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The Dysphagia Outreach Project Giving Event

The Dysphagia Outreach Project Giving Event 2020

Guest Post By:  Jessica Lasky, MS, CCC-SLP and Allison Boyer, MA, CCC-SLP

Who We Are

The Dysphagia Outreach Project is a 100% volunteer-run 501(c)(3) nonprofit organization that was founded in 2019. The mission of the Dysphagia Outreach Project is to provide meaningful assistance to low-income individuals affected by dysphagia via our Dysphagia Food Bank and educational efforts. This organization relies on both product and monetary donations to provide our recipients with the safest and most evidence-based dysphagia products shipped right to their front door at no cost to them. The Dysphagia Outreach Project also provides free education to patients and families, as well as clinicians and physicians. Additionally, the volunteer branch allows clinicians across the country to contribute to this cause and is the backbone of the organization which enables the Dysphagia Outreach Project to operate in all fifty states in the USA. 

Dysphagia In Adults

How does dysphagia affect the adult population? Dysphagia affects 1 out of 25 adults annually; moreover, dysphagia is associated with lost workdays, with the average person with dysphagia missing 12-13 days annually. Women are more likely than men to report swallowing problems. Stroke and neurological causes are the number 1 and 2 reported etiologies (Bhattacharyya, 2014). Additionally, 1 in 6 adults reported swallowing difficulties. Of those, half of them never discussed their dysphagia concerns with their physician or medical team. They suspected that a lot of the dysphagia in these cases were treatable (Adkins, C et al., 2020). 

Dysphagia After Stroke

In patients who are status post-stroke (cerebrovascular accident, or CVA), they recover swallowing function gradually, and therapeutic interventions for dysphagia generally are successful. In a prospective investigation of 128 patients admitted because of acute stroke, a swallowing abnormality was detected in 51% on clinical examination and in 64% on videofluoroscopy at initial presentation (Masiero S et al., 2008). Additionally, patients who have had a stroke are likely to decrease their dietary intake, which increases their risk of malnutrition or exacerbates existing malnourishment. In an investigation of the nutritional status of patients with stroke who were admitted to a rehabilitation service, 49% had malnutrition, and 65% of those with dysphagia were malnourished. (Odderson IR, et al., 1995). 

Dysphagia In Pediatrics

An estimated 116,000 newborn infants are discharged from short-stay hospitals with a diagnosis of feeding problems, according to the National Hospital Discharge Survey from the CDC (National Center for Health Statistics, 2010). Prevalence is estimated to be 30%–80% for children with developmental disorders (Delaney, 2008). According to the Centers for Disease Control and Prevention (CDC), survey interviews indicated that within the past 12 months, 0.9% of children (approximately 569,000) ages 3–17 years are reported to have swallowing problems (Bhattacharyya, 2015; Black, Vahratian, & Hoffman, 2015). Additionally, a study by Kooi-van Es et al found that out of 295 children with neuromuscular disease, dysphagia and dysarthria had a pooled overall prevalence of 47.2% and 31.5%, respectively. The investigators reported that 90.0% of children with dysphagia had chewing problems, while 43.0% had swallowing problems, and 33.3% demonstrated difficulties with both chewing and swallowing (Kooi-Van et al, 2020). Lastly, prevalence rates of oral dysphagia in children with craniofacial disorders are estimated to be 33%–83% (Caron et al., 2015; de Vries et al., 2014; Reid, Kilpatrick, & Reilly, 2006). 

Dysphagia Outreach Project Statistics 

Here at The Dysphagia Outreach Project, no single person within the organization–from the founders to the occasional volunteer–is paid anything. We are a 100% volunteer-based organization. Any donations that come to us go straight to our recipients or to keep the lights on. As of the year 2020, 81% of our recipients are pediatric. Ninety percent of our pediatric recipients are under five years of age and 60% of our recipients are under 24 months old. We’ve received over 10,000 items and distributed over 8,600 of those items. Our average recipient family size is 3.6 people and the average recipient family income is just over $40,000 per year. Lastly, the Dysphagia Outreach Project boasts 151 registered volunteers, whose combined efforts are one of the primary reasons that we are able to provide the help that we do! 

The Giving Event

In order for us to continue to provide this level of assistance to individuals and families in need, we need your help! The Dysphagia Outreach Project will be hosting its annual fundraiser, The Giving Event, which will be held the week of Giving Tuesday [Monday, November 30th to Friday, December 4th]. Following Thanksgiving, Giving Tuesday is a day associated with international charitable giving which marks the beginning of the Christmas and holiday season.  

