★ 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.

★ Electrical Injury and Mild Traumatic Brain Injury

It's time once again for an edition of SLPs Blogging About Research! For information about this, or if you want to participate, you can find out more here.

Acute care speech pathology is a world all its own. Interestingly, it is not an environment conducive to therapy. Rather, I like to think of it more as a place for a lot of assessment, followed by maintenance and, naturally, more assessment. Most of the time, patients are too ill, or their injuries too recent, to begin to establish meaningful change in a therapeutic way.

This isn't to say that we don't have our own goals. Quite the opposite, actually. I remain a big believer that getting started early is the best way to begin on the road to recovery. Where I feel I can make a difference is to get in early and establishing some baselines for function. At the acute stage, there is often concern for evolving infarcts, or even the possibility of new ones. If a stroke is hemorrhagic, it doesn't make sense to push much for therapy because it's changing. Recovery, in general, requires medical stability, and at the acute stage stability is tepid at best.

An additional challenge of acute care is being able to recognize mild traumatic brain injuries. In the midst of the more severe cases, it's easy to encounter patients with mild TBI and feel like they're in relatively good shape. After working extensively with trauma patients, I've found that medical teams are often quick to dismiss head injuries if visible clots or bleeds are not seen on scans. Ask any neurologist or neurosurgeon, and they'll readily confirm that a clean MRI or CT does not necessarily indicate a lack of head injury. This is where SLPs come in handy on a multidisciplinary team.

The hospital where I work also happens to house a Burn Unit, which, as its name suggests, specializes in the care and treatment of burns. Several months ago, I evaluated a patient who was status post electrical shock injury with resulting brief pulseless electrical activity. Though the patient was what we affectionately like to call a "walkie talkie", I requested a consult out of concern for possible anoxic brain injury. I noticed some cognitive deficits in my initial evaluation, most prominent of which were attention and memory. When I brought this up to the team, a psychiatry fellow introduced me to a new world of mild traumatic brain injury, and one that did not necessarily involve any physical trauma to the head or brain.

The Neuropsychological Effects of Electrical Injury: New Insights By Pliskin et al.

The authors of this study note that, despite evidence, the following four assumptions remain common (as of the writing of the article) about patients with electrical injury:

  1. a more visible burn will indicate greater psychological difficulties
  2. low voltage exposures will not cause significant neuropsychological problems
  3. electrical injury patients who experience changes are not premorbidly psychologically stable
  4. electrically injured patients are faking their difficulties for secondary gain (i.e. workers' compensation)

The study focused on electrical injury peripheral to the head (no direct electrical contact to the head) and the source of electrical injury was a power source only (no lightning strike patients were included). Also, none of the patients studied had sustained a known head injury. They were separated into two groups: acute (seen within 3 months post-injury) and postacute (seen after 3 months post-injury). A control sample of electricians was used, and none had a history of prior electrical injury, neurological disease or lesion, head injury, or psychiatric illness.

The study was then split into three groups.

Study 1: Symptom Profiles

The participants and the control group were administered two assessments: the Neuropsychological Symptom Checklist (NSC) and the Beck Depression Inventory (BDI), and "[r]esults indicated that the EI (electrical injury) group had a much higher self-reported rate of phsyical, cognitive, and emotional symptoms" (143). In addition to physical complaints such as paresthesias (tingling), EI patients indicated cognitive difficulties such as difficulty with concentration, word-finding in conversation, memory, attention (feeling distracted), and "slower thinking".

Also of note, the authors point out that findings "were not statistically related to severitry of physical injury, voltage exposure, involvement in litigation, or previous psychiatric history" (143). What's more, they found that patients who were further post-injury actually reported more symptoms than the more newly injuried. "[T]he high frequency of specific cognitive complaints in the EI sample may be surprising, especially considering that no patient sustained a direct mechanical electrical contact to the head" (144). What's more telling, for me is their comment that "little is known about the pathway that electricity takes once it enters the body after perifpheral contact despite apparent hand to hand or hand to foot injuries" (144).

