Persistence of respiratory-swallowing coordination after laryngectomy

Respiratory-Swallow Coordination in Individuals with Parkinson's Disease: A Systematic Review and Meta-Analysis

BACKGROUND

Swallowing impairment, including altered physiology and aspiration, occur across the progression of Parkinson's disease (PD). The phase of respiration during which a swallow is initiated has been linked to swallowing impairment and aspiration in cohorts with dysphagia following stroke and head and neck cancer treatment, but has been understudied in PD. If similar findings are shown in individuals with PD, the implications for swallowing assessment and treatment are significant.

OBJECTIVE

The aim of this systematic review and meta-analysis of literature was to examine respiratory-swallow coordination measures and potential implications on swallowing physiology in individuals with PD.

METHODS

An extensive search of 7 databases (PubMed, EMBASE, Central, Web of Science, ProQuest Dissertations & Theses, Scopus, and CINAHL) with predetermined search terms was conducted. Inclusion criteria were individuals with PD and the use of objective evaluations of respiratory-swallow coordination.

RESULTS

Of the 13,760 articles identified, 11 met the inclusion criteria. This review supports the presence of atypical respiratory swallow patterning, respiratory pause duration and lung volume at swallow initiation in individuals with PD. The meta-analysis estimated an occurrence of 60% of non-expiration-expiration and 40% of expiration-expiration respiratory phase patterns surrounding swallowing.

CONCLUSION

Although this systematic review supports the occurrence of atypical respiratory-swallow coordination in individuals with PD, the evidence is limited by the variability in the methods of data acquisition, analysis, and reporting. Future research examining the impact of respiratory swallow coordination on swallowing impairment and airway protection using consistent, comparable, and reproducible methods and metrics in individuals with PD is warranted.

Respiratory-swallow coordination and swallowing impairment in head and neck cancer

BACKGROUND

The aim of the study was to determine the link between frequency of optimal respiratory-swallow coordination, swallowing impairment, and airway invasion in head and neck cancer (HNC) patients.

METHOD

A cross-sectional study of a heterogeneous group of HNC patients (49), precancer (N = 30) or postcancer treatment (N = 29), participated in a single Modified Barium Swallow Study (MBSS) with synchronized respiratory data.

RESULTS

Spearman correlation coefficients revealed significant negative correlations between optimal respiratory-swallow phase pattern and objective measures of swallowing impairment: penetration-aspiration scale max, pharyngeal total, and oral total scores with Spearman correlation coefficients of -0.53 (z .001), -0.50 (P < .001), and -0.43 (P = .002), respectively. Optimal respiratory-swallow pattern was significantly decreased (P = .03) in patients after cancer treatment compared with another patient group before cancer treatment.

CONCLUSION

These findings indicate that as the percentage of optimal respiratory-swallow phase patterns increase, swallowing impairment decreases in the HNC patient population.

Respiratory-Swallow Training Methods: Accuracy of Automated Detection of Swallow Onset, Respiratory Phase, Lung Volume at Swallow Onset, and Real-Time Performance Feedback Tested in Healthy Adults

Background Preliminary studies have shown that respiratory-swallow training (RST) is a successful treatment for oropharyngeal head and neck cancer patients with refractory dysphagia. Refining the RST protocol with automated analysis software to provide real-time performance feedback has the potential to improve accessibility, reproducibility, and translation to diverse clinical settings. Method An automated software program for data acquisition and analysis developed to detect swallows, determine respiratory phase, calculate lung volume at the onset of the swallow, and provide real-time performance feedback was tested for feasibility in a small cohort of healthy adults. Outcome Measures Percent difference in swallow detection and accuracy of real-time performance feedback of respiratory phase and lung volume at swallowing onset between the automated software and the manual gold standard method were determined. Results The automated software program accurately detected the onset of the swallow on 91% of the swallows completed during the training trials. Feedback of respiratory phase and lung volume was accurate on 94% of the trials in which the swallow was accurately detected. Conclusions This novel, automated, and real-time RST software successfully detected the onset of the swallow, respiratory phase, and lung volume at swallow onset and provided appropriate real-time performance feedback with a high degree of accuracy in healthy adults. The software has the potential to improve the accessibility, efficiency, and translation of RST to diverse patient populations.

