Editor's Note: This text is a transcript of the course Thickened Liquids in Clinical Practice: The Plot “Thickens”, presented by Angela Mansolillo, MA, CCC-SLP, BCS-S.
After this course, participants will be able to:
Today, I will be talking about thickening. I will talk about why we do it, whether we should be doing it, when we should be doing it, and how to do it if we do decide to do it.
Let's start by briefly discussing swallow physiology related to thick liquid swallows. We know that a swallow is not a swallow is not a swallow. I tell my students that all the time. Swallows look different depending on what we're swallowing, the thickness of it, the size of the bolus, the temperature of the bolus, and the shape of the bolus.
According to research conducted by Steele and colleagues in 2019, when swallowing thick liquids, some changes occur, such as the swallow onset occurring high in the pharynx. That's probably due to the slower transit. We see a shorter laryngeal vocal closure reaction time, so less time to full closure. We see a reduction in the opening of the upper esophageal sphincter. This is true for both slightly and mildly thick liquids. We don't get quite the same excursion of the upper esophageal sphincter if you will. We tend to see more residue with thick liquids. In general, we don't see a lot of residue overall in healthy swallows, just slightly more. This may have some implications for our folks with reduced pharyngeal clearance, and I'll talk more about that later.
However, there are essentially no differences in terms of pharyngeal constriction, hyoid position, and no change in the overall sequencing of the swallow events related to thickening. So everything happens in the same sequence, whether we are swallowing thin liquids or thick liquids.
Interestingly, Dr. Steele's study also found that there were no clear boundaries in terms of swallow physiology along the current consistency continuum. Liquids are divided into thin, slightly thick, mildly thick, moderately thick, etc., if you know the IDDSI format. But swallow physiology doesn't line up that way. Those are artificial lines that we have drawn in terms of dividing up the liquid type, but there are no clear demarcations regarding swallow physiology along those lines. In other words, when we move from mildly thick to moderately thick, it's not like something magically changes in terms of swallow physiology. It's more of a continuum.
We can review the evidence associated with thinner liquids in terms of what we know about swallow physiology. We are more likely to see laryngeal penetration for thinner liquids as compared to a paste consistency as compared to a puree. We also see an earlier onset of swallow apnea with thin liquids. That's likely because the thinner liquids are moving faster, and so the swallow response is a little quicker. Additionally, there is a decreased duration of the upper esophageal sphincter opening for thin liquids.
With thick liquids, there is decreased excursion with the amount of opening, but with thin liquids, we tend to see decreased duration. In other words, the sphincter stays open for a little less time.
What about breathing and swallow coordination as we move from thin to thick? A study by Valenzano and colleagues (2020) looked at healthy subjects and their breathing-swallow coordination for thin liquids and thick liquids. It did not find any real differences. They continued to see consistent post-swallow exhalation. If you're unfamiliar with the research around breathing-swallow coordination, most of the time, most subjects use an 'exhale, a little swallow, exhale some more' pattern. The swallow is bracketed by the exhalation. That post-swallow exhalation is important in terms of improving airway protection. So it's good that it's there most of the time whether we are swallowing thin liquids or thick liquids.
The other factor that the researchers looked at in terms of breathing-swallow coordination was the duration of the respiratory pause, that period of swallow apnea, or breathing cessation, that occurs when we swallow. That was also found to be fairly consistent across liquid consistencies.
Thickened Liquids: Risks and Benefits
There are some changes in terms of swallow physiology when we move from thin liquids to thick liquids, but I wanna talk a little bit about the risks and benefits of thickening as an intervention.
Benefits of Thickening
Some research looked at patients with oropharyngeal cancers who were undergoing radiation therapy, and found a reduction in aspiration in those patients when they moved to thick liquids (Barbon et al., 2021). An older study (Rofes et al., 2014) examined patients with neurologically based dysphagia. These were folks with stroke. They also had patients with neuromuscular diseases and elderly folks. They found that thickening in these populations did, in fact, reduce aspiration risk. Additionally, a couple of studies looked specifically at patients with stroke and found that thickening actually reduced aspiration in those folks as well (Bolivar-Prados et al., 2019; Vilardell et al., 2016).
Digging a little deeper into the data from these studies, however, you will see that while thickening reduced aspiration risk, it increased residue in some of these patients.
