Post-Extubation Dysphagia: Critical Information for Critical Patients

Editor’s Note: This text is a transcript of the course, “Post-Extubation Dysphagia: Critical Information for Critical Patients” presented by Angela Mansolillo, MA, CCC-SLP, BCS-S.

Learning Outcomes

After this course, participants will be able:

• Identify three patient characteristics and risk factors for post-extubation dysphagia.
• List four potential causes of dysphagia in recently extubated patients.
• Describe three strategies for assessment of post-extubation dysphagia in critically ill patients.

Introduction

I am very happy to talk about post-extubation dysphagia. I have had a lot of experience with folks who were recently extubated even before the COVID-19 epidemic. Since then, we've had even more experience. I do want to clarify that we're not going to talk a lot about COVID. Course 9653 is a separate course that is specifically on dysphagia in COVID patients. So, while some of this information certainly applies to COVID patients who have been recently extubated that will not be the focus of this course.

Let's start by doing a very quick review of some basic information about respiration and ventilation to make sure we're all on the same page. Respiration and ventilation are terms that are sometimes used interchangeably but the fact is they are different and refer to different parts of the breathing process. So, we need to make a differentiation.

Ventilation refers to the actual mechanical movement of the air, the expansion of the rib cage, and the movement of the musculature that helps to bring air into our lungs. Respiration, on the other hand, is the gas exchange portion of the process. It is both an internal and an external process.

The reason that respiration occurs is that gas molecules will always move from high pressure to low pressure. So, we bring that air into our lungs through our ventilation. Moving from high pressure to low, the gas molecules will move through the pulmonary capillaries into the alveolar spaces.

From the alveolar spaces, the gas molecules then have access to the bloodstream. Red blood cells attach themselves to the oxygen molecules and essentially take the oxygen everywhere it needs to go. The endpoint is essentially every cell in every organ everywhere in your body.

Again, moving from high pressure to low, the oxygen diffuses through those cell membranes and there's a conversion to energy that occurs. The by-product of that conversion is CO2. The gas exchange that occurs in every cell in your body is internal respiration. Now you have CO2 building in the cell. The CO2 diffuses back into the bloodstream, this time the venous bloodstream, and is carried back into the lungs. Rising levels of CO2 trigger the next ventilation. Then, the process begins again.

The gas exchange that occurs in the lungs is external respiration because you're interacting with an external air source. That may or may not be very interesting to you. But the important question, as we sit across from our clients, is how often does that process have to repeat itself in order for that client to maintain oxygenation throughout their body. In other words, what's the respiratory rate?

Respiratory Rate

Respiratory rate is an important clinical indicator.  When it comes to swallowing, it's critically important to pay attention to this.  Below are norms for resting respiratory rate because respiratory rate is a moving target.

• Adults: 15-16 bpm
• Older Adults: 20’s 
• >35 = impending respiratory failure 
•  >25-30 = deterioration in the coordination of breathing/swallowing is likely

Your respiratory rate right now is different than when you get off the treadmill. But we do have norms for resting respiratory rate in breaths per minute (BPM). The norm for resting respiratory rate in adults is 15-16 breaths per minute. You can see that that goes up a bit in our elderly folks. It starts to increase as we get into our 60's and 70's. It increases even a little bit more in our 80's and 90's until we're somewhere in the low to mid 20's for resting respiratory rate in the elderly.

From a clinical perspective, if a client has a resting respiratory rate of 25-30 breaths per minute, whether that's normal aging or the result of some sort of critical illness, there's going to be some deterioration in breathing-swallow coordination.  Additionally, if you have a client who has a resting respiratory rate of 35 breaths per minute or more, this is someone who's in real trouble and in impending respiratory failure.

Work of Breathing

In addition to respiratory rate, we also want to pay attention to the work of breathing.

This is a term you'll hear me use a few times throughout the course, and you'll come across it quite a bit as you talk with respiratory therapists, pulmonologists, and intensivists. When we use the term “work of breathing,” we're talking about the energy that's required to do two things: 1) move air through some fairly narrow airways, and 2) expand the lungs against that natural recoil of the rib cage and the musculature.

For most of us, most of the time the work of breathing is negligible. We're rarely even aware of our breathing although you're probably thinking about it right now.  So, most of the time we're not really aware of our breathing, but we know that’s not true for a lot of our clients. For our clients who have some chronic respiratory disease or acute respiratory condition, they are thinking about their breathing. They are working hard to breathe and they are aware of their breathing.

