A tribute to Steven Leder, PhD, CCC-SLP
Aspiration can mean “a strong desire to achieve something high or great,” per Merriam-Webster, or “a hope or ambition of achieving something,” per Google. Steven Leder, PhD, CCC-SLP achieved greatness. The phrases in the picture above came lovingly from Speech-Language Pathologists (SLPs) around the world upon news of his passing on May 16, 2016.
He and his many colleagues aspired to shift the conventional and sometimes outdated thinking in the field of medical Speech-Language Pathology and dysphagia clinical practice. In the preface of The Yale Swallow Protocol, a book he co-authored with Debra M. Suiter, PhD, CCC-SLP, BCS-S, they described their aspirations for clinicians after the years of research that went into the protocol. Their wish is for clinicians to “digest our new ideas with an open mind and then incorporate them into your daily clinical practice. This is reward enough for us.”
Steven Leder worked tirelessly to help SLPs and the medical community understand what information can and cannot be gleamed from a bedside swallowing examination. Without “x-ray vision” (meaning instrumental evaluations via x-ray and endoscopy), what can we infer from bedside signs about risks of aspiration and dysphagia? I have referred to his wisdom numerous times in prior articles (i.e., Dysphagia Evaluation Guides Treatment: Ask Many Questions!).
In this week of his passing, I have thought of little else. I have been reviewing his prolific research, and it is awe-inspiring. For example, an author search of “Leder SB” in PubMed reveals 100 publications! The actual total is 138 publications and books, per Dr Clarence T. Sasaki’s memoriam.
In this blog, my aim is to summarize some of his work within the topic of aspiration. Future articles may further explore his research on tracheotomy tubes, post-extubation dysphagia, Fiberoptic Endoscopic Evaluation of Swallowing (FEES) and more.
5 Steven Leder Lessons Learned on Aspiration
1. Absent gag does NOT equal aspiration risk and dysphagia!
Speech-Language Pathologists often hear that a patient was kept NPO (no food or liquid by mouth) because he had no gag. In 1996, Leder started debunking that myth with his article: “Gag Reflex and Dysphagia.” He noted that the gag reflex was absent in 13% of normal healthy adult volunteers. 85% of patients referred for a bedside swallowing evaluation due to an absent gag were actually able to start eating.
In 1997, he further proved his point with instrumental testing in: “Videofluoroscopic evaluation of aspiration with visual examination of the gag reflex and velar movement.”
I actually kept this paper on my clipboard through the end of the 1990’s and into the 2000’s, constantly sharing it with the medical team. To this day, I include it in the dysphagia myth-busters section of presentations at hospitals.
He studied 100 patients under videofluoroscopy, while simultaneously testing the gag reflex and velar movement.
- 95% of patients without a gag reflex had NO aspiration. There was no correlation between advancing age and absent gag reflex.
- 93% of the patients who did aspirate on a videofluoroscopic swallow study had normal gag reflexes and normal velar movement on phonation.
He emphasized the physiologic difference between the gag and velar movement. He documented only one person with abnormal velar elevation, whereas 28 out of 100 subjects had an abnormal gag reflex (i.e., absent or hyperactive).
After this study, SLPs had evidence to shift the medical team’s focus away from the gag and towards the cough reflex and other predictors.
2. Oxygen Saturation is not a marker of aspiration
In 2000, Steven Leder studied arterial oxygen saturation to see if it was a valid marker of aspiration that could be used during bedside assessment. He found that oxygen saturation does not correlate with aspiration, stating: “Although SpO2 has theoretical clinical importance in dysphagia management, it does not appear to be a clinically relevant indirect marker of aspiration status (page 204).” See my prior blog on Critical Lab Values in Dysphagia for further information.
So with the gag reflex and oxygen saturation out, what do we do?
3. Steven Leder and Debra Suiter set out to strengthen the 3-ounce Water Swallow Challenge
Leder and Suiter started this work in the late 1990’s and first published in 2008. That is dedication! They sought to create an improved screen that could be applied to a heterogeneous population of all ages. A screen should determine if an aspiration risk is present, refer for formal swallowing evaluations when needed, and provide oral feeding recommendations.
In “Clinical Utility of the 3-ounce Water Swallow Test” (Suiter & Leder, 2008) the criteria for failure of the screen were based on DePippo’s 1992 criteria:
Drink 3-ounces from a cup or straw without interruption. Mark as a failure if:
- Inability to drink the entire amount. (Note: in 2011 and 2012, they expanded this to be “inability to drink the entire amount, stopping and starting”).
- Coughing or choking up to 1 minute after completion. (Note: in 2011 and 2012, they modified this to state: “coughing and choking during or immediately after completion”).
- Presence of post-swallow wet-hoarse vocal quality. (Note: this aspect of the test was removed in subsequent studies in 2011 and 2012).