A 2016 literature review found that, in general, there was evidence to support the idea that thickening increases airway protection and reduces aspiration risk, but there was a fair amount of evidence to demonstrate the thickening also increased residue in the pharynx (Newman et al., 2016). Perhaps even more importantly, there was evidence of decreased quality of life and increased dehydration risk. Here's the crux of the problem for a lot of our patients: They don't like the thick liquids, and so they don't drink them. Then, they become dehydrated and experience a decrease in quality of life.
Research from 2019 showed that thick liquids have the potential to reduce coughing, choking, discomfort, and the associated stress that goes along with those (Lippert et al., 2019). We have probably all seen those patients who may not be aspirating, but the thin liquids make them cough. The cough is effective; it keeps the material out of the airway, but it is so uncomfortable. Every time they drink, they're coughing, coughing, coughing. So, in those situations, thickening can increase comfort and may actually have a positive impact on quality of life.
There's also evidence to support the idea of thickening to increase comfort in patients at the end of life. Again, these are patients for whom the thin liquids are just too uncomfortable, and they can't manage them.
Miranda and colleagues in 2020 asked the question, "Do thickening products add any nutrition?" Is there any nutritional value for our clients who are using them? The evidence is inconclusive, but the answer is essentially "maybe." Starch thickeners have the potential to add calories. It's not a lot of calories, but they do have the potential to add some calories. So, that may have a positive impact on some of our patients who are struggling to get enough intake. Their research also found that xanthan gum products have the potential to add fiber. Again, these are not huge amounts, but there is the potential for some fiber contribution.
Risks of Thickening
Thickening has the potential to result in a number of issues. As I said earlier, people don't like thickened liquids, and so they don't adhere to our recommendations. When they do, they report poor quality of life. When they do drink thick liquids, there are issues with satiety. There are issues with consistency. This happens when there are a number of different caregivers involved, and we aren't getting the same consistency. There is an impact on digestion and gastrointestinal function. There's a potential impact on lung function if the thick liquids are aspirated. There is also an impact on medications, which we will talk about some more as well, and certainly the risk of dehydration.
Inconsistent Consistency. Let's review these risks in more detail, looking at the issue of preparation first. Two older studies looked at thickening. (I'm not aware of any more recent research in this area because we established this problem back in the '90s.) The Garcia et al. study (2010) looked at 42 healthcare professionals, of SLPs, nurses, nurses aides, and OTs - anybody in the facility who was involved in thickening. The second study conducted by Glassburn and Deem in 1998 was specific to SLPs.
Participants in both studies were asked to prepare liquids in a nectar-thick range and a honey-thick range. This was before we had the IDDSI standards. The data shows that none of the participants were very good at it. In the Garcia study, of the 42 health professionals who thickened liquids daily as part of their job, none got three out of three correct in the nectar range. Half of the participants got at least two out of three products in the nectar range. And even fewer participants were able to correctly thicken in the honey range.
The Glassburn and Deem study showed very poor inter and intra-subject reliability among SLP participants. Please understand that I'm not trying to blame the healthcare practitioners in the studies. They were doing their best. This is often an issue with the products. The products are difficult to use; we have a different base liquid to start with. Thus, preparation issues are inherent in the process.
Adherence. The bigger issue we have is adherence. We can recommend them, but people don't like thick liquids, so they won't adhere to them. Think about dietary recommendations that someone has made for you. Perhaps to cut calories, cut back on carbs, or cut out caffeine. We know that these are things we should be doing. But none of them are very pleasant, and we often don't adhere, and we often don't adhere consistently. Some days, we may skip that caffeine, but there might be days when we really want that morning coffee. Our patients are the same. We see real inconsistencies in terms of adherence. So, it's important not to consider adherence an all-or-nothing thing. People's adherence will vary.
Palatability. One barrier to adherence is palatability. These products don't taste good. They don't feel good in your mouth. They have a really unusual mouth feel that can be really difficult for patients to accept. Thickeners have the potential to suppress the flavor of the actual liquid and leave a new flavor, particularly a bitter, astringent aftertaste. For some people, the bigger issue is actually the change in the texture, the change in the mouth feel. People report that the liquid feels grainy, lumpy, or slimy.
