuity of illness (do we expect them to make a quick or slow recovery?), and scheduling (always a challenge for videofluoroscopic studies). Sometimes, the passage of time is a key component both in terms of patient recovery and discerning need for further evaluation.

Treatment

The authors note that "treatments for all types of dysphagia have been relatively underexplored, especially for patients recovering from critical illnesses" (2401). Currently, we (a) modify diet textures, (b) modify posture (a la chin tuck or head turn), (c) use therapeutic exercises, and (d) use enteral feeding tubes. Varying success has been ascribed to each method, and the use of each varies among clinicians and institutions.

As I've reflected on my own practice with critically ill patients, I've found I use a combination of the above. Each has its own merits and drawbacks.

  • Texture modification. I like to think of texture modification as a "band-aid" solution. It's a nice temporary tool but not always sustainable in the long-term. I find texture modification most useful for issues with dentition as well as attention; maybe a patient can't sustain enough attention to really masticate well, but have no problem with a liquids, pudding or puree textures. Maybe a patient has sustained a physical injury which cannot handle pressure on the mandible or palate. Maybe a patient left their dentures at home.
  • Postural modifications. I feel similarly to postural modifications as I do to texture modifications. Maybe a chin tuck or head turn works great for my immediate safety, but I don't want to do that forever. There's a reason they're called compensatory strategies. The goal is to compensate well enough until more long-lasting change can be achieved.
  • Therapeutic exercises. I tend to use these sparingly, but largely because critical illness generally doesn't lend itself well to such pursuits. Rather, I find them useful once patients are medically stable. In my case, medical stability usually means transfer to rehab. That said, my current caseload consists mostly of pulmonary patients, so I do end up coordinating with respiratory therapists to ensure breathing exercises are incorporated daily. I work with patients on these exercises and apply them to speech (increasing vocal intensity and duration of exhale for longer utterances, for example) as well as swallowing (improving reserve and breath control and practicing with PO trials).
  • Enteral feeding tubes. I have been fortunate to work closely with many excellent dietitians. For critically ill patients, nutrition plays an integral role in recovery, and quite often patients are unable to consume adequate nutrition in the early stages of recovery. In patients who are extubated but remain severely altered, the risk might be that they're too agitated to really eat well. In patients who are extubated and retain high oxygen requirements, they may not be able to even coordinate their breath well enough to swallow; they also, quite often, run the risk of re-intubation.

Where to next?

Though this article did not describe any really new information, I found it to be very descriptive of the SLP's role with critical care patients, and a great introduction for providers of all backgrounds. I also loved how much it helped me think about not only what I do, but why I do it. I'm left wondering if my current approach is the best approach, or if there are other ways I may approach things to continually improve the services I provide. I like to think the answer to that is a resounding yes.

Article Citation

Macht, Madison, MD, Wimbish, Tim, MS, CCC-SLP, Bodine, Cathy, PhD, CCC-SLP, and Moss, Marc, MD. (October 2013.) ICU-Acquired Swallowing Disorders. Critical Care Medicine, vol. 41, #10, 2396-2405.

★ Cognitive Dysfunction in ICU Patients

Every month a group of #SLPeeps blogs about research. For formation, you can find more out about it here.

For my previous post, I talked about mild TBI resulting from electrical injury. That was an article focusing on a general disorder resulting from a specific injury. This month, I found an article that was something of an extension of this idea: general disorder(s) resulting from general illness. I spend a good deal of time in the intensive care unit, and my current rotation is focused on medicine patients. I work in both the medical ICU as well as the medicine sub-acute units. I work every day with a population who we don't typically think of as being our target audience.

One of the challenges of acute care, as I've mentioned previously, is that the intensity of patients' illness prevents doing any meaningful therapy. This isn't a bad thing; we're taught in school to start therapy immediately, but I've learned that there's a caveat to this. Starting therapy early is helpful only once a patient is medically stable. Without that last component, therapy is bound to be anything but effective.

The article I selected this month is not a study itself, but rather a "narrative review". The authors noted that unlike other clinical outomes, "cognitive function in critical care survivors has not been deeply studied."

The Study

The primary medical diagnosis discussed in the study was acute respiratory distress syndrome (ARDS). ARDS can be associated with a number of other diagnoses, such chronic obstructive pulmonary disease (COPD) or sepsis, but the requirement of mechanical ventilation was emphasized in the review.

The authors wanted to compare cognitive impairment at time of hospital discharge and then again later on, all in the context of acute illness (i.e. other than neurological injury, which are more widely studied). "At hospital discharge, 70% to 100% of patients were determined to have cognitive impairment... At 1- and 2-year follow-up, the prevalence of cognitive impairment was 46% to 78% and 25% to 47%, respectively." Though there is a decline observed in prevalence, it's interesting that there is cognitive impairment at all; these are patients we often receive consults for as primarily swallowing patients due to prolonged intubation. What's even more interesting: "the domains of cognitive function most commonly affected were attention and concentration, memory, and executive function." The caveat is that the severity of deficits rated across studies, but it is interesting to note that these are all areas in which speech pathologists work with other patients.

