A method to objectively assess swallow function in adults with suspected aspiration

Pharyngeal manometry and impedance provide information on swallow function. We developed a new analysis approach for assessment of aspiration risk.

We studied 20 patients (30-95 years old) with suspected aspiration who were referred for videofluoroscopy, along with controls (ages 24-47 years). The pharyngeal phase of liquid bolus swallowing was recorded with manometry and impedance. Data from the first swallow of a bolus and subsequent clearing swallows were analyzed. We scored fluoroscopic evidence of aspiration and investigated a range of computationally derived functional variables. Of these, 4 stood out as having high diagnostic value: peak pressure (PeakP), pressure at nadir impedance (PNadImp), time from nadir impedance to peak pressure (TNadImp-PeakP), and the interval of impedance drop in the distal pharynx (flow interval).

During 54 liquid, first swallows and 40 clearing swallows, aspiration was observed in 35 (13 patients). Compared to those of controls, patient swallows were characterized by a lower PeakP, higher PNadImp, longer flow interval, and shorter TNadImp-PeakP. A Swallow Risk Index (SRI), designed to identify dysfunctions associated with aspiration, was developed from iterative evaluations of variables. The average first swallow SRI correlated with the average aspiration score (r = 0.846, P < .00001 for Spearman Rank Correlation). An average SRI of 15, when used as a cutoff, predicted aspiration during fluoroscopy for this cohort (κ = 1.0).

Pressure-flow variables derived from automated analysis of combined manometric/impedance measurements provide valuable diagnostic information. When combined into an SRI, these measurements are a robust predictor of aspiration.