The Giving Event will go live on The Dysphagia Outreach Project’s Facebook page at 8 pm EST, every night for 5 nights, starting on Monday, November 30th. We will be awarding a TON of cool prizes [think exclusive CEU courses, memberships to hugely popular SLP subscription services, a brand new iPad, and MUCH MORE]! 

How to Donate

For every $5 dollars you donate, your name will be entered on our virtual prize wheel. The more donations = the more entries! Each night of the Giving Event, a Dysphagia Outreach Project representative will spin the wheel to select a prize winner at random. To enter, please text GIVINGEVENT to 44-321 and follow the prompts to submit your donation. Together, we can make the holidays of those experiencing dysphagia a little bit brighter. 

References

Adkins C, Takakura W, Spiegel BMR, Lu M, Vera-Llonch M, Williams J, Almario CV. Prevalence and Characteristics of Dysphagia Based on a Population-Based Survey. Clin Gastroenterol Hepatol. 2020 Aug;18(9):1970-1979.e2. doi: 10.1016/j.cgh.2019.10.029. Epub 2019 Oct 24. PMID: 31669055; PMCID: PMC7180111.
Bhattacharyya N. The prevalence of dysphagia among adults in the United States. Otolaryngol Head Neck Surg. 2014 Nov;151(5):765-9. doi: 10.1177/0194599814549156. Epub 2014 Sep 5. PMID: 25193514.
Caron, C. J. J. M., Pluijmers, B. I., Joosten, K. F. M., Mathijssen, I. M. J., van der Schroeff, M. P., Dunaway, . . . Koudstaal, M. J. (2015). Feeding difficulties in craniofacial microsomia: A systematic review. International Journal of Oral & Maxillofacial Surgery, 44, 732–737.
Delaney AL, Arvedson JC. Development of swallowing and feeding: prenatal through first year of life. Dev Disabil Res Rev 2008;14:105–17.
de Vries, I. A. C, Breugem, C. C., van der Heul, A. M. B., Eijkemans, M. J. C., Kon, M., & Mink van der Molen, A. B. (2014). Prevalence of feeding disorders in children with cleft palate only: A retrospective study. Clinical Oral Investigations, 18, 1507–1515.
Kooi-van Es M, Erasmus CE, de Swart BJM, et al. Dysphagia and Dysarthria in Children with Neuromuscular Diseases, a Prevalence Study. J Neuromuscul Dis. 2020 Mar 11. [Medline].
Masiero S, Pierobon R, Previato C, Gomiero E. Pneumonia in stroke patients with oropharyngeal dysphagia: a six-month follow-up study. Neurol Sci. 2008 Jun. 29(3):139-45. [Medline].
National Center for Health Statistics. (2010). Number of all-listed diagnoses for sick newborn infants by sex and selected diagnostic categories [Data File]. Retrieved from https://www.cdc.gov/nchs/data/nhds/8newsborns/2010new8_numbersick.pdf
Odderson IR, Keaton JC, McKenna BS. Swallow management in patients on an acute stroke pathway: quality is cost effective. Arch Phys Med Rehabil. 1995 Dec. 76(12):1130-3. [Medline].
Reid, J., Kilpatrick, N., & Reilly, S. (2006). A prospective, longitudinal study of feeding skills in a cohort of babies with cleft conditions. The Cleft Palate–Craniofacial Journal, 43,702–709.

Want More?

Want to find out more about thickened liquids, altered food consistencies and thickeners?   You can read more about them by clicking the links below!

IDDSI

The Great Thickener Challenge

Pre-Made Pureeds…..Not All the Same

The Cost of Thickened Liquids

 Looking to give after this event is over?   You can find their website here.

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IDDSI

The International Dysphagia Diet Standardisation Initiation is here and being utilized in many facilities.

IDDSI was created to replace the National Dysphagia Diet and to standardize food and liquid consistencies.

I’m sure you have probably been in a number of facilities that interpret Mechanical Soft, Dysphagia Soft, etc a little different than other facilities.   Some facilities allow a number of food items on one diet level that another facility adds into a different level.

IDDSI

IDDSI involves 5 food consistency levels and 5 liquid levels.

So what do these levels mean?

Level 0 (Thin) is a liquid that flows like water.   (Flow test 1 ml or less in the syringe.)

