Temporal and durational patterns associating respiration and swallowing

Timing of True Vocal Cords Closure for Safe Swallowing: A Review of 5 Studies Using 3D Analysis Using Computerized Tomography (CT)

Timely and complete laryngeal closure is critical for a successful swallow. Researchers have studied laryngeal closure, including true vocal cords (TVC) closure, closure of the arytenoids to the epiglottis base (laryngeal vestibule closure), and epiglottic inversion, but the most commonly available imaging tools have limitations that do not allow the study of these components individually. Swallowing computerized tomography (CT) has enabled three-dimensional dynamic visualization and quantitative evaluation of swallowing events providing a unique view of swallowing-related structures and their motion. Using CT, TVC closure can be visualized and evaluated on any plane or cross-section without being obscured by of laryngeal vestibule closure or epiglottis inversion. The current review summarizes the results of five papers evaluating the effects of bolus consistency and volume, posture, and age on TVC closure. The combined results of these studies suggest that TVC closure is responsive to oral sensory input based on bolus consistency and size and can be modulated in response to conditions perceived to increase the risk of airway invasion. These results are meaningful for dysphagia rehabilitation as it suggests that interventions to improve TVC closure are likely to enhance airway protection.

Pulmonary function and sarcopenia as predictors of dysphagia in cervical spinal cord injury

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To determine the risk factors associated with dysphagia in individuals with cervical spinal cord injury (CSCI) and analyze the differences between individuals with improved penetration-aspiration (PA) and persistent PA on follow-up.

SETTING

Tertiary inpatient rehabilitation facilities.

METHODS

Medical records of individuals with CSCI admitted between December 2009 and February 2023 who underwent a videofluoroscopic swallowing study (VFSS) were retrospectively reviewed. Multivariate logistic regression analysis was performed to assess risk factors for dysphagia. Differences between individuals with improved PA and persistent PA were analyzed using an independent t-test.

RESULTS

In total, 149 participants were enrolled. Age (odds ratio (OR) 1.08, 95% confidence interval (CI) 1.04-1.12), percentage of forced vital capacity to predicted normal (FVC (% predicted)) (OR 0.90, 95% CI 0.85-0.94), and skeletal muscle index (OR 0.89, 95% CI, 0.79-0.99) were significant factors associated with the risk of PA. Based on the receiver operating characteristic curve analysis, the cut-off values for age, FVC (% predicted), and skeletal muscle index were determined as 56.0, 45.7, and 41.0, respectively. A secondary analysis of the follow-up VFSS was conducted on 38 participants. The follow-up FVC (% predicted) and degree of weight loss differed significantly between the improved PA and persistent PA groups.

CONCLUSIONS

Older age, low FVC (% predicted), and low skeletal muscle index can be predictors of dysphagia in patients with CSCI. On follow-up VFSS, individuals with improved PA demonstrated greater improvement in FVC (% predicted).

Effectiveness of Swallowing and Oral Care Interventions on Oral Intake and Salivary Flow of Patients Following Endotracheal Extubation at a Tertiary Care Center: A Randomized Controlled Trial

Introduction

Endotracheal intubation and mechanical ventilation are the most frequently used life-sustaining interventions in critical care. Prolonged intubation can lead to post-extubation dysphagia, affecting the individual's nutritional level and communication ability. Thereupon, this study aims to assess the effectiveness of swallowing and oral care interventions in resuming oral intake and increasing salivary flow in post-extubation patients.

Methods

A randomized controlled trial was conducted in critical care units of a tertiary care setting, where 92 post-extubation patients who had undergone intubation for≥48 hours were enrolled. The intervention group received swallowing and oral interventions, including safe swallowing education (SSE), toothbrushing, salivary gland massage, oral cavity, and swallowing exercises. In contrast, the control group received standard oral care every 8th hour. Oral intake was assessed daily with the Functional Oral Intake Scale, and the salivary flow measurement was assessed with oral Schirmer's test on the 1st, 3rd, and 7th day after extubation.

