Nutrition Connection: Making Dysphagia Easier to Swallow
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(reprinted from Nutrition & Foodservice Edge, March 2012)
No doubt, as long as man has walked the earth, someone— somewhere—has experienced difficulty in swallowing.
As a condition, swallowing difficulty—or dysphagia—has been studied for decades. But as a condition requiring a specialized oral diet, dysphagia is just a “kid.” Prior to the 1970s, people unable to swallow were most often nutritionally managed by using enteral tube feedings. Returning the individual to oral feeding was typically the goal, but healthcare professionals lacked a unified plan to get them there. Fortunately for patients, healthcare professionals discovered that an active interdisciplinary approach to diagnosis, management, and rehabilitation techniques can help normalize the swallowing process. Improved swallowing often results in a return to normal eating, and that serves to speed recovery and improve quality of life. It was the recognition of a lack of dysphagia diet standards and the value of teamwork that ignited the creation of the National Dysphagia Diet: Standardization for Optimal Care.
The concept of a National Dysphagia Diet (NDD) was conceived in the early 1990s as a way to decrease the confusion in communications between healthcare professionals, patients, and caregivers. At the time, a survey with clinicians showed that more than 40 different terms were used to label solid food textures, and at least 18 different names were used to describe liquid consistencies. This was the motivation behind forming a NDD Task Force of speech-language pathologists, dietitians, food scientists, and manufacturers that would collectively begin to untangle cluttered dysphagia diet practices. The goal of the NDD was to standardize terminology and procedures based on best practices of the time.
One step in developing the NDD was to seek a more scientific foundation for the dysphagia diet that would be based on key rheological properties of foods and fluids. This foundation would help create consistency across the food industry, both in manufacturing and foodservice operations. To be scientific, the food properties needed to be objective, measurable, and include all foods within the diet continuum. In the end, the diet needed to address both solid textures and liquid viscosities. And most importantly, the diet needed to be something that could be transferred from facility services to at-home care. But what is food and fluid rheology and how does that relate to eating? Food rheology is the science of identifying and measuring food textures. With an understanding of these textures it becomes possible to measure and relate any given food to the ability (or inability) to chew, manipulate, and swallow that item. To summarize, this means that a diet for dysphagia is not as simple as puree, mince, or chop—that is only one part of the matrix.
Basic Forces of Chewing and Swallowing
To understand the NDD, it’s important to understand the physical forces of the chewing and swallowing process that most people take for granted. Five basic effects result from the forces that occur during chewing and swallowing. See Figure 1.
Figure 1: Forces of Chewing and Swallowing
Food is compressed. This means the food item is deformed by force, such as when the tongue pushes a food up against the roof of the mouth and basically squishes it.
Food can be adhesive. Some foods are attracted to another surface. Peanut butter is very adhesive. Oil is not at all sticky.
Food becomes tensile. Food can be extended (stretched) due to force. Think of dough being extruded from a cookie press. Food extrusion occurs in the process of swallowing when the food bolus moves through the esophagus by way of peristaltic waves. These waves stretch and pull the food bolus along until it reaches the stomach.
Food is sheared (cut) by the grinding force of molar teeth.
Food can be fractured (broken) by biting it into pieces.
The type of food will dictate which, and how much, of these forces are needed to manipulate the item enough to enable swallowing it. For example, applesauce is much easier to eat as compared to apple slices as compared to a whole apple.
Any food can be defined by its textural characteristics. More than two dozen food textures have been identified, however, only eight of these textures are considered most significant in treating dysphagia. Food textures share descriptions that are similar to those of chewing and swallowing.