Level 1 (Slightly Thick) Thicker than water, but is not quite Mildly Thick (formerly Nectar Thick).   (Flow test 1-4 ml remains in syringe).   This may include formula or commercially available nutrition drinks such as Boost or Ensure.

Level 2 (Mildly Thick formerly Nectar Thick).   Flows off a spoon but is thicker than water.   Requires increased effort to drink from a straw.   (Flow test 4-8 ml left in the syringe.)

Level 3 (Moderately Thick formerly Honey Thick).  This level takes a moderate effort to drink through a straw, but can be drunk from a cup.   This level can be taken from a spoon, but is too thin for a fork.   (Flow test 8-10 ml left in the syringe.)

Level 4 (Pureed/Extremely Thick formerly Pudding Thick).  Usually can be administered via spoon, however may also be eaten via fork.  Cannot be taken through a straw, usually taken via spoon.   There should be no lumps, requires no chewing and the liquid should not separate.   (Flow Test 10 ml remains in the syringe.)   Spoon tilt test-should fall off the spoon in single spoonful.   Should sit in a mound on top of the spoon/fork with minimal dripping through the fork.

Level 5 (Minced and Moist) Small lumps in the bolus (no larger than 4mm width and 15mm length for adults), can be eaten using spoon or fork.   Liquid should not separate from food.   (Fork test minimal pressure to mash with no blanching of the thumbnail  to white while pressing.)  (Spoon test should fall off the spoon in a cohesive mound with little to none left on the spoon.)

Level 6 (Soft and Bite Sized) Can be eaten with a fork, spoon or chopsticks.   Each piece should be no larger than 15mm.   Chewing is required with this consistency, however biting or cutting is not required.   (Fork test, when a fork is pressed against the food, the thumbnail should blanch or turn white to squash or break apart the food).   (Spoon test pressure from the spoon can cut, squish, mash or break apart the food and it will not return to its shape.)

Level 7 (Easy to Chew) Normal, everyday soft foods.   Size of food is not restricted.   Requires the ability to bite/chew food.   (Fork/Spoon Test food is easily cut with pressure from a fork/spoon, thumbnail blanches or turns white when applying pressure to the food until it smashes, breaks apart or crumbles without resuming its original shape.

Level 7 (Regular) Normal, everyday food.

Transitional Foods (Fork/Spoon test, add 1 ml water, wait 1 minute, when applying pressure on the fork/spoon on the food, thumbnail blanches while applying pressure until the food breaks or smashes.)

Some examples of transitional foods?

Ice chips
Ice cream/Sherbet if assessed as suitable by a Dysphagia specialist
Japanese Dysphagia Training Jelly sliced 1 mm x 15 mm
Wafers (also includes Religious Communion wafer)
Waffle cones used to hold ice cream
Some biscuits/ cookies/ crackers
Some potato crisps – only ones made or formed from mashed potato (e.g. Pringles)
Shortbread
Prawn crisps
Veggie Stix™
Cheeto Puffs™
Rice Puffs™
Baby Mum Mums™
Gerber Graduate Puffs™

For everything you need to know regarding IDDSI, visit the website here.

Do you want easily printable information sheets for each level and testing for each level?    Find that here.

Want samples and examples for testing liquids/foods?   Find that here.

Evidence supporting IDDSI can be found here.

IDDSI documentation has been translated in multiple languages that you can download here.

Available languages:

  • Chinese
  • Farsi
  • French
  • German
  • Greek
  • Italian
  • Norwegian
  • Portuguese
  • Spanish
  • Swahili

Need help with implementation of IDDSI into your facility?   You can download documents here.

 

 

 

Supplementary Notice: Modification of the diagrams or descriptors within the IDDSI Framework is DISCOURAGED and NOT RECOMMENDED. Alterations to elements of the IDDSI framework may lead to confusion and errors in diet texture or drink selection for patients with dysphagia. Such errors have previously been associated with adverse events including choking and death.

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How Does Cognition Affect Swallowing

Cognition can impact many facets of life including swallowing.

Patients may be confused  enough that they don’t “recognize” food in their mouth and effectively may not know what to do with that food.

For example, when I was working in the acute care hospital, I evaluated a patient in the ICU that had sodium levels outside of normal parameters.  This person had difficulty recognizing solids in their mouth and would just sit with the solid sitting on the tongue.   This patient had increased confusion and agitation.   They were able to swallow pureeds and thin liquids.    Once their sodium levels returned to a number within normal limits, their swallowing function also returned to normal.

