Blue Dye Test

Evans Blue Dye Test and Oropharyngeal Dysphagia

John R. Ashford, Ph.D., CCC-SLP

            Herbert McLean Evans, in 1914, was the first to use a biological staining agent and it is now used as a biological dye and clinical diagnostic agent.  Eastman Kodak Company purchased Evan’s blue dye in 1936, and it has been used for many clinical purposes including estimation of blood volume, determination of cardiac output, determining the size of myocardial infarction, assessing vascular permeability, detecting lymph nodes, and diagnosis and identification of tumors. It is sold under the name “Evans blue” (1).

            The use of Evan’s blue dye as a test for aspiration in patients with tracheostomy tubes was reported by Cameron, Reynolds, and Zuidema in 1973 (2). It was tested as a bedside evaluation and required four drops of a 1% solution of dye to be placed on the tongue of patients with a tracheostomy.  The incidence of aspiration of their saliva was then documented.  It was positive if the blue dye was suctioned from the tracheostomy tube. Cameron et al. reported that 42 of 61 (69%) patients with tracheostomy aspirated.  Later, Spray, Zuidema, and Cameron (3) used this procedure to identify trach cuff size, volume, and pressure modifications that reduced aspiration potential.

            The Modified Evan’s Blue Dye Test (MEBDT) was first described by Thompson-Henry and Braddock in 1995 (4).  The major modification was the patient was given food and liquids that were dyed blue rather than placing drops on the tongue, as done by the Evan’s Blue Dye Test (EBDT).  As with the EBDT, if blue material was suctioned from the tracheostomy tube, the test was considered positive for aspiration.  In their study, Thompson-Henry and Braddock reported the test did not detect aspiration in any of their 5 patients and that false-positive results were possible. However, this study received harsh criticism for its lack of research design strength. The main criticism was that it did not compare the MEBDT with simultaneous or subsequent FEES or MBS results (as gold standards) and the modified procedure from the original blue dye application may have led to the negative results (5). As Leder (5) points out, the Evan’s Blue Dye Test was not developed as a diagnostic test for aspiration; it is a screening tool to identify possible aspiration with tracheotomy tube use.

            Subsequently, several studies have reported attempts at validating the MEBDT. Brady, Hildner, & Hutchins (6) completed 20 consecutive simultaneous MEBDTs and videofluoroscopic swallow studies on patients with tracheostomies.  Overall, the MEBDT showed a 50% false-negative rate, or it did not show visual evidence of aspiration  when aspiration actually occurred. However, this test identified aspiration in 100% of patients who aspirated more than trace amounts but failed to identify trace amounts of aspiration. Donzelli, Brady, Wesling, and Craney (7) simultaneously compared MEBDT and FEES and reported amazingly similar results as Brady et al. (6)—50% false-negative error rate in detecting aspiration. There are a few pitfalls associated with these findings: (a) if the cuff is inflated, immediate aspirate may not be visually evident and may require time to seep around the cuff; (b) trace amounts of aspirate may appear sizeable on an instrumental study, but in volume are miniscule.  Very small amount of trace aspirate can mix with tracheal mucous and not be discernable to the eye; and (c) immediate suction following the test trial may occur too soon, not allowing the blue test material to make its way down the trachea beyond the end of the tracheostomy tube where it can be suctioned. Procedures may be a factor.

            Using FEES and VFSS findings as comparisons, several studies have reported the sensitivity and specificity of the MEBDT.  Béchet, Hill, Gilheaney, and Walshe (8) reported a systematic review of six studies on the diagnostic accuracy of the MEBDT. There were significant disparities in study design and patient characteristics.  Administration procedures varied greatly across studies.  Sensitivity estimates varied from 38% to 95% indicating that the MEBDT is unreliable in detecting aspiration in patients with tracheostomies. However, these studies also showed overall high specificity values ranging from 79% to 100% suggesting that MEBDT correctly identifies patients who do not aspirate. Further examination of these findings can be found in the references below (9-14).

            As stated previously, the MEBDT is not a diagnostic test; it is a screening test and made to be used in conjunction with more accurate diagnostic tests, such as FEES and VFSS (14). Fiorelli et al. (13) have provided a simple guideline to follow:   A positive MEBDT test result – oral feeding should not be allowed; a negative MEBDT test result – should undergo FEES before feeding.

            In 2021, Freud, Hamburger, Kaplan, & Henkin (15) introduced a new blue dye test called the Sheba Blue Dye Test (SBDT) based on the MEBDT. The SBDT evaluates the patient over three evaluative sessions in a single visit with increasing quantities of food. There is a strict protocol to follow.  Results have shown better stability of test findings over three sessions versus one session with the MEBDT.  It is recommended the Freud et al. paper be studied before implementing this tool.  Further, this new test has not undergone the scrutiny of comparison with instrumental procedures and is needed. The authors, like those of the MEBDT, state this is a screening test but may be useful if instrumental studies are not available.