Factors Associated with Cognitive Impairment

The authors note that pre-existing cognitive impairment is difficult to rule out, and that a certain amount of pre-existing cognitive impairment may be prevalent especially in elderly ICU patients. Conditions such as genetic predisposition to Alzheimer's dementia (apolipoprotein E4, or APOE4) demonstrate a "stronger association with duration of elirium than age, severity of illness score, sepsis, or benzodiazepine use". Other factors to consider are pre-existing psychiatric impairment, such as depression. The authors also note that 10-58% of survivors of critical illness suffer from depression.

The above risk factors may indicate an increased likelihood for developing cognitive impairment. "The pathogenesis of cognitive impairment following critical illness is not fully understood but may represent an accelerated neurodegenerative process tht develops in in vulnerable hosts." Delirium is becoming more widely understood to not simply be "confusion" related to illness, but rather something that can have more significant and long-lasting effects. "[P]atients who suffered a longer duration of delirium had greater overall brain atrophy and ventricular enlargement as well as smaller superior frontal lobes and hippocampal volumes 3 months following hospital discharge." There were further findings of loss of white matter in the corpus collosum and internal capsule.

Clinical Variables

The first variable listed is hypoxia, which is not foreign to SLPs. We often consider hypoxic injuries relevant, and that consideration transcends area of expertise. An additional component the others discuss is hypotension; while we so often recognize hypertension as a risk factor for such things as stroke or aneurysm (heck, hypertension even earns itself the casually tossed about HTN shorthand), hypotension could be seen as a red flag for possible anoxic injury.

Other variables noted included sepsis, dysglycemia, delirium, and sleep efficiency. Patients with sepsis were observed to have "cognitive and functional decline... [and had] deficits in verbal learning and memory and were seen to have significant reductions in left hippocampal volume compared with healthy controls." Even EEG results showed changes, reflecting more low-frequency activity, "indicating a nonspecific brain dysfunction." Dysglycemia refers to fluctuations in blood sugar levels. The authors noted that "patients with a highest blood glucose level (>153.5 mg/dL) and those with with greater fluctuations in blood glucose had three times the odds of being cognitively impaired at 1 year compared with patients who did not experience either glycemic condition." Associated impairment with dysglycemia and hyperglycemia included deficits in visuo-spatial skills.

As I mentioned above, delirium is becoming more widely acknowledged as a relevant condition that can have lasting effects. I've been noticing it being discussed more frequently on rounds among more and more medical teams. Deliriums is defined as "an acute change in mental status that is characterized by inattention and a fluctuating course... [and] it is associated with longer lengths of stay, increased duration of mechanical ventilation, and higher risk of death." The link between delirium, which was once considered temporary (and still is, in some ways), and cognitive impairment is "hypothesized to be mediated directly or indirectly through a systemic inflammatory response," leading to chronic neuroinflammation and neurotoxicity.

Finally, sleep is a large component of cognitive well-being. A common theme among many of my patients is how hard it can be to get good sleep. It's easy to see why this is: patients are frequently woken for vital signs throughout the night, carted away for tests, or simply get restless (being stuck in bed for days, weeks or even months on end is astonishingly hard on the body). Though the studies found didn't report cognitive outcomes, they did note that "sleep fragmentation (quantified by actigraphy) was associated with a nearly 1.5-fold increased risk of incident Alzheimer disease after controlling for demographics, total daily rest time, chronic medical conditions, and the use of medications."

Moving Forward

Though we often concern ourselves initially with swallowing safety when we first begin working with ICU patients, it would behoove us to not look too lightly at cognitive status. Early on, I developed a habit of monitoring cognition from the moment I start working with a patient so that I could monitor their progress. I used to think of it as a way to really see (and document) how my patients are doing, but now I have even more reason to do so. Sure, I might shrug off confusion as "par for the course", but I will be watching closely to see how long it takes patients to really clear.

I attended a lecture recently that discussed delirium, and one of the most interesting points discussed was how easing sedation, spontaneous breathing trials daily, and early mobilization were helpful in reducing length of time for mechanical ventilation as well as reducing delirium. If these ideas pan out as they're hypothesized to, perhaps cognitive function may be more spared. The authors also point out that improving sleep efficiency can impact recovery. With that in mind, I found myself this week advocating for a patient with sleep apnea to be able to use his CPAP (no order had been written, and though he had his machine, it had not yet been cleared for use); he was so exhausted he kept falling asleep during my evaluation. Not only do patients perform better with rest; it may also help prevent further cognitive deficits down the road.

As I learn more about delirium and its long-term effects, I see potential for how SLPs can be assets to multidisciplinary teams. I'm learning to see how duration of delirum is as important, if not more important, than the "severity" of the delirium. This new information may begin to shed light on why we encounter patients who present with cognitive deficits (especially "frequent flyer" patients) with unclear etiology; we may be seeing early markers of cognitive decline resulting from chronic illnesses that lend themselves to chronic delirium.

Article Citation

Wilcox, M. Elizabeth, MD, MPH, et al. (September 2013.) Cognitive Dysfunction in ICU Patients: Risk Factors, Predictors, and Rehabilitation Interventions. Critical Care Medicine, vol. 41, #9, S81-S98.