Continue reading How Does Cognition Affect Swallowing

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Dysphagia Following Extubation Part 2

We know that intubation can impact the swallow.   How does intubation affect swallowing?

Is it a strength deficit or a sensory deficit?

This post will take a look at studies that look at the impact of intubation on sensation of the tongue and the larynx.

Continue reading Dysphagia Following Extubation Part 2

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Dysphagia Following Extubation Part 1

When it comes to patients that are intubated, there are a lot of factors to consider.

What is their current diagnosis, why are they intubated, how long were they intubated?   Was intubation traumatic?   Have they self-extubated?

There is a lot of discussion over the timing of the evaluation.   Traditionally, it has been thought that there needs to be a period of 24 hours following extubation to allow for recovery.

This series of posts will break down what the evidence tells us regarding post extubation dysphagia.

Continue reading Dysphagia Following Extubation Part 1

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FEES Following Extubation

The 1998 Paper

Leder, Cohn and Moller investigated the incidence of aspiration following extubation in critically ill trauma patients.

The study looked at 20 patients who required oropharyngeal intubation for at least 48 hours.   All FEES were completed around 24 hours following extubation.

Remember, aspiration is when the bolus enters the airway, below the level of the true vocal cords (as defined in this study).  Silent aspiration is when there is no accompanying behavior such as a cough or throat clear with aspiration.

During this study, 9/20 (45%) of patients were found to aspirate and 4/9 (44%) were silent aspirators.   Silent aspiration was seen in 20% of this population.   8/9 of the patients that aspirated were able to resume an oral diet within 10 days of their initial FEES.

Findings during this study:

  1.  A nasogastric tube was not associated with aspiration.
  2. Traumatic intubation was noted in 5/20 patients and 4/5 of these patients aspirated.
  3. Only the Glasgow Coma Scale rating on admission exhibited a significant difference regarding aspiration status.  (Low ratings had a higher incidence of aspiration).
  4. Trauma patients have an increased incidence of aspiration.

The authors suggest that early identification of aspiration following trauma and intubation is indicated to reduce the risk of pulmonary compromise.

There are still many questions following this study, including patients intubated for shorter than 48 hours and which variables impacted aspiration (brain injury, age, traumatic intubation, sedatives, neuromuscular blockers, respiratory status).

Some newer studies indicate:

“Patients aged >55 yrs and those with vallecular stasis on FEES examination were at significantly higher risk of postextubation aspiration. All patients with pneumonia had an associated aspiration episode.”

With prolonged orotracheal intubation, patients are at risk of aspiration following extubation.  (Barquist, Brown,  Cohn,  Lundy and Jackowski)

The  incidence of aspiration determined by FEES was 56% and 25% of  patients were silent aspirators. The patients found to aspirate were intubated for a mean duration of 8 days, 7.7 days for non-aspirators.  70% of the patients who aspirated  thin liquids while 30% aspirated  puree.  63% of the patients that aspirated showed improved swallowing and tolerated an oral diet by the time of discharge.   (Ajemian, Nirmul, Anderson, Zirlen and Kwasnik)

Instrumental assessments are critical for patients, particularly after intubation 48 hours or longer.

References:

Leder, S. B., Cohn, S. M., & Moller, B. A. (1998). Fiberoptic endoscopic documentation of the high incidence of aspiration following extubation in critically ill trauma patients. Dysphagia13(4), 208-212.

Barquist, E., Brown, M., Cohn, S., Lundy, D., & Jackowski, J. (2001). Postextubation fiberoptic endoscopic evaluation of swallowing after prolonged endotracheal intubation: a randomized, prospective trial. Critical care medicine29(9), 1710-1713.

Ajemian, M. S., Nirmul, G. B., Anderson, M. T., Zirlen, D. M., & Kwasnik, E. M. (2001). Routine fiberoptic endoscopic evaluation of swallowing following prolonged intubation: implications for management. Archives of surgery136(4), 434-437.

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Why the Dye?

The many colors of FEES

You’ve maybe witnessed a FEES exam.   It can sometimes be quite colorful.

Often, green food coloring is used during the exam.   This helps to make the bolus “stand out” in the pharynx.   You may also see blue food coloring used or even white food coloring or naturally white foods such as milk to really make the materials visible if aspirated.