Breathing and Swallowing

It seems, to me, that we have a design flaw.  We have a system where food and liquid have to pass where we breathe. I'm not sure who thought that was such a great idea but it certainly makes sense if you think about it from an evolutionary perspective. If we look at early human beings, the larynx was actually much higher in the airway, tucked under the tongue base in a more protected position. As human beings evolved, those laryngeal structures descend. We saw increased access to the larynx for voice and that led to the development of spoken communication and language. But it did put the airway in a more precarious position.

What developed simultaneously were a lot of redundancies in terms of airway protection.  So, even though the airway is in this precarious position there are a lot of layers of airway protection. We swallow hundreds and hundreds of times a day without really concentrating on swallowing. We do it safely most of the time because there are layers of protection. All the things you do to keep that bolus moving - the push you put on the bolus with your tongue, the pharyngeal constriction, the stripping wave on the posterior pharyngeal wall - all of the things we do to keep the food and liquid moving also help to protect the airway by keeping the food and liquid away from the airway. All the things we do to close the airway itself - the laryngeal excursion, the closure of the laryngeal valve, the vocal fold adduction, the contact between the underside of the epiglottitis and the top of the airway, the arytenoid specifically – also help to protect the airway.

But maybe the most important thing we do to protect the airway during swallowing is we stop breathing. We don't breathe and swallow simultaneously. That period of swallow apnea or respiratory pause, depending on your preference for the term, is critical to airway protection. It's also variable.  It tends to change with the bolus, not surprisingly. With larger boluses, we see earlier onset of breathing cessation and longer durations.  But we also see differences in different client populations. In the elderly, not people with dysphagia necessarily but as part of normal aging, we tend to see longer durations of respiratory pause across bolus types.

With disordered swallowing, we see changes. We tend to see longer periods of respiratory pause with patients whose underlying issue is neurological. For example, patients with neuromuscular disease or individuals with CP tend to have longer durations of respiratory pause. These folks stop breathing in time to swallow but have a lag in terms of getting back to it.

We tend to see shorter durations of respiratory pause in patients whose underlying issue is respiratory. They can't breathe very well so they need to get back to breathing. So, they tend to have shorter than typical periods of respiratory pause (Palmer and Hiemmae, 2003).

I did not include stroke because there are conflicting studies. Some studies have shown that patients post-stroke have longer durations of respiratory pause. Others have shown shorter durations of respiratory pause. So, it's not really clear because they don't fit easily into one of these categories. It probably has to do with the variability of stroke patients.

Respiratory - Swallow Coordination

As we talk about breathing-swallow coordination or respiratory-swallow coordination, the pattern that we see most commonly is inhale, exhale a little, swallow, exhale some more. The swallow typically interrupts the exhalation early in the exhalatory part of the cycle. But there's some variability in this.  As we look at our elderly clients, we tend to see post-swallow inhalation occurring more commonly. Those of us who would not yet consider ourselves elderly also demonstrate a post-swallow inhalation occasionally with larger boluses or with serial swallows.

For example, let's say you come in after having been outside on a hot day and you grab your water bottle and you swallow, swallow, swallow, swallow, swallow. You have a long period of respiratory pause, so you're going to be air hungry and you're going to need a post-swallow inhalation.

Here's the point of this course, we tend to see post-swallow inhalation more commonly in patients with underlying respiratory compromise. Again, if they can't breathe very well, they need to return to breathing quickly with an inhalation because they're air hungry.

Why Post-Swallow Exhalation

What is the function of that post-swallow exhalation? What purpose does it serve? It turns out there is more than one purpose. The obvious one is that it helps to facilitate airway clearance. If your swallow had not been very efficient and you had a little residue near your airway and you inhale post-swallow, you will pull that material into your airway. But if you consistently exhale post-swallow you can kind of push out anything that's trying to get into your airway.

The post-swallow exhalation helps to facilitate laryngeal closure and laryngeal elevation. It also helps to facilitate esophageal clearance, which is a pressure relationship.  If you've ever heard me speak before you have heard me say a million times, “What happens in one part of the body affects what happens in other parts of the body.” This is particularly true for respiration and GI functions.  They are very closely linked. This relationship between esophageal clearance and post-swallow exhalation is a pressure relationship. As you inhale, your lungs are inflated and they put pressure on the esophagus. But as you're exhaling, post-swallow, that pressure is coming off of the esophagus. So, the esophagus can do its work in clearing the material that you just swallowed more efficiently. So that post-swallow exhalation serves a lot of purposes.

