Transcutaneous Electrical Stimulation on the Submental Area: The Relations of Biopsychological Factors with Maximum Amplitude Tolerance and Perceived Discomfort Level.

Transcutaneous electrical stimulation (TES) is a frequently used adjunctive modality in dysphagia rehabilitation. Stimulating deeper swallowing muscles requires higher TES amplitude. However, TES amplitude is limited by maximum amplitude tolerance (MAT). Previous studies have reported high interindividual variability regarding MAT and perceived discomfort. This variability might be one of the potential reasons of conflicting outcomes in TES-based swallowing studies. MAT and perceived discomfort are influenced by a variety of biopsychological factors. The influence of these factors related to swallow applications is poorly understood. This study explored the relation of biopsychological factors with MAT and perceived discomfort related to TES in the submental area. A convenience sample of thirty community-dwelling older adults between 60 and 70 years of age provided data for this study. Gender, submental adipose tissue thickness, perceptual pain sensitivity, and pain-coping strategies were evaluated for each subject. Subsequently, MAT and perceived discomfort level were determined using TES on the submental area. Relation of different biopsychological variables with MAT and discomfort level was examined using Pearson and Spearman correlation, and Mann-Whitney U test. Results indicated that neither gender nor adipose thickness was related to MAT and perceived discomfort. Among studied pain-coping strategies, catastrophizing was significantly related to MAT(r = - 0.552, p < .002). Distraction was significantly related to perceived discomfort level (r = - 0.561, p < 0.002). Given the negative impact of pain catastrophizing on MAT and the positive impact of distraction on perceiving discomfort, these coping strategies should be considered as amplitude-limiting and discomfort-moderating factors in TES-based dysphagia rehabilitation.

The Effects of Electrical Stimulation Pulse Duration on Lingual Palatal Pressure Measures During Swallowing in Healthy Older Adults.

Limited research in swallowing physiology has suggested that the most common existing transcutaneous electrical stimulation (TES) protocol (VitalStim) may not penetrate to layers of tissue to affect deep swallowing muscles. TES amplitude is the primary parameter that determines the depth of electrical current penetration (DECP). Preliminary work suggests that replacing a long-pulse duration with a short-pulse duration can increase maximum amplitude tolerance (MAT) within subjects' comfort level. Increasing MAT may indicate a higher DECP. The current study evaluates this premise in reference to the effects of varying pulse duration on lingual-palatal pressure during swallowing. Thirty healthy older adults (60-70 years of age) participated in this study. Each subject swallowed three trials of 10 mL pudding under three TES conditions: no stimulation, short-pulse duration, and long-pulse duration. TES was delivered using two pairs of surface electrodes on the submental muscles. MAT and perceived discomfort levels were identified separately for short and long-pulse TES conditions. Lingual-palatal peak pressure, pressure integral, and pressure duration were measured under each condition. Two-way repeated measures ANOVAs were conducted to identify within subject effects of TES condition and tongue bulb location. Lingual-palatal pressure and pressure integral were significantly reduced in the short-pulse duration condition. MAT was significantly higher in the short-pulse duration versus the long-pulse duration condition. Furthermore, MAT was significantly correlated with lingual-palatal pressure. Changing pulse duration had no significant impact on tongue pressure duration. Results suggest that a short-pulse duration may penetrate deeper into muscles involved in swallowing. The specific impact is reflected in a reduced upward pressure of the tongue on the palate during swallowing. This 'restrictive' effect of TES on tongue pressure may have the potential to be used during a resistive exercise paradigm for tongue elevation during swallowing.

Transcutaneous electrical stimulation on the anterior neck region: The impact of pulse duration and frequency on maximum amplitude tolerance and perceived discomfort.

