Bolus Clearance Ratio Elevated in Patients With Neurogenic Dysphagia Compared With Healthy Adults: A Measure of Pharyngeal Efficiency

Abstract

Purpose: Postswallow pharyngeal residue is a risk factor for aspiration, implies swallowing inefficiency, and increases the work of eating. The Bolus Clearance Ratio (BCR) is a derived metric that relates quantities of bolus material observed in the pharynx at two different points: before and after a swallow. The ratio provides a percentage estimate of bolus clearance. In healthy adults, mean BCR is < .05; that is, less than 5% of an ingested bolus is retained in the pharynx. The aim of this study was to compare BCR measures from patients referred for videofluoroscopic swallow studies with concerns related to stroke ( n = 100) or other neurological conditions ( n = 131, including Parkinson's disease and dementia) with BCRs for 139 healthy adults across the age range. Method: BCR for a 20 ml of thin liquid barium bolus was measured. Additional metrics included age, penetration–aspiration scale (PAS) score, and quantitative measures of timing and displacement. Correlations were explored between BCR and pharyngeal constriction ratio (PCR), pharyngoesophageal segment opening (PESmax), maximum hyoid displacement (HMax), and total pharyngeal transit time (TPT). Results: BCR values for patients with stroke ( Mdn = 9%, interquartile range [IQR]: 19%, range: 0%–73%) and other neurological conditions ( Mdn = 9%, IQR: 16%, range: 0%–96%) were significantly higher than in healthy norms ( Mdn = 2%, IQR: 4%, range: 0%–16%, p < .001). BCR was significantly correlated with age ( R s = .23, p < .01), TPT ( R s = .20, p < .01), PCR ( R s = .55, p < .01), PESmax ( R s = −.17, p < .01), HMax ( R s = −.16, p < .01), and PAS ( R s = .38, p < .01). Conclusions: BCR was elevated in patients with neurogenic dysphagia in comparison with healthy norms and was significantly associated with increased aspiration severity (i.e., PAS). BCR was also correlated with pharyngeal timing and displacement parameters, with the strongest correlation with pharyngeal constriction—a measure of pharyngeal strength. The BCR offers clinicians a simple, quantitative measure of bolus residue and, therefore, pharyngeal efficiency and may be used to assess change in patients over time and with treatment.