Preliminary investigation of swallowing apnea duration and swallow/respiratory phase relationships in individuals with cerebral vascular accident

The Influence of Side-Lying Position on Oropharyngeal Swallow Function in At-Risk Infants: An Exploratory Study

This investigation assessed the effect of side-lying position on infant oropharyngeal swallow physiology. Infant modified barium swallow studies (MBS) recordings were retrospectively examined in matched-pairs comparing at-risk infants swallowing in both an upright/cradled position and a side-lying position. Swallow parameters were measured independently and through a consensus coding approach. Infants fed in side-lying position showed a decrease in airway invasion severity as compared with when those same infants were fed in an upright/cradled position (P = .009). Bolus location at the time of swallow initiation was higher when infants were fed in side-lying position as compared with cradle position (P = .024), representing decreased risk of airway invasion. Infants fed in side-lying position demonstrated fewer swallows per breaths (P = .032). This pilot study validates the need for additional research to further define the mechanisms related to this improvement, and to determine how diagnosis and medical stability moderate these findings.

Cross-System Integration of Respiration and Deglutition: Function, Treatment, and Future Directions

Swallowing occurs preferentially in the expiratory phase of the quiet breathing cycle and at mid-to-low tidal volume. This coordinative pattern imparts important biomechanical advantages to swallowing and airway protection and facilitate laryngeal elevation, laryngeal vestibular and vocal fold closure, and cricopharyngeal sphincter opening. This preferred coordinative relationship between breathing and swallowing is impaired in a variety of patient populations, including head and neck cancer survivors with dysphagia. We developed a training protocol to re-establish more optimal phasing of swallowing with breathing in these patients with striking outcomes, including reduced swallowing physiological impairments and improved airway protection. This motivated us to continue to refine and expand this training protocol and develop new assistive technologies for swallowing monitoring outside of the lab. In this review, we highlight the origins of our optimal respiratory-swallowing coordination hypothesis, describe the biomechanical advantages it provides, carefully describe our training protocol and findings, and chart a course for the next phase of this work. Our overall goal is to harness technology combined with carefully constructed learning paradigms to improve the lives of patients with impaired respiratory-swallowing coordination consequent to a variety of pathologies including head and neck cancer and degenerative neurological conditions such as Parkinson's disease.

Feasibility study of the Nox-T3 device to detect swallowing and respiration pattern in neurologically impaired patients in the acute phase

Dysphagia is a frequent complication in neurologically impaired patients, which can lead to aspiration pneumonia and thus prolonged hospitalization or even death. It is essential therefore, to detect and assess dysphagia early for best patient care. Fiberoptic endoscopic and Videofluoroscopy evaluation of swallowing are the gold standard exams in swallowing studies but neither are perfectly suitable for patients with disorders of consciousness (DOC). In this study, we aimed to find the sensitivity and specificity of the Nox-T3 sleep monitor for detection of swallowing. A combination of submental and peri-laryngeal surface electromyography, nasal cannulas and respiratory inductance plethysmography belts connected to Nox-T 3 allows recording swallowing events and their coordination with breathing, providing time-coordinated patterns of muscular and respiratory activity. We compared Nox-T3 swallowing capture to manual swallowing detection on fourteen DOC patients. The Nox-T3 method identified swallow events with a sensitivity of 95% and a specificity of 99%. In addition, Nox-T3 has qualitative contributions, such as visualization of the swallowing apnea in the respiratory cycle which provide additional information on the swallowing act that is useful to clinicians in the management and rehabilitation of the patient. These results suggest that Nox-T3 could be used for swallowing detection in DOC patients and support its continued clinical use for swallowing disorder investigation.

Dysphagia after cardiac surgery: Prevalence, risk factors, and associated outcomes

OBJECTIVES

The study objectives were to determine the prevalence of swallowing impairment in adults after cardiac surgery and examine associated risk factors and health-related outcomes.

METHODS

A prospective single-center study was conducted in postoperative adult cardiac surgery patients with no history of dysphagia. A standardized fiberoptic endoscopic evaluation of swallowing was performed within 72 hours of extubation. Blinded raters completed validated outcomes of swallowing safety and efficiency. Demographic, surgical, and postoperative health-related outcomes were collected. Univariate and multivariable regression analyses were performed with odds ratios (OR) and 95% confidence intervals (CIs).

RESULTS

In 182 patients examined, imaging confirmed inefficient swallowing (residue) in 52% of patients and unsafe swallowing in 94% (65% penetrators, 29% aspirators). Silent aspiration was observed in 53% of aspirators, and 32% did not clear aspirate material. Independent risk factors for aspiration included New York Heart Association III and IV (OR, 2.9; CI, 1.2-7.0); reoperation (OR, 2.0; CI, 0.7-5.5); transesophageal echocardiogram images greater than 110 (OR, 2.6; CI, 1.1-6.3); intubation greater than 27 hours (OR, 2.1; CI, 0.8-5.3); and endotracheal tube size 8.0 or greater (OR, 3.1; CI, 1.1-8.6). Patients with 3 or 4 identified risk factors had a 16.4 (CI, 3.2-148.4) and 22.4 (CI, 3.7-244.7) increased odds of aspiration, respectively. Compared with nonaspirators, aspirators waited an additional 85 hours to resume oral intake, incurred $49,372 increased costs, and experienced a 43% longer hospital stay (P < .05). Aspiration was associated with pneumonia (OR, 2.6; CI, 1.1-6.5), reintubation (OR, 5.7; CI, 2.1-14.0), and death (OR, 2.8; CI, 1.2-9.0).

CONCLUSIONS

Tracheal aspiration was prevalent, covert, and associated with increased morbidity and mortality.

Deglutition and the Regulation of the Swallow Motor Pattern

Despite centuries of investigation, questions and controversies remain regarding the fundamental genesis and motor pattern of swallow. Two significant topics include inspiratory muscle activity during swallow (Schluckatmung, i.e., "swallow-breath") and anatomical boundaries of the swallow pattern generator. We discuss the long history of reports regarding the presence or absence of Schluckatmung and the possible advantages of and neural basis for such activity, leading to current theories and novel experimental directions.

