Silent Aspiration: A Closer Look
Silent aspiration is difficult to assess when screening a patient for dysphagia as well as during the clinical (bedside) swallow evaluation. Asking a patient to elicit a cough does not provide information about airway response. An absent cough while eating and drinking also does not reliably indicate absence of aspiration, as aspiration may be silent. However, coughing while eating and drinking remains the number one reason for referral to speech-language pathologist and the “water swallow test” remains a common dysphagia screen.
Prior research has found that when patients consume consecutive sips from larger volumes and do not have any symptoms, the test accurately rules out aspiration. It has been hypothesized that larger bolus aspiration increases stimulation to the airway receptors, increasing the chance of eliciting a cough (even patients who silently aspirate smaller amounts). Unfortunately, those who do not cough even with the enhanced stimulation will continue to be missed. And if a patient coughs, it does not help distinguish between patients who are silent aspirators and patients who aspirate with a cough response, limiting the speech-language pathologist’s (bedside) clinical reasoning.