Results

The baseline demographic and clinical characteristics showed that the groups were homogenous. The intervention group achieved total oral intake two days earlier than the control group. Findings also showed that the participants in the intervention group had a significant increase in salivary flow than in the control group on the 3rd and 7th days of the intervention.

Conclusion

Swallowing and oral care interventions help post-extubation patients resume early oral intake and increase salivary flow after prolonged intubation. Hence, it improves the patient's outcome toward a healthy life.

Toward a robust swallowing detection for an implantable active artificial larynx: a survey

Total laryngectomy consists in the removal of the larynx and is intended as a curative treatment for laryngeal cancer, but it leaves the patient with no possibility to breathe, talk, and swallow normally anymore. A tracheostomy is created to restore breathing through the throat, but the aero-digestive tracts are permanently separated and the air no longer passes through the nasal tracts, which allowed filtration, warming, humidification, olfaction, and acceleration of the air for better tissue oxygenation. As for phonation restoration, various techniques allow the patient to talk again. The main one consists of a tracheo-esophageal valve prosthesis that makes the air passes from the esophagus to the pharynx, and makes the air vibrate to allow speech through articulation. Finally, swallowing is possible through the original tract as it is now isolated from the trachea. Yet, many methods exist to detect and assess a swallowing, but none is intended as a definitive restoration technique of the natural airway, which would permanently close the tracheostomy and avoid its adverse effects. In addition, these methods are non-invasive and lack detection accuracy. The feasibility of an effective early detection of swallowing would allow to further develop an implantable active artificial larynx and therefore restore the aero-digestive tracts. A previous attempt has been made on an artificial larynx implanted in 2012, but no active detection was included and the system was completely mechanic. This led to residues in the airway because of the imperfect sealing of the mechanism. An active swallowing detection coupled with indwelling measurements would thus likely add a significant reliability on such a system as it would allow to actively close an artificial larynx. So, after a brief explanation of the swallowing mechanism, this survey intends to first provide a detailed consideration of the anatomical region involved in swallowing, with a detection perspective. Second, the swallowing mechanism following total laryngectomy surgery is detailed. Third, the current non-invasive swallowing detection technique and their limitations are discussed. Finally, the previous points are explored with regard to the inherent requirements for the feasibility of an effective swallowing detection for an artificial larynx. Graphical Abstract.

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.

Swallowing and aspiration during sleep in patients with obstructive sleep apnea versus control individuals

Study Objectives

There are only a few reports on voluntary swallowing during sleep; therefore, this study aimed to propose a method for observing voluntary swallowing during sleep using polysomnography. The frequency of voluntary swallowing during sleep and the factors related to swallowing and aspiration during sleep were investigated.

Methods

Polysomnography records of 20 control subjects and 60 patients with obstructive sleep apnea (OSA) (mild, moderate, and severe groups; n = 20 each) were collected. Simultaneous increases in the electromyographic potentials of the submental and masseter muscles, termed coactivation, and declining oronasal airflow (SA) were extracted as “swallowing.” The cough reflex that occurred during sleep was extracted as “aspiration.” The frequency of swallowing events was compared among the different OSA severity groups. Subsequently, a multivariate regression analysis was performed.

Results

The average frequency of coactivation with SA in control subjects was 4.1 events/h and that without SA was 1.7 events/h. These frequencies increased with the severity of OSA during non-REM sleep. The distance of the hyoid to the Frankfurt plane was associated with the frequency of coactivation with (β = 0.298, p = 0.017) as well as without SA (β = 0.271, p = 0.038). The frequency of coactivation without SA was associated with aspiration (B = 0.192, p = 0.042).

Conclusions

Our data provide new insights into the relationship between swallowing and aspiration during sleep. We found that the longer the distance from the hyoid bone to the Frankfurt plane, the higher the coactivation without SA, which could lead to aspiration during sleep.

Clinical Trials

Retrospective observational study of swallowing during sleep in obstructive sleep apnea patients using polysomnography, https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr_view.cgi?recptno=R000050460, UMIN000044187.