Effects of Bolus Holding on Respiratory-Swallow Coordination in Parkinson's Disease

PURPOSE

The aim of this study was to examine the effects of bolus holding on respiratory-swallow coordination (RSC) in people with Parkinson's disease (PD).

METHOD

People with PD were prospectively recruited to undergo RSC assessment using simultaneous respiratory inductive plethysmography and flexible laryngoscopy. During RSC assessment, participants swallowed 5-ml thin liquid boluses during held and nonheld swallowing tasks. Measures of RSC were analyzed for each swallow, which included respiratory pause duration, lung volume at swallow initiation, respiratory phase patterning, and the presence of paradoxical respiratory movements. Multilevel statistical modeling was used to determine if differences in RSC were present between the held and nonheld tasks.

RESULTS

Thirty-three participants were enrolled. When compared to the nonheld swallows, the held swallows exhibited shorter respiratory pauses (p = .001, R ² = .019), lower lung volumes at swallow initiation (p < .001, R ² = .116), more frequent exhale-swallow-exhale patterns (p < .001, OR = 4.30), and less frequent paradoxical respiratory movements (p = .001, OR = 0.43).

CONCLUSIONS

Findings from this study revealed that bolus holding significantly influences RSC in people with PD. This demonstrates that bolus holding may be an efficacious strategy to immediately improve RSC in PD. However, clinicians and researchers should consider avoiding bolus holding during swallowing evaluations if attempting to assess RSC behaviors that are most typical for the examinee.

Effects of Carbonation on Swallowing: Systematic Review and Meta-Analysis

OBJECTIVES

The effectiveness of the use of carbonation in preventing penetration/aspiration or enhancing swallowing function in adults remains unclear. This systematic review aimed to evaluate the effectiveness of carbonation on improving swallowing function in adult subjects.

METHODS

Literature published before March 2021 was inspected using MEDLINE, CINAHL, Web of Science Core Collection, The Cochrane Library, Cochrane Central Register of Controlled Trials, and Ichushi-web databases. We searched for intervention studies or randomized control trials considering the effects of carbonated liquids on swallowing function. The risk of bias was assessed using the Cochrane tool for assessing the risk of bias for randomized controlled trials and the Risk of Bias Assessment Tool for Nonrandomized Studies.

RESULTS

The systematic review identified 19 studies with a total of 586 participants. The effects of carbonation on swallowing function are diverse. Overall, most studies showed that carbonation promotes swallowing function compared to other liquids. Five studies were included in the quantitative synthesis. Meta-analysis showed that carbonated liquids prevent aspiration (risk difference [RD] -0.27%, 95% confidence interval [CI] -0.44 to -0.10; I²  = 0%; number needed to treat 3.8, 95% CI 2.2 to 15.0; moderate quality of evidence) when compared to noncarbonated thin liquids. Carbonated liquids also increased the duration of swallowing apnea than did noncarbonated liquids (standardized mean difference 0.25 (mean difference 0.36 seconds), 95% CI 0.03 to 0.47; I²  = 0%; low quality of evidence).

CONCLUSIONS

Carbonation had favorable effects on swallowing function. Further in-depth studies are needed to clarify the benefits of carbonation.

LEVEL OF EVIDENCE

NA Laryngoscope, 2022.

Advanced Machine Learning Tools to Monitor Biomarkers of Dysphagia: A Wearable Sensor Proof-of-Concept Study

Introduction

Difficulty swallowing (dysphagia) occurs frequently in patients with neurological disorders and can lead to aspiration, choking, and malnutrition. Dysphagia is typically diagnosed using costly, invasive imaging procedures or subjective, qualitative bedside examinations. Wearable sensors are a promising alternative to noninvasively and objectively measure physiological signals relevant to swallowing. An ongoing challenge with this approach is consolidating these complex signals into sensitive, clinically meaningful metrics of swallowing performance. To address this gap, we propose 2 novel, digital monitoring tools to evaluate swallows using wearable sensor data and machine learning.

Methods

Biometric swallowing and respiration signals from wearable, mechano-acoustic sensors were compared between patients with poststroke dysphagia and nondysphagic controls while swallowing foods and liquids of different consistencies, in accordance with the Mann Assessment of Swallowing Ability (MASA). Two machine learning approaches were developed to (1) classify the severity of impairment for each swallow, with model confidence ratings for transparent clinical decision support, and (2) compute a similarity measure of each swallow to nondysphagic performance. Task-specific models were trained using swallow kinematics and respiratory features from 505 swallows (321 from patients and 184 from controls).

Results

These models provide sensitive metrics to gauge impairment on a per-swallow basis. Both approaches demonstrate intrasubject swallow variability and patient-specific changes which were not captured by the MASA alone. Sensor measures encoding respiratory-swallow coordination were important features relating to dysphagia presence and severity. Puree swallows exhibited greater differences from controls than saliva swallows or liquid sips (p < 0.037).

Discussion

Developing interpretable tools is critical to optimize the clinical utility of novel, sensor-based measurement techniques. The proof-of-concept models proposed here provide concrete, communicable evidence to track dysphagia recovery over time. With refined training schemes and real-world validation, these tools can be deployed to automatically measure and monitor swallowing in the clinic and community for patients across the impairment spectrum.

Respiratory-swallow coordination in a rat model of chemoradiation

BACKGROUND

Chemoradiation treatment (CRT) for head and neck cancer (HNC) is associated with postswallow inhale events that elevate the risk of penetration/aspiration. The purpose of this study was to assess the validity of a rat model for investigating the effect of CRT on respiratory-swallow coordination.

METHODS

Videofluoroscopic swallow study was performed on 10 Sprague-Dawley rats 3 months post-CRT (3 mg/kg Cisplatin, 10 fractions of 4.5 Gy/day radiotherapy to tongue base), and 10 naïve controls. We examined the effect of CRT on swallow apnea duration, diaphragm movement, and bolus kinematics.

RESULTS

CRT rats had a significant increase in postswallow inhale (p = 0.008), which was associated with significantly longer swallow apnea durations, lower diaphragm displacement at swallow onset, and faster pharyngoesophageal bolus speed.

