Video Fluoroscopy Swallow Study
The VFSS was performed with collaboration between an OT and a radiologist in the fluoroscopy suite, using barium to label a variety of food stuffs: thin liquid, thick liquid, purees and solids as appropriate for the age and skill of the child. Children were scanned using a Siemens Axiom Iconos R200 Fluoroscopy system at a frame rate of 15 per second. Barium sulfate for suspension 98% w/p for oral use (E-Z-EM Canada) was diluted with food liquids and solids according to the child’s capabilities. Radiation emission in MSv units was recorded, although it was not possible to determine the exact effective dose, due to variations in screening time and body surface area exposed.
Care was taken to make the child and family comfortable, so as to replicate as closely as possible the child’s natural feeding environment and obtain results that represent the reality at home. This included the child being fed by their usual caregiver and being positioned on a purpose-built adaptable chair that could be adjusted in a way that mimics the usual feeding position, see figure 1. Since nasogastric tubes tend to slow several phases of swallowing,13 they were removed prior to the examination. Pulsed serial x-rays of the oropharynx and esophagus were taken from a lateral view. The distal esophagus and stomach were included for assessment of reflux. Multiple swallows were assessed when the history indicated a possible increased risk for aspiration developing with fatigue. In these cases, multiple swallows were performed without the use of fluoroscopy using a safe substance with a later repetition of fluoroscopic swallow using the highest risk substance to reduce radiation exposure.
The OT reviewed the prose VFSS report and scored it by choosing the most appropriate category on the eight-point penetration-aspiration scale (table 1) for each fluid/ food consistency trialed. Children scoring 1 to 5 represented no aspiration (NA), and those scoring 6 to 8 were classified as having oro-pharyngeal aspiration (OPA). Within OPA, a score of 6 or 7 was graded as having overt aspiration, i.e. detection of material below the level of the true vocal folds. A score of 8 was designated silent aspiration (SA), i.e. detection of material below the level of the true vocal folds without cough or other laryngeal response within 20 seconds.14 Since clinical assessment cannot accurately diagnose silent aspiration, we used the term “suspected silent aspiration”, noting the limitations of this description. For both CFE and VFSS, children were classified as displaying “no aspiration”, “overt aspiration” or “silent aspiration” based on the most pathological behavior encountered, “silent aspiration” being regarded the most severe form. When a child displayed silent aspiration with any texture, they were categorized as silent aspirators, even if they aspirated overtly with a different texture, so as to reflect the highest risk pattern.