- Viscosity (applies only to liquids)
Lab instruments and software programs are used in food development and manufacturing to measure the texture dimensions of individual foods. The NDD Task Force measured and analyzed more than 120 different foods to arrive at the NDD Diet Levels and where foods are assigned within each level. Figure 2 shows how foods can be plotted by a descriptive texture across a force continuum. To illustrate how to interpret the continuum, consider the example for ‘biteability.’ It is very easy to bite a piece of a corn muffin. It takes such little effort that front teeth can accommodate the bite. A graham cracker is only a little more difficult to bite. A ginger snap, however, is a firm crunchy cookie that requires even more biting force than the cracker. As a food is more “biteable” we begin to shift it around from the front teeth to the incisor teeth, which are designed for biting harder foods. Peanut brittle is “tooth breaking tough” and very difficult to bite to the degree that a person would rarely use front teeth for the bite, but rather shift to the stronger incisor teeth. Again, a person spends little time thoughtfully determining how to “attack” a food; the actions come naturally from years of experience in eating.
Translating Science to Diet Prescription
People may have assumed that a group simply sat around a table and arbitrarily decided the NDD diet levels and which foods should be assigned to each of those levels. The science and analysis described here actually took much subjective choice out of the NDD development. The analysis clearly showed textural break points between each of the NDD diet levels. While it was not possible to scientifically analyze all the foods and food combinations that exist on menus, the data collected from the tested foods served as benchmarks for categorizing similar type foods into diet levels as described in Figure 3a. A similar approach of measuring and analyzing viscosity and shear was used to define thickened liquids by assigning viscosity ranges as shown in Figure 3b. This compilation of several years of work from the NDD Task Force represents today’s National Dysphagia Diet standards.
Figure 2: Semisolid/Solid Food Texture Measurement Scale
|Cohesiveness||gel dessert||vanilla pudding||tapioca pudding||dough|
|Adhesiveness||vegetable oil||marshmallow fluff||oatmeal||canned peas||peanut butter|
|Firmness||whipped cream||cheese spread||orange section||cream cheese|
|Springiness||cream cheese||hot dog||marshmallow||Knox® blocks|
|Biteability||corn muffin||graham cracker||ginger snap||peanut brittle|
|Hardness||egg white||hot dog||carrot||hard candy|
|Yield Stress||water||ketchup||Miracle Whip®||carrot baby food||tomato paste|
© 2000 Med-Diet Laboratories, Inc. Source: National Dysphagia Diet Task Force. National Dysphagia Diet: Standardization for Optimal Care. Chicago: American Dietetic Association, 2002.
Figure 3 a: National Dysphagia Diet Levels -- Summarized—Foods
|Level 1: Dysphagia Pureed|
|For moderate to severe dysphagia. The diet consists of pureed, homogenous, and cohesive foods. Foods should be “pudding like.” Any food that requires bolus formation, controlled manipulation, or chewing should be excluded.|
|Level 2: Dysphagia Mechanically Altered|
|For mild to moderate oral and/or pharyngeal dysphagia.
This level consists of all foods from Level 1,
plus foods that are moist, soft-textured, and easily
formed into a bolus. Pieces can be no larger than
one-quarter inch. This is a transition level from
pureed texture to more solid foods and some ability
to chew is required. The ability to tolerate mixed
textures at this level will be individualized.
|Level 3: Dysphagia Advanced|
|For mild dysphagia. This level consists of most textures except very hard, sticky, or crunchy foods. Foods should still be moist and in “bite-size” pieces at the oral phase of the swallow, more chewing ability is required.|
|Level 4: Regular Diet|
|All foods allowed, as tolerated.|
Figure 3b: National Dysphagia Diet Levels -- Summarized Liquids
|Nectar-like||Slightly thicker than water; the consistency of un-set gelatin|
|Honey-like||A liquid with the consistency of honey|
|Spoon-thick||A liquid with the consistency of pudding|
Putting the NDD Into Practice
Speech-language pathologists (SLP) use a variety of tools to assess an individual’s ability to chew and swallow safely and assign a diet level. Several evaluation methods [Figure 4] are available for a speech-language pathologist to use in assigning dysphagia severity. None of the methods are a perfect match to the NDD; however, the severity scale most closely correlated to the NDD is the Dysphagia Outcome and Severity Scale (DOSS). The DOSS uses a scale of 7 (normal in all situations) to 1 (severe; unable to tolerate any oral intake safely). In lieu of other evaluation tools, using the DOSS offers a fairly systematic way to match NDD diet level to the patient as shown in Figure 5. A key take-away from this chart should be that the dysphagia diet is a continuum; oftentimes an individual is starting the next level while still in the prior one.