Respiratory-swallow coordination involves three things. One is that respiratory-swallow pattern, which again is typically exhale-swallow-exhale, but has some variability. The second component is lung volume initiation. Where were you in your cycle? How full were your lungs when you swallowed? Generally, we swallow at the middle part of the lung range (low-middle to middle lung ranges or 42-55%) of vital capacity. Folks who are not able to expand their lungs very well, and can't get to the middle part of that lung range easily may run into some difficulty here. Finally, the third component of respiratory-swallow coordination is the duration of respiratory pause (0.5 to 1.5 seconds).

When one or more components of respiratory-swallow coordination are impaired, we often see swallow impairment as well. We see longer pharyngeal transit times. We see pharyngeal residue. There are delays in the initiation of the swallow response. We will also see penetration and aspiration when one or more of these respiratory-swallow coordination components are impaired.

Endotracheal Intubation

Let's talk about our patients of interest for this - those who have recently been extubated. Endotracheal intubation is what occurs when an endotracheal tube (ET tube) is passed through the mouth, through the throat, through the vocal folds, and into the trachea. If you watch medical shows you've seen them do this on TV a million times. Some emergency room doctor cranks the guy's head back, looks for the chords, and in they go. It does actually happen very quickly. It's often done emergently because people can't breathe.  There is the risk of laryngeal trauma as this is occurring. Once that ET tube is in the trachea, a balloon cuff at the end of it is inflated to hold it in place.

Again, this is often done emergently, but not always. Obviously, it’s done for surgeries in some cases. It allows access to mechanical ventilation. It is meant to be a short-term solution for respiratory distress. Patients who require longer periods of access to ventilation generally would convert to a tracheostomy and may remain on the vent. But they would be connected through the trach tube and not through the ET tube. I say "generally," because recently in this age of COVID we have seen longer periods of intubation via ET tube. The conversion from intubation to trach is an aerosol-generating procedure and is risky for the physicians and respiratory therapists who are involved.  Obviously, it is risky for the patient, but certainly for the team in terms of their exposure to the virus.

We're seeing patients who have been intubated for longer periods of time than we used to see. Why does this matter to us as a dysphagia therapist? Because dysphagia after that ET tube comes out is fairly common. Fairly common is sort of a general term. As you can see below, we don't really have a great handle on the numbers. There's a lot of variability in terms of the prevalence numbers.

• 56% of patients undergoing FEES within 48 hours of extubation aspirated (Ajemian et al, 2001)
• 86% of patients undergoing VFSS post-extubation demonstrated aspiration (Partik et al, 2000)
• Review: 3-93% (Brodsky et al, 2020)
• Meta-analysis revealed dysphagia rate of 41% (McIntyre et al, 2020)

Dr. Brodsky did a review that was just recently published.  Looking at the range, three to 93% of patients recently extubated demonstrated some degree of dysphagia. When you see numbers like that you have to conclude that we don't really know. Why is there such variability? The simple answer to that is there's a lot of variability in the research and there's a lot of variability in the patients. In the research, we use different assessment tools, we use different screening tools, the timing is different, etc. When did they evaluate for dysphagia? Was it two hours after the extubation? Was it 24 hours after the extubation? Was it two days after the extubation? We know with these patients that could potentially make a huge difference. Again, there's a lot of variability in these patients.

There's a tendency to sort of talk about trach patients or respiratory patients or post-extubation patients as if they are this homogeneous group but they're not. There are many things that get a patient to the point where they need to be intubated: trauma, neurological deficits, respiratory distress, COVID, drug abuse, drug overdose, alcohol overdose. Before intubation, they were a widely variable group of folks.  So that variability is certainly something we're going to see once that ET tube is removed as well.

Who’s at Risk?

It is, however, a fairly well-studied population.  There's a lot of research to review. When we look at who amongst the folks who have been intubated and then extubated is at risk for swallowing impairment, we do start to get a handle on who those high-risk folks are.  If a patient goes in with the following comorbidities then they are more likely to have some dysphagia once they are extubated.

• Was the intubation done emergently? Those folks are going to be more likely to have dysphagia than the patient who was intubated for surgery, or failed to wean for a period of time and then eventually weaned
• Poor pre-morbid functional status
• Underlying neurological problems
• Underlying GI problems
• Underlying kidney or renal problems
• COVID - We're seeing quite a bit of dysphagia in our COVID patients whether they've been intubated or not and certainly post-extubation.

How do we get a handle on who amongst these patients is going to need our assessment and management?  Does age make a difference? Well, maybe. It depends on what the underlying ideology is. In cardiac and trauma patients, older patients were more likely to have dysphagia. But in surgical and neurological patients, older patients were not any more likely than younger patients to have post-extubation dysphagia (Brodsky, et al, 2020).