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 Phase and Lung Volume Patterns During Swallowing in Healthy Adults: A Systematic Review and Meta-Analysis

Purpose The coordination of respiration with swallowing is critical for facilitation of airway protection and the efficiency of movements that propel ingested material through the upper aerodigestive tract. Confirmation of a predominant pattern in healthy adults provides a platform for comparison to aberrant patterns observed in the population with swallowing impairment (dysphagia). Method A comprehensive search of published research in MEDLINE via PubMed 1946-2018, Embase 1947-2018, and Proquest Dissertations & Theses Global 1861-2018 was completed. Results Thirty-seven articles meeting inclusion criteria were selected for data extraction, and the findings were reviewed. In addition, a meta-analysis of the data was completed. A significantly higher occurrence ( p < .001) of expiration prior to and following the swallow was found when compared to 3 other patterns. The predominance of the pattern was influenced by increases in bolus volume when controlling for participant sample size. Conclusion Determination of this predominant pattern provides a normative framework for evaluating respiratory-swallow coordination in adults across the age span and highlights the relevance for assessing and incorporating respiratory swallowing coordination during assessment and interventions.

Optimizing Respiratory-Swallowing Coordination in Patients With Oropharyngeal Head and Neck Cancer

Swallowing impairment (dysphagia) represents the highest functional morbidity in oropharyngeal (OP) head and neck (HNC) treated either with surgical approaches followed by radiation or with more recent organ preservation protocols, including combined chemotherapy and radiation. Despite the promising overall increasing survival rates, swallowing impairments remain chronic, are often resistant to traditional swallowing therapy, and have devastating consequences on health and well-being. The respiratory-swallow cross-system approach presented here extends beyond traditional swallowing interventions that commonly targets muscles and structures alone, and is instead, directed toward the re-establishment of optimal respiratory-swallowing coordination. Results from our work investigating a respiratory-swallow treatment (RST) paradigm is presented, including results from an RST clinical trial in HNC patients, primarily with OP cancers, with chronic and with intractable dysphagia post-cancer and post-traditional swallowing treatment. Future work will investigate the impact of RST on the degree and durability of clinical outcomes, including oral intake and quality of life, while also examining the potential added benefits of a home practice program that uses a commercially available and easy to use recording and analysis hardware and software.

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.

Non-invasive Assessment of Swallowing and Respiration Coordination for the OSA Patient

The objectives of this study are to investigate swallowing and its coordination with respiration in patients with obstructive sleep apnea (OSA). This is a prospective cohort study conducted in a tertiary referred Medical Center. A non-invasive method of assessing swallowing was used to detect the oropharyngeal swallowing parameters and the coordination with respiration during swallowing. The system used to assess swallowing detected: (1) movement of the larynx using a force-sensing resistor; (2) submental muscle activity using surface electromyography; and (3) coordination with respiration by measuring nasal airflow. Five sizes of water boluses (maximum 20 mL) were swallowed three times, and the data recorded and analyzed for each participant. Thirty-nine normal controls and 35 patients with OSA who fulfilled the inclusion criteria were recruited. The oropharyngeal swallowing parameters of the patients differed from the controls, including longer total excursion duration and shorter duration of submental muscles contraction. A longer swallowing respiratory pause (SRP), temporary coordination with respiration during swallowing, was demonstrated in the patients compared with the controls. The frequency of non-expiratory/expiratory pre- and postswallowing respiratory phase patterns of the patients was similar with the controls. There was significantly more piecemeal deglutition in OSA patients when clumping 10- and 20-mL water boluses swallowing together (p = 0.048). Oropharyngeal swallowing and coordination with respiration affected patients with OSA, and it could be detected using a non-invasive method. The results of this study may serve as a baseline for further research and help advance research methods in obstructive sleep apnea swallowing studies.

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.

