Reliability and validity of cervical auscultation

We conducted a two-part study that contributes to the discussion about cervical auscultation (CA) as a scientifically justifiable and medically useful tool to identify patients with a high risk of aspiration/penetration. We sought to determine (1) acoustic features that mark a deglutition act as dysphagic; (2) acoustic changes in healthy older deglutition profiles compared with those of younger adults; (3) the correctness and concordance of rater judgments based on CA; and (4) if education in CA improves individual reliability. The first part of the study focused on a comparison of the "swallow morphology" of dysphagic as opposed to healthy subjects' deglutition in terms of structure properties of the pharyngeal phase of deglutition. We obtained the following results. The duration of deglutition apnea is significantly higher in the older group than in the younger one. Comparing the younger group and the dysphagic group we found significant differences in duration of deglutition apnea, onset time, and number of gulps. Just one parameter, number of gulps, distinguishes significantly between the older and the dysphagic groups. The second part of the study aimed at evaluating the reliability of CA in detecting dysphagia measured as the concordance and the correctness of CA experts in classifying swallowing sounds. The interrater reliability coefficient AC1 resulted in a value of 0.46, which is to be interpreted as fair agreement. Furthermore, we found that comparison with radiologically defined aspiration/penetration for the group of experts (speech and language therapists) yielded 70% specificity and 94% sensitivity. We conclude that the swallowing sounds contain audible cues that should, in principle, permit reliable classification and view CA as an early warning system for identifying patients with a high risk of aspiration/penetration; however, it is not appropriate as a stand-alone tool.