Of course, individual preferences play into adherence as well. Two studies were done a few years apart but essentially had the same design (Macqueen et al, 2003; Horwarth, et al, 2005). Both studies asked folks with dysphagia to taste test a number of thickened liquids. They had nectar-thick liquids and honey-thick liquids. Starch-based thickeners, xanthan-gum-based thickeners and naturally thick liquids were used. And they had hot and cold thickeners. A number of different options were available for the participants to taste and see what the most appealing thickened liquid combination was. Not surprisingly, there was no agreement in either study. That's why there are a number of different flavors of ice cream in the grocery store. Everybody likes something different. Why would we expect that it would be any different for thickeners?
But there's an important point, and the reason I included these studies is because everybody likes something different. That's important for us to remember. Often in our facilities or in our practices, we may only have one product available. But if we had options for our patients, if they could try a couple of different starch thickeners, or different gum thickeners, or the thickener with juice versus water versus milk, etc., then we could help them to find the combination of thickener and liquid that is the most palatable for them. If we can do that, perhaps we can increase adherence. So, considering individual preferences can be an important tool for improving adherence. It's about texture, it's about taste, etc.
A study was conducted in Korea with patients with dysphagia in 2013 by Shim and colleagues. They had a number of patients who had a recommendation for thick liquids following their instrumental assessment. They found a significant lack of compliance or adherence. Inpatients, not surprisingly, were more compliant than outpatients. This is probably due to having fewer options and fewer choices. Outpatients had more ability to demonstrate their lack of adherence. And the reason, when they dug in to see why people were not following these recommendations, was about dissatisfaction with texture and taste. Many of these folks also said, "It's harder to swallow. This is not making it easier for me." Other participants complained about the overall inconvenience of preparing thick liquids. So, adherence is more than just people not liking the thick liquids.
This next study contains my favorite thing I've ever read in a research study. In 2018, McCurtin and colleagues interviewed folks who were using thick liquids. This is a study that came out of the UK. Participants were asked to describe their experience with thick liquids. Some of the responses included, "Awful, vile, wallpaper paste. It tasted like poison." My all-time favorite comment about thick liquids is, "It looked like frog spawn." So, who wants to drink that?
What can we do to improve adherence? As I said earlier, adherence is not an all-or-nothing thing; it's not a one-time decision. Think about your own adherence to your own health recommendations. There are days you do what the doctor thinks you should be doing, and there are some days that you don't. The same is true for our patients. Their adherence will vary with a number of things, including their own perception of risk. That's why it's important to involve patients in the decision-making and have them take a look at the instrumental assessments so they're aware of what the physiological issues are.
One study looked at adding food flavorings such as lemon extract or vanilla to thick liquids (Vidal-Casariego et al., 2021). They found that people seemed to like them better. So, that's an interesting option to keep in your toolbox.
Quality of Life. Of course, there is the issue of impact on quality of life. One study interviewed hospitalized patients (Lim et al., 2016). These were not folks with dysphagia. They had no cognitive impairment. They were given samples of thick liquids to try and were asked to imagine the following scenario, "You are in perfect health with the single exception that until you die," (so for the rest of your life), "you need to take all of your liquids at the thickness that you've just seen and sampled." Participants in the study were not happy about that.
Then, the researchers asked the participants how long they would be willing to live like this. "How much of your life, your future, would you be willing to trade to avoid the thick liquids?" Participants in this study were willing to trade four to five years out of a potential 10-year lifespan to avoid the thick liquids. That's a big statement. We need to take it seriously that the impact on quality of life for some of our patients is huge and one we need to think carefully about and talk to our patients about so that they can make that risk-benefit analysis for themselves as well.
Access. Another issue is access. Sometimes, access to thickened liquids is part of the issue. Some interesting research has been conducted where unannounced observations were made of patients in hospital beds and skilled nursing facilities to see if they have access to fluids. In other words, was the water pitcher by the bed? Was thickened liquid available? A 2012 study by McGrail and Kelchner found that patients who were consuming thin liquids had beverages within their reach 88% of the time. (That actually seems a little high to me. I'm not sure we're doing as good a job in my facility.) But in that same facility, patients with thick liquid recommendations had beverages within their reach far less consistently - 56% of the time.
Thick liquids are not easy. You can't just put the water pitcher by the bed. It has to be measured, mixed, and prepared. So, we find that folks who have a requirement for thick liquids are offered liquids less frequently because of the preparation time and the preparation burden. This is true for my pediatric clients as well.