CONCLUSION

The rat CRT model is valid for the study of respiratory-swallow coordination due to the consistency of findings in this study with those reported in clinical CRT studies in HNC.

Speech therapy aspects in patients’ palliative care

ABSTRACT Purpose: to describe the speech therapy aspects of patients treated by the palliative care team in a hospital. Methods: an observational and cross-sectional study, performed from medical records of patients treated under Palliative Care Program, in a hospital, from July to September 2018. Information from the anamnesis and speech-language assessments, which were analyzed by frequency measures, were collected. Results: the sample was composed by 41 medical records, including 25 males and 16 females, with an average age of 61.2 years and hospitalization average time of 20.7 days. Oral feeding was present in 73% of the sample. It was observed that 24% of the patients had impaired expressive language, 56% had reduced maximum phonation times and 34% showed altered mobility phonoarticulatory organs. For swallowing, 22% showed difficulty in some consistency. A nutritional feeding was verified in 74% of the sample and the remaining was making use of comfort feeding. In relation to assistance, 46% of the sample was under management, 7% in therapy, and the remaining did not have follow-up indication. Conclusion: relevant alterations to orofacial motricity, voice, language and swallowing were found in patients under palliative care.

Quantitative Videofluoroscopic Analysis of Swallowing Physiology and Function in Individuals With Chronic Obstructive Pulmonary Disease

Purpose Dysphagia is a serious extra pulmonary manifestation of chronic obstructive pulmonary disease (COPD). However, the nature of abnormalities in swallowing physiology in COPD has yet to be clearly established. We explored the frequency of swallowing measures outside the healthy reference range in adults with COPD. Method Participants were 28 adults aged 41-79 years (18 men, 20 women) with stable COPD. Disease severity was classified as GOLD (Global Initiative For Chronic Obstructive Lung Disease) Stages 1 (4%), 2 (25%), 3 (53%), and 4 (18%). Participants underwent a videofluoroscopy and swallowed 20% w/v thin barium in, followed by 20% w/v mildly, moderately, and extremely thick barium prepared with a xanthan gum thickener. Blinded duplicate ratings of swallowing safety, efficiency, kinematics, and timing were performed according to the ASPEKT method (Analysis of Swallowing Physiology: Events, Kinematics and Timing). Comparison data for healthy adults aged < 60 years were extracted from an existing data set. Chi-square and Fisher's exact tests compared the frequencies of measures falling < 1 SD/ > 1 SD from mean reference values (or < the first or > the third quartile for skewed parameters). Results Participants with COPD did not display greater frequencies of penetration-aspiration, but they were significantly more likely (p < .05) to display incomplete laryngeal vestibule closure (LVC), longer time-to-LVC, and shorter LVC duration. They also displayed significantly higher frequencies of short upper esophageal sphincter opening, reduced pharyngeal constriction, and pharyngeal residue. Conclusion This analysis reveals differences in swallowing physiology in patients with stable COPD characterized by impaired safety related to the mechanism, timing, and duration of LVC and by impaired swallowing efficiency with increased pharyngeal residue related to poor pharyngeal constriction.

Respiratory-Swallow Coordination Training Improves Swallowing Safety and Efficiency in a Person With Anoxic Brain Injury

Purpose The aim of this study was to assess the effects of respiratory-swallow coordination training (RSCT) on respiratory-swallow coordination (RSC), swallowing safety (penetration/aspiration), and swallowing efficiency (pharyngeal residue) in a person with anoxic brain injury. Method A 68-year-old man with anoxic brain injury, tachypnea, and severe dysphagia was recruited to participate in a prospective AABAA single-subject experimental design. RSC, swallowing safety, and swallowing efficiency were measured at each assessment using respiratory inductive plethysmography and flexible endoscopic evaluations of swallowing. Data were analyzed descriptively using Cohen's d effect size. Outcome measures were compared pre-RSCT to post-RSCT, and pre-RSCT to a 1-month retention assessment. Results Improvements in RSC were observed immediately post-RSCT (d = 0.60). These improvements were maintained upon retention assessment 1 month later (d = 0.60). Additionally, improvements in swallowing safety (d = 1.73), efficiency (d = 1.73), and overall dysphagia severity (d = 1.73) were observed immediately post-RSCT and were maintained upon retention assessment 1 month later (d = 1.73). Conclusions Clinically meaningful improvements in RSC were observed following four sessions of RSCT, which were subsequently associated with large improvements in swallowing safety and efficiency. RSCT may be an efficacious, clinically feasible skill-based exercise for people with anoxic brain injury, suboptimal RSC, and dysphagia. Future work is needed to expand these findings in a larger cohort of people with dysphagia.

A Systematic Review of the Influence of Bolus Characteristics on Respiratory Measures in Healthy Swallowing

There have been a number of studies on the effect of bolus volume, consistency, texture, temperature and taste on the oropharyngeal swallowing physiology. However, its influence on the respiratory function associated with swallow is not well understood. This study aimed at systematically analysing and documenting the prevailing research literature on respiratory functions before, during, and after healthy swallows of boluses with varied characteristics. The PRISMA guidelines were followed for retrieval of relevant research. From among the 48,329 reports screened for inclusion criteria, 25 articles were included for data extraction. Each of these reports was evaluated for its design, methodology and reporting quality and also the level of evidence provided by them. The results revealed that the scientific evidence in this regard was restricted to level II. Majority of the studies included considered bolus volume as the variable than bolus consistency, taste or temperature. Expiratory phase was preferred surrounding the apnea irrespective of volume, consistency or taste but changed with temperature variations across age groups. The reports are equivocal on the duration of respiratory apnea, and length of respiratory cycles before and after the apnea. The temporal coordination of pharyngeal swallow events was found to be independent of bolus volume. This review concluded that bolus characteristics have differential effects on the respiratory functions during swallow beyond a 'central sensory threshold' level. Objective standardization of bolus characteristics may be the immediate requirement for generalization of future research findings in this direction.

