Monday, March 28, 2011

The 3 ounce water test as a general dysphagia screening tool

Dysphagia is the Greek word for 'bad eating,' and is used in English for problems with swallowing. Specifically, taking food or liquid into the lungs instead of the stomach. A lot of people that have had strokes, tumors, traumatic brain injuries, cancers, or long term debilitating diseases are at risk for dysphagia.

Aspiration is the word used to describe food or liquid below the level of the vocal chords. So if you aspirate food or liquid, you have dysphagia. Identifying dysphagia is a role of the Speech Language Pathologist (SLP). It isn't always easy, because it's important to get the diagnosis right. Patients that have dysphagia may have to change what they eat and drink, including thickening water, soda, juice, coffee, etc, as well as blending solid foods to make them softer. Obviously nobody likes to have green beans that were put in the blender and then the resulting puree put in a mold so that they'll still look like green beans...

Recent research by Debra M. Suiter and Steven B. Leder has indicated that a 3 ounce water swallow test can help rule out dysphagia. The patient drinks 3 ounces of water. If they can drink it all at once with no choking, coughing, or a wet sounding voice, then it is fairly certain that the person doesn't have dysphagia. Specifically, thousands of patients were given the Fiberoptic Endoscopic Evaluation of the Swallow (FEES), where a tube with a camera goes through the nose and into the throat, from where a clinician can see anything going into the airway before or after the swallow. They were marked either pass or fail according to their ability to swallow 6 boluses (bites) of stuff. Three 5 ml boluses of thin liquid (water), and three 5 ml boluses of puree (applesauce consistency stuff) Then, regardless of passing or failing the FEES, the patients were the 3 ounce swallow test, and it was noted again who passed and failed.

Of those that did not aspirate on the 3 ounce swallow test, 96% were shown to not aspirate on the FEES. This is really good, because it supposedly means that if you can drink down 3 ounces of water and not show signs of aspiration, you're good to eat and drink and it won't go to your lungs. Of those that did not pass the 3 ounce water test, around half passed the FEES, which means that if you fail the 3 ounce test (can't finish, choke, cough, have wet voice afterwards) then the 3 ounce water test doesn't indicate if you really have dysphagia, or if you're alright.

The Joint Commission on Accreditation of Healthcare Organizations (JCAHO) has just become The Joint Commission (TJC) Wow. I just learned that. Anyway JCAHO as I will continue to call them, has recently followed the advice of Steven B. Leder and Debra M. Suiter and required that nurses be trained to give and interpret the 3 ounce water swallow test as a dysphagia screening for all stroke patients. If the patient passes, then they get the regular diet with all liquids, and if they fail, they get referred to the speech therapists (synonymous with speech language pathologist) This may mean that some patients get to resume a normal diet much sooner, because nurses are around 24/7, where SLPs work the more traditional 9-5 ish schedule.

There are some negatives to this however, that may not have been considered. 1) Some nurses may not know/remember how to administer and interpret results. Nurses have a lot to do without adding this to their load. 2) There is a tendency by nurses and doctors to use this screening on non-stroke patients. In most cases this will be ok. In some cases, it is definitely not ok. SLPs are trained to know the difference. Doctors and nurses are not. 3) The difference between a screening and an evaluation is easily lost. Passing the screening should be able to allow a general diet and all liquids. But this is not the case. Many patients have cognitive and other health issues that would prohibit regular food even if they can swallow it alright. For example, if a patient take a sip of soda and then tunes out of the world without swallowing, it may well end up in his lungs. This is a major problem, not a minor one. 4) There is such a thing as silent aspiration. A large number of studies suggest that around half of patients will aspirate without coughing, throat clearing, wet voice, etc. These patients don't exist in Leder's study. His hypothesis is that the large bolus size makes silent aspiration impossible. A study by Cathy Lazarus refutes this. She had (has?) people drink 3 ounces of thin liquid (barium) and takes side view X-rays of it going down (this is called an MBS or VFSS) and, as of March 2009, had found that 7 of 10 aspirators did so silently. 5) The 3 ounce water test only shows if water is aspirated. Many people with a weak swallow and reduced sensation have food residue in their mouths and throats, and this often falls into the airway later, resulting in aspiration. These guys may be fine swallowing water, but thick solids cause aspiration. This is another group that has dissappeared in this study. Where are they? 6) 3 ounces is a lot of liquid. Many SLPs never use the 3-ounce water test. In an extremely dysphagic patient, 3 ounces of water in the lungs is enough to cause immediate and severe repercussions to the health of a patient.

Much of my source material for this blog came from the following link which is an ASHA article from May 2009 by Nancy B Swigert entitled "Hot Topics in Dysphagia."

Additionally, the Leder article about the results of the 3 ounce swallow test, titled "Clinical Utility of the 3-ounce Water Swallow Test," published in Dysphagia (2008) has some significant issues. 1) the research has not been duplicated by other researchers. In science, everything needs to be looked at by many eyes, and a lot of findings are found to be false with time in this way. 2) the study was not randomized. Everyone had it done, so factors of time, place, and referrals become relevant. 3) the study was not blinded: Leder did both the FEES and the 3 ounce water test and knew the results of one before administering the other. 4) the order in which they were administered never varied. Having the FEES first may have tired borderline and severely dysphagic patients, such that only the healthiest (and non-dysphagic) swallowers passed the 3 ounce water swallow test. Note that in real life, weakened patients won't be as tired when they get it, increasing the chance that they'll pass it but still aspirate at a full meal. 5) The article itself claims that the 3 ounce water swallow test will be wrong in saying a patient has a safe swallow 5 percent of the time. What about those 5% of people? 6) The study was done by an internationally renowned swallowing expert. Shouldn't the 3 ounce water screenings be done in a study by nurses to see if the results are similar before requiring hospitals across the country to have their nurses implement it? How often will busy nurses giving the screening be wrong?

At the end of the day, the 3-ounce water test solves some problems, but causes others. I think the Leder study needs replication with improved methods.

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