Screening

The most commonly used diagnostic test for aspiration is the bedside swallow evaluation. This test includes a patient interview, a physical exam, and the assessment for signs of aspiration. While this is usually performed by a speech-language pathologist, to streamline the diagnostic evaluation some of the more sensitive components of the bedside swallow evaluation can be performed individually or in combination as screening tests.[88] These screening tests include a patient’s attempts to swallow small quantities of water or ice chips while being observed by a nurse, a speech-language pathologist, or a physician. Screening tests should be considered whenever aspiration is suspected based on the presence of risk factors. Furthermore, all patients suffering from an acute stroke should undergo a bedside swallow evaluation by a speech-language pathologist, largely because between 40% and 78% of stroke patients have dysphagia.[16][68]​​​​ Dysphagia program studies applied as a result of these screening methods could substantially reduce the rates of pneumonia in stroke patients.[89]

Bedside swallow evaluation

Patients thought to have any risk factors for aspiration should undergo a complete neurologic evaluation before feeding.[90] This includes assessing cortical functions, bulbar muscles, gag reflex, and cough reflex. Alert patients with cough who are at high risk of aspiration should be observed drinking small amounts of water. If the patient coughs or shows signs of aspiration, the patient should be referred for a detailed swallowing evaluation.[27] Early bedside swallow screening (within 1 day of admission and before any oral intake) and dysphagia management in patients with acute stroke reduces the risk of aspiration pneumonia, may be cost-effective, and may assure quality care with optimal outcome.[91] If doubt exists or if silent aspiration is suspected, imaging studies should be performed.[16]​ Phonetic assessment independent of and during the swallow provocation tests may be a useful adjunct to bedside tests for aspiration risk, but it is not validated.[88][92]​ Although a multitude of other screening tests are available, they have variable sensitivity.[93]​ In the opinion of the authors, however, there may be a benefit to obtaining an assessment of aspiration risk from more than one test.

Flexible endoscopic evaluation of swallowing

Flexible endoscopic evaluation of swallowing (FEES) can be performed by speech pathologists at the bedside. With the use of a flexible fiberoptic scope, direct evidence of aspiration is documented by detecting the presence of food or a thick liquid over the vocal cords. The test also assesses the vocal cord function. In a study of critically ill trauma patients, FEES performed within 24 hours after extubation showed aspiration in 45% of the patients, of whom almost half were silent aspirators. These patients resumed an oral diet at a mean of 5 days after extubation and had no pulmonary complications.[50]​​ FEES avoids exposure to radiation; however, modified barium swallow is noninvasive and more widely available.[56]​​[94]

Videofluoroscopic swallowing study and modified barium swallow

For these tests, the patient swallows barium under fluoroscopic imaging. Passage or retention of the radiopaque material in the respiratory tract is seen.[16] On videofluoroscopic swallowing study, 38% of patients with acute stroke had overt aspiration and 67% had silent aspiration.[95] Modified barium swallow performed in patients with indwelling tracheostomies on positive-pressure ventilation showed an incidence of aspiration of 50%, and 77% of these patients were silent aspirators.[46]

Emerging assessments for dysphagia

Interventions targeting improved respiratory sensation and respiratory mechanics may prove to be beneficial in patients (such as those with Parkinson disease) who have impaired airway protection.[96]​ Various tests of respiratory mechanics have been employed to determine aspiration risk or at least the ability to compensate for a respiratory event. For example, a reduction in the peak cough flow was an independent risk factor for pneumonia.[97]​ Phonetic screening is a novel technique that may be used to identify dysphagia and aspiration risk at the bedside.[92]

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