Early Satiety. There are also gastrointestinal issues related to thickeners, particularly early satiety (Cichero, 2013). People tend to drink less when they are drinking thick liquids, not only because they don't like the taste but because they feel full faster. This is a big issue for our pediatric clients, or particularly infants and young children. All of that fiber and starch in the thickened liquids make people feel full more quickly. They eat and drink less and then feel full for longer. As a result, more time goes by before they're ready for another drink or something else to eat. I
Additionally, the slower oral transit time means that the liquid is in your mouth for a slightly longer amount of time. So, there's slightly longer exposure to the taste and texture receptors, which also helps to contribute to satiety. It's tricking your brain into thinking that you're drinking more than you actually are.
Thick liquids are digested more slowly, which can contribute to that feeling of fullness as well. Thickeners also slow down the absorption of nutrients from the liquid. That means your body is getting satiety signals for a longer period of time because the nutrition from the liquid has yet to be absorbed.
Many things are going on in your gut and in that brain-gut connection when we put a thick liquid recommendation in place that contributes to the feeling of satiety and decreased intake.
Other GI Impacts. In addition to early satiety, there are other gastrointestinal issues that we should be aware of. If you are working with infants, using xanthan gum thickeners is contraindicated because of the link to necrotizing enterocolitis. Across products, thickening can result in constipation, which is probably related to dehydration and the decreased amounts of intake that I've been talking about. There doesn't seem to be anything inherently constipating about the thickened liquids, particularly when we use thickening products, but people drink less, and so they become more dehydrated and become more constipated. There is also increased gastric emptying time and the potential for mucosal injury to the gut related to some increase in regurgitation. This is not a common side effect of thickeners, but it has been documented in a small number of patients (Levy et al., 2019; Salvatore et al., 2018; Miyazawa et al., 2006; Gosa et al., 2011).
Cough Response. There is a question about the impact on the cough response. An interesting study conducted by Miles and colleagues in 2018 had almost 200 inpatients who had been referred for FEES studies due to a question of dysphagia. There was a wide variety of diagnoses among the patients. They found that thicker fluids decreased the likelihood of aspiration. However, when folks aspirated the thick liquids, they were more likely to demonstrate silent aspiration with the thick liquids. For reasons that we don't completely understand, there is this potential for diminishing the cough response, which is certainly not a desirable outcome.
This study by Miles and colleagues highlights the importance of instrumental assessment. If you've heard me speak before, you know that I am a big fan of clinical assessment. I get much information from my bedside or clinical evaluation. But I also understand its limitations, and this is one of them. This study tells us if we provide a patient with thin liquids and they're coughing and sound wet at bedside, and then we think, "Okay, let's try thickening and see what happens," and they sound better, it may not mean the thickening is doing what we hope it is. Meaning it's not necessarily reducing the aspiration. It may mean, unfortunately, that the thickening is actually resulting in silent aspiration. Therefore, it is important to consider access to instrumental assessment if we suspect aspiration. And this study points out that importance.
Lung Impacts. What about the impacts of thickeners on pulmonary function? Not all lung infections are related to aspiration, and we know that everybody who aspirates doesn't inevitably end up with aspiration pneumonia. But the thickening may be a problem in and of itself. An animal study examined different types of thickeners' impact on pulmonary function (Nativ-Zelzer et al., 2018). The researchers instilled water, thickened water with cornstarch and water thickened with xanthan gum into the lungs of rabbits over three days to determine the survival rate, the pulmonary inflammation rate, and infection rate.
All of the rabbits who had water instilled survived, but the rabbits who had the cornstarch-thickened water instilled in their lungs had a very low survival rate. All of the rabbits who had xanthan gum-thickened water instilled into their lungs survived over the three days, but had higher rates of pulmonary inflammation, lung congestion, and lung edema than the other two groups. It's important to realize that in the unthickened water group, those rabbits actually had much better outcomes.
Even though this was not a human study and we need to be careful how we interpret it, it does plant that seed of worry for our patients who might actually be aspirating the thickened liquid, and that thickened liquid is actually in the lungs.
What About Outcomes?