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.

Utilizing Pulmonary Function Parameters to Predict Dysphagia in Individuals With Cervical Spinal Cord Injuries

Objective

To utilize pulmonary function parameters as predictive factors for dysphagia in individuals with cervical spinal cord injuries (CSCIs).

Methods

Medical records of 78 individuals with CSCIs were retrospectively reviewed. The pulmonary function was evaluated using spirometry and peak flow meter, whereas the swallowing function was assessed using a videofluoroscopic swallowing study. Participants were divided into the non-penetration-aspiration group (score 1 on the Penetration-Aspiration Scale [PAS]) and penetration-aspiration group (scores 2–8 on the PAS). Individuals with pharyngeal residue grade scores >1 were included in the pharyngeal residue group.

Results

The mean age was significantly higher in the penetration-aspiration and pharyngeal residue groups. In this study, individuals with clinical features, such as advanced age, history of tracheostomy, anterior surgical approach, and higher neurological level of injury, had significantly more penetration-aspiration or pharyngeal residue. Individuals in the penetration-aspiration group had significantly lower peak cough flow (PCF) levels. Individuals in the pharyngeal residue group had a significantly lower forced expiratory volume in 1 second (FEV1). According to the receiver operating characteristic curve analysis of PCF and FEV1 on the PAS, the cutoff value was 140 L/min and 37.5% of the predicted value, respectively.

Conclusion

Low PCF and FEV1 values may predict the risk of dysphagia in individuals with CSCIs. In these individuals, active evaluation of swallowing is recommended to confirm dysphagia.

An Exploration of Lung Volume Effects on Swallowing in Chronic Obstructive Pulmonary Disease

Purpose Chronic obstructive pulmonary disease (COPD) limits respiration, which may negatively impact airway safety during swallowing. It is unknown how differences in lung volume in COPD may alter swallowing physiology. This exploratory study aimed to determine how changes in lung volume impact swallow duration and coordination in persons with stable state COPD compared with older healthy volunteers (OHVs). Method Volunteers ≥ 45 years with COPD (VwCOPDs; n = 9) and OHVs (n = 10) were prospectively recruited. Group and within-participant differences were examined when swallowing at different respiratory volumes: resting expiratory level (REL), tidal volume (TV), and total lung capacity (TLC). Participants swallowed self-administered 20-ml water boluses by medicine cup. Noncued (NC) water swallows were followed by randomly ordered block swallowing trials at three lung volumes. Estimated lung volume (ELV) and respiratory-swallow patterning were quantified using spirometry and respiratory inductive plethysmography. Manometry measured pharyngeal swallow duration from onset of base of tongue pressure increase to offset of negative pressure in the pharyngoesophageal segment. Results During NC swallows, the VwCOPDs swallowed at lower lung volumes than OHVs (p = .011) and VwCOPDs tended to inspire after swallows more often than OHVs. Pharyngeal swallow duration did not differ between groups; however, swallow duration significantly decreased as the ELV increased in VwCOPDs (p = .003). During ELV manipulation, the COPD group inspired after swallowing more frequently at REL than at TLC (p = .001) and at TV (p = .002). In conclusion, increasing respiratory lung volume in COPD should improve safety by reducing the frequency of inspiration after a swallow.

High-flow nasal cannula oxygen therapy was effective for dysphagia associated with respiratory muscle paralysis due to cervical spinal cord injury: A case report

RATIONALE

Respiratory muscle paralysis due to low cervical spinal cord injury (CSCI) can lead to dysphagia. Noninvasive positive airway pressure (PAP) therapy can effectively treat this type of dysphagia. High-flow nasal cannula (HFNC) oxygen therapy can generate a low level of positive airway pressure resembling PAP therapy, it may improve the dysphagia.

PATIENT CONCERNS

The patient was an 87-year-old man without preexisting dysphagia. He suffered a CSCI due to a dislocated C5/6 fracture, without brain injury, and underwent emergency surgery. Postoperatively (day 2), he complained of dysphagia, and the intervention was initiated.