Coordination of oro-pharyngeal food transport during chewing and respiratory phase

When eating solid food, the tongue intermittently propels triturated food to the oropharynx or valleculae, where a bolus accumulates before swallowing. The tongue motion during this food transport (stage II transport, STII) is distinctly different from that during chewing, and is more similar to the oral propulsive stage of swallowing. Therefore, we tested the hypothesis that the onset of STII cycles was more likely to occur during expiration than inspiration. Videofluorography was recorded in a lateral projection while 10 healthy subjects ate solid foods. Respiration was concurrently monitored with plethysmography. Jaw motion cycles were classified as masticatory or swallowing. Masticatory cycles were further divided into chewing cycles and STII cycles. STII cycles were defined as those with bolus propulsion through the fauces by the tongue squeezing against the palate (without swallowing). Overall, 28% (62/223) of chewing cycles were initiated during inspiration, compared with only 12% (9/76) of STII cycles in this phase. The fraction of masticatory cycles occurring during inspiration was significantly smaller for STII cycles than for chewing cycles (Odds Ratio: 0.37 [95% CI: 0.17-0.78], p=0.01). All 36 swallowing cycles had onset during expiration. Our findings reveal that stage II oro-pharyngeal food transport is linked to expiration, as is the oral propulsive stage of swallowing. This suggests a similarity in the neural control of these two feeding behaviors.

Coordination of breathing with nonrespiratory activities

Many articles in this section of Comprehensive Physiology are concerned with the development and function of a central pattern generator (CPG) for the control of breathing in vertebrate animals. The action of the respiratory CPG is extensively modified by cortical and other descending influences as well as by feedback from peripheral sensory systems. The central nervous system also incorporates other CPGs, which orchestrate a wide variety of discrete and repetitive, voluntary and involuntary movements. The coordination of breathing with these other activities requires interaction and coordination between the respiratory CPG and those governing the nonrespiratory activities. Most of these interactions are complex and poorly understood. They seem to involve both conventional synaptic crosstalk between groups of neurons and fluid identity of neurons as belonging to one CPG or another: neurons that normally participate in breathing may be temporarily borrowed or hijacked by a competing or interrupting activity. This review explores the control of breathing as it is influenced by many activities that are generally considered to be nonrespiratory. The mechanistic detail varies greatly among topics, reflecting the wide variety of pertinent experiments.

The interaction between breathing and swallowing in healthy individuals

In this article, we aimed at investigating the interaction between breathing and swallowing patterns in normal subjects. Ten healthy volunteers were included in the study. Diaphragm EMG activity was recorded by a needle electrode inserted into the 7th or 8th intercostal space. Swallowing was monitored by submental EMG activity, and laryngeal vertical movement was recorded by using a movement sensor. A single voluntary swallow was initiated during either the inspiration or expiration phases of respiration, and changes in EMG activity were evaluated. When a swallow coincided with either inspiration or expiration, the duration of the respiratory phase was prolonged. Normal subjects were able to voluntarily swallow during inspiration. During the inspiration phase with swallowing, diaphragmatic activity did not ceased and during the expiration phase with swallowing, there was a muscle activity in the diaphragm muscle.

Lung volume measured during sequential swallowing in healthy young adults

PURPOSE

Outcomes from studying the coordinative relationship between respiratory and swallow subsystems are inconsistent for sequential swallows, and the lung volume at the initiation of sequential swallowing remains undefined. The first goal of this study was to quantify the lung volume at initiation of sequential swallowing ingestion cycles and to identify the respiratory pattern(s) surrounding each sequential swallow ingestion cycle. The second goal was to compare these results with existing data for single swallows.

METHOD

Twenty healthy young adults served as participants, 9 males and 11 females, between 19 and 28 years of age (M = 22 years of age). Participants completed 2 trials each of 100 mL of water self-delivered by cup and by straw. Calibrated respiratory inductance plethysmography, surface electromyography, and a contact throat microphone were used to detect respiratory parameters, identify swallow-related muscle contraction, and identify swallowing sounds, respectively.

RESULTS

Significantly higher lung volume initiation for trials delivered by straw and more variable respiratory patterns surrounding cup and straw sequential swallowing ingestion cycles existed compared with single swallows.

CONCLUSIONS

Results show that as the physiologic demands of swallowing deviate from single, small bolus swallows, the integration of the swallowing and respiratory systems change. This may reflect obligate differences in airway protection strategy and prolonged competition for respiratory resources.

Classification of healthy and abnormal swallows based on accelerometry and nasal airflow signals

BACKGROUND

Dysphagia assessment involves diagnosis of individual swallows in terms of the depth of airway invasion and degree of bolus clearance. The videofluoroscopic swallowing study is the current gold standard for dysphagia assessment but is time-consuming and costly. An ideal alternative would be an automated abnormal swallow detection methodology based on non-invasive signals.