You may be aware of a couple of studies conducted a few years ago that are now under the umbrella of what is called "Protocol 201." This was the first and one of the few, randomized controlled studies examining swallow interventions. The researchers looked at three interventions: chin-down head position with regular liquids, nectar-thick liquids, and honey-thick liquids (Logemann et al., 2008; Robbins et al., 2008).
The subjects in this huge multi-center study were elderly patients with Parkinson's disease and/or dementia. They were given modified barium swallow studies looking at each of the three interventions to see which one had the greatest impact on aspiration risk. They concluded that honey-thick liquids were most effective at reducing aspiration risk in those subjects.
For the second part of the study, they took those folks for whom there was no clear benefit to any of those interventions (these were folks who were either going to aspirate or weren't going to aspirate - there was no clear benefit.) Those subjects were randomly assigned to one of those three interventions for 90 days. At the end of 90 days, the honey-thick group had more hospitalizations for urinary tract infections, more dehydration, more hospitalizations for pneumonia, longer hospitalizations for pneumonia, and more deaths. So thickening to that honey-thick level looked good immediately because it had a positive impact on reducing aspiration risk in the moment. However, the long-term outcomes were not so good.
Let's think about this. Remember, we had subjects who were aspirating and who were not aspirating in each of the intervention groups. So, in that honey-thick group, what happened to the folks who were not aspirating? They got dehydrated and ended up in the hospital with dehydration and urinary tract infections. What happened to the folks in the group who were aspirating the honey-thick liquids? They got bad pneumonia. So whether your thick liquid intervention is working to prevent aspiration or not, there are going to be some potential outcomes on health that we need to be aware of, and we need to think about managing.
There is an interesting longitudinal study of over 500 subjects known to be aspirators. They were followed for over four years to see who developed aspiration pneumonias. Results of the study showed no significant differences in pulmonary events related to PAS scores. So, it didn't matter if the subject received a five, six, seven, or eight on the Penetration Aspiration Scale. The degree, depth of the aspiration, and the response to aspiration didn't seem to matter. Also, there were no significant differences in pulmonary events related to the diet the participants were on, with one exception. The folks who were NPO actually got sick the quickest.
Also, etiology mattered. Why was this person experiencing dysphagia? The subjects experiencing dysphagia secondary to frailty or deconditioning were also more likely to get sick. The point of these studies, and the point that I'm trying to make, is there is no one-size-fits-all intervention for individuals with dysphagia. We need to think about their potential for adherence. We must consider the impact on quality of life from their perspective, not ours. We need to consider the associated and underlying medical conditions that could be factors.
A meta-analysis was conducted in 2018 by Beck and colleagues. They concluded that thickening liquids does not have a positive impact on quality of life. It does not have a positive impact on hydration status, lung health, or mortality. Again, the point is that we may think we are doing what is in our patients' best interest when we thicken, but that may not always be the case, unfortunately.
A "Cochrane Review" from 2018 looked at food and liquid modification for swallow difficulties in patients with dementia. Researchers concluded that "clinicians should be aware that while thickening fluids may have an immediate positive effect on swallowing, the long-term impact of thickened fluids on the health of the person with dementia should also be considered." (The italics are mine.) Therefore, we need to think about the impact of what we are doing outside of being hyper-focused on airway protection
Thickeners and Medications
The question often comes up about thickeners and medications that our patients are taking. There are potential interactions that we need to be aware of. 1) Thickeners have the potential to decrease medication availability, 2)The increase in thickness of the liquid can slow the dissolution and disintegration of the medication, 3) Thickeners may be physically incompatible with some liquid medications. They just may not work, 4) Thickeners have a slow transit time; that's what we use them for. But that may have an impact on where the medication is absorbed. The impact appears to be more significant with xanthan gum thickeners than with starch-based thickeners.
Much research has been conducted in the last couple of years looking at thickeners and specific medications because the impact is different. I cannot say, "When you use this thickener, it has this impact on drug dissolution," because it matters which drug it is. There are different results with different medications. The bulleted list is a compilation of the more recent research on specific medications studied.