Does the duration of the intubation matter? We can be a bit more definitive in saying, yes, it does.  Those patients who have fairly short durations of intubation - less than 12 hours - are at significantly lower risk for dysphagia post-extubation. The longer that ET tube is in, the more likely it is that we're going to see some dysphagia once they've been extubated.

Why Dysphagia?

Why is there dysphagia in these patients in the first place? There's usually more than one issue:

• Underlying illness
• Medication
• Laryngeal trauma
• Impaired sensation
• Breathing-swallow discoordination
• Reflux
• Something else???

We've been talking about comorbidities and underlying illnesses that brought the patients to the point where they needed intubation in the first place. There can also be medication effects. These patients have often been sedated and may still have some remnants of those sedating medications on board. If it was an intubation that was done emergently there may be some laryngeal trauma or some impaired laryngeal sensation.  Certainly, these are often folks who still have some respiratory compromise and are therefore likely to have some breathing-swallow discoordination.

Again, we can't discount the relationship between the respiratory system and the GI system. We know that folks who had reflux disease are going to be more likely to have some post-extubation dysphagia in some cases because of all of those interrelationships between the respiratory system and the GI system. Also, in some patients, there may be many other things going on that we just haven't identified yet.

We always have to ask ourselves why was this person intubated in the first place? Why were they in critical care in the first place?  Was it trauma? Was it a stroke? Was it respiratory disease? Was this an opioid overdose?

How long have they been in the ICU? Prolonged periods of illness often create ICU-acquired weakness which is probably also contributing to the dysphagia that we're seeing in these folks. You've heard the expression, “Use it or lose it.” These are patients who were not swallowing with high frequency for the duration of the intubation.

In some cases, this can be a fairly prolonged period of disuse atrophy and their swallow function is going to be less efficient as a result of not having used it. We know that in some of these folks we're seeing some diaphragmatic dysfunction, weakness in the diaphragm because of the longer-term dependency on the vent.  We see respiratory muscle weakness in these ICU patients as well. This is all part of generalized weakness. Physical therapists and occupational therapists will tell you that these folks are just generally weak. They can't lift their arms to feed themselves. They don't have enough strength to sit at the edge of the bed or stand on their own sometimes. The weakness in the respiratory muscles and the weakness in the swallow muscles are part of this generalized weakness that we see in patients with prolonged durations of intubation.

Laryngeal trauma. I mentioned laryngeal trauma as another source of dysphagia. Think about this tube sitting in the airway between the vocal folds and rubbing up against the folds.  There can be swelling, mucosal breakdown, bleeding, granulation tissue, stenosis in the glottis and also subglottically. Sometimes we see vocal fold paralysis. There was a very interesting article that was published and the contention of this author is that we're probably missing a lot of subglottic stenosis and subglottic injuries related to intubation because most of these patients are not getting direct laryngoscopy (Stocker, 2018). It's an indirect assessment. So, we're probably missing a lot of what's going on below the level of the vocal folds in terms of trauma and damage.

The result of that trauma, as speech pathologists well know, is a change in vocal quality. Dysphonia, hoarseness, pain, stridor, dyspnea and of course, swallowing impairments are caused by the laryngeal trauma. 

Alteration in airway sensitivity. Another factor that we mentioned in terms of causative factors for dysphagia is alteration in airway sensitivity. In a study that was published in 2019, researchers looked at laryngeal sensation in patients who had recently been extubated and correlated that to swallow function. They found that when the duration of the intubation was short (i.e., less than a hundred hours in this study) when the patient had impaired laryngeal sensation, they were more likely to aspirate.  There was a fairly direct correlation in those patients.

In patients who had longer periods of intubation (i.e., one hundred hours or more), the impaired sensation was not as predictive. What's predicting the dysphagia is probably not the change in laryngeal sensation but whatever it is that kept the patient intubated for one hundred hours or more. At that point, we have to start looking at more of the medical comorbidities and the ICU acquired weakness.

What's causing that alteration in sensation? Probably the presence of the tube. But, we can't just assume that's what it is. Remember, these are complicated patients with multiple comorbidities. The presence of an underlying neurological impairment might be contributing to alterations in sensation. The sedating medications might still be contributing. A lot of these patients are not that awake and alert and that may be part of the picture as well.

Breathing/Swallow Discoordination. Another potential cause of the dysphagia is breathing-swallow discoordination. These are folks who are still experiencing some degree of respiratory compromise so they're going to be air hungry. They are more likely to demonstrate a post-swallow inhalation. If they have some disorder in pharyngeal transit and they have some residue, then that residue combined with the post-swallow inhalation is obviously going to be problematic.