Study 2: Neuropsychological Function

The next step of the study was to determine if any objective data could be found to support the cognitive complaints noted in the first part of the study. They tested the following:

  1. intelligence (Wechsler Adult Intelligence Scale - Revised)
  2. learning and memory (Logical Memory and Visual Reporduction subtests of Wechsler as well as California Verbal Learning Test (CVLT))
  3. attention and concentration (Paced Auditory Serial Addition Test (PASAT), Stroop test, and trailmaking test)
  4. motor function (grooved pegboard)
  5. depression screening (Beck Depression Inventory)

The study found significant differences, with "poor performances on measures of attention and concentration, motor speed/dexterity, and memory performance... [and] visual memory performance in particular was worse in the EI group, especially in initial acquisition of new information" (145). Once again, the study also found that postacute patients had even lower scores than acute patients.

Study 3: Longitudinal Outcome

The study found that these symptoms and functional deficits could be present for years after an accident, with an average report of 3.9 years. Further study is indicated to better understand these long-term implications.

The study concludes almost more questions than it started with. The biggest one: "why are patients who were seen postacutely up to five years after injury apparently worse from a psychological and nueropsychological standpoint than patients who were evaluated acutely?" (147). The authors question if it takes time for effects to truly become apparent, or if these patients represent only a small subset of electrical injury patients. Further studies are indicated.

The Takeaway

I have to thank my psychiatrist colleague for sending me this article. Even though the focus is from a psychological perspective, I found the information immensely helpful and a definite asset to my clinical foundation. I appreciate more than ever how vital it is to be part of a multidisciplinary team.

Though electrical injury is thankfully a relatively rare diagnosis in my practice, I feel more prepared to work with patients and having this information will go a long way for patient and family education. For example, with the patient that sparked this discussion earlier this year, I was able to provide the patient and family with information and resources in the event that difficulty might arise following discharge.

Article Citation

Pliskin, Neil H., et al. (November 1999.) The Neuropsychological Effects of Electrical Injury: New Insights. Annals of the New York Academy of Sciences, vol. 888, pp. 140-149.

★ Let's Get Drowsy

If you asked me to, I wouldn't be able to count the number of times I've watched someone's blood being drawn. I've observed many a phlebotomist do their thing, and normally find it rather amusing to watch, especially when two of them team up and try to hunt along someone's arm to find a vein. Formerly a squeamish person, my time spent in an acute care hospital as an SLP quickly killed most of what I had always considered my very weak stomach.

In short, I am a pro at watching things happen to other people.

What I am not, however, is a pro at having said things happen to me.

Following the ASHA convention in San Diego, I promptly threw everything I owned into a U-Haul and moved 750 miles to start a new job. I had thought I had all the paperwork I needed, but alas I could not find my immunization records.

When I sheepishly pointed this out to the charge nurse at my employee health pre-assignment appointment today, she decreed that it was too late for me to hunt them down at home, and said "Don't worry, sweetie, we'll just draw some blood and test your antibodies that way."

As if that's supposed to reassure me.

And now we play a favorite speech game:

  • Fortunately, the woman at the lab who was going to suck my blood was very nice.
  • Unfortunately, it turns out I'm a hard stick.
  • Fortunately, she distracted me by continuing genial conversation.
  • Unfortunately, she had to dig around my arm a bit to find the vein, a process that was, for lack of a better phrase, very painful.

Long story short, I had three full test tubes worth of blood yanked from my previously untouched, full-blooded body. I hadn't eaten since 9am (and it was 1:30 by that point), and I had to rush over to HR to fill out paperwork, where I no doubt impressed the poor HR person with my delayed responses to his questions. I'm pretty sure I also asked what today's date was like five or twelve times in the space of twenty minutes.

I've spent the rest of my day in alternate states of hyperactivity followed by sudden lulls.

My point here is that I have witnessed blood being drawn on many occasions when doing speech or swallow evaluations in the hospital, and haven't given it much thought. In the grand scheme of what goes on in an acute care facility, I always assumed blood labs were pretty low key.

Now that I've experienced what it can do to myself, a person who is always on the go and rarely needs more than 6 hours of sleep to be fully rested for a day ahead, I'll likely think twice about the cognitive implications of drawing blood. I'll keep my eye out for decreased response time, or for changes in one's ability to focus. I'll remember that I, a healthy person rather than a hospitalized one, was in a completely different frame of mind and body for the rest of the day after having my own blood drawn.

Sometimes personal experience is the best teacher.

Other times, it leaves you craving a good snack.