Sensitivity of the Blue Dye Food Test for Detecting Aspiration in Patients with a Tracheotomy

Aims: To explore the sensitivity and specificity values for aspiration with the blue dye food test (BDFT) in tracheotomized patients undergoing inpatient rehabilitation and explore what impact, if any, the accumulated oropharyngeal secretion level has upon the accuracy of the BDFT.

Methodology: Simultaneous BDFT and fiberoptic endoscopic evaluation of swallowing (FEES) procedure were conducted with 21 tracheotomized patients. The patient’s accumulated oropharyngeal secretion level was evaluated first using a 5-point secretion severity scale. The patients then received ice chips and various boluses which were dyed blue. The BDFT was considered positive for aspiration when blue tinged material was present upon tracheal suctioning, around the stoma site, or on the tracheotomy tube upon its removal. The FEES was considered positive for aspiration when the bolus passed through the vocal folds as observed by nasal endoscopy. In cases where no blue material was observed on the BDFT, the additional step of subglottal viewing through the tracheostoma was performed.
Results: Results revealed the sensitivity of the BDFTfor the detection of aspiration was only 0.4 when compared to the FEES during simultaneous examinations. Statistically significant differences were observed between secretion severity level and a positive BDFT as Group 1 (true positive BDFT) mean secretion level was 4.5, Group 2 (false negative BDFT) was 2.33, and Group 3 (true negative BDFT) was 2.0 (F=8.143, p=0.003).
Conclusion: Results further support that the BDFT demonstrates poor sensitivity for aspiration detection in patients with a tracheotomy. Results reveal for the first time the potential influence accumulated oropharyngeal secretions may have upon the likelihood of a positive BDFT. Results do not support use of the BDFT in isolation for definitive detection of aspiration. Potential uses for the BDFT in a clinical setting are discussed.