These are folks who are not going to have normal tolerance for that period of respiratory pause again. They're going to have shorter than typical periods of respiratory pause combined with that post-swallow inhalation which is potentially going to get them into trouble in terms of airway protection.

The Role of Reflux

Again, we have to consider the GI system because we can't talk about the respiratory system without talking about the GI system. They are very closely coordinated in the body.

We know that reflux plays a role in terms of post-extubation dysphagia. In these patients who are working harder to breathe, energy is going to breathing. That means energy is being pulled away from digestion. When the work of breathing increases then digestion slows down. Delayed gastric emptying is going to increase reflux. If the reflux is high enough, if there is full column reflux, then there's a potential interaction with the airway.

We also know that the crural muscles of the diaphragm are important in terms of maintaining the function of the lower esophageal sphincter in the esophagus. Remember the esophagus passes through the diaphragm. If there's a weakness in the diaphragm as a result of long term vent dependence, there is potentially going to be some impairment in the functioning of the lower esophageal sphincter. All of these things can potentially contribute to reflux. Again, if the reflux is coming high, if you have full column reflux, then there's potential interaction with the airway.

There was an interesting study that Dr. Brodsky did looking at patients who had been intubated for various periods of time. The interesting part was that they followed the patients long-term.  These were patients who had some degree of dysphagia post extubation. They didn't all necessarily leave the hospital with dysphagia, but they did evaluate them at discharge and then followed up at intervals for up to five years. At the time of discharge, about a third of them still had some dysphagia. As they did the follow-ups, they found that about a quarter of them continued to report dysphagia symptoms for as long as six months or so. They continued to follow up and by the time they were getting to five-year follow-ups, all of the dysphagia had resolved.

Interestingly enough, the duration of intubation was not a predictor of long-term recovery. The important predictor in terms of how long it was going to take these patients to improve was actually related to the duration of their ICU stay. So that concept of disuse atrophy and ICU related weakness is an important one to keep in mind.

What does that mean for us in terms of our work with these clients? Should we be initiating oral feeding? When should we be initiating oral feeding after they have been extubated? There is conflicting advice in the literature. Some studies have indicated that by waiting 24 hours, patients are doing better and can be put on less restricted diets. But Dr. Leder did a study in 2019 that said a lot of these folks are able to start an oral diet fairly quickly. So why should we make everybody wait 24 hours? That is actually the philosophy in my facility.  A swallow screen post-extubation is generally done by nursing and the post-extubation order is actually linked to a swallow evaluation order.  We get called in on all of those folks whether they have passed the screen or not and we will then make the decision.  If this is someone who's not really awake and alert, is still kind of sedated, we're going to wait until the next day.   If someone looks pretty good we'll go in and do that evaluation more quickly.

Assessment

What is involved in the evaluation? I want to discuss screening, clinical assessment, and instrumental assessment.

Swallow Screening

There is a course on swallow screening that I would encourage you to take a look at (Course 9047). I took a deep dive into swallow screening tools and looked at which ones had been validated on which populations. In general, we know that there is a lot of variability in terms of these screening protocols and how they are used. There's also a lot of variability in terms of the tools themselves.

There are a lot of swallow screening tools available.  To my knowledge, only three of them included patients with post-extubation dysphagia in their sample. One was the bedside swallowing evaluation, which sounds like an evaluation, but is actually a screening. Another one was the Yale Swallow Protocol and one was the Post-Extubation Dysphagia Screening tool which was designed specifically for patients with post-extubation dysphagia. Let's look closer at these three screening tools. 

Bedside Swallowing Evaluation. The bedside swallowing evaluation is a screening tool designed to be administered by a speech-language pathologist. It involves the administration of very small amounts of food and liquid such as ice chips, nectar, puree, thin liquids, half of a cracker. These are very small amounts.

In a research study, the bedside swallow eval screening was given followed by the three-ounce water test for comparison (Lynch et al., 2017).  The bedside screening eval didn't actually do that well.  It had fairly low specificity and sensitivity. So, it wasn't very good at ruling in or ruling out aspiration as compared to the three-ounce water test. However, it is one of the tools that did include patients with post-extubation dysphagia so I wanted to mention it.

Yale Swallow Screen. The Yale Swallow Screening tool is probably the best studied of all of the swallow screening tools that are available. It involves a very brief cognitive screen looking at orientation and following directions, an abbreviated oral mechanism examination, and the three-ounce water test. This is a very well-validated screening tool. The sample size was large and included a wide variety of ages and a wide variety of diagnoses, including patients with post-extubation dysphagia.  This is probably the one that is best validated if you're looking for something for post-extubation dysphagia in your facility.