References

  1. Yao, L., Xue, X., Yu, P., Ni, Y.& Chen, F. (2018). Evans Blue Dye: A Revisit of Its Applications in Biomedicine. Contrast Media & Molecular Imaging, 2018 https://doi.org/10.1155/2018/7628037.
  2. Cameron, J. L., Reynolds, J., & Zuidema, G. D. (1973). Aspiration in patients with tracheostomies. Surgery, gynecology & obstetrics, 136(1), 68–70.3
  3. Spray, S. B., Zuidema, G. D., & Cameron, J. L. (1976). Aspiration pneumonia; incidence of aspiration with endotracheal tubes. American journal of surgery, 131(6), 701–703. https://doi.org/10.1016/0002-9610(76)90181-1
  4. Thompson-Henry, S., Braddock, B. The modified Evan’s blue dye procedure fails to detect aspiration in the tracheostomized patient: Five case reports. Dysphagia10, 172–174 (1995). https://doi.org/10.1007/BF00260973
  5. Leder, S.B. Comment on Thompson-Henry and Braddock: The modified Evan’s Blue Dye procedure fails to detect aspiration in the tracheostomized patient: Five case reports. Dysphagia11, 80–81 (1996). https://doi.org/10.1007/BF00385805
  6. Brady, S. L., Hildner, C. D., & Hutchins, B. F. (1999). Simultaneous videofluoroscopic swallow study and modified Evans blue dye procedure: An evaluation of blue dye visualization in cases of known aspiration. Dysphagia, 14(3), 146–149. https://doi.org/10.1007/PL00009596
  7. Donzelli, J., Brady, S., Wesling, M., & Craney, M. (2001). Simultaneous modified Evans blue dye procedure and video nasal endoscopic evaluation of the swallow. The Laryngoscope, 111(10), 1746–1750. https://doi.org/10.1097/00005537-200110000-00015
  8. Béchet, S., Hill, F., Gilheaney, Ó., & Walshe, M. (2016). Diagnostic Accuracy of the Modified Evan’s Blue Dye Test in Detecting Aspiration in Patients with Tracheostomy: A Systematic Review of the Evidence. Dysphagia, 31(6), 721–729. https://doi.org/10.1007/s00455-016-9737-3
  9. Peruzzi, W. T., Logemann, J. A., Currie, D., & Moen, S. G. (2001). Assessment of aspiration in patients with tracheostomies: comparison of the bedside colored dye assessment with videofluoroscopic examination. Respiratory care, 46(3), 243–247.
  10. Belafsky, P. C., Blumenfeld, L., LePage, A., & Nahrstedt, K. (2003). The accuracy of the modified Evan’s blue dye test in predicting aspiration. The Laryngoscope, 113(11), 1969–1972. https://doi.org/10.1097/00005537-200311000-00021
  11. O’Neil-Pirozzi, T. M., Lisiecki, D. J., Jack Momose, K., Connors, J. J., & Milliner, M. P. (2003). Simultaneous modified barium swallow and blue dye tests: a determination of the accuracy of blue dye test aspiration findings. Dysphagia, 18(1), 32–38. https://doi.org/10.1007/s00455-002-0081-4
  12. Winklmaier, U., Wüst, K., Plinkert, P. K., & Wallner, F. (2007). The accuracy of the modified Evans blue dye test in detecting aspiration in head and neck cancer patients. European archives of oto-rhino-laryngology : official journal of the European Federation of Oto-Rhino-Laryngological Societies (EUFOS) : affiliated with the German Society for Oto-Rhino-Laryngology – Head and Neck Surgery, 264(9), 1059–1064. https://doi.org/10.1007/s00405-007-0299-8
  13. Fiorelli, A., Ferraro, F., Nagar, F., Fusco, P., Mazzone, S., Costa, G., Di Natale, D., Serra, N., & Santini, M. (2017). A New Modified Evans Blue Dye Test as Screening Test for Aspiration in Tracheostomized Patients. Journal of cardiothoracic and vascular anesthesia, 31(2), 441–445. https://doi.org/10.1053/j.jvca.2016.07.031
  14. Linhares Filho, T. A., Arcanjo, F., Zanin, L. H., Portela, H. A., Braga, J. M., & da Luz Pereira, V. (2019). The accuracy of the modified Evan’s blue dye test in detecting aspiration in tracheostomised patients. The Journal of laryngology and otology, 133(4), 329–332. https://doi.org/10.1017/S0022215119000471
  15. Freud, D., Hamburger, A., Kaplan, D., & Henkin, Y. (2021). The Sheba Medical Center Protocol for Bedside Evaluation of Swallowing Disorders Among Tracheotomized Patients. Dysphagia, 10.1007/s00455-021-10384-3. Advance online publication. https://doi.org/10.1007/s00455-021-10384-3

May 30, 2022

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