- Levetiracetam (Keppra) not impacted (Ilgaz et al., 2022)
- No impact on levofloxacin (Levaquin) with coating intact, but when crushed, dissolution was delayed (Takahashi et al., 2020)
- Ciprofloxacin (Cipro) dissolution was delayed when crushed and with coating intact (Takahashi et al., 2020)
- Acetaminophen (Tylenol) dissolution is delayed in both dissolved and crushed forms (Manrique et al., 2016)
In a 2022 study, Keppra was not impacted by thickeners. There was no impact on Levaquin when the coating was intact. But when the medication was crushed and taken with a thickened liquid, there was an impact on dissolution. Again, we need to think not only about the medication, but how the medication is being administered. Dissolution of Cipro was delayed when the medication was crushed and given with the coating intact, and Tylenol dissolution was delayed in both forms as well.
A study from 2014 looked at four different medications: some beta-blockers, calcium channel blockers, and anticoagulants. Dissolution of all four medications was slowed when mixed with thickened water.
- Amlodipine (Norvasc) – calcium channel blocker
- Atenolol (Tenormin) – beta blocker
- Carbamazepine (Tegretol) –anti-convulsant
- Warfarin (Coumadin) – anti-coagulant
We must consider if our patients, who are on a thick liquid recommendation, are taking their medication with that thick liquid. If they are, there may be some implications in terms of drug dissolution. It's always a good idea to let the pharmacist know when a patient is taking their medications with thickened liquids so they can be aware.
Thickening liquid medications has the potential to slow the dissolution and disintegration of the medication. When thickening a liquid medication, that is considered an "off-license" use of that medication, and the legal implications are unclear. So I always make sure that the physician, the nurse, the pharmacist, and everybody on the team knows the patient is using thick liquids.
Dehydration risk is the main issue with thickening. Study after study has demonstrated that when a thick liquid recommendation is implemented, patients fail to meet their daily fluid requirements. There is some research to demonstrate that thickened liquids have the potential to support hydration. A specific population of patients using very specific protocols actually drank more when the liquids were thickened (Sezgin et al., 2018; Goroff et al., 2018). So, it's not all negative.
This brings us to the issue of water availability. Patients, nurses, and other SLPs often ask, "When we use a commercial thickener, how much of the original liquid is available for hydration?" Actually, the vast majority of the liquid is available and returned to the bloodstream. However, there are some differences between types of thickeners.
Starch thickeners break down throughout the alimentary tract, starting in the mouth. There's a substance in saliva that starts to break down the starch in everything we eat and drink, including starch-thickened liquids. That starch thickener starts to break down before the liquid has even reached the pharynx and continues to break down all the way through the alimentary tract. Gum and gel thickeners, on the other hand, tend to remain fairly intact all the way through the upper GI system and don't start to break down until they're through the stomach, the duodenum, and into the intestines. They remain intact through much of the gastrointestinal tract.
But neither type of thickener appears to have a huge impact on returning that water to the system. Water absorption across thickener types generally exceeds 95% of the total. Most of the liquid is being returned to the system. So why are people becoming dehydrated? It's not the products themselves in that regard. The products are returning 95% or greater of the fluid into the system. So the issues are most likely access to thickened liquids for some patients, low palatability for most patients, and early satiety for most patients as well. Those are more likely the contributing factors to dehydration. It's not that the products are inherently dehydrating.
What do we do to improve hydration? First, let me say that the purpose of this course is not to convince you never to use thick liquids, although I do use them very judiciously and would recommend that you do the same. There are times when it is an appropriate intervention. However, when we put a thick liquid intervention into place, we must also have a plan for hydration. It's irresponsible to thicken liquids and not address the hydration issue it is causing.
Your plan will probably vary from patient to patient and may vary depending on the setting that you're in. But there are some suggestions and strategies to improve hydration.
- Offer liquids more frequently. There are skilled nursing facilities that have "happy hours" and fluid rounds. Talk to the nurses about med pass. The nurse usually interacts with the patient during that med pass several times daily. That's a good opportunity to encourage some fluids.
- Work with the dietician to identify foods that have higher fluid content to incorporate more of those high-fluid foods, like fruits and vegetables, into the dietary plan.
- Use sensory input to improve fluid intake. Different temperatures and different flavors might be more palatable to an individual patient.
- Carbonation can help improve swallow function in some patients. You may want to evaluate that as an alternative to thickening.
- Naturally thick liquids or natural thickeners such as potato flakes or quinoa flour might be more palatable for some patients.
- Water protocols are another important tool.
