ORLANDO, FL-A novel device that was developed to help improve cough in patients with Parkinson’s disease (PD) has an intriguing additional effect-it helps improve swallow function too. It could prove useful in people with conditions such as PD early on in the course of cough and swallowing dysfunction.
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June 2008The device, called the Expiratory Muscle Strength Trainer (EMST), is a new hand-held device about the size of an inhaler, and is used by patients to help strengthen the muscles that are used in cough. The device, and how it came to be, was described at the recent annual COSM conference by Teresa Pitts, MA, a doctoral student in communication sciences and disorders at the University of Florida, who spoke at the Neurology Working Group panel at the American Laryngological Assocation (ALA) session.
The device is a resistance trainer. The patient has to generate an expiratory airflow to meet the threshold for what the therapist demands. It’s a spring-loaded valve and it has a release so when they meet the threshold the valve releases and the air can move through, Ms. Pitts told ENT Today. She presented data describing patient experience with the device as well as details of findings relating to cough and swallow studies.
Airway protection is especially important in a neurogenic population such as PD patients. The question is how to clinically treat this population to improve their swallow and cough functions. Indeed, aspiration pneumonia is the leading cause of death in PD patients.
It is a problem that needs to be caught, and treated early on. Clinically this is something clinicians need to be aware of as being a problem, and that their patients are beginning to develop an inability to cough and to respond to that, she said. She described some of the cough and swallow findings from her center.
Connection Between Dysphagia and Cough
Dysphagia begins early in PD, but it is sometimes difficult to diagnose. The literature would say most of are silent aspirators. We would say they have little to no awareness of the fact the bolus has entered the airway, and they have little to no cough response, Ms. Pitts said.
In many examinations, coughs are elicited by the physician, who asks the patient to cough up a bolus. There are three phases in a cough. First is the inspiratory phase, where air is moved into the pulmonary system through movement of the diaphragm. Next is the compression phase, in which the abdominal wall begins to contract. Third is the expiratory phase, a ballistic action of the respiratory muscles to produce high linear airflows.
But was there a connection between dysphagia and cough? Earlier studies had shown that with stroke patients, as swallow function got worse, cough function declined too. In stroke patients, it is difficult to elicit volunteer cough in severe aspirators.
Ms. Pitts described findings from two groups of 20 cognitively intact PD patients studied for relationships between dysphagia and cough. They were divided into two groups: one with symptoms of dysphagia, and the other with no dysphagia symptoms but who had slightly dysfunctional cough. They all had mild to moderate PD.
Patients were asked to swallow large 30-cc boluses. Such a large bolus was used in order to challenge the patient’s ability to swallow.
If you challenge the system, we begin to see the impairment. If we let them act within their normal range, then they still can look pretty normal-especially in this population with milder disease, Ms. Pitts said.
Penetration-aspiration scores were measured, using a scale of 1 to 8. This describes the depth at which the material enters the airway. The level of the laryngeal vestibule would be a 3, for instance, whereas getting below the level of the vocal fold with no response is an 8. Video fluoroscein exams were judged by two people.
All three phases of cough were measured. Cough volume acceleration was also measured, which we think is an indirect measure of how effective a cough is, she said. Measurements of air displacement were performed with pneumotacograph. Cough data were compared to normative data in the medical literature, as well as between the two groups.
The penetration-aspiration group was found to have reduced expiratory peak flow. Compared with normal rates, our penetration-aspiration group are falling outside the normal range, she said. The non-penetration-aspiration group still fell within normal range for duration and peak expiratory flow.
Overall, patients in the penetration-aspiration group had a general slowing down of cough. They seem to have difficulty moving and switching from the inspiratory phase to the expiratory phase …we’re seeing really long compression times. The pattern that’s emerging is that it takes longer for them to get through the entire action, Ms. Pitts said.
Expiratory Muscle Strength Training
The question then arose as to whether expiratory muscle strength training would help make cough more effective in PD patients. Researchers developed the device that is now known as EMST. The device has a spring-loaded valve that can be set at different pressure levels, and the maximum expiratory pressure patients produce can be measured. Patients train at 75% of their maximum.
Sent home with the device, PD patients were told to do five sets of five breaths, five days a week, for a total of four weeks. Ms. Pitts presented data from 10 patients who had dysphagia and who penetrated or aspirated into the laryngeal vestibule during swallow tasks.
In these patients, we had a significant change in inspiratory phase, the duration significantly decreased. The duration of the compression phase decreased. The duration of the expiratory phase rise time decreased. And with that duration of the expiratory phase rise time decreasing, we had an increase in our cough volume accelerating-an indirect measure of how effective cough is, Ms. Pitts said.
However, in an interview she added that it was not known whether these changes were clinically significant. We didn’t measure sputum production, so as a researcher I can’t say necessarily it was a clinically significant improvement, but it’s a statistically significant improvement, she said.
There was also a significant decrease in the penetration-aspiration scores, pre- to post-treatment, indicating that the treatment decreased the depth the material entered the airway during the swallow. Not only did training result in a safer swallow, but it also resulted in a more productive cough, she said.
Ms. Pitts speculated that a possible reason for improvement in swallowing is strengthening of the muscles that control the hyoid, something that is vital for the pharyngeal phase of the swallow. It is also possible there were changes in subglottic pressure during swallow. Researchers plan to continue investigations into swallow and cough functions and how the device may affect them.
Paul Castellanos, MD, Associate Professor of Otolaryngology at the University of Alabama at Birmingham, had not heard about the device until the presentation at COSM. I think this is very exciting work…particularly for patients who are not clearly in need of being made NPO or are taking things by mouth, but have an abnormal swallowing study, he said.
In his practice, he has many silent aspirators. I still allow them to eat, but I have not been able to do anything to really rehabilitate them, he said. This device just might be the key to help these patients.
©2008 The Triological Society