High sensitivity, but High false-positive rate:
The 3-ounce water challenge showed high sensitivity in 2008. It predicted aspiration in true aspirators 96.5% of the time. In other words, 96.5% of people who failed the 3-ounce water challenge also aspirated on the FEES.
However, there was a high false-positive rate: 55.7% of subjects who failed the 3-ounce water challenge actually had no aspiration per the FEES. This could be due to the protocol of the FEES (given just prior to the 3-ounce water challenge), which consistently used 6 trials of puree and thin liquid boluses of only 5 cc each (2008; 2011a). Potentially, patients failed to continuously drink or coughed on the the full 3 ounces, but had not aspirated on smaller 5 cc size sips.
Ever since the creation of the 3-ounce water screen by DePippo, et al. (1992; 1994) and cautions raised by Garon, et al. (1995), SLPs have been worried about missing silent aspirators with just a sip-test. “What about all those potential false negatives,” we asked.
Steven Leder discussed this repeatedly at conferences. (I remember an elevator discussion I had with him in Toronto. He was always willing to share!) He assured us that if a patient can continuously drink 3 ounces without any stopping, then it is highly likely that he is safe for oral intake. Otherwise, it would be like waterboarding.
Leder and Suiter showed that with adherence to strict criteria for test failure, the false negatives should be low. I think many swallow screens are not administered so accurately. The 2008 and 2011 studies used non-blinded highly trained SLPs to administer all water challenges.
However, more recently, research has addressed nursing-administered screening in Warner, et al., 2014. There was good agreement between SLPs and nurses (98.01%), after nurses received a web-based training in all aspects of the Yale Swallow Protocol. A low rate of false negatives was maintained.
Additionally, research has been conducted with double-blinded raters and using videofluoroscopy rather than FEES for validation (Suiter, et al., 2014).
We need to make sure swallow screens are performed and scored according to strict criteria by trained staff.
As Leder and colleagues showed in 2011, silent aspiration is volume-dependent: 58% of people who had silently aspirated smaller volumes of liquid and puree, went on to show a cough reflex when given a full 3-ounce challenge. The 2011 false negative rate was less than 2%, which as they indicated is due to the large heterogeneous sample used. The false negative rate in the 2008 study was 1.5%, meaning only 17 out of 1151 subjects passed the 3-ounce water swallow test but were made NPO (not able to eat or drink) per the FEES results.
Steven Leder cautioned to use good judgement:
It has to be stressed that some severe patients were excluded from the 2011 water swallow challenge (i.e., severe dysphagia, aspiration on previously administered boluses, inability to manage secretions). Leder et al., (2012) excluded 5 stroke subjects (i.e., 1 brainstem stroke) due to lethargy, poor arousal, inability to participate. See Leder Lessons #4 & #5 below for other populations, per Steven Leder, that should not be screened. Additionally, at the end of the 2008 article (p249), Suiter & Leder encouraged clinicians to use good judgement. Even though 98.5% of patients who passed the 3-ounce water swallow test were successful with oral intake, the clinician has to consider a multitude of other patent-specific factors:
- Cognitive issues
- Following directions
- Self-feeding skills
- Limb apraxia or non-dominant limb used
- Attention issues
- Deconditioned patients/generalized weakness
With all of these issues, I had not been concerned in the past about over-referral, thinking we need to evaluate these more complex and risky patients. We synthesize all the issues to promote safe eating and swallowing. I remember reacting strongly to the 2008 conclusions regarding screening: “taking into consideration any patient-specific factors that may impact resumption of safe oral intake, recommendations for specific diet consistencies can be made, e.g., puree, chopped, soft-solid, or regular diet.” I do not think screens should lead to complex recommendations. Looking back at my copy of the 2008 article, I wrote: “Are we giving away our job? SLPs are trained to provide specific diet recommendations.” Now looking back, I see that it is a balance. Too many false-positives may mean overly cautious and limiting a person’s access to eating and drinking.
Take-home message from early years with the water challenge:
Too many false-positives with the water swallow challenge may unnecessarily restricting a person’s oral intake. Since silent aspiration, for the most part, seems to be volume-dependent, then we do not have to be so restrictive if the person tolerates 3-ounces without any stopping and starting (Leder, et al., 2011a). This desire to not be overly restrictive seemed to be a driving force behind his poster he and team presented at this year’s DRS (personal communication at DRS, February, 2016).
4. Expanding the Swallow Screen into The Yale Swallow Protocol
Steven Leder and colleagues taught us to take “extra care” with our patient when we know that the odds of the patient aspirating are high (Leder, et al., 2009, p294).
How do we know when a patient is at high risk prior to giving them food and liquid trials?