OBJECTIVE

Building upon promising results from single-axis cervical accelerometry, the objective of this study was to investigate the combination of dual-axis accelerometry and nasal airflow for classification of healthy and abnormal swallows in a patient population with dysphagia.

METHODS

Signals were acquired from 24 adult patients with dysphagia (17.8±8.8 swallows per patient). The abnormality of each swallow was quantified using 4-point videofluoroscopic rating scales for its depth of airway invasion, bolus clearance from the valleculae, and bolus clearance from the pyriform sinuses. For each scale, we endeavored to automatically discriminate between the 2 extreme ratings, yielding 3 separate binary classification problems. Various time, frequency, and time-frequency domain features were extracted. A genetic algorithm was deployed for feature selection. Smoothed bootstrapping was utilized to balance the two classes and provide sufficient training data for a multidimensional feature space.

RESULTS

A Euclidean linear discriminant classifier resulted in a mean adjusted accuracy of 74.7% for the depth of airway invasion rating, whereas Mahalanobis linear discriminant classifiers yielded mean adjusted accuracies of 83.7% and 84.2% for bolus clearance from the valleculae and pyriform sinuses, respectively. The bolus clearance from the valleculae problem required the lowest feature space dimensionality. Wavelet features were found to be most discriminatory.

CONCLUSIONS

This exploratory study confirms that dual-axis accelerometry and nasal airflow signals can be used to discriminate healthy and abnormal swallows from patients with dysphagia. The fact that features from all signal channels contributed discriminatory information suggests that multi-sensor fusion is promising in abnormal swallow detection.

Pharyngeal swallowing sound profile assessed after partial and total laryngectomy

Recently, we described three components of a normal pharyngeal swallowing sound. The aim of the present study was to identify variations of these components using synchronized acoustic-radiological data in partially laryngectomized (PL) and totally laryngectomized (TL) patients before and after surgery. In this prospective study, from January 2003 to December 2006 we enrolled 14 patients in a PL group and 9 patients in a TL group. A fluoroscopy camera and a microphone were connected to a computer to obtain acoustic-radiological data (25 images/s). The subjects were asked to perform six deglutitions of 10 ml of barium suspension. The average durations of the sound variables were measured before and after surgery. The duration of the preoperative pharyngeal sound was 602 ms in the PL group and 562 ms in the TL group. It was significantly decreased after the TL (296 ms) and was increased after the PL (740 ms). A typical profile of the swallowing sound for each group was obtained. This study allowed us to describe the main variations of the pharyngeal swallowing sound induced by PL and TL. This noninvasive tool could be useful to assess postoperative swallowing function.

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.

Speech breathing in speakers who use an electrolarynx

Speakers who use an electrolarynx following a total laryngectomy no longer require pulmonary support for speech. Subsequently, chest wall movements may be affected; however, chest wall movements in these speakers are not well defined. The purpose of this investigation was to evaluate speech breathing in speakers who use an electrolarynx during speech and reading tasks. Six speakers who use an electrolarynx underwent an evaluation of chest wall kinematics (e.g., chest wall movements, temporal characteristics of chest wall movement), lung volumes, temporal measures of speech, and the interaction of linguistic influences on ventilation. Results of the present study were compared to previous reports in speakers who use an electrolarynx, as well as to previous reports in typical speakers. There were no significant differences in lung volumes used and the general movement of the chest wall by task; however, there were differences of note in the temporal aspects of chest wall configuration when compared to previous reports in both typical speakers and speakers who use an electrolarynx. These differences were related to timing and posturing of the chest wall. The lack of differences in lung volumes and chest wall movements by task indicates that neither reading nor spontaneous speech exerts a greater influence on speech breathing; however, the temporal and posturing results suggest the possibility of a decoupling of the respiratory system from speech following a total laryngectomy and subsequent alaryngeal speech rehabilitation.

LEARNING OUTCOMES

The reader will be able to understand and describe: (1) The primary differences in speech breathing across alaryngeal speech options; (2) how speech breathing specifically differs (i.e., lung volumes and chest wall movements) in speakers who use an electrolarynx; (3) How the coupling of speech and respiration is altered when pulmonary air is no longer used for speech.