DIAGNOSIS

Based on clinical findings, dysphagia in this case, may have arisen due to impaired coordination between breathing and swallowing, which typically occurs in patients with CSCI who have reduced forced vital capacity.

INTERVENTIONS

HFNC oxygen therapy was started immediately after the surgery, and swallowing rehabilitation was started on Day 2. Indirect therapy (without food) and direct therapy (with food) were applied in stages. HFNC oxygen therapy appeared to be effective because swallowing function temporarily decreased when the HFNC oxygen therapy was changed to nasal canula oxygen therapy.

OUTCOMES

Swallowing function of the patient improved and he did not develop aspiration pneumonia.

LESSONS

HFNC oxygen therapy improved swallowing function in a patient with dysphagia associated with respiratory-muscle paralysis following a CSCI. It may have prolonged the apnea tolerance time during swallowing and may have improved the timing of swallowing. HFNC oxygen therapy can facilitate both indirect and direct early swallowing therapy to restore both swallowing and respiratory function.

Respiratory-Swallow Coordination in Healthy Adults During Drinking of Thin to Extremely Thick Liquids: A Research Note

Purpose Respiratory-swallow coordination is vital for airway protection, preventing aspiration, or penetration of foreign material into the airway. With the implementation of the International Dysphagia Diet Standardization Initiative definitions for different liquid consistencies used in dysphagia management, it is important to establish whether respiratory-swallow coordination patterns differ across these consistencies. This study aimed to evaluate respiratory behaviors during swallowing across the spectrum from thin to extremely thick liquids in healthy adults less than 60 years of age. Method Thirty healthy adults, aged 21-55 years, each consumed 54 naturally sized cup sips or spoonfuls of liquid stimuli prepared in thin, slightly thick, mildly thick, moderately thick, and extremely thick consistencies. Half of the stimuli were prepared using barium and half with a lemon-flavored water. Concurrent respiratory and swallowing pressure signals were collected to evaluate the respiratory phase pattern and pause duration associated with the swallow. Results An expiration-swallow-expiration pattern was the dominant respiratory phase pattern, observed in 92.7% of the trials, with no significant effect of consistency. Respiratory pause duration was found to be significantly shorter with barium stimuli (0.73 s) compared to nonbarium stimuli (0.78 s) (p < .001, Cohen's d = .2), with no notable effects based on the factors of sex or liquid consistency. Conclusions In a convenience sample of healthy adults under the age of 60 years, consistent respiratory-swallow phasing and stable timing across the spectrum from thin to extremely thick liquids was observed. The data from this study can serve as preliminary reference data to which assessment information for individuals with dysphagia or respiratory challenges can be compared.

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.

Respiratory-Swallow Coordination Training and Voluntary Cough Skill Training: A Single-Subject Treatment Study in a Person With Parkinson's Disease

Purpose Airway protective disorders are common in Parkinson's disease (PD), yet effective methods to rehabilitate these life-threatening impairments are limited. This study examined the effects of two skill-based treatments aimed at improving swallowing and cough in a severely dysphagic person with PD: respiratory-swallow coordination training (RSCT) and voluntary cough skill training (VCST). It was hypothesized that (a) RSCT would improve respiratory-swallow coordination and swallowing safety and efficiency and (b) VCST would improve reflex and voluntary cough effectiveness. Method An 81-year-old man with midstage PD and severe dysphagia was recruited for study participation. The study utilized a multiple-baseline ABACA experimental design with a 2-month delayed retention assessment. Measures of respiratory-swallow coordination, swallowing safety and efficiency, and cough effectiveness were collected at each assessment using respiratory inductive plethysmography, flexible endoscopic evaluations of swallowing, and spirometry. Data were analyzed descriptively using baseline corrected tau and standard mean difference effect sizes (d). Results Large effect sizes were observed immediately following RSCT for respiratory-swallow coordination (d = 9.17), penetration-aspiration (d = 12.88), vallecular residue (d = 1.75), piriform residue (d = 4.15), and overall dysphagia severity (d = 1.83). Large effect sizes were also observed immediately following VCST for single voluntary cough (d = 4.30), sequential voluntary cough (d = 3.28), and reflex cough (d = 5.58). Improvements were maintained 2 months later for all outcome measures except single voluntary cough. Discussion This is the first study to examine the effects of RSCT and VCST in a person with PD. Robust improvements in respiratory-swallow coordination and swallowing safety and efficiency were achieved following four sessions of RSCT, and significant improvements in reflex and voluntary cough strength were seen following four sessions of VCST. Future work is needed to study these treatments in larger cohorts of people with PD.