Post-Extubation Screening. Finally, there's the Post-Extubation Screening, which is a tool designed specifically for this population. It is designed to be used by nurses. It doesn't involve a water screen. In fact, there's no food or liquid given at all, but it is an assessment of level of alertness, respiratory status, medical complexity, and overt signs and symptoms of dysphagia. The nurse can document these factors and make a determination about whether a patient requires a full swallow evaluation by speech-language pathology.

This is not the kind of screening tool that we need in my facility. It's not the kind of screening tool that some of you need in your facilities if you already have a process in place for triggering swallow evaluations for these patients. If you don't have a process in place this might be a good screening to look at because it gives nursing some criteria, some warning signs, that suggest a person is likely to have some swallowing difficulty and speech-language pathology should probably take a look at them.

Swallow Screening. Finally, in terms of screening, I want to direct you to another very good review by Dr. Brodsky on screening tools. He and his colleagues reviewed all of the water swallow screens and found that they are very valuable as screening tools.  They also determined that larger volumes (i.e., serial swallowing) were better for ruling out aspiration, but smaller volumes were better at ruling in aspiration. So, a good screening tool will allow you to do both sequentially.

A recent review of clinical approaches to dysphagia in the ICU found that best practice includes a universal swallow screening for patients who have been intubated and are now extubated, followed by clinical assessment, and augmented by instrumental assessment whenever possible. So, there's some nice evidence to support what is most likely the clinical practice in your facility.

Watch Breathing

We don't have any established evaluation protocols for this population. But, what do we know?  What should we be paying attention to? I'll watch the breathing. That seems like an obvious thing to say. But it's important to pay attention to it because respiratory rate is an important clinical indicator. What is the respiratory rate of that patient when you walk in the room and then what happens to it when you start to administer food and liquid? When you start, in other words, to impose the demands of swallowing on the respiratory system, what happens to that respiratory rate?

Watch the depth of respiration. Remember good swallow-breathing coordination occurs when the swallow is at the middle part of the lung range.  If this is a patient who has very shallow breaths and can't really expand their lungs very well then, it’s probably not getting to the middle part of the lung range.

Watch for that post-swallow pattern. Are you seeing a consistent post-swallow exhalation or is this someone who's demonstrating a post-swallow inhalation? If so, then they're air hungry. Perhaps they have a shorter than typical duration of respiratory pause. When are you seeing that post-swallow inhalation? Are you seeing it all the time? Are you seeing it right from the beginning? Are you seeing it after the patient started to get a little more tired? Is it fatigue-related?

Respiratory Factors Associated with Aspiration

There is some research that was conducted by Steele and Cicero in 2014. It wasn’t done specifically with patients with post-extubation dysphagia, there were a variety of underlying etiologies in this research.  But they set out to determine what respiratory factors are associated with aspiration. They noted that respiratory rate, inconsistent breathing-swallow coordination, post-swallow inhalation, and shorter than typical periods of respiratory pause were all associated as well as low baseline oxygen saturation.  

We will come back to the idea of pulse oximetry in a minute. But notice that it's not a drop in oxygen saturation during swallow trials that was associated with aspiration but the baseline number is the one to pay attention to.

Dyspnea

We should also be paying attention to the work of breathing and looking for dyspnea. Dyspnea is one of those umbrella terms that encompasses all of those signs and symptoms of breathing discomfort.  We can evaluate it during both speech and swallowing because both are dependent on respiration. Look for that increasing respiratory rate but also look for increased work of breathing.

Watch the respiratory muscles. Is this someone who is getting tired? Is this someone who has to stop more frequently when they're speaking to take a breath. Can they only get a few syllables out? Do they have low vocal intensity? Are you seeing activation of the accessory muscles?

Respiratory Muscle Strength

Again, we want to look at the overall work of breathing. Respiratory rate is certainly part of that but we want to really look at the overall work of breathing. We want to pay attention to the respiratory muscle function. Does this person appear to have respiratory muscle strength that is sufficient for speech and swallowing?

Some of your patients will have undergone pulmonary function tests.  So, you might have some data there. We can also get baseline levels with EMST and there is some research supporting the use of a peak flow meter during cough to get an assessment of respiratory muscle strength. We will talk about that in a bit more detail shortly.

If you don't have any of these options available to you, do what SLPs always do and use your clinical observation skills. Look at the patient. Can they sit upright? Are they able to move in the bed or sit on the edge of the bed? Remember trunk muscles and respiratory muscles are all part of the same system.  If there is trunk weakness then there is respiratory muscle weakness.

