This Letter to the Editor was created in response to the article titled, “Instrumental Assessment of Aero-Resistive Expiratory Muscle Strength Rehabilitation Devices” by Dietsch et al. (2024). The article aims to compare six expiratory muscle strength training (EMST) devices and investigates their minimum trigger pressure, variability across the settings, and stability. The models tested include five positive expiratory pressure (PEP) devices, Acapella, TheraPEP, Threshold PEP, EMST75, and EMST150. It also includes a combined inspiratory and expiratory muscle training device, the Breather. We have several concerns about the integrity of results presented regarding the Breather as presented in the article. These include the heterogeneity of device sample used, as well as inadequate methodology and the experimental setup.

Background Dysarthria frequently occurs as a result of stroke and adversely impacts speech sound production, making it more difficult for the listener to understand what the person with dysarthria is attempting to communicate. This in turn may lead to social isolation, depression, and increased cost of care. Some studies have underscored the importance of respiratory muscle strengthening as it relates to improvement of speech intelligibility. This retrospective investigation examined the effects of a combined Respiratory Muscle Training (cRMT) protocol upon speech intelligibility in persons post single cerebrovascular accident (CVA). Methods The clinical data of 10 patients who requested pro bono speech therapy for the diagnosis and treatment of dysarthria following a single stroke was utilized for this study. The intervention group was treated with three 5-minute sessions with cRMT each day for 28 consecutive days. The control group received no cRMT and no other therapeutic exercise intervention during the time period. Respiratory and speech intelligibility were assessed pre- and post-intervention in terms of peak expiratory flow, subject self-perception of intelligibility, and word level intelligibility. Results After 28 days of cRMT, the intervention group exhibited significant gains compared to the control group in PEF (IG: 73.12% vs CG: 4.66%), Self-Perception of Intelligibility (IG: 72.38% vs CG: 0.83%), and the word task of the Assessment of Intelligibility of Dysarthric Speech (AIDS) (IG: 43.92% vs. CG: 0%). Conclusion These data suggest cRMT is a feasible and effective treatment for improving breath support and speech intelligibility in persons with dysarthric speech.

Background: Although dysphonia is less prevalent than dysphagia following cerebrovascular accidents, dysphonia does contribute to the burden of disease resulting from stroke. Strengthening muscles of the larynx and respiratory tract through respiratory muscle training (RMT) has proven effective in improving voice after neurological insult. However, approaches to strengthen only the expiratory muscle groups (EMST) dominate the clinical study literature, with variable outcomes. By focusing on exhalation, the contribution of inspiratory muscles to phonation may have been overlooked. This study investigated the effect of combined respiratory muscle training (cRMT) to improve voice function in stroke patients. Methods: Recorded data of twenty patients with dysphonia following stroke were allocated to an intervention (IG) or a control group (CG) based upon whether they chose cRMT or not while awaiting pro bono voice therapy services. The intervention group (N=10) was treated daily with three 5-minute sessions of complete resistive respiratory muscle training for 28 days, while the control group (N=10) received no cRMT or other exercise intervention. Perceptual and acoustic measurements as well as a pulmonary function test were assessed pre-and post-intervention. Results: The intervention group demonstrated significant improvements after 28 days of combined respiratory muscle training (cRMT) in peak flow (127%), patient self-perception of voice improvement (84.41%), as well as in five of the six categories of the Consensus Auditory-Perceptual Evaluation of Voice (CAPE-V) overall severity (63.22%), breathiness (61.06%), strain (63.43%), pitch range (48.11%) and loudness (57.51%), compared to the control group who did not receive treatment. Furthermore, cRMT also led to significant improvements in maximum phonation time (212.5%) and acoustic parameters of vocal intensity and semitone range. Conclusion: This pilot study shows promise of the feasibility and effectiveness of cRMT to lessen the signs and symptoms of dysphonia while simultaneously improving breath support.

Background: Dysphagia is prevalent with cerebrovascular accidents and contributes to the burden of disease and mortality. Strengthening of the dysfunctional swallow muscles through respiratory muscle training (RMT) has proven effective in improving swallow effectiveness and safety. However, approaches to strengthen only the expiratory muscle groups (EMST) dominate the clinical study literature, with variable outcomes. This study investigated the effect of a simultaneous inspiratory and expiratory muscle strengthening strategy to improve swallowing function in stroke patients. Methods: Twenty post-stroke patients were randomly assigned to either intervention group (IG) or control group (CG). The intervention group was treated with three 5-minute sessions of resistive respiratory muscle training every day for 28 days, while the control group received no RMT. Respiratory and swallow outcomes were assessed pre- and post-intervention and included Mann Assessment of Swallowing Ability (MASA), Fiberoptic Endoscopic Evaluation of Swallowing (FEES) with Penetration/Aspiration Scale (PAS), Functional Oral Intake Scale (FOIS), patient visual analogue scale (VAS), and peak expiratory flow (PEF). Results: After 28 days, the intervention group demonstrated greater improvements (pVal < 0.05) in PEF (IG: 168.03% vs CG: 17.47%), VAS (IG: 103.85% vs CG: 27.54%), MASA (IG: 37.28% vs CG: 6.92%), PAS (IG: 69.84% vs CG: 12.12%), and FOIS (IG: 93.75% vs CG: 21.21%). Conclusion: Combined resistive inspiratory and expiratory muscle training is a feasible and effective method to improve signs and symptoms of dysphagia in stroke patients.

Background: Limited access to the comprehensive assessment of disorders of the upper aerodigestive tract is a barrier to care in rural health facilities. Assessment of the full aerodigestive tract requires a variety of specialists. The inability to access the necessary specialists can result in misdiagnosis, underdiagnosis, and increased associated mortality. Currently, no single differential diagnostic exam comprehensively assesses all functions of the upper aerodigestive tract to bridge this gap. The purpose of this study is to investigate the feasibility and safety of a novel procedure called ADS that can bridge this gap. Methods: Results from 18,464 ADS procedures were retrospectively analyzed for feasibility, safety and comfort. Results: 96.8% of ADS procedures were successfully completed without complication, confirming the efficacy of the procedure. Conclusions: ADS is a single procedure for the assessment of physiological functions of the upper aerodigestive tract, including swallow, voice, respiration, and cough while also screening for impaired gastric retention and obstructive sleep apnea, which may pose additional urgent and emergent airway threats. ADS may improve health outcomes in underserved populations, e.g., those in a rural community, referred to by other health professionals due to complaints of aerodigestive symptoms and signs.

Limited access to comprehensive assessment of physiological disorders of the upper aerodigestive tract by different specialties represents a barrier to care in rural healthcare settings, which may lead to misdiagnosis, underdiagnosis, and increased associated mortality. No single differential diagnostic exam for the comprehensive assessment of all functions of the upper aerodigestive tract is available to bridge this gap. We present a single procedure for assessment of physiological functions of the upper aerodigestive tract including swallow, voice, respiration, and cough while also screening for gastric retention and obstructive sleep apnea which might contribute to these disorders. Our procedure, called Aerodigestoscopy (ADS), represents a procedure incorporating other established exams as integral components to evaluate patients with aerodigestive disorders. Patients who might particularly benefit from our ADS diagnostic algorithm are those in a rural community referred by other health professionals due to complaints of aerodigestive symptoms and signs. We present a brief overview of how the procedure was developed, what it includes, and retrospective safety data from over 18,000 ADS procedures performed over the last 10 years, demonstrating safety and feasibility of this procedure.