Maximum amplitude tolerance (MAT) has been known as a primary factor determining the depth of electrical current penetration. However, the effect of varying transcutaneous electrical stimulation (TES) parameters on MAT and discomfort level is poorly understood. Furthermore, limited information exists regarding the biopsychological factors that may impact MAT and discomfort. The primary aims of this study were to compare the effects TES protocol with varying levels of pulse duration (300 µs vs 700 µs) and frequency (30 Hz vs 80 Hz) on the MAT and discomfort in healthy older adults. The exploratory aim of this study was to examine relationships between submental adipose tissue thickness, pain sensitivity and gender with MAT and discomfort. Twenty-four healthy older adults participated in this study. Transcutaneous electrical stimulation was delivered to the submental region. Maximum amplitude tolerance and discomfort were measured for each condition. Furthermore, submental adipose tissue thickness and pain sensitivity were measured for each subject. Maximum amplitude tolerance was significantly increased for the TES protocols with short-pulse duration [F (3, 69) = 38.695, P < .0001]. Discomfort was similar across different TES protocols. Submental adipose tissue thickness (r = .30, P < .003) and pain sensitivity (r = -.43, P < .0001) were related to MAT. Pain sensitivity rating was also related to discomfort (r = .45, P < .0001). In conclusion, using TES protocols with short-pulse duration may increase the MAT. Higher amplitude stimulation may increase the impact on deep swallowing muscles. In addition, submental adipose tissue thickness and pain sensitivity are potential biopsychological factors that may affect MAT and discomfort.

Treating Cough Due to Non-CF and CF Bronchiectasis With Nonpharmacological Airway Clearance: CHEST Expert Panel Report.

BACKGROUND: In bronchiectasis due to cystic fibrosis (CF) and other causes, airway clearance is one of the mainstays of management. We conducted a systematic review on airway clearance by using non-pharmacological methods as recommended by international guidelines to develop recommendations or suggestions to update the 2006 CHEST guideline on cough. METHODS: The systematic search for evidence examined the question, "Is there evidence of clinically important treatment effects for non-pharmacological therapies in cough treatment for patients with bronchiectasis?" Populations selected were all patients with bronchiectasis due to CF or non-CF bronchiectasis. The interventions explored were the non-pharmacological airway clearance therapies. The comparison populations included those receiving standard therapy and/or placebo. Clinically important outcomes that were explored were exacerbation rates, quality of life, hospitalizations, and mortality. RESULTS: In both CF and non-CF bronchiectasis, there were systematic reviews and overviews of systematic reviews identified. Despite these findings, there were no large randomized controlled trials that explored the impact of airway clearance on exacerbation rates, quality of life, hospitalizations, or mortality. CONCLUSIONS: Although the cough panel was not able to make recommendations, they have made consensus-based suggestions and provided direction for future studies to fill the gaps in knowledge.

Pharmacological profile of the NOP agonist and cough suppressing agent SCH 486757 (8-[Bis(2-Chlorophenyl)Methyl]-3-(2-Pyrimidinyl)-8-Azabicyclo[3.2.1]Octan-3-Ol) in preclinical models.

We describe the pharmacological and pharmacokinetic profiles of SCH 486757, a nociceptin/orphanin FQ peptide (NOP) receptor agonist that has recently entered human clinical trials for cough. SCH 486757 selectively binds human NOP receptor (K(i)=4.6+/-0.61nM) over classical opioid receptors. In a guinea pig capsaicin cough model, SCH 486757 (0.01-1mg/kg) suppressed cough at 2, 4, and 6h post oral administration with a maximum efficacy occurring at 4h equivalent to codeine, hydrocodone, dextromethorphan and baclofen. The antitussive effects of SCH 486757 (3.0mg/kg, p.o.) was blocked by the NOP receptor antagonist J113397 (12mg/kg, i.p.) but not by naltrexone (10mg/kg, p.o.). SCH 486757 does not produce tolerance to its antitussive activity after a 5-day BID dosing regimen. After acute and chronic dosing paradigms, SCH 486757 (1mg/kg) inhibited capsaicin-evoked coughing by 46+/-9% and 40+/-11%, respectively. In a feline mechanically-evoked cough model, SCH 486757 produces a maximum inhibition of cough and expiratory abdominal electromyogram amplitude of 59 and 61%, respectively. SCH 486757 did not significantly affect inspiratory electromyogram amplitude. We examined the abuse potential of SCH 486757 (10mg/kg, p.o.) in a rat conditioned place preference procedure which is sensitive to classical drugs of abuse, such as amphetamine and morphine. SCH 486757 was without effect in this model. Finally, SCH 486757 displays a good oral pharmacokinetic profile in the guinea pig, rat and dog. We conclude that SCH 486757 has a favorable antitussive profile in preclinical animal models.