Pulse Oximetry

You probably know that pulse oximetry measures the percent of hemoglobin that is saturated with oxygen. So, it measures oxygen saturation. Remember red blood cells attach themselves to the oxygen molecules to take the oxygen everywhere it needs to go. We want the vast majority of those red blood cells to be carrying oxygen at any given moment.  

The pulse oximeter sends a beam of light through the bloodstream. Red blood cells that are carrying oxygen reflect that light differently than red blood cells that are not. That's the percentage that we get from pulse oximetry.

There have been a lot of studies that tried to find a relationship between a drop in oxygen saturation on the pulse-ox and an aspiration event. But it just doesn't exist. The better thing to pay attention to is that baseline number. What's the patient's oxygen saturation when you walk into the room? If this is someone who's sitting at 93-94% to start and then we do swallow trials and they're holding their breath every time they swallow, they will have no reserve and nowhere to go but down. That's the more important thing to pay attention to. If you are working with a patient and doing swallow trials and you're watching that saturation level drop, drop, drop that doesn't tell you that they've aspirated but it does tell you that they're not doing well,  It tells you that the work of breathing is increasing. It tells you that they are not managing the demands that repeated swallowing is placing on that system. Are they aspirating? I don't know. But do we need to give them a break? Yes.

Cough

We can also look at cough. We know that cough and swallow are very connected and there's a growing body of research to support measuring peak expiratory flow rate to get a sense of respiratory muscle function for cough and swallowing. We're starting to get some norms for peak flow.

I have to say, full disclosure, that I don't have a lot of experience with this myself.  In my facility, we were in the process of implementing peak flow meters just before the quarantine and COVID.  Our infection control folks were looking into this to see how we could make it work and then they, obviously, got busy with COVID. So, this has been kind of on hold at our facility.

Instrumental Assessment

What about instrumental assessment? Some patients are not always going to be appropriate for modified barium swallow studies because it requires transportation outside of the ICU. They may not be medically stable enough for that. They may not be awake and alert enough.  They may be too agitated for an MBS and if that's what you have for instrumental assessment then you're going to have some limitations. If you have the ability to do FEES, then you have the option to go to the patient.

Management

As we're thinking about management considerations, we need to think about the overall level of acuity. How is this patient doing overall? Are they going to be able to participate in therapeutic intervention? What does their endurance look like? What is their cognitive level? Can they use strategies? Will they recall them? Will they understand them? Can you put some sort of compensatory strategy into place? These are factors that we have to think about with all of our clients.

This certainly holds true for our post-extubation patients as well. These are sick people. They're in critical care units, they are fragile, they are medically complex. So, we are working very closely with the intensivist, with the pulmonologists, perhaps with an ENT, with the respiratory therapists, nurses, dieticians, PT, and OT.

It's going to be important to expect and plan for fluctuations in performance. What you see when you do a swallow evaluation at 10:00 o'clock this morning may be very different from what the nurse sees when he/she is helping with dinner at 5:00 PM tonight. Additionally, that may be very different from what the overnight nurse sees when she's doing medication administration at 2:00 in the morning.

What we tend to do in my facility is give options. We include more than one type of food on the diet order so that the nurse or the CNA has an option. If they're really not that doing that well, then they have some pudding. They have a pureed option. If they're awake and alert and doing great then they have a softer texture item that they can work with.  We try to be as flexible in our recommendations as possible, knowing that they're going to be fluctuations in performance.

There is a very sophisticated therapeutic technique that we employ called waiting.  Time is on your side with these patients.  Remember that longitudinal study where folks were followed over a period of time and they continued to get better as time went by.  Waiting a little bit can sometimes be a very effective management tool.

Specific Management Strategies

I want to talk about diet, exercise, and some compensatory strategies. We don’t want to be too careful with the diet.  Remember these are folks who haven't been swallowing much so we don't want to exacerbate that disuse atrophy. If we make these folks NPO that just prolongs the period of time they're going without any swallow practice. So, we want to be really careful not to do that.

We want to give our post-extubation patients some opportunity to swallow.  It's our job to figure out what the safest thing is going to be. But they should have some opportunity and some ability to practice swallowing. Allow for some fluctuation in status. Make sure they have some options available to them and that nursing staff has some options available to them as well.

I am not a big fan of thickening for these patients because of the risks.  We know that if the thickener does what it's supposed to do and it prevents you from aspirating that's a good thing. But we also know that doesn't always happen. Particularly with patients with a lot of fluctuation in performance, aspirating a thick liquid is going to be more dangerous in your lungs and harder to clear.  That, to me, is an unacceptable risk in patients who are recovering from a severe respiratory disorder or disease.  So, I tend to not use thickeners with these clients.  I'll use water or ice chips if I think the risk is high. If I do thicken it is rarely past a half nectar or a nectar thickness because if I don’t know what a patient’s aspiration status is from one hour to the next then I want to make sure that if they do aspirate then they aspirate something they can clear.