Silent aspiration

Silent aspiration has been reported in over 40% of patients referred for evaluation of swallowing in a rehabilitation hospital and as many as 77% of ventilator-dependent patients have silent aspiration.   It is imperative that we are able to “see” the aspiration.

Study using blue food coloring

In a study by Leder, Acton, Lisitano and Murray (2005), 20 adults were evaluated using FEES, 9 subjects with food that was dyed blue (2 drops of blue in 60cc of pudding and 120 cc of milk) and 11 subjects with regular non-dyed food (yellow pudding, white skim milk).

The study looked at 4 areas:

  1.  the stage transition characterized by depth of bolus flow to at least the vallecula prior to the pharyngeal swallow.
  2. evidence of bolus retention in the vallecula or pyriform sinuses after the pharyngeal swallow
  3. laryngeal penetration
  4. tracheal aspiration

Three SLPs interpreted the studies with 100% agreement in the non-dyed food and in the dyed food.

The dye was changed to green from blue after several deaths resulted from blue dye that was placed in tube feeding.

This study found that the “important variable in detecting both bolus flow to and location in the pharynx and larynx is how well a bolus reflects light (it must be brighter than the tissue it is resting on).   Therefore, the endoscopist can be assured of reliable FEES results using regular, non-dyed food trials.”

Study using green food coloring

Another study by Marvin, Gustafson and Thibeault found that the use of green food coloring improved judgement of airway invasion as compared to white foods.    

References:

Leder, S. B., Acton, L. M., Lisitano, H. L., & Murray, J. T. (2005). Fiberoptic endoscopic evaluation of swallowing (FEES) with and without blue-dyed food. Dysphagia20(2), 157-162.

Marvin, S., Gustafson, S., & Thibeault, S. (2016). Detecting aspiration and penetration using FEES with and without food dye. Dysphagia31(4), 498-504.

Splaingard, M. L., Hutchins, B., Sulton, L. D., & Chaudhuri, G. (1988). Aspiration in rehabilitation patients: videofluoroscopy vs bedside clinical assessment. Archives of physical medicine and rehabilitation69(8), 637-640.

Elpern, E. H., Scott, M. G., Petro, L., & Ries, M. H. (1994). Pulmonary aspiration in mechanically ventilated patients with tracheostomies. Chest105(2), 563-566.

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FEEST or Famine…..

You know about FEES….

You’ve more than likely heard about FEES (Flexible Endoscopic Evaluation of Swallowing) by this time.  If not, take a look around this blog because I have been blogging about FEES all month!

But have you heard about FEEST?

Have you heard of FEEST?  Flexible Endoscopic Evaluation of Swallowing with Sensory Testing is another method to evaluate swallowing using instrumentation.

The FEEST exam is performed much like FEES with an endoscope passed transnasally to assess the swallow.   FEEST, however adds an air-pulse stimuli that is delivered to the mucosa innervated by the superior laryngeal nerve to elicit the laryngeal adductor reflex (LAR).

So what is LAR?

“The laryngeal adductor reflex (LAR) is an involuntary protective response to stimuli in the larynx. The superior laryngeal nerve (SLN) acts as the afferent limb and the recurrent laryngeal nerve (RLN) as the efferent limb of this reflex, which is modulated by the central nervous system.”

What can I see with FEEST?

FEEST, not only allows you to evaluate the pharyngeal swallow and the sensory aspect of the larynx and the mucosa innervated by the superior laryngeal nerve, you can also evaluate manifestations of GERD such as Larynopharyngeal Reflux (LPR) which can include sensation of bolus, voice changes or asthma.

What do you think?

Do you think that FEEST may be an appropriate exam for your patients?  What patients are appropriate for FEEST?

References:

Domer, A. S., Kuhn, M. A., & Belafsky, P. C. (2013). Neurophysiology and clinical implications of the laryngeal adductor reflex. Current otorhinolaryngology reports1(3), 178-182.

Rees, C. J. (2006). Flexible endoscopic evaluation of swallowing with sensory testing. Current opinion in otolaryngology & head and neck surgery14(6), 425-430.Thompson, D. M. (2003).

Laryngopharyngeal sensory testing and assessment of airway protection in pediatric patients. The American journal of medicine115(3), 166-168.

O‘Horo, J. C., Rogus‐Pulia, N., Garcia‐Arguello, L., Robbins, J., & Safdar, N. (2015). Bedside diagnosis of dysphagia: a systematic review. Journal of hospital medicine10(4), 256-265.