Well, thanks to Leder, Suiter & Warner, 2009 and Leder, Suiter, Murray & Rademaker, 2013 there is a protocol. Leder and Suiter at The Annual ASHA Convention in 2012 described this as expanding from a simple screen to a protocol, “incorporating a richer patient-oriented environment.”
Before you evaluate how your patient swallows foods and liquid, you can have the patient:
- Answer orientation questions: What is your name; Where are you; and what year is it?
- Follow three one-step commands. The person fails this if unable to follow all three commands without visual cues/model (e.g., Open you mouth; Stick out your tongue; Smile).
- Perform oral motor movements (for this you may give cues and models as needed). Key movements: Lingual range of motion (protrude tongue beyond lips and lateralize to labial commissures bilaterally). Symmetrically smile and pucker.
The 2009 study included 4,070 acute-care patients who had been referred to Speech-Language Pathology. Results showed:
- If a person is unable to answer the orientation questions, he has 31% greater odds of aspirating.
- If a person cannot follow the three 1-step directions, then the odds ratios are as follows:
- Odds of aspirating thin liquid are 57% higher
- Odds of aspirating puree are 48% greater
- Odds of aspirating both puree and liquid, and being deemed unsafe for any oral intake, are 69% greater in that person who is unable to follow directions versus one who can follow directions.
The 2013 study included 3,919 patients who had the cognitive ability to participate in oral mechanism examination. They included only three movements in the investigation to determine if aspects of this exam contribute to the odds of aspiration (e.g., labial closure, lingual range of motion, and facial symmetry). The univariate analysis indicated that only lingual range of motion was significantly associated with aspiration. If a patient has abnormal lingual range of motion, he is more likely to be an aspirator (with an odds ratio 2.37). The step-wise logistic regression analysis showed that if a person has incomplete lingual range of motion, the odds of him aspirating are 2.72 times higher than in a person with complete range of motion. Facial symmetry was associated with increased odds of aspiration, but much weaker at 0.76. Leder and colleagues still cautioned that lip closure, despite not being associated with increased odds of aspiration, is still a crucial part of our assessment of the oral phase of the swallow.
“Incomplete lingual range of motion was an independent risk factor for aspiration, regardless of labial closure and facial symmetry (p373, 2013).”
Overall, if a patient is not oriented, cannot follow commands and has incomplete or absent lingual movement on your oral mechanism examination, then proceed with caution.
“In this case, a dysphagia testing protocol that (typically) starts with thin liquids should be modified to begin with puree consistency which has the potential to be swallowed more successfully (p294, 2009).”
Much more can be said about Steven Leder and his colleagues’ work on The Yale Swallow Protocol: An Evidence-Based Approach to Decision Making, but please refer to the book by Springer publications for further information.
5. When Do You Skip the Screen & Go Right to an Instrumental Evaluation?
All screens have exclusionary criteria, preventing the nurse from giving 3 ounces of water. For example, if the patient is not alert enough, one could discontinue and re-screen within 24 hours. When reviewing research on screening protocols, we ask: “What was the inclusion criteria?” At the Dysphagia Research Society’s annual meeting in February of this year, Steven Leder reviewed inclusion criteria used for his team’s new research on how and when to assess patients who are post-extubation, using The Yale Swallow Protocol as a screen and FEES when appropriate (Leder, et al., 2016). The patients received a 3-ounce water swallow challenge if they were:
- answering orientation questions,
- following directions,
- cleared for oral alimentation, and
- stable from a respiratory standpoint.
This does exclude quite a number of critically ill patients post-extubation. This shows that when we use good judgement along with reliable and valid standardized protocols, we are not overly restrictive. Leder urged poster session attendees to follow a standardized practice at their institutions with reliable and valid methods.
Leder, Suiter & Green (in Silent aspiration risk is volume-dependent, 2011a, p307) stated that patients with head and neck cancer, those who have a tracheotomy tube, and those who require pulmonary toilet should NOT be tested with a 3-ounce water swallow challenge.
All patients with a tracheotomy tubes need instrumental testing to rule-out dysphagia, stated Clarence Sasaki and Steven Leder, in Comments on Selected Recent Dysphagia Literature, in the June, 2016 Dysphagia journal. They strongly advised against efforts to develop screening tools for patients with tracheotomy tubes.
“We are of the strong opinion that all patients needing a tracheotomy tube require instrumental testing. Only endoscopy or videofluoroscopy can examine the upper airway, evaluate (pharyngeal and) laryngeal functioning, determine aspiration status, diagnose dysphagia, and recommend an appropriate oral diet.”
I have to also acknowledge Leder and Sasaki for their thoroughness in semantics:
In this Comments article, Sasaki and Leder re-educated readers twice on the precise term is “tracheotomy” and not “tracheostomy,” “since the tracheal mucosa is not brought into continuity with the skin when a tracheotomy is performed.”