There is currently a lot of research on using water protocols with patients with dysphagia, and the research is overwhelmingly positive. Most studies demonstrated an increase in fluid intake in patients who were using water protocols and improved patient-reported quality of life. Murray and colleagues, 2016 reported a reduction in urinary tract infections in the patients using the water protocol.
All but one study reported no increase in pneumonia rates associated with the water protocol. The one study that did see an increase in pneumonia related to the water protocol was a study conducted in 2011 by Karagiannism and colleagues. They reported that the patients who got sick were those with degenerative conditions and significant reductions in mobility. Those studies have helped identify patients who are not appropriate for water protocols. For example, the patient who is coughing incessantly and is uncomfortable.
Other exclusion criteria include patients who have impaired cognition such that they can't understand how to do the protocol. They don't understand why they can have water, but they can't have other liquids unthickened. They don't understand why they can have water outside of mealtime but not with their mealtimes. The patient has to be able to understand the protocol and be a participant in the protocol.
Patients who have active infections, oral infections, and lung infections are also not appropriate. Patients with poor oral hygiene who do not respond to intervention would also not be appropriate. Additionally, significant reductions in mobility and degenerative conditions are contraindications for thickening liquids.
The field has known about the positive impacts of water protocols for a long time, but they're not being implemented consistently in facilities or even with individual patients. There seem to be many roadblocks in that regard. Some research from the last couple of years looked at what some of those roadblocks and barriers have been
- Patient’s cognitive impairments
- Insufficient documentation
- Perception of increased workload
- Perception of increased risk for patients
- Established culture of thick liquid utilization
There are roadblocks related to the patient's cognitive impairment, but many are institutional barriers, such as documentation on the process, a perception of increased workload, a perception that it is unsafe, and an established culture of thick liquid utilization. As SLPs, we have to take some responsibility for that. We spent a long time convincing people in healthcare that thicker was safer, and now we're saying, "Well, maybe not always." So, we are turning a big ship as we think about changing people's minds. That's certainly one of the barriers that we are up against.
Research has identified some facilitators, though, in terms of implementing water protocols. Clear communication, easy-to-follow protocols, peer support, and modeling are considered to be facilitators (Murray et al., 2021; Barker et al., 2019).
Ice Chip Protocol
The ice chip protocol was described in 2018 by Pisenga and Langmore. It was actually a protocol that many SLPs have been using informally for a long time. But Susan Langmore described it in a much more scientific way than most of us could have. The ice chip protocol allows for assessing swallowing in significantly impaired folks. With this protocol, patients who might have significant dietary restrictions, might be NPO, or might be receiving their nutrition via NG tube or G-tube, are allowed ice chips. Like the water protocol, this accompanies a standardized oral care protocol. The patients are allowed ice chips. We've been utilizing this protocol in my ICU for many years to assess improvements in swallow function. It's a way for patients to practice swallowing, keep their mouths wetter and more comfortable, and can help patients and/or family members feel like they're doing something.
Often, in the ICU, when our patients are very impaired, our best intervention is waiting. We use a tried and true intervention called, "Let's wait and see what happens tomorrow," and hope there will be some improvement in overall function that will result in an improvement in swallow function. And sometimes, that is the best we can do with our very compromised patients. But this protocol gives patients and family members something to try. And we've had really positive outcomes in my ICU. Even with our NPO patients, we almost always allow ice chips and water sips. We have to get that swallow going. Our patients will not get better at swallowing if they never do it. The ice chip protocol may be a safe way to do that.
There is also some research on systematic weaning protocols that have been studied in pediatric populations. Wolter and colleagues did a systematic thinning of the thick liquid and gradually gave the children practice with a liquid that was slightly thicker than the week before (2018). And they've successfully used these protocols to wean pediatric clients off their thick liquids.
There also might be some room for some variability in terms of thickening. A study conducted by Dr. Steele in 2014 identified that, as human beings, we cannot perceive small differences in thickness in very thick liquids. We can perceive the difference when the liquid is thinner, but as the liquid gets thicker, it is harder to perceive differences in thickness. If we can't perceive a difference, is it really going to have an impact on swallow function?
As a result, there was a movement toward the idea that we need something between thin and nectar. Now with the IDDSI levels, we have those slightly thick liquids that may be just thick enough for patients without needing to go to mildly thick.