Effects of Expiratory Muscle Strength Training on Videofluoroscopic Measures of Swallowing: A Systematic Review

Purpose Expiratory muscle strength training (EMST) is increasingly utilized in dysphagia rehabilitation; however, little is known about the effects of this approach on swallowing function or physiology. We conducted a systematic review to appraise and synthesize evidence regarding the effects of EMST on videofluoroscopic measures of swallowing in individuals with medical diagnoses, in which dysphagia is a concern. Method A literature search was conducted according to Cochrane guidelines. Of 292 nonduplicate articles, 11 were judged to be relevant for review. These underwent detailed review for study quality, risk of bias evaluation, and synthesis of swallowing outcomes. Results The selected articles described EMST in a variety of patient populations using either the EMST150 or the Phillips Threshold positive expiratory pressure device. The typical protocol involved five sets of five breaths through the device (25 breaths/day), 5 days per week for 4 weeks. Exercise loads were set between 50% and 75% depending on the population, and treatment was typically supervised by a clinician weekly. The Penetration-Aspiration Scale was the most commonly reported videofluoroscopic outcome measure. Conclusions differed as to whether or not swallowing improved following a course of EMST. Differences in videofluoroscopy protocols, methods of summarizing participant performance, and statistical approaches across studies meant that meta-analysis of swallowing outcomes could not be completed. Conclusion This review failed to find clear evidence regarding the effects of EMST on videofluoroscopic measures of swallowing. Heterogeneity in the etiologies and baseline severity of dysphagia across studies and in the methods used to measure swallowing outcomes was a particular barrier to data synthesis.

Respiratory-Swallow Pattern Following Total Laryngectomy

The goal of this study was to further characterize respiratory patterns in total laryngectomees with attention to respiratory-swallow pattern as it relates to presence/absence of tracheoesophageal puncture (TEP) and bolus consistency. It was hypothesized that participants with TEP would exhibit respiratory-swallow patterns that were significantly different than those without TEP and that bolus consistency (thin or solid) would modulate respiratory-swallow pattern. Data were collected from 12 adults (8 male), aged 46-67 years (mean 57) status post total laryngectomy (1-30 years; average 6 years). Those actively receiving chemoradiation, with history of esophageal cancer, with neurologic disease, with history of lung cancer, with known or suspected recurrence of head and neck cancer (HNC), or with severe cognitive deficits were excluded. Laryngectomy participants were asked to swallow three sips of water and three bites of graham cracker. Submental surface EMG activity was used to detect swallows and a custom stoma mask in line with a pneumotachograph measured airflow during the swallows. Non-parametric Mann-Whitney test for differences was used to detect significance for our dependent variables, TEP or bolus consistency and independent variables, respiratory-swallow pattern. Laryngectomee's showed preference for swallow during inspiration which is inconsistent with the expiratory pattern preference found in healthy adults with intact larynges by McFarland et al. (Respir Physiol Neurobiol 234:89-96, 2016) but consistent with the pattern preference for inspiration (or non-dominant respiratory-swallow phase pattern) found in the HNC population at-large by Brodsky et al. (J Appl Physiol 112(10):1698-1705, 2012). No significant difference was found in swallow pattern with regards to presence/absence of TEP or bolus consistency.

Respiratory-swallowing coordination in normal subjects: Lung volume at swallowing initiation

This study was designed to investigate the significance of bolus types and volumes, delivery methods and swallowing instructions on lung volume at swallowing initiation in normal subjects in a single experiment using a multifactorial approach. Our broad range goal was to determine optimal lung volume range associated with swallowing initiation to provide training targets for dysphagic patients with disordered respiratory-swallow coordination. Our hypothesis was that swallows would be initiated within a limited range of quiet breathing lung volumes regardless of bolus volume, consistency or task. Results confirmed this hypothesis and revealed that swallows were initiated at mean lung volume=244ml. Cued swallows were initiated at lower quiet breathing volumes than un-cued swallows (cued=201ml; un-cued=367ml). Water boluses were initiated at slightly higher quiet breathing volumes than solids. Data suggest that swallows occur within a restricted range of lung volumes with variation due to instructions, bolus type and other experimental variables.

Integrated non-invasive measurements reveal swallowing and respiration coordination recovery after unilateral stroke

BACKGROUND

Oropharyngeal dysphagia is common after a stroke. Understanding the physiology of swallowing and its coordination with respiration in stroke recovery is crucially important.

METHODS

A non-invasive swallowing assessment method was used to detect oropharyngeal swallowing and respiration coordination simultaneously during the swallowing process. This system detected movement of the larynx, submental muscle activity, and nasal airflow. Six different sizes of water boluses (maximum of 20 mL) were swallowed and assessed for each subject.

KEY RESULTS

We recruited 59 healthy participants and 38 first ever unilateral stroke patients completed baseline and follow-up assessments at 3, 6, and 9 months poststroke. The results showed that oropharyngeal swallowing parameters in unilateral stroke deviate from normal patterns. For respiration coordination, the unilateral stroke group had longer swallowing apnea duration but similar frequencies of pre- and postswallowing respiratory phase patterns compared with the healthy controls. The probability of piece-meal deglutition was higher in the stroke group than in the control group. Additionally, there were gradually decreasing piece-meal deglutition probabilities among the stroke patients at follow-up, and none differed statistically from those of the controls at 6 months poststroke.

CONCLUSIONS & INFERENCES

The non-invasive swallowing and respiration assessment method applied in this study detected the changes manifested in swallowing and respiration during the subacute phase of recovery in 6 months after a unilateral stroke. The study results serve as a baseline for further research and help advance dysphagia research methodologies. These assessments may be combined with bedside evaluations for clinical application.

Effects of morphine and midazolam on pharyngeal function, airway protection, and coordination of breathing and swallowing in healthy adults

BACKGROUND

Drugs used for sedation in anesthesia and intensive care may cause pharyngeal dysfunction and increased risk for aspiration. In this study, the authors investigate the impact of sedative doses of morphine and midazolam on pharyngeal function during swallowing and coordination of breathing and swallowing.