The pilot study examining the effects of swallowing position on lung volume fraction and the coordination between respiration and non-nutritive swallowing reflex

Background

Body position might affect the coordination between respiration and swallowing. This study was carried out to test the hypothesis that during swallowing, coordinated movements of muscle groups such as the diaphragm and rectus abdominis muscles are important to control normal swallowing apnea.

Objective

To investigate this hypothesis, respiratory parameters, swallowing apnea and muscle activity were measured in each of four body positions: sitting position with feet on the floor, 30° reclining position, lateral position, and standing position.

Methods

All measurements were performed in nine healthy subjects. Nasal airflow was measured using a pneumotachometer and muscle activity was measured using an electromyograph. All lung volume fraction parameters were measured using spirometer and swallowing apnea time was calculated.

Results

The maximum inspiratory volume was 2.76 ± 0.83 L in the 30° reclining position, which was significantly larger than that in the other positions (p = .0001). The preliminary expiratory volume was 1.05 ± 0.42 L in the 30° reclining position, which was significantly smaller than that in the other positions (p < .0001). The swallowing apnea time during water swallowing was 1.17 ± 0.35 sec in the lateral position and 0.87 ± 0.28 sec in the 30° reclining position, which tended to be longer than the 0.78 sec in the sitting position.

Conclusion

We conclude that both lateral and reclining positions require a longer period of swallowing apnea compared to the sitting and standing positions. Differences in body position may significantly influence the coordination between respiration and swallowing.

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.

Nocturnal swallowing and arousal threshold in individuals with chronic spinal cord injury

Respiratory complications are potential causes of death in patients with spinal cord injury (SCI). Nocturnal swallowing could be related to transient arousals and could lead to fragmented sleep in SCI patients. However, the impact of nocturnal swallowing on breathing and sleep physiology in SCI is unknown. The objectives of this study were 1) to determine whether nocturnal swallowing is more common in SCI than in able-bodied (AB) subjects, 2) to determine the role of nocturnal swallowing on arousal threshold (ArTh) in SCI individuals with sleep-disordered breathing (SDB), and 3) to determine the effect of continuous positive airway pressure (CPAP) treatment on nocturnal swallowing. A total of 16 SCI and 13 AB subjects with SDB completed in-laboratory polysomnography with a pharyngeal catheter. A swallowing event (SW) was defined as a positive spike in pharyngeal pressure and was used to calculate the swallow index (SI) defined as a number of SW/total sleep time. Each SW was assessed for a relationship to the sleep stages and respiratory cycle phases, and associated arousals and ArTh were calculated. SI was higher in the SCI group compared with AB subjects during wake and different sleep stages ( P < 0.05). SWs were found to be significantly higher in the late expiratory phase in the group with SCI compared with the other respiratory phases and were eliminated by CPAP ( P < 0.05). ArTh for the subjects with SCI was significantly lower ( P < 0.05) compared with the AB subjects. Nocturnal swallowing is more common in SCI than in AB individuals who have SDB, particularly during the expiratory phase. The ArTh is significantly lower in SCI (indicating increased arousal propensity), which may contribute to the mechanism of sleep disturbances in SCI. NEW & NOTEWORTHY Nocturnal swallowing is common in patients with chronic spinal cord injury (SCI) and is associated with frequent arousals from sleep. The lower arousal threshold during sleep in SCI may contribute to the mechanism of sleep disturbances that are commonly found in cervical and high thoracic SCI. Continuous positive airway pressure may play a therapeutic role in alleviating nocturnal swallowing, which may contribute to reduced risk of aspiration.

