Effect of a Reduced Frame Rate for Videofluoroscopic Swallowing Studies on the Recognition of Aspiration in Adult Patients.

The aim of this study was to clarify the effects of reduced frame rates in videofluoroscopic swallowing studies (VFSS) on aspiration assessment. The consecutive key frames (CKFs), that is, the range of key frames that are essential for penetration-aspiration scale (PAS) scoring of abnormal laryngeal penetration (ALP) and aspiration, was defined using retrospective 30-frames/second (fps) VFSS records for 50 adult dysphagia patients at an acute care university hospital. The results showed that the CKFs was larger in 24 aspiration patients than in 26 ALP patients, and its distribution was wider. The minimum CKFs that included no trace of residual liquid (TRL) was 8 for aspiration. When reducing the frame rate in seven steps to 3.75 fps, the complete disappearance of CKFs with no TRL was seen in only four ALP patients. With partial disappearance of CKFs, the PAS scoring of ALP and aspiration even with a reduction to 3.75 fps agreed consistently and almost completely with that at 30 fps, and high reliability was obtained. This study was exploratory, but 3.75 fps was the lower limit that satisfied the criteria in analyses after defining the acceptable level for frame rate reductions in assessing aspiration.