Coordination of respiration and swallowing: functional pattern and relevance of vocal folds closure

CONTEXT: Breathing and swallowing coordination, despite the expressive number of study, remain as theme deserving further research. OBJECTIVE: To identify a coordination pattern between swallowing and the natural breathing pause that occur in association with it (swallowing apnea) and also the relevance of the vocal folds closure in this process. METHODS: Sixty-six adults, male and female, including normal health people, post-laryngectomy individuals and patients with digestive complaints without dysphagia were analyzed. The respiratory air flux interruptions produced by wet requested swallows and dry, requested and spontaneous swallows, were registered using thermo and piezoelectric receptors coupled to synectics medical manometry equipment, using Polygram upper 4.21 software. The results were analyzed with the Chi-square (3×2) and (2×2) nonparametric independency test with P = 0.05. RESULTS: Swallowing apnea is a preventive breathing stop that start just before and stay present during all deglutition pharyngeal phase. It is a well coordinated phenomena that occur as pattern in association with low elastic resistance of the lung, on the expiratory final phase until inspiration initial phase. This breathing stoppage it is usually followed by a short expiraton preceding a new breathing cycle. The swallow apnea and vocal folds closure are both independents mechanisms. CONCLUSION: It is possible to suppose that in the subconscious condition, swallowing apnea is integrated under coordination of the same control mechanism that also involves the elastic resistance of the lung.

Swallowing and respiratory pattern in young healthy individuals recorded with high temporal resolution

The coordination of swallowing and respiration is essential for a safe swallow. Swallowing consists of several subsecond events. To study this, it is important to use modalities with high temporal resolution. In this study, we have examined young healthy individuals with simultaneous videofluoroscopy, videomanometry and respiratory recording, all with high temporal resolution. The onset of 13 predetermined swallowing and respiratory events and the surrounding respiratory phase pattern were studied in different body positions and during different respiratory drives. An increased respiratory drive was induced by breathing 5% CO(2). The results demonstrated a highly repeatable and fixed temporal coordination of the swallowing pattern despite body position and respiratory drive. Previous studies have demonstrated a period of centrally controlled apnoea during swallowing. This apnoea period has a variable length, varying from 1 to 5 s. During increased respiratory drive, we could demonstrate a significantly shorter period of apnoea during swallowing, mainly due to an earlier resumption of respiration. The high temporal recordings in this study have revealed that swallowing during expiration is present basically in all healthy individuals. This swallowing respiratory pattern seems to be appropriate for a safe swallow. This knowledge will be used as a reference for future studies on how swallowing and respiratory coordination might be altered due to ageing and diseases.

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.

Anatomy and physiology of feeding and swallowing: normal and abnormal

Eating and swallowing are complex behaviors involving volitional and reflexive activities of more than 30 nerves and muscles. They have two crucial biologic features: food passage from the oral cavity to stomach and airway protection. The swallowing process is commonly divided into oral, pharyngeal, and esophageal stages, according to the location of the bolus. The movement of the food in the oral cavity and to the oropharynx differs depending on the type of food (eating solid food versus drinking liquid). Dysphagia can result from a wide variety of functional or structural deficits of the oral cavity, pharynx, larynx, or esophagus. The goal of dysphagia rehabilitation is to identify and treat abnormalities of feeding and swallowing while maintaining safe and efficient alimentation and hydration.

The effects of a total laryngectomy on speech breathing

PURPOSE OF REVIEW

Alaryngeal speech rehabilitation following a total laryngectomy is a multifactorial disorder that includes changes in phonation, respiration, and overall general health. Tracheoesophageal speech is the preferred method of rehabilitation. In this approach, pulmonary air support is diverted from the trachea into the esophagus to generate voicing. Tracheoesophageal speakers must overcome radical upper airway changes, increased resistance in the phonatory source, reduced sensory feedback from the respiratory system, and probable respiratory compromise. This review integrates previous laryngectomy research with recent studies investigating kinematics in tracheoesophageal speakers.

RECENT FINDINGS

Tracheoesophageal speakers are often very intelligible and communicate effectively, but little has been done to investigate the physiological demands of tracheoesophageal speech on speakers. Two recent studies have specifically investigated speech breathing behaviors in tracheoesophageal speakers. Both investigations reported increased effort and differences in speech breathing compared to laryngeal speakers; however, continued research is needed to understand the effects of a total laryngectomy on speech breathing.