We don't have a lot of research on exercise in patients who are post-extubation but the one to consider is effortful swallow. It's easy and doesn't require any equipment. I just tell patients, “When you're having some ice chips or taking a sip of water, swallow harder than you normally would. Put a little effort into it to make it an exercise.” This is also helpful for families, as well, because they can provide that cue and feel like they're doing something to make things a little bit better. So, I think that an effortful swallow is the way to go.

Expiratory muscle strength training is a very effective therapeutic technique that has been studied in other populations with respiratory muscle weakness. But we don't have any data specific on post-extubation dysphagia. In this age of COVID, you have to figure out the infection control for having the device in the room.

Questions and Answers

With post-extubation, you mentioned that you don't use thickened fluids. Is this before an instrumental study or even after one where thickeners appeared successful in preventing penetration aspiration?

That's a really good question. We try to avoid thickened liquids whenever possible whether or not we have instrumental assessment. If we've done an instrumental assessment and the patient did better with nectar or honey, we may not necessarily recommend that because of the fluctuations that we see in these folks.  A swallow study is a moment in time, and that’s particularly true for patients who are post-extubation. They are fluctuating so much that it's really difficult to make broad recommendations based on that swallow study. I'm not saying don't do a swallow study. I'm saying understand that it's not going to give you insight into how they're doing an hour from now, two hours from now, or six hours from now.

For that reason, we tend to rely on water protocols and oral hygiene. We call it “chips and sips” or “water sips and ice chips”.

You were talking about what we do after they have been extubated. Because we know that every day that they are intubated, you're increasing the amount of disuse atrophy that they're experiencing, is there anything that can be done while they are still intubated? If the person is conscious and able to participate, are there any interventions that can be done while the person still has the tube that might help lessen the effects of disuse atrophy? Or is there not much you can do with that tube in there?

There's just not much you can do with the tube in. But for patients who are getting non-invasive mechanical ventilation, those folks could some breathing exercises, some work with the peak flow meter, and maybe effortful swallows. This is me surmising and I can't point you to a study on this yet, but patients who are on BIPAP, CPAP, or high-flow nasal cannula who have some of the same issues with disuse atrophy, that may be a group of folks that we can help.

Would you delay a swallow eval with a patient who is still requiring high levels of oxygen? For example, via a high-flow nasal cannula or something similar?

Yes, I have a pre-COVID answer and a post-COVID answer to that question. Before COVID I would have said, “Nah, you know, if they're working that hard to breathe and they need high-flow nasal cannula, I would defer that swallow eval. It just puts too much demand on the respiratory system.” Post-COVID, we've just seen folks who need these interventions for so long that to delay the swallow eval seems like a bad idea. To make them wait for long period of time would be poor quality of care.

So, lately, we've been doing swallow evals. Sometimes we do the swallow eval and we say it's just not safe. But we have been going in and doing swallow evals on folks, not BIPAP or CPAP, but high-flow nasal cannula, and most of the time the recommendation is ice chips.

Can you tell us more about your chips and sips protocol?

It's often the recommendation that we make in those first few hours after extubation. Now I have to back up and say that our ICU does a fabulous job with oral hygiene. I can't always say that happens in some of the other units in my hospital. But our critical care unit does a really good job with that. So that's sort of the baseline that we're working with because not only do we have the relationship to aspiration pneumonia, but we know that good oral hygiene keeps ventilator-associated pneumonias down too. There are many good reasons to do it in critical care units and my facility does a good job with that.

With a good oral hygiene program in place, we will often recommend ice chips and water sips freely throughout the day, before we order a diet. We rarely walk out of the room after a swallow eval without a recommendation for something to swallow. It might be just single ice chips - four or five ice chips an hour. There's a lot of variability, obviously, depending on the patient and what they've got for support. If they've got a family member there who can do that with them that always helps. But we rarely walk out of the room without a recommendation for something to swallow. At the low end, it might be just single ice chips spaced apart several times an hour.  At the higher end of that it might be ice chips and water sips as freely as the patient wants. From there, the next level up would be to order a diet with a tray.

Is there some timing guidance on swallow evals for patients requiring intermittent BIPAP use? Is that a before COVID after COVID type answer too?

The answer is actually the same. We don't have any convincing literature one way or the other for patients with BIPAP. My pre-COVID and post-COVID answer are the same in terms of my clinical practice. If patients are on BIPAP, we defer the swallow eval.