Kim, T., Goodhart, K., Aviv, J. E., Sacco, R. L., Diamond, B., Kaplan, S., & Close, L. G. (1998). FEESST: a new bedside endoscopic test of the motor and sensory components of swallowing. Annals of Otology, Rhinology & Laryngology107(5), 378-387.

Aviv, J. E., Kaplan, S. T., Thomson, J. E., Spitzer, J., Diamond, B., & Close, L. G. (2000). The safety of flexible endoscopic evaluation of swallowing with sensory testing (FEESST): an analysis of 500 consecutive evaluations. Dysphagia15(1), 39-44.

Aviv, J. E., Kim, T., Thomson, J. E., Sunshine, S., Kaplan, S., & Close, L. G. (1998). Fiberoptic endoscopic evaluation of swallowing with sensory testing (FEESST) in healthy controls. Dysphagia13(2), 87-92.

http://www.feesst.com/index.php

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MBSS AND FEES. Why Not Both?

MBSS VS. FEES

Whenever you read the literature, you often see MBSS vs. FEES or a similar thought comparing the two tests, attempting to find the superior, gold standard assessment.

On social media, we seem to have 2 camps.   Team MBSS and Team FEES.   You can’t be friends and in separate camps!!  (Completely joking here!!!)

Many facilities choose one test or the other.   You can either request MBSS or FEES.  They’ll have a contract for Mobile MBSS or Mobile FEES.   In the hospital, it’s either/or.

What would happen if we try to change that thought.   What if, we changed from an either/or to a both.

What If…….

What if companies had the option of both.  Maybe the ability to do both tests at one time?  Even if they are completed at different times.  Both tests give you such a varied viewpoint of the swallow while often providing the same information regarding the swallow.

The literature says……

The majority of the research tells us that we see the same pharyngeal events with FEES that we see with MBSS including decreased back of tongue control/oral containment resulting in premature posterior loss of bolus, decreased hyolaryngeal excursion, decreased epiglottic introversion, decreased laryngeal closure resulting in penetration/aspiration or vallecular residue.   We may see decreased opening of the Pharyngoesophageal Sement (PES)/Upper Esophageal Sphincter (UES)  resulting in pyriform sinus residue and maybe aspiration.  We can see residue on the posterior pharyngeal wall due to decreased pharyngeal squeeze/stripping wave.

So, in fact, with either test we can see the physiological events of the swallow that lead us into a plan of treatment.

Much of the research states that residue, aspiration, etc are all rated as more severe when using FEES.

What about the doctors

Look at physicians.   they will often order a CT scan for a stroke patient.   When this doesn’t give them all the information needed, they often then order an MRI.   The CT and MRI do give different viewpoints and provide some different information and compliment each other very well.

Anecdotal thoughts.

In my experience, not just reading the research, when a patient had a FEES (performed by me) and later had an MBSS (performed by a colleague) the findings were exactly the same leading to identical recommendations.   In fact, I did not know until after the test that the patient was going to have an MBSS and the other SLP did not know until after the test, the results from the FEES.

Changing our thinking.

So let’s work on changing our thinking to BOTH tests, not just one or the other.  Let’s educate other medical professionals that we are looking for much more than just aspiration or penetration and that we can do so much more than just change a diet.

Let’s make a change!

References:

Aviv, J. E. (2000). Prospective, randomized outcome study of endoscopy versus modified barium swallow in patients with dysphagia. The Laryngoscope110(4), 563-574.

Schatz, K., Langmore, S. E., & Olson, N. (1991). Endoscopic and videofluoroscopic evaluations of swallowing and aspiration. Annals of Otology, Rhinology & Laryngology100(8), 678-681.

Brady, S., & Donzelli, J. (2013). The modified barium swallow and the functional endoscopic evaluation of swallowing. Otolaryngologic Clinics of North America46(6), 1009-1022.

Leder, S. B., Sasaki, C. T., & Burrell, M. I. (1998). Fiberoptic endoscopic evaluation of dysphagia to identify silent aspiration. Dysphagia13(1), 19-21.

Bastian, R. W. (1991). Videoendoscopic evaluation of patients with dysphagia: an adjunct to the modified barium swallow. Otolaryngology—Head and Neck Surgery104(3), 339-350.

Langmore, S. E. (2003). Evaluation of oropharyngeal dysphagia: which diagnostic tool is superior?. Current opinion in otolaryngology & head and neck surgery11(6), 485-489.