There is so much more to say about Steven Leder, PhD, CCC-SLP and his incredible contributions to our field. My heart goes out to his family and friends. I cannot imagine how hard this is for his colleagues and team at Yale and all the researchers who have collaborated with him for years. I keep thinking, “He was not done his work!” I thank you in advance for keeping his research, questions and wisdom alive!
“We are confident that our research and recommendations
to improve patient care by fostering safer swallowing
will stand the test of time.”
(Leder & Suiter, 2012c, p295)
I look forward to more sharing from the dysphagia community and beyond. Please use comments section below.
A memorial fund has been established to support his ongoing research collaborations with both the speech-language pathologists and the residents at Yale (per the Dysphagia Research Society’s information).
Donations can be made to:
Yale School of Medicine, Steven B. Leder Memorial Fund.
800 Howard Ave., 4th Floor, Room 422
New Haven, CT 06510
Donations are tax-deductible; individuals who donate will receive a tax deduction letter.
Karen Sheffler, MS, CCC-SLP, BCS-S of SwallowStudy.com
Leder, SB. (1996). Gag reflex and dysphagia. Head Neck, 18 (2), 138-141.
Leder, SB. (1997). Videofluoroscopic evaluation of aspiration with visual examination of the gag reflex and velar movement. Dysphagia, 12 (1), 21-23.
Leder, S.B. (2000). Use of arterial oxygen saturation, heart rate, and blood pressure as indirect objective physiologic markers to predict aspiration. Dysphagia, 15 (4), 201-205.
Suiter, DM & Leder, SB. (2008). Clinical utility of the 3-ounce water swallow test. Dysphagia, 23, 244-250.
Leder, SB, Suiter, DM & Warner, HL. (2009). Answering orientation questions and following single-step verbal commands; Effect on aspiration status. Dysphagia, 24, 290-295.
Leder, SB, Suiter, DM & Green, BG. (2011a). Silent aspiration risk is volume-dependent. Dysphagia, 26, 304-309.
Leder, SB, Suiter, DM, Warner, HL & Kaplan, LJ. (2011b). Initiating safe oral feeding in critically ill intensive care and step-down unit patients based on passing a 3-ounce (90 milliliters) water swallow challenge. The Journal of Trauma Injury, Infection, and Critical Care, 70 (5), 1203-1207.
Leder, SB, Suiter, DM, Warner, HL, Acton, LM & Swainson, BA. (2012a). Success of recommending oral diets in acute stroke patients based on passing a 90-cc water swallow challenge protocol. Top Stroke Rehabil, 19 (1), 40-44.
Leder, SB, Suiter, DM, Warner, HL, Acton, LM & Siegel, MD. (2012b). Safe initiation of oral diets in hospitalized pateints based on passing a 3-ounce (90cc) water swallow challenge protocol. QJ Med, 105, 257-263.
Leder, SB & Suiter, DM. (2012c). Letter to the editor: Silent aspiration risk is volume-dependent: Reply to Letter to the Editor. Dysphagia, 27, 295-296.
Leder, SB, Suiter, DM, Murray, J & Rademaker, AW. (2013). Can an oral mechanism examination contribute to the assessment of odds of aspiration? Dysphagia, 28, 370-374.
Warner, HL, Suiter, DM, Nystrom, KV, Poskus, K & Leder, SB. (2014). Comparing accuracy of the Yale swallow protocol when administered by registered nurses and speech-language pathologists. Journal of Clinical Nursing, 23 (13-14), 1908-1915.
Suiter, DM, Sloggy, J & Leder, SB. (2014). Validation of the Yale Swallow Protocol: A prospective double-blinded videofluoroscopic study. Dysphagia, 29 (2), 199-203.
Leder, SB, Warner, HL, Suiter, DM, Bhattacharya, B, Rosenbaum, SH & Schuster, K. (2016, February). How and When to Begin Safe Oral Alimentation in Post-Extubation Intensive Care Unit Patients. Poster presented at the Dysphagia Research Society Annual Meeting, Tucson, AZ.
Sasaki, CT & Leder, SB. (2016). Comments on selected recent dysphagia literature. Dysphagia, 31 (3), 486-490.
DePippo, KL, Holas, MA & Reding, MJ. (1994). The Burke dysphagia screening test: Validation of its use in patients with stroke. Arch Phys Med Rehabil, 75, 1284-1286.
DePippo, KL, Holas, MA & Reding, MJ. (1992). Validation of the 3-oz water swallow test for aspiration following stroke. Arch Neurol, 49, 1259-1261.
Garon, BR, Engle, M & Ormiston, C. (1995). Reliability of the 3-oz water swallow test utilizing cough reflex as sole indicator of aspiration. Neurorehabil Neuro Repair, 9, 139-143.