Clinical feeding examination with cervical auscultation for detecting oropharyngeal aspiration: A systematic review of the evidence

Acoustic characteristics associated with liquid swallowing sounds of different bolus consistencies in young healthy adults

BACKGROUND

Cervical auscultation has been used clinically as an augmentative procedure for swallow examination. Despite its frequent use for screening and preliminary assessment of swallowing, the usefulness of cervical auscultation is controversial due to a lack of sufficient research, particularly in quantifying swallowing sounds.

AIMS

To document the acoustic characteristics of normal swallowing sound associated with swallowing bolus of different consistencies among younger healthy adults.

METHODS & PROCEDURES

A total of 30 healthy young adult participants swallowed 5 ml thickened liquids of four different consistencies (slightly thick, mildly thick, moderately thick and extremely thick) prepared using a starch-based commercial thickener, and the corresponding swallowing sounds were recorded using a wireless accelerometric stethoscope. An array of acoustic measures including duration of swallowing sound (DSS), duration to peak intensity (DPI), frequency at peak intensity (FPI), peak intensity (PI), average intensity (AI), and difference between peak and average intensity (DPAI) values associated with the swallowing signals were obtained.

OUTCOMES & RESULTS

In general, increased durational measures of the swallowing sounds were associated with an increase in bolus consistency. Intensity measures including PI, AI and DPAI were found to be stable across different consistencies. The change in FPI did not appear to be particularly meaningful due to its high variability. In addition, no significant differences were observed between men and women.

CONCLUSIONS & IMPLICATIONS

Swallow sounds associated with different bolus consistencies could be quantified and used to differentiate consistencies. The present findings could serve as a reference for future swallowing research of normal and dysphagic population.

WHAT THIS PAPER ADDS

What is already known on the subject Cervical auscultation using traditional stethoscope has been used as part of an informal clinical swallow examination by practitioners. Validity of cervical auscultation is controversial, possibly due to the lack of normative data on swallow sounds. What this paper adds to existing knowledge The present study explored the possibility of using wireless accelerometric stethoscopy for cervical auscultation for dysphagia screening. Acoustic profiles of swallow sounds associated with boluses of different consistencies in healthy individuals were examined. What are the potential or actual clinical implications of this work? Findings contribute to our knowledge about the acoustic characteristics of swallow sounds of boluses of different consistencies in healthy young individuals. The study provides normative clinical data on cervical auscultation using wireless accelerometric stethoscope for normal swallow.

Dysphagia management: Does structured training improve the validity and reliability of cervical auscultation?

Purpose: Cervical auscultation (CA) uses a stethoscope or microphone to complement the clinical swallow examination by interpreting swallowing sounds and swallow-respiratory coordination. This study investigated the effects of structured CA training on CA-rating agreement with Flexible Endoscopic Evaluation of Swallowing (FEES) and CA rater reliability.Method: Thirty-nine speech-language pathologists participated in a structured CA training course at Gothenburg University. They rated nine swallow-respiratory sound recordings which were simultaneously recorded during FEES. Swallow sounds were rated six weeks prior to the CA-workshop using two binary yes/no questions, (1) Safe, (2) Dysphagia, and a third Dysphagia Severity rating. Swallow sounds were rated again (re-randomised) one month post CA-workshop.Result: Agreement with FEES (validity) improved significantly (p < 0.05) pre-post training for the Safe and Dysphagia questions, with post training sensitivities >90% and specificities at 76% and 85% respectively. Dysphagia severity rating improved non-significantly. Intra-rater reliability improved significantly with kappa statistics >0.90 post training. Improvements for inter-rater reliability were noted, though non-significant.Conclusion: Results demonstrate that with structured training, the validity of CA (to detect a Safe/Dysphagic swallow) significantly improves, as does intra-rater reliability. This is congruent with literature identifying the positive effects of structured training improving instrumental dysphagia assessment.

A study of acoustic characteristics of voluntary expiratory sounds produced before and immediately after swallowing

To evaluate the expiratory sounds produced during swallowing recorded simultaneously with videofluorographic examination of swallowing (VF) using fast Fourier transform (FFT), and to examine the relationship between dysphagia and its acoustic characteristics. A total of 348 samples of expiratory sounds were collected from 61 patients with dysphagia whose expiratory sounds were recorded during VF. The VF results were evaluated by one dentist and categorized into three groups: safe group (SG), penetration group (PG), and aspiration group (AG). The duration and maximum amplitude of expiratory sounds produced were measured as the domain characteristics on the time waveform of these sounds and compared among the groups. Time window-length appropriate for FFT and acoustic discriminate values (AD values) of SG, PG, and AG were also investigated. The groups were analyzed using analysis of variance and Scheffé's multiple comparison method. The maximum amplitude of SG was significantly smaller than those of PG and AG. The mean duration in SG (2.05 s) was significantly longer than those in PG (0.84 s) and AG (0.96 s). The AD value in SG was significantly lower than those in PG and AG. AD value detects penetration or aspiration, and can be useful in screening for dysphagia.