The Risk of Penetration-Aspiration Related to Residue in the Pharynx.
Catriona M Steele, Melanie Peladeau-Pigeon, Emily Barrett and 1 others
PMID 32598168WHAT IT FOUND
Residue left in the throat before a new swallow significantly raises the risk of aspiration.
This applies even when using a thin liquid wash to clear the residue, meaning the act of washing can itself cause airway invasion.
Key findings
01Clearing swallows with preswallow residue above 1% showed a 4.60-fold increase in the odds of penetration-aspiration for thin liquids compared to clean baseline swallows.
02Swallows of additional material (washes) with preswallow residue above 1% showed a 1.86-fold increase in the odds of penetration-aspiration for thin liquids.
03Penetration-aspiration occurred in 9% of thin liquid washes when preswallow residue was present above the 1% threshold.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The study had a small number of clearing swallows for thick consistencies (n=35 total for moderately and extremely thick), limiting conclusions about those textures. Residue measurement was limited to the valleculae and pyriform sinuses; residue in other pharyngeal areas was not included. The study could not distinguish the consistency of the residue itself, only the consistency of the new bolus being swallowed. The threshold for 'safe' residue is not definitively established; the authors note that risk may emerge below 1%, but data were insufficient to confirm the exact boundary.
Declared interests
Funding was provided by the first author's RO1 grant from the National Institute on Deafness and Other Communication Disorders.
The easy way to misread this
Do not assume that thickening liquids prevents aspiration in all cases. While thick liquids had lower aspiration rates on clean baseline swallows, this study did not test the risk of using thin liquid washes to clear thick residue, so the safety of that specific clinical practice remains unverified.