Impact of expiratory muscle strength training on voluntary cough and swallow function in Parkinson disease.

BACKGROUND: Cough provides high expiratory airflows to aerosolize and remove material that cannot be adequately removed by ciliary action. Cough is particularly important for clearing foreign particles from the airway in those with dysphagia who may be at risk for penetration/aspiration (P/A). Expiratory muscle strength training (EMST) was tested to improve cough and swallow function. METHODS: Ten male participants, diagnosed with Parkinson disease (PD), with videofluorographic evidence of penetration or with evidence for aspiration of material during swallow of a thin 30-mL bolus, completed 4 weeks of an EMST program to test the hypothesis that EMST would improve cough and/or swallow function. Measured parameters from an airflow waveform produced during voluntary cough, pre-EMST and post-EMST, included inspiration phase duration, compression phase duration (CPD), expiratory phase peak flow (EPPF), expiratory phase rise time (EPRT), and cough volume acceleration (VA) [ie, the EPPF/EPRT ratio]. The swallow outcome measure was the degree of P/A during the swallow task. RESULTS: There was a significant decrease in the duration of the CPD and EPRT; the decrease in EPRT resulted in a significant increase in cough VA. Significant decreases in the P/A scores were found posttraining. CONCLUSIONS: The results demonstrate that EMST is a viable treatment modality for a population of participants with PD at risk of aspiration.

Expiratory muscle strength training in persons with multiple sclerosis having mild to moderate disability: effect on maximal expiratory pressure, pulmonary function, and maximal voluntary cough.

OBJECTIVE: To determine the effect of expiratory muscle strength training (EMST) on maximal expiratory strength, pulmonary function, and maximal voluntary cough in persons with multiple sclerosis (MS) having mild to moderate disability. DESIGN: Before-after trial. SETTING: Assessments were completed in the privacy of the subject's home or exercise physiology laboratory. PARTICIPANTS: Seventeen persons with MS were age- and sex-matched to 14 healthy controls. INTERVENTION: Eight weeks of EMST and 4 weeks of detraining. MAIN OUTCOME MEASURES: Maximal respiratory pressures, pulmonary function, and maximal voluntary cough were assessed 3 times (pretraining, posttraining, detraining). Maximal expiratory pressure (MEP) was assessed weekly and training intensity adjusted based on the new measurement. RESULTS: Subjects with MS had lower MEP, decreased pulmonary function, and weaker maximal voluntary cough at each assessment. EMST increased MEP and peak expiratory flow. However, improvement in maximal voluntary cough only occurred in subjects with a moderate level of disability when the MS group was subdivided into mild and moderate disability levels based on the Expanded Disability Status Scale. CONCLUSIONS: EMST is a viable tool to enhance the strength of the respiratory muscles. However, further work is needed to determine the best parameters to assess change in cough following EMST.

Effects of vagal afferent stimulation on cervical spinothalamic tract neurons in monkeys.

The purpose of this study was to determine if electrical stimulation of vagal afferents inhibited activity of primate spinothalamic tract (STT) neurons located in cervical segments of the spinal cord. Previous studies show vagal inhibition of STT neurons in more caudal segments of the cord, which receive visceral spinal inputs and somatic inputs from proximal body regions. We hypothesized that activation of vagal afferents would inhibit cervical STT neurons that were excited by cardiopulmonary sympathetic afferents and not inhibit those cells inhibited or unaffected by this visceral input. Because visceral pain is referred to proximal somatic fields, we also hypothesized that STT neurons with excitatory somatic fields confined to distal areas would not be inhibited by vagal stimulation. In 42 cervical STT neurons, we found no difference in effects of vagal stimulation between cells excited or not excited by stimulation of cardiopulmonary sympathetic afferents. Responses to vagal stimulation also were the same for cervical STT cells with proximal or distal somatic fields. Furthermore, there was no difference in the inhibitory effects of vagal stimulation in cervical as compared to thoracic STT neurons. We concluded that vagal afferent stimulation causes a general inhibitory effect at all levels of the spinal cord on neurons which transmit nociceptive information.