SUMMARY

The physiological changes following a laryngectomy, especially in the ability to produce tracheoesophageal speech, are not well known. Rehabilitation for these individuals requires an understanding of the changes in respiration that might influence speech breathing behaviors.

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.

Swallowing and dysphagia rehabilitation: translating principles of neural plasticity into clinically oriented evidence

PURPOSE

This review presents the state of swallowing rehabilitation science as it relates to evidence for neural plastic changes in the brain. The case is made for essential collaboration between clinical and basic scientists to expand the positive influences of dysphagia rehabilitation in synergy with growth in technology and knowledge. The intent is to stimulate thought and propose potential research directions.

METHOD

A working group of experts in swallowing and dysphagia reviews 10 principles of neural plasticity and integrates these advancing neural plastic concepts with swallowing and clinical dysphagia literature for translation into treatment paradigms. In this context, dysphagia refers to disordered swallowing associated with central and peripheral sensorimotor deficits associated with stroke, neurodegenerative disease, tumors of the head and neck, infection, or trauma.

RESULTS AND CONCLUSIONS

The optimal treatment parameters emerging from increased understanding of neural plastic principles and concepts will contribute to evidence-based practice. Integrating these principles will improve dysphagia rehabilitation directions, strategies, and outcomes. A strategic plan is discussed, including several experimental paradigms for the translation of these principles and concepts of neural plasticity into the clinical science of rehabilitation for oropharyngeal swallowing disorders, ultimately providing the evidence to substantiate their translation into clinical practice.

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.

Respiratory-swallowing interactions during sleep in premature infants at term

Non-nutritive swallowing occurs frequently during sleep in infants and is vital for fluid clearance and airway protection. Swallowing has also been shown to be associated with prolonged apnea in some clinical populations. What is not known is whether swallowing contributes to apnea or may instead help resolve these clinically significant events. We studied the temporal relationships between swallowing, respiratory pauses and arousal in six preterm infants at term using multi-channel polysomnography and a pharyngeal pressure transducer. Results revealed that swallows occurred more frequently during respiratory pauses and arousal than during control periods. They did not trigger the respiratory pause, however, as most swallows (66%) occurred after respiratory pause onset and were often tightly linked to arousal from sleep. Swallows not associated with respiratory pauses (other than the respiratory inhibition to accommodate swallowing) and arousal occurred consistently during the expiratory phase of the breathing cycle. Results suggest that swallowing and associated arousal serve an airway protective role during sleep and medically stable preterm infants exhibit the mature pattern of respiratory-swallowing coordination by the time they reach term.

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

Swallowing apnea duration (SAD) and swallow-respiratory phase relationships were examined in individuals with cerebral vascular accident (CVA) and dysphagia who aspirated (n=11) and did not aspirate (n=15). Simultaneous videofluoroscopic and respiratory measures were recorded across 5-, 10-, 15-, and 20-ml thin and thick liquid bolus trials. These data were also compared with that previously acquired with healthy older adults (n=20). A moderate amount of systematic missing data was evidenced in the individuals who were dysphagic and especially those who aspirated subsequently limiting inferential analyses. Only 1 of the 11 participants who aspirated and 7 of the 15 who did not aspirate completed all 16 conditions. Six of the remaining ten who aspirated had missing data subsequent to termination of trials due to aspiration risk. The remaining four and seven of the eight who did not aspirate had missing data due to poor respiratory waveforms. From the remaining data, it was found that SAD and respiratory phase relationships differed among individuals with dysphagia and CVA (i.e., those who aspirate vs. those who do not aspirate) and healthy older adults. SAD was found to be longer for those who aspirated versus those who did not for all bolus viscosities and volumes with the exception of thick-liquid 10-ml boluses. In addition, SAD from those that aspirated was twice as long as that found in healthy older adults for all conditions. Regarding respiratory phase relationships, there was a difference between the proportions of respiratory patterns in those who aspirated versus those who did not. Those who aspirated demonstrated a markedly greater percentage of swallows that interrupted inhalation. In addition, the inhale-swallow-inhale pattern occurred with a greater frequency as swallowing severity increased. Healthy older adults, those who did not aspirate, and those who aspirated used the inhale-swallow-inhale pattern 0.1%, 3.0%, and 9.0%, respectively.