Research Corner: VFSS and Frame Rate

For those  of you not on the ASHA List Serve, I am sharing a post regarding a recent publication about frame rate for Pediatric Videofluroscopic Swallow Studies. The post was written by Heather Bonilha, PhD,  who is  a speech-language pathologist and medical researcher who specializes in voice and swallowing disorders. For over 15 years, she has been studying the impact of temporal resolution (ex. frame rate) on diagnostic accuracy and treatment recommendations with a specific focus on MBSSs. We are so grateful for contributions, and for her post, which infomrs our practice.

The recently published article is:  Layly, J., Marmouset, F., Chassagnon, G., Bertrand, P., Sirinelli, D., Cottier, J. P., & Morel, B. (2019). Can We Reduce Frame Rate to 15 Images per Second in Pediatric Videofluoroscopic Swallow Studies? Dysphagia. doi:10.1007/s00455-019-10027-8

To quote from her post:

 I am reaching out to the SIG13 forum to express my concerns related to a very recently published article: Layly, J., Marmouset, F., Chassagnon, G., Bertrand, P., Sirinelli, D., Cottier, J. P., & Morel, B. (2019). Can We Reduce Frame Rate to 15 Images per Second in Pediatric Videofluoroscopic Swallow Studies? Dysphagia. doi:10.1007/s00455-019-10027-8 I’ve never made a post like this but am compelled based on my concern for quality patient care to post this one. I want to informally point out some information that clinicians and researchers should consider when evaluating the merits of the article referenced above. 

Points to consider when evaluating the merit and clinical implications of the research article “Can We Reduce Frame Rate to 15 Images per Second in Pediatric Videofluoroscopic Swallow Studies?”:

The most significant point is that one can not notice a difference in something that isn’t there. When studying the impact of technical parameters of MBSS, one must use cases where the phenomenon (penetration / aspiration in this case) exists. If the patient doesn’t penetrate/ aspirate at 30 frames per second (fps) there is not a possibility to find it at 15fps, falsely leading to a result of agreement in diagnostic accuracy between 30 & 15 fps. Thus, any study of pulse rate / frame rate must be limited to that in which a phenomenon (penetration/aspiration, reduced laryngeal elevation, delayed initiation of pharyngeal swallow etc.) is detectable at 30fps. Therefore, of the 190 swallows studied in the above referenced article only 46 are pertinent to addressing the research question. By including all 190 swallows, the results of the study are significantly biased towards revealing no differences between 15 and 30fps.

Next, it is necessary to consider more than penetration/aspiration when determining whether technical factors influence diagnostic accuracy. Our treatments have a goal of reducing penetration/aspiration, but we do that by modifying swallowing physiology (not assessed by, for instance, by the penetration-aspiration scale (PAS)). Strong clinical implications regarding the suitability of using 15 vs 30fps must consider more than just PAS. The authors correctly state in the discussion that “15 fps may be adequate to record aspiration and penetration in children; however, more subtle biomechanical and kinematic phenomena may be missed at the slower sampling frequency due to the rapidity of the physiological swallowing components.”

The technique used to down sample the 30fps recording to 15fps does not allow the raters to be blinded to the higher versus lower frame rates as the higher frame rates (30 fps) will be twice as long as the 15fps swallows. There is a statement that using the 15fps recordings did not change the treatment plan for the patients. However, impact on treatment plan was not a variable in the research study and no data related to treatment plans / recommendations were presented.

There is a statement that using 15fps instead of 30fps is “an efficient way to reduce the ionizing radiation exposition in children”. However, radiation exposure, and more importantly, radiation risk, was not assessed in the study.

For these reasons, I strongly recommend a careful evaluation of the research methods and conclusions of the article “Can We Reduce Frame Rate to 15 Images per Second in Pediatric Videofluoroscopic Swallow Studies?” I will be formally writing a Letter to the Editor of Dysphagia; however, that is a lengthier process and I felt that the potential clinical ramifications dictated a more immediate response. Therefore, before the formal Letter to the Editor can be published, I hope that clinicians are encouraged to read the published article with critical appraisal prior to incorporating it in their evidence-based clinical practice.

Please feel free to contact me off-line at bonilhah@musc.edu regarding this. Sincerely,

Heather Bonilha  

Bonilha, H.S., Blair, J., Carnes, B., Huda, W., McGrattan, K., Humphries, K., Michaels, Y., Martin-Harris, B. (2013). Preliminary investigation of the effect of pulse rate on judgments of swallowing impairment and treatment recommendations. Dysphagia, 28(4): 528-538. [PMID: 23559454] [PMCID: PMC3762944]

Bonilha, H.S., Huda, W., Wilmskoetter, J., Martin-Harris, B., Tipnis, S.V. (2019). Radiation risks to adult patients undergoing Modified Barium Swallow Studies. Dysphagia. [PMID: 30830303] [PMC Journal – In Process]

Bonilha, H.S., Wilmskoetter, J., Tipnis, S.V., Martin-Harris, B., Huda, W. (2019). Relationships between Dose Area Product, radiation exposure time and projection in adult Modified Barium Swallow Studies. American Journal of Speech-Language Pathology. [PMC Journal – In Process]

Bonilha, H.S., Wilmskoetter, J., Tipnis, S.V., Martin-Harris, B., Huda, W. (2018). Estimating thyroid doses in Modified Barium Swallow Studies. Health Physics, 115(3): 360-368. [PMID: 30045116] [PMC Journal – In Process]

Bonilha, H.S., Wilmskoetter, J., Martin-Harris, B., Tipnis, S.V., Huda, W. (2017). Effective dose per unit kerma area product conversion factors in adults undergoing Modified Barium Swallow Studies. Radiation Protection Dosimetry, 16:1-9. [PMID: 28204745] [PMCID: PMC5927331]

Bonilha, H.S., Humphries, K., Blair, J., Hill, E., McGrattan, K., Carnes, B., Huda, W., Martin-Harris, B. (2013). Radiation exposure time during MBSS: Influence of swallowing impairment severity, medical diagnosis, clinician experience, and standardized protocol use. Dysphagia, 28(1): 77-85. PMID: 22692431

Martin-Harris, B., Carson, K.A., Pinto, J.M., Lefton-Greif, M.A. (2019). BaByVFSSImP© A novel measurement tool for videofluoroscopic assessment of swallowing impairment in bottle-fed babies: establishing a standard. Dysphagia. [PMID 30955137]

Lefton-Greif, M.A., Arvedson, J.C. (2016). Pediatric feeding/swallowing: yesterday, today and tomorrow. Semin Speech Lang 37:298-309. [PMID 27701706]

Arvedson, J.C., Lefton-Greif, M.A. (2017). Instrumental assessment of pediatric dysphagia. Semin Speech Lang 38:135-146. [PMID 28324903]

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