METHODS

Pharyngeal function, coordination of breathing and swallowing, and level of sedation were assessed by manometry, videoradiography, measurements of respiratory airflow, and a visual analog scale in 32 healthy volunteers (age 19 to 35 yr). After baseline recordings, morphine (0.1 mg/kg) or midazolam (0.05 mg/kg) was administered intravenously for 20 min, followed by recordings at 10 and 30 min after the end of infusion.

RESULTS

Pharyngeal dysfunction, seen as misdirected or incomplete swallowing or penetration of bolus to the airway, increased after morphine infusion to 42 and 44% of swallows compared with 17% in baseline recordings. Midazolam markedly increased incidence of pharyngeal dysfunction from 16 to 48% and 59%. Morphine prolonged apnea before swallowing, and midazolam increased the number of swallows followed by inspiration.

CONCLUSION

Morphine and midazolam in dosages that produce sedation are associated with increased incidence of pharyngeal dysfunction and discoordinated breathing and swallowing, a combination impairing airway protection and potentially increasing the risk for pulmonary aspirations.

Respiratory-swallow training in patients with head and neck cancer

OBJECTIVE

To test a novel intervention to train swallowing to occur in the midexpiratory to low expiratory phase of quiet breathing to improve swallowing safety and efficiency.

DESIGN

Safety and efficacy nonrandomized controlled trial with 1-month follow-up.

SETTING

Ambulatory clinics.

PARTICIPANTS

Patients (N=30) with head and neck cancer (HNC) and chronic dysphagia completed the intervention. Fifteen of these patients participated in a 1-month follow-up visit.

INTERVENTIONS

Training protocol based on hierarchy of motor skill acquisition to encourage autonomous and optimal respiratory-swallowing coordination. Visual feedback of respiratory phase and volume for swallowing initiation was provided by nasal airflow and rib cage/abdomen signals.

MAIN OUTCOME MEASURES

Respiratory-swallow phase pattern, Modified Barium Swallow Impairment Profile (MBSImP) scores, Penetration-Aspiration Scale (PAS) scores, and MD Anderson Dysphagia Inventory scores.

RESULTS

Using visual feedback, patients were trained to initiate swallows during the midexpiratory phase of quiet breathing and continue to expire after swallowing. This optimal phase patterning increased significantly after treatment (P<.0001). Changes in respiratory-swallowing coordination were associated with improvements in 3 MBSImP component scores: laryngeal vestibular closure (P=.0004), tongue base retraction (P<.0001), and pharyngeal residue (P=.01). Significant improvements were also seen in PAS scores (P<.0001). Relative to pretreatment values, patients participating in 1-month follow-up had increased optimal phase patterning (P<.0001), improved laryngeal vestibular closure (P=.01), tongue base retraction (P=.003), and pharyngeal residue (P=.006) MBSImP scores and improved PAS scores (P<.0001).

CONCLUSIONS

Improvements in respiratory-swallowing coordination can be trained using a systematic protocol and respiratory phase-lung volume-related biofeedback in patients with HNC and chronic dysphagia, with favorable effects on airway protection and bolus clearance.

Anesthesia and increased hypercarbic drive impair the coordination between breathing and swallowing

BACKGROUND

Coordination between breathing and swallowing helps prevent aspiration of foreign material into the respiratory tract. The authors examined the effects of anesthesia and hypercapnia on swallowing-breathing coordination.

METHODS

In a randomized controlled crossover study, general anesthesia with propofol or sevoflurane was titrated using an up-down method to identify the threshold for suppression of the motor response to electrical stimulation of the forearm. Additional measurements included bispectral index, genioglossus electromyogram, ventilation (pneumotachometer), and hypopharyngeal pressure. During wakefulness and at each level of anesthesia, carbon dioxide was added to increase the end-tidal pressure by 4 and 8 mmHg. A swallow was defined as increased genioglossus activity with deglutition apnea and an increase in hypopharyngeal pressure. Spontaneous swallows were categorized as physiological (during expiration or followed by expiration) or pathological (during inspiration or followed by an inspiration).

RESULTS

A total of 224 swallows were analyzed. Anesthesia increased the proportion of pathological swallows (25.9% vs. 4.9%) and decreased the number of swallows per hour (1.7±3.3 vs. 28.0±22.3) compared to wakefulness. During anesthesia, hypercapnia decreased hypopharyngeal pressure during inspiration (-14.1±3.7 vs. -8.7±2 mmHg) and increased minute ventilation, the proportion of pathological swallows (19.1% vs. 12.3%), and the number of swallows per hour (5.5±17.0. vs. 1.3±5.5).

CONCLUSIONS

Anesthesia impaired the coordination between swallowing and respiration. Mild hypercapnia increased the frequency of swallowing during anesthesia and the likelihood of pathological swallowing. During anesthesia, the risk for aspiration may be further increased when ventilatory drive is stimulated.

Can mano-videoendoscopy substitute for videofluorography in evaluation of upper esophageal sphincter function?

CONCLUSIONS

Mano-videoendoscopy (MVE), a manometry technique with endoscopic confirmation of the pressure catheter, can supplement the information on upper esophageal sphincter (UES) function, and overcomes the drawbacks of videoendoscopic swallowing study (VESS).

OBJECTIVES

This study aimed to investigate the possibility of replacing videofluorographic swallowing study (VFSS) with MVE, as a test to precisely evaluate UES function.

METHODS

Data from 52 patients with dysphagia were retrospectively reviewed. All patients underwent both MVE and VFSS for evaluation of dysphagia. The manometry was performed with a transnasally inserted catheter (2.6 mm outer diameter and four pressure sensors) under endoscopic observation. The sensors were kept at the tongue base, upper pyriform sinus, apex of pyriform sinus, and UES. We statistically compared the manometric parameters of UES relaxation with fluorographic UES opening.

RESULTS

Fluorographic UES opening was diagnosed as good in 34 patients and poor in 18 patients. The nadir pressure, pressure drop, and pressure rise in the UES had significant correlation on the fluorographic UES opening. Stepwise logistic regression test revealed that pressure drop, the gap between the resting pressure and the nadir of UES pressure, was a robust parameter for predicting fluorographic UES opening, and the cut-off level to anticipate good fluorographic opening was ≥ 33.5 mmHg (specificity, 0.853; sensitivity, 0.759).

