Do Ratings of Swallowing Function Differ by Videofluoroscopic Rate? An Exploratory Analysis in Patients After Acute Stroke

Objective: To determine differences between continuous videofluoroscopic swallow studies (VFSS)with a pulse rate and frame rate of 30 and the same swallows reduced to 15 frames per second (fps)on measures of swallowing function in patients after acute ischemic stroke. Design: Blinded comparison. Setting: Acute hospital. Participants: Patients after ischemic stroke (N=20). Interventions: Not applicable. Main Outcome Measures: Single and sequential sips of thin liquids, single sips of nectar liquids, pudding, and cookie boluses were rated on measures of timing of swallowing events, Modified Barium Swallowing Impairment Profile component scores, and Penetration-Aspiration Scale scores. The ratings for videos at 15 fps and 30 fps were compared by Wilcoxon signed rank tests. Results: Pharyngeal transit time was longer and bolus entry into the hypopharynx was later for 30 fps than for 15 fps. Components of Oral Residue and Pharyngoesophageal Segment Opening ratings were more severe for 15 fps than 30 fps, whereas Bolus Transport and Initiation of Pharyngeal Swallow were rated as more severe for 30 fps than for 15 fps. There was no difference between 30 fps and 15 fps on the remaining measures, including Penetration-Aspiration Scale scores. Conclusion: Continuous VFSS recorded at 30 fps and their down-sampled 15 fps duplicates yielded contrasting results on certain durational and functional measures of swallowing, though not on others. VFSS should be administered continuously or at 30 pulses per second for valid assessment of swallowing while using other methods to reduce radiation exposure.