What are some predictors of aspiration?
There are certain behaviors to look for at bedside that may be predictors of aspiration. Some of the behaviors typically include: cough, dysphonia, dysarthria, watering eyes/runny nose/sneezing, and absent gag response.
Cough is the main behavior that is thought to be a reliable predictor of aspiration. There is plenty of evidence in the literature saying that is true. For example, Smith-Hammond compared subjective clinical assessments of signs of aspiration (Smith-Hammond et al., 2009). In addition to cough, she looked at absent swallow response and difficulty handling secretions. She then compared those subjective assessments to objective measures of cough, and found that clinical signs were about 74% accurate for detecting aspiration. There was fairly low sensitivity, and higher specificity, which means there is a pretty high rate of false negative responses relying on those clinical signs. The objective measures of voluntary cough were more accurate, as might be expected. In reality, in clinical practice, many SLPs do not have access to those objective measures. There is some information saying those clinical signs are pretty good. But, if you have access to more objective measures, that is even better.
Some studies have indicated that the presence of dysphonia (breathiness, hoarseness or harshness) is predictive of aspiration. If someone has a breathy vocal quality, perhaps they're not fully adducting their vocal folds; therefore, they have decreased airway protection at the level of the vocal folds, perhaps placing them at increased risk of aspiration.
Wet vocal quality has traditionally been thought of as a predictor of aspiration. If it can be heard after someone has swallowed, that is considered to be a pretty good predictor of, at least penetration or perhaps aspiration. However, clinicians don't always hear wet vocal quality when there is material sitting in the larynx during phonation. Just because we don't hear it, does not necessarily mean that the person didn't aspirate or penetrate.
Additionally, a separate study by Georgia Malandraki in 2011 found that reduced pitch elevation was predictive of poorer scores on the Penetration-Aspiration Scale (an eight-point scale developed by J. Rosenbeck and colleagues).
Dysarthria has also been looked at as a predictor of aspiration. Researchers, Daniels et al. and McCullough et al. (2005) found that the presence of dysarthria is significantly associated with increased aspiration risk in individuals with stroke.
Watering Eyes/Runny Nose/Sneezing
The presence of watering eyes, runny nose and sneezing is frequently discussed when determining predictors of aspiration. In fact, they are autonomic reflexive responsive to irritants to the eyes or nose and should NOT be considered reliable predictors of aspiration. Watering eyes and a runny nose occur due to trigeminal field irritation (irritants to cornea, nasal mucosa, etc.). I suppose if nasal regurgitation occurs, that would qualify as an irritant and cause rhinorrhea. However, I am completely unaware of any evidence that these symptoms (or sneezing) are indications of aspiration.
Absent Gag Response
I have received referrals from physicians simply based on the fact that a patient does not have a gag response. Steve Leder conducted a study in 1996 looking at individuals with an absent gag response and found the vast majority of them were able to eat a normal diet safely. The gag response was absent in 13% of individuals who did not have dysphagia. He concluded that the absence of gag response does not appear to be a predictor of dysphagia.
Debra Suiter is Director of the University of Kentucky Voice and Swallow Clinic in Lexington, Kentucky. Together with Dr. Steven Leder, Dr. Suiter developed the Yale Swallow Protocol, a tool for determining aspiration risk. Dr. Suiter’s research and clinical interests focus on assessment and treatment of adults with swallowing disorders.