Cervical auscultation as an adjunct to the clinical swallow examination: a comparison with fibre-optic endoscopic evaluation of swallowing

This prospective, single-blinded study investigated the validity and reliability of cervical auscultation (CA) under two conditions; (1) CA-only, using isolated swallow-sound clips, and (2) CSE + CA, using extra clinical swallow examination (CSE) information such as patient case history, oromotor assessment, and the same swallow-sound clips as condition one. The two CA conditions were compared against a fibre-optic endoscopic evaluation of swallowing (FEES) reference test. Each CA condition consisted of 18 swallows samples compiled from 12 adult patients consecutively referred to the FEES clinic. Patients' swallow sounds were simultaneously recorded during FEES via a Littmann E3200 electronic stethoscope. These 18 swallow samples were sent to 13 experienced dysphagia clinicians recruited from the UK and Australia who were blinded to the FEES results. Samples were rated in terms of (1) if dysphagic, (2) if the patient was safe on consistency trialled, and (3) dysphagia severity. Sensitivity measures ranged from 83-95%, specificity measures from 50-92% across the conditions. Intra-rater agreement ranged from 69-97% total agreement. Inter-rater reliability for dysphagia severity showed substantial agreement (rs = 0.68 and 0.74). Results show good rater reliability for CA-trained speech-language pathologists. Sensitivity and specificity for both CA conditions in this study are comparable to and often better than other well-established CSE components.

Physiological factors related to aspiration risk: a systematic review

Penetration-aspiration is considered the most serious component of oropharyngeal dysphagia. Clinicians regularly evaluate the pathophysiology of swallowing and postulate reasons or mechanisms behind penetration-aspiration. In this article we share the results of a two-stage literature review designed to elucidate the association between abnormalities in physiological measures of swallowing function and the occurrence of penetration-aspiration. In the first stage, a broad scoping review was undertaken using search terms for nine different structures involved in oropharyngeal swallowing. In the second stage, based on the results of the initial search, a more focused systematic review was undertaken which explored the association between aspiration and abnormalities in respiratory, tongue, hyoid, and laryngeal function in swallowing. A total of 37 articles underwent detailed quality review and data extraction in the systematic review. The results support measurement of tongue strength, anatomically normalized measures of hyoid movement, bolus dwell time in the pharynx while the larynx remains open, respiratory rate, and respiratory swallow phasing as parameters relevant to aspiration risk.

Effects of chemesthetic stimuli mixtures with barium on swallowing apnea duration

OBJECTIVES/HYPOTHESIS

This study tested the hypotheses that swallowing apnea duration (SAD) will increase given barium versus water, chemesthetic stimuli (i.e., water < ethanol, acid, and carbonation) mixed with barium, age (older > younger), and genetic taste differences (supertasters > nontasters).

STUDY DESIGN

Prospective group design.

SETTING

University Medical Center.

METHODS

Eighty healthy women were identified as nontasters and supertasters, equally comprising two age groups: 18 to 35 years and 60+ years. The KayPentax Swallowing Signals Lab was used to acquire SAD via nasal cannula during individually randomized swallows of 5 mL barium, 2.7% w/v citric acid with barium, carbonation with barium, and 50:50 diluted ethanol with barium. Data were analyzed using path analysis, with the mediator of chemesthetic perception, adjusted for repeated measures.

RESULTS

Significant main effects of age (P = .012) and chemesthetic stimuli (P = .014) were found, as well as a significant interaction between chemesthetic stimuli and age (P = .028). Older women had a significantly longer SAD than younger women. Post hoc analyses revealed that barium mixed with ethanol elicited a significantly longer SAD than other bolus conditions, regardless of age group. There were no significant differences in SAD between barium and water conditions, and no significant effect of chemesthetic perception (P > .05).

CONCLUSIONS

Ethanol added to barium elicited longer SAD compared to plain barium, but not the other chemesthetic conditions. Older women had a longer SAD than younger women in all conditions. These findings may influence design of future studies examining effects of various stimuli on SAD.

Coordination of tongue activity during swallowing in mouth-breathing children

Habitual mouth breathing is often accompanied by habitual anterior tongue thrust, instead of a lip closure, in order to create the anterior seal necessary for the initiation of physiological deglutition. We tested the null hypothesis of no significant influence of oral maneuver and the use of oral screens on tongue coordination and position during deglutition in 29 subjects (age = 6-16; mean = 9.69 years; 13/16 female/male) with habitual open-mouth posture using intraoral polysensography. The target parameters for swallowing were swallowing-associated nasal airflow interruption (NAI) and coordination of tongue-palate contact during NAI. Conventional myofunctional maneuvers could be facilitated and made more efficient, in terms of increasing the numbers of favorable early tongue-palate contacts typical of somatic swallowing, if accompanied by the application of an oral screen. Habitual open-mouth breathing does not necessarily coincide with distinctively pronounced proportions of late tongue-palate contact.

Main taste effects on swallowing apnea duration in healthy adults

OBJECTIVE

This study examined swallowing apnea duration (SAD) and respiratory phase patterns as a function of taste, tastes combined with barium, age, and genetic taste group.

STUDY DESIGN

Prospective group design.

SETTING

University medical center.

SUBJECTS AND METHODS

Eighty healthy adult women were identified as nontasters and supertasters and equally comprised 2 age groups: 18 to 35 years (n = 40) and 60+ years (n = 40). The KayPentax Swallowing Signals Lab was used to acquire SAD and respiratory phase patterns via nasal cannula during randomized 5-mL swallows of water, 1.0 M sucrose (sweet), 1.0 M sodium chloride (salty), and 0.032 M caffeine (bitter) alone and mixed with barium. The SAD and respiratory patterns were analyzed in a linear mixed model and a binary logistic regression generalized estimating equation model, respectively.