Implementing the National Dysphagia Diet
The dysphagia diet is more than simply adjusting food texture. The diet is a critical tool within someone’s total therapy plan to improve their quality of life. A small informal survey (done by this author) from the fall of 2011 indicated that just over 60 percent of healthcare facilities use the NDD for guidance for their dysphagia diet menu. This opens the question of what the other 40 percent of healthcare facilities are providing for a dysphagia diet in their respective operation. Implementing the NDD does not have to be a daunting task, especially when it is approached with small goals. Most facilities have a Wound Care Team; consider creating the Dysphagia Care Team. Use a Dysphagia Care Team to review the ideas shown in the checklist, take inventory of current facility practices, and make a simple plan to move forward.
Figure 4 : Dysphagia Severity Scales
|Dysphagia Outcome and Severity Scale (DOSS)|
|Functional Severity Levels for Dysphagia|
|Rehabilitation Institute of Chicago Functional Swallowing Scale (RIC-FSS)|
|Dysphagia Severity Rating Scale for Parkinson’s Disease|
|Amyotrophic Lateral Sclerosis (ALS) Severity Scale
Figure 5 : Correlation o f DOSS and NDD Texture Levels
|Dysphagia Outcome and Severity Scale (DOSS)|
|Recommended NDD Diet Levels||1||1 and 2||2 and 3||3 and 4||4||4||4|
Source: National Dysphagia Diet Task Force. National Dysphagia Diet: Standardization for Optimal Care. Chicago: American Dietetic Association, 2002.
Checklist for Best Practice
- Regularly meet as an interdisciplinary dysphagia team (medical director, speech, nursing, dietary, and others).
- Review current menu, recipes, and special dysphagia products with the facility speech-language pathologist to align diet objectives.
- Challenge kitchen staff to do more with dysphagia diet plate presentations.
- Train new facility hires about facility dysphagia diet standards.
- Annually retrain facility staff on the importance of the dysphagia diet standards.
- Discuss implementing dysphagia-specific protocols (oral hygiene, hydration, satisfaction survey, etc.).
- Provide discharge education for patients/caregivers (where applicable).
Science and practice are rarely in sync, and healthcare is often left to watch and wait for the next new medicine, therapy, super food, or best practice. Few would argue that the time has come for the NDD to be refreshed. For today, however, the National Dysphagia Diet: Standardization for Optimal Care represents the best information available to guide the dysphagia diet. Standards and best practices are useful professional tools because they offer guidance where all the answers may not yet be available. Not only does a good standard guide the practitioner, it also is informative for the patient, caregivers, regulators, and the greater public audience. Any facility that is not using the NDD as the standard for their dysphagia diets may create an opening to ethical and legal liability. Of most importance, individuals living with dysphagia deserve to receive the most current standards of care, including those of the NDD. If your facility is still waiting to implement the National Dysphagia Diet, wait no longer— your clients are depending on you.
1. Groher, M. Dysphagia Diagnosis and Management, 2nd Ed. Stoneham, MA: Butterworth-Heinemann, 1992.
2. Logeman, J. Evaluation and Treatment of Swallowing Disorders. Austin, TX: PRO-ED, 1983.
3. National Dysphagia Diet Task Force. National Dysphagia Diet: Standardization for Optimal Care. Chicago: American Dietetic Association (now Academy of Nutrition and Dietetics), 2002.
4. Sonies, B. Dysphagia: A Continuum of Care. Maryland: Aspen Publishers 1997
by Debbie Zwiefelhofer, RD, LD
Debbie Zwiefelhofer, RD, LD is the President for Nutrition Affairs LLC, Minneapolis, MN. Visit www.NutritionAffairs.com or contact her at firstname.lastname@example.org