Choosing a Product
When choosing a thickening product or protocol for your patient, you have to think about the mechanism of the thickener, how the thickener works, what it costs and what it takes to prepare it. Starch thickeners take longer to thicken, but they are easy to manage because we can mix them by hand. Gel thickeners thicken more quickly and they maintain their viscosity over time, but they're a little bit more difficult. They often require shaking or whisking, which is an added care burden for the person responsible for that.
We also know that when we are thickening, we are adding cost to the care of that patient. That cost will vary with the product and with the viscosity. Obviously, the more product you need, the higher the cost. This may not be an issue in a facility, but certainly, for patients who are trying to manage thick liquids at home, it can be problematic. There is actually a study that showed that when time and labor involved in thickening are added to the equation, that makes pre-thickened liquids actually look more cost-effective from a facility point of view.
Thickening isn't easy, it isn't consistent, and the end product will vary considerably depending on the temperature, the base liquid, the time post, and how long ago you thickened it. There are also specific product differences. So, there is a lot of variability in this intervention that we will simply have to live with.
What Can We Do?
I encourage regular reassessment of patients so nobody is on a thick liquid intervention for longer than needed. Involve physical and occupational therapy in the care plan so that we can help patients improve their mobility and toileting initiatives. The idea being that some of our folks don't like to drink because then they have to go to the bathroom. If we're also thickening, it just adds to that burden of hydration.
To conclude, think not only about the benefits of thickening but also the risks as they apply to your particular patient. There are many options, and the more options we have and the more involved patients are in that choice, the better adherence we will get. Finally, I will say one more time: If you put a thick liquid recommendation into place, you have to have a plan for hydration.
Questions and Answers
Referring back to the various studies related to water protocols, you said there were reduced UTIs compared to the control group. Do you think that's due to better hydration in those folks who were on the free water protocols?
It did seem to be. Only one of the studies used urinary tract infection as an outcome measure, but they did see fewer UTIs in the group that was getting the water, and they did attribute it to hydration status.
Overall, are you saying that it's okay to do ice chips with patients who are NPO in order to practice swallowing?
Yes, I am, and so is Susan Langmore, as long as an oral hygiene protocol is in place.
If someone's on thickened liquid and meds are crushed in applesauce, will that help with med dissolution?
It may or may not. There are a lot of studies that have looked at what happens when we combine food with medication. And again, there's a lot of variability. Some medications do slow in terms of their dissolution when added to food, but it may or may not, and I'm not an expert here. It may or may not be the same medications that interact with the thick liquids. But whether you're taking the medication with a thick liquid or taking the medication whole or crushed in applesauce, for example, there is that potential. So we need to make sure that the physician and the pharmacist are aware of what we're doing.
I know that was just a rabbit study - but there seem to be more issues with morbidity after using the corn starch thickener in the lung versus xanthan gum. Do you think it has to do with the sugars and corn starch attracting bacteria?
It could be. There's a lot we know about pulmonary clearance. But there is also a lot that we don't know. It may be related to bacteria. It may also have something to do with mucociliary clearance, in that perhaps the starch is harder for the cilia to grab onto. I don't think that we know for sure. But there's clearly some impact on pulmonary clearance. What that is specifically, we don't know.
Have any studies been done on pulmonary clearance for natural thickeners (e.g., potato flakes, quinoa) versus the "more unnatural ones"?
No, I don't think we know. We know that food will be more of a challenge for pulmonary clearance. As a general rule, we must try to have as much assurance as possible that the thick liquid is doing what we want it to do. In other words, it is preventing the aspiration. If it's not, or if it's not consistently, and there's a chance that your patient is aspirating the thick liquid, we're actually putting them at higher risk than if we had just not thickened at all. So, we have to be sure that the thick liquid is doing what it's intended to do.
Would you do the Frazier or the free water protocol with someone who has a bit of residual thrush?
No, probably not. If there's any infection, including an oral infection, we don't do the protocol in my facility. Thrush actually has its own set of issues. But if there is an infection anywhere, including an oral or pharyngeal infection, depending on where the thrush is, the immune system's more compromised, and there will be less potential for good pulmonary clearance.
(*See handout for a list of references.)
Mansolillo, M. (2023). Thickened liquids in clinical practice: the plot “thickens.” SpeechPathology.com. Article 20622. Available at www.speechpathology.com