RESULTS

A significant main effect of age was found (P = .007). Older women demonstrated longer SAD than younger women. There were no significant effects of taste or genetic taste group on SAD. There was a significant interaction between barium and supertaster status; SAD was shorter in supertasters when barium was included. There were no significant differences in respiratory patterns between age groups, genetic taste groups, or among taste stimuli.

CONCLUSION

Advanced age elicited longer SAD, a robust finding in repeated investigations from multiple laboratories. Main tastes did not affect SAD or respiratory phase patterns. Genetic taste group altered SAD when barium was combined with the taste. That is, taste + barium shortened SAD in supertasters. This finding may affect clinical management of dysphagia patients and warrants further investigation.

Effects of chemesthetic stimuli, age, and genetic taste groups on swallowing apnea duration

OBJECTIVE

This study tested the hypotheses that swallowing apnea duration (SAD) will increase given chemesthetic stimuli (ie, water < ethanol, acid, and carbonation), age (older > young), and genetic taste differences (supertasters > nontasters).

STUDY DESIGN

Prospective group design.

SETTING

University medical center.

SUBJECTS AND METHODS

Eighty healthy adult women were identified as nontasters and supertasters, equally comprising 2 age groups: 18 to 35 years (n = 40) and 60+ years (n = 40). The KayPentax Swallowing Signals Lab was used to acquire SAD via nasal cannula during individually randomized swallows of 5 mL deionized water, 2.7% w/v citric acid, seltzer water, and 50:50 diluted ethanol/water. Data were analyzed using path analysis, with the mediator of chemesthetic perception, adjusted for repeated measures.

RESULTS

Significant main effects of chemesthetic stimuli (P = .002), age (P < .001), and genetic taste differences (P = .04) on SAD were found. Older women and supertasters had longer SADs than young women and nontasters. Post hoc analyses revealed ethanol and acid boluses elicited significantly longer SADs than water boluses did. There was no significant effect of chemesthetic perception (P > .05).

CONCLUSION

SAD in healthy women increased with changes in chemesthetic stimuli, older age, and in supertasters versus nontasters. It is unclear at this stage if increased SAD is a helpful mechanistic change (potentially protective against aspiration) or a maladaptive change (associated with aspiration). Future research should use these chemesthetic changes in bolus properties to assess if increased SAD decreases aspiration in patients with dysphagia while accounting for genetic taste differences.

Configurable portable/ambulatory instrument for the analysis of the coordination between respiration and swallowing

Physiological studies of swallowing and the diagnosis and treatment of dysphagia are crucially dependent of detailed information of respiratory and feeding events. Home telemonitoring is of great interest in this area, where large numbers of people have long term conditions. The purpose of this study was twofold: (1) describe a new configurable instrument that can be used in ambulatory and telemedicine applications and (2) evaluate the performance of this device in the description of physiological and abnormal events during water swallowing. The instrument is able to detect when water is beginning to enter the mouth of the volunteer, to unobtrusively monitor the respiration, and to characterize the elevation of the larynx. The performance of the system was tested in normal subjects and patients with dysphagia, showing results in close agreement with the physiology. We concluded that the developed system could be a useful tool for the ambulatory evaluation of respiratory and feeding events and for the implementation of telemedicine services, contributing to reduce the costs of the assistance offered to patients with dysphagia.

Breathing and swallowing in normal man--effects of changes in body position, bolus types, and respiratory drive

BACKGROUND

Coordination of breathing and swallowing is essential for airway protection and dyscoordination may cause morbidity and mortality.

METHODS

Using a recently developed technique for high accuracy respiratory measurements of airflow during swallowing, we investigated the effects of body position (upright vs left lateral), bolus type (spontaneously swallowed saliva vs water), and respiratory drive (normo- vs hypercapnia) on coordination of breathing and swallowing in 32 healthy volunteers.

KEY RESULTS

Swallows were in all cases (100%) proceded by expiration and 98% were also followed by expiration, regardless of body position, bolus type, or respiratory drive. While the endpoint of postswallow apnea correlated well to the endpoint of pharyngeal swallowing, duration of preswallow apnea was highly variable. In a small fraction of swallows followed by inspiration (3%), the expiratory phase before swallowing and duration of postswallow apnea was significantly longer. Body position and respiratory drive affected the increase in upper esophageal sphincter tone during inspiration. Increased respiratory drive also reduced swallowing frequency and shortened duration of preswallow apnea. Water swallows had longer duration of preswallow apnea.

CONCLUSIONS & INFERENCES

Swallowing occurs during the expiratory phase of respiration, and the fraction of swallows preceded and followed by expiration approach 100% in healthy humans. This integration between breathing and swallowing remains unchanged regardless of body position, bolus characteristics, or respiratory drive. Our results provide a platform for future studies aiming at understanding how this integration is changed by aging, diseases, and drugs.

Respiratory-swallowing coordination and swallowing safety in patients with Parkinson's disease

The purpose of this study was to determine if individuals with Parkinson's disease (PD) demonstrate abnormal respiratory events when swallowing thin liquids. In addition, this study sought to define associations between respiratory events, swallowing apnea duration, and penetration-aspiration (P-A) scale scores. Thirty-nine individuals with PD were administered ten trials of a 5-ml thin liquid bolus. P-A scale score quantified the presence of penetration and aspiration during the swallowing of a 3-oz sequential bolus. Participants were divided into two groups based on swallowing safety judged during the 3-oz sequential swallowing: Group 1 = P-A ≤ 2; Group 2 = P-A ≥ 3. Swallows were examined using videofluoroscopy coupled with a nasal cannula to record respiratory signals during the event(s). Findings indicated that expiration was the predominant respiratory event before and after swallowing apnea. The data revealed no differences in our cohort versus the percentages of post-swallowing events reported in the literature for healthy adults. In addition, individuals with decreased swallowing safety, as measured by the P-A scale, were more likely to inspire after swallows and to have shorter swallowing apnea duration. Individuals who inspired before swallow also had longer swallowing apnea duration. The occurrence of inspiratory events after a swallow and the occurrence of shorter swallowing apnea durations may serve as important indicators during clinical swallowing assessments in patients at risk for penetration or aspiration with PD.