Evaluation of swallowing ability using swallowing sounds in maxillectomy patients

Maxillectomy for oral tumours often results in debilitating oral hypofunction, which markedly decreases quality of life. Dysphagia, in particular, is one of the most serious problems following maxillectomy. This study used swallowing sounds as a simple evaluation method to evaluate swallowing ability in maxillectomy patients with and without their obturator prosthesis placed. Twenty-seven maxillectomy patients (15 men, 12 women; mean age 66.0 ± 12.1 years) and 30 healthy controls (14 men, 16 women; mean age 44.9 ± 21.3 years) were recruited for this study. Participants were asked to swallow 4 mL of water, and swallowing sounds were recorded using a throat microphone. Duration of the acoustic signal and duration of peak intensity (DPI) were measured. Duration of peak intensity was significantly longer in maxillectomy patients without their obturator than with it (P < .05) and was significantly longer in maxillectomy patients without their obturator than in healthy controls (P < .025 after Bonferroni correction). With the obturator placed, DPI was significantly longer in maxillectomy patients who had undergone soft palate resection than in those who had not (P < .05). These results suggest swallowing ability in maxillectomy patients could be improved by wearing an obturator prosthesis, particularly during the oral stage. However, it is difficult to improve the oral stage of swallowing in patients who have undergone soft palate resection even with obturator placement.

Vibration over the larynx increases swallowing and cortical activation for swallowing

Sensory input can alter swallowing control in both the cortex and brainstem. Electrical stimulation of superior laryngeal nerve afferents increases reflexive swallowing in animals, with different frequencies optimally effective across species. Here we determined 1) if neck vibration overlying the larynx affected the fundamental frequency of the voice demonstrating penetration of vibration into the laryngeal tissues, and 2) if vibration, in comparison with sham, increased spontaneous swallowing and enhanced cortical hemodynamic responses to swallows in the swallowing network. A device with two motors, one over each thyroid lamina, delivered intermittent 10-s epochs of vibration. We recorded swallows and event-related changes in blood oxygenation level to swallows over the motor and sensory swallowing cortexes bilaterally using functional near infrared spectroscopy. Ten healthy participants completed eight 20-min conditions in counterbalanced order with either epochs of continuous vibration at 30, 70, 110, 150, and 70 + 110 Hz combined, 4-Hz pulsed vibration at 70 + 110 Hz, or two sham conditions without stimulation. Stimulation epochs were separated by interstimulus intervals varying between 30 and 45 s in duration. Vibration significantly reduced the fundamental frequency of the voice compared with no stimulation demonstrating that vibration penetrated laryngeal tissues. Vibration at 70 and at 150 Hz increased spontaneous swallowing compared with sham. Hemodynamic responses to swallows in the motor cortex were enhanced during conditions containing stimulation compared with sham. As vibratory stimulation on the neck increased spontaneous swallowing and enhanced cortical activation for swallows in healthy participants, it may be useful for enhancing swallowing in patients with dysphagia.NEW & NOTEWORTHY Vibratory stimulation at 70 and 150 Hz on the neck overlying the larynx increased the frequency of spontaneous swallowing. Simultaneously vibration also enhanced hemodynamic responses in the motor cortex to swallows when recorded with functional near-infrared spectroscopy (fNIRS). As vibrotactile stimulation on the neck enhanced cortical activation for swallowing in healthy participants, it may be useful for enhancing swallowing in patients with dysphagia.

Physiology Of Drowning: A Review

Drowning physiology relates to two different events: immersion (upper airway above water) and submersion (upper airway under water). Immersion involves integrated cardiorespiratory responses to skin and deep body temperature, including cold shock, physical incapacitation, and hypovolemia, as precursors of collapse and submersion. The physiology of submersion includes fear of drowning, diving response, autonomic conflict, upper airway reflexes, water aspiration and swallowing, emesis, and electrolyte disorders. Submersion outcome is determined by cardiac, pulmonary, and neurological injury. Knowledge of drowning physiology is scarce. Better understanding may identify methods to improve survival, particularly related to hot-water immersion, cold shock, cold-induced physical incapacitation, and fear of drowning.