Respiratory-swallow phase patterns and their relationship to swallowing impairment in patients treated for oropharyngeal cancer

BACKGROUND

Unstable respiratory-swallowing coordination has been associated with disorders and disease. The goals of this study were (1) to describe respiratory-swallow patterns in patients with dysphagia consequent to treatments for cancers of the oropharynx and (2) to determine the association between respiratory-swallow patterns, airway invasion, and overall severity of swallowing impairment.

METHODS

This prospective, cross-sectional design compared respiratory-swallow patterns in 20 patients treated for oropharyngeal cancer and 20 healthy, age-matched control participants. Nasal airflow direction was synchronously recorded with videofluoroscopic imaging in participants who swallowed 5-mL thin liquid barium boluses.

RESULTS

Respiratory-swallow patterns differed between groups. Most control participants initiated and completed swallowing bracketed by expiratory airflow. Swallowing in patients often interrupted inspiratory flow and was associated with penetration or aspiration of the bolus.

CONCLUSIONS

We suggest nonexpiratory bracketed respiratory-swallowing phase patterns in patients with oropharyngeal cancer may place patients at greater risk of airway penetration or aspiration during swallowing.

Comparison of sequential swallowing in patients with acute stroke and healthy adults

OBJECTIVES

To compare hyolaryngeal complex (HLC) movement and leading-edge-of-the-bolus location patterns of sequential swallowing in patients with stroke and healthy adults, and to determine whether these patterns affect swallowing safety.

DESIGN

Between-groups comparison.

SETTING

Veterans hospital.

PARTICIPANTS

Consecutively admitted patients with acute unilateral supratentorial stroke (right hemisphere damage, n=13; left hemisphere damage, n=16) and age-matched healthy participants (n=25).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

HLC movement pattern, bolus location, Penetration-Aspiration (P-A) Scale score.

RESULTS

No significant group differences were observed for HLC movement pattern, bolus location, and P-A Scale score. Specific HLC movement patterns and bolus location were not associated with a higher P-A Scale score. A significant correlation between HLC movement pattern and bolus location was observed. Bolus location was typically inferior to the valleculae between swallows when the HLC was partially elevated. Across all groups, P-A Scale scores were significantly higher during sequential swallowing than single swallows.

CONCLUSIONS

HLC movement pattern and bolus location do not appear related to airway invasion, at least in persons without significant dysphagia. Given higher P-A Scale scores during sequential swallowing as compared with single swallows, sequential swallowing should always be evaluated in all patients.

Coordination of Mastication, Swallowing and Breathing

The pathways for air and food cross in the pharynx. In breathing, air may flow through either the nose or the mouth, it always flows through the pharynx. During swallowing, the pharynx changes from an airway to a food channel. The pharynx is isolated from the nasal cavity and lower airway by velopharyngeal and laryngeal closure during the pharyngeal swallow. During mastication, the food bolus accumulates in the pharynx prior to swallow initiation. The structures in the oral cavity, pharynx and larynx serve multiple functions in breathing, speaking, mastication and swallowing. Thus, the fine temporal coordination of feeding among breathing, mastication and swallowing is essential to provide proper food nutrition and to prevent pulmonary aspiration. This review paper will review the temporo-spatial coordination of the movements of oral, pharyngeal, and laryngeal structures during mastication and swallowing, and temporal coordination between breathing, mastication, and swallowing.

Clinical implications of respiratory-swallowing interactions

PURPOSE OF REVIEW

Swallowing disorders impact the health and quality of millions of lives of patients across the age spectrum. The broad scope of the problem is in contrast to the volume of methods that we have to treat the problem. Investigators are testing interventions that go beyond the swallowing system and are targeting those that cross or overlap with swallowing function. This review will highlight the potential clinical implications of respiratory-swallowing cross-system interaction in health and disease.

RECENT FINDINGS

A collection of current studies demonstrates a tight neural coupling between the central control of respiration and swallowing. Results from recent studies suggest that this neural coupling may be altered under certain conditions of development, age, disease, and eating/swallowing tasks.

SUMMARY

The functional significance of cross-system neural control on respiratory-swallowing coordination is far from understood. Preliminary data, however, show destabilization of respiratory-swallowing patterns in various neurological diseases and in head and neck cancer. These findings suggest the need to develop a line of research that tests the effects of therapeutic strategies that transcend swallowing and include cross-system interactions such as respiratory-swallow phase patterning.

Respiration during feeding on solid food: alterations in breathing during mastication, pharyngeal bolus aggregation, and swallowing

During feeding, solid food is chewed and propelled to the oropharynx, where the bolus gradually aggregates while the larynx remains open and breathing continues. The aggregated bolus in the valleculae is exposed to respiratory airflow, yet aspiration is rare in healthy individuals. The mechanism for preventing aspiration during bolus aggregation is unclear. One possibility is that alterations in the pattern of respiration during feeding could help prevent inhalation of food from the pharynx. We hypothesized that respiration was inhibited during bolus aggregation in the valleculae. Videofluorography was performed on 10 healthy volunteers eating solid foods with barium. Respiration was monitored concurrently with plethysmography and nasal air pressure. The timing of events during mastication, food transport, pharyngeal bolus aggregation, and swallowing were measured in relation to respiration. Respiratory cycle duration decreased during chewing (P < 0.001) but increased with swallowing (P < 0.001). During 66 recordings of vallecular bolus aggregation, there was inspiration in 8%, expiration in 41%, a pause in breathing in 17%, and multiple phases (including inspiration) in 35%. Out of 98 swallows, 47% started in the expiratory phase and 50% started during a pause in breathing, irrespective of bolus aggregation in the valleculae. Plethysmography was better than nasal manometry for determining the end of active expiration during feeding and swallowing with solid food. The hypothesis is rejected in that respiration was not inhibited during bolus aggregation. These findings suggest that airflow through the pharynx does not have a role in preventing aspiration during bolus aggregation in the oropharynx.

Dysphagia: implications for older people

This review opens with an outline definition of dysphagia, its causes, and why it is vital that people involved in the health care of older people should be aware of it. A brief consideration of prevalence is followed by an overview of assessment options. We conclude with a section on management.