Sour taste increases swallowing and prolongs hemodynamic responses in the cortical swallowing network

Sour stimuli have been shown to upregulate swallowing in patients and in healthy volunteers. However, such changes may be dependent on taste-induced increases in salivary flow. Other mechanisms include genetic taster status (Bartoshuk LM, Duffy VB, Green BG, Hoffman HJ, Ko CW, Lucchina LA, Weiffenbach JM. Physiol Behav 82: 109-114, 2004) and differences between sour and other tastes. We investigated the effects of taste on swallowing frequency and cortical activation in the swallowing network and whether taster status affected responses. Three-milliliter boluses of sour, sour with slow infusion, sweet, water, and water with infusion were compared on swallowing frequency and hemodynamic responses. The sour conditions increased swallowing frequency, whereas sweet and water did not. Changes in cortical oxygenated hemoglobin (hemodynamic responses) measured by functional near-infrared spectroscopy were averaged over 30 trials for each condition per participant in the right and left motor cortex, S1 and supplementary motor area for 30 s following bolus onset. Motion artifact in the hemodynamic response occurred 0-2 s after bolus onset, when the majority of swallows occurred. The peak hemodynamic response 2-7 s after bolus onset did not differ by taste, hemisphere, or cortical location. The mean hemodynamic response 17-22 s after bolus onset was highest in the motor regions of both hemispheres, and greater in the sour and infusion condition than in the water condition. Genetic taster status did not alter changes in swallowing frequency or hemodynamic response. As sour taste significantly increased swallowing and cortical activation equally with and without slow infusion, increases in the cortical swallowing were due to sour taste.

Subclinical dysphagia in persons with Prader-Willi syndrome

Prader-Willi Syndrome (PWS) is caused by a genetic imprinting abnormality resulting from the lack of expression of the paternal genes at 15q11-q13. Intellectual disability, low muscle tone, and life-threatening hyperphagia are hallmarks of the phenotype. The need for the Heimlich maneuver, death from choking, and pulmonary infection occur in a disproportionally high number of persons with PWS. The widely held belief is that eating behaviors are responsible for choking and aspiration; yet, no investigation had sought to determine if swallowing impairments were present in persons with PWS. To address this research and clinical gap, simultaneous videofluoroscopy and nasal respiratory signals were used to record swallowing function and breathing/swallowing coordination in 30 participants with PWS. Subjects consumed thin liquid and barium cookies under two randomized conditions as follows: (i) controlled (cues to swallow and standardized bolus sizes); (ii) spontaneous (no cues or bolus size control). Under videofluoroscopy, the cohort showed disordered pharyngeal and esophageal swallowing in both conditions with disturbances in timing, clearance, and coordination of swallowing with the respiratory cycle. No participant showed a sensory response such as attempting to clear residue or coughing; thereby supporting the lack of overt symptoms. We conclude that the high death rate from choking and pulmonary infection in children and adults with PWS may be related, in part, to underlying, asymptomatic dysphagia. The combination of rapid eating and dysphagia would increase the risk of aspiration-related morbidity and mortality. © 2016 Wiley Periodicals, Inc.

Assessment of impaired coordination between respiration and deglutition in children and young adults with ataxia telangiectasia

AIM

This cross-sectional investigation aimed to assess the value of non-invasive measures of temporal respiratory-swallow coupling in individuals with ataxic swallowing.

METHOD

Twenty participants (11 males, 9 females; range 9-21y) with ataxia telangiectasia were presented with water and pudding boluses. Their 193 swallows were compared with 2200 swallows from 82 age-matched healthy controls. The two components of airway protection during swallowing that were analyzed were: direction of peri-deglutitive airflow and duration of deglutitive inhibition of respiratory airflow (DIORA).

RESULTS

Safe expiratory patterns of peri-deglutitive airflow occurred significantly less often in participants with ataxia telangiectasia than in age-matched control participants (younger p<0.015 and older p<0.001). The frequency of an expiratory pattern of peri-deglutitive airflow increased with age in participants in the comparison group (p=0.006), but not in those with ataxia telangiectasia (p=0.234). With age, mean duration of DIORA decreased in controls (p<0.001) but was unchanged in participants with ataxia telangiectasia (p=0.164).

INTERPRETATION

Non-invasive quantitative measures of respiratory-swallow coupling capture temporal relationships that plausibly contribute to airway compromise from dysphagia. Changes in respiratory-swallow coupling observed with advancing age in control participants were not seen in participants with ataxia telangiectasia. Measures of perturbations may herald swallowing problems prior to development of pulmonary and nutritional sequelae.

Sleep Stage Coordination of Respiration and Swallowing: A Preliminary Study

Swallowing is an important physiological response that protects the airway. Although aspiration during sleep may cause aspiration pneumonia, the mechanisms responsible have not yet been elucidated. We evaluated the coordination between respiration and swallowing by infusing water into the pharynx of healthy young adults during each sleep stage. Seven normal subjects participated in the study. During polysomnography recordings, to elicit a swallow we injected distilled water into the pharynx during the awake state and each sleep stage through a nasal catheter. We assessed swallow latency, swallow apnea time, the respiratory phase during a swallow, the number of swallows, and coughing. A total number of 79 swallows were recorded. The median swallow latency was significantly higher in stage 2 (10.05 s) and stage 3 (44.17 s) when compared to awake state (4.99 s). The swallow latency in stage 3 showed a very wide interquartile range. In two subjects, the result was predominantly prolonged compared to the other subjects. There was no significant difference in the swallow apnea time between sleep stages. The presence of inspiration after swallowing, repetitive swallowing, and coughing after swallowing was more frequent during sleep than when awake. This study suggests that the coordination between respiration and swallowing as a defense mechanism against aspiration was impaired during sleep. Our results supported physiologically the fact that healthy adult individuals aspirate pharyngeal secretions during sleep.

Swallowing function and chronic respiratory diseases: Systematic review

BACKGROUND

The precise coordination between breathing and swallowing is an important mechanism to prevent pulmonary aspiration. Factors that alter breathing patterns and ventilation, such as chronic respiratory diseases, may influence that precise coordination of breathing and swallowing.

PURPOSE

The purpose of this systematic literature review is to examine the effects of chronic respiratory diseases on swallowing function.

METHOD

Literature searches were performed using the electronic databases PubMed and Embase. All articles meeting the eligibility criteria up to March 2016 were included.

RESULTS

All articles included studied Chronic Obstructive Pulmonary Diseases (COPD) or Obstructive Sleep Apnea (OSA); no studies involving other respiratory diseases were found. A total of 1069 abstracts were retrieved, of which twenty-six studies met the inclusion criteria; eleven studies dealt with OSA and fifteen studies dealt with COPD.

CONCLUSION

The outcome data indicate that chronic respiratory diseases increase the prevalence of oropharyngeal dysphagia (OD) in patients. However, the relative small number of studies, differences in selection criteria, definitions and assessment techniques used for diagnosing OSA, COPD, and OD point to the need for further research.

Noninvasive Mechanical Ventilation Improves Breathing-Swallowing Interaction of Ventilator Dependent Neuromuscular Patients: A Prospective Crossover Study

BACKGROUND

Respiratory involvement in neuromuscular disorders may contribute to impaired breathing-swallowing interactions, swallowing disorders and malnutrition. We investigated whether the use of non-invasive ventilation (NIV) controlled by the patient could improve swallowing performances in a population of neuromuscular patients requiring daytime NIV.

METHODS

Ten neuromuscular patients with severe respiratory failure requiring extensive NIV use were studied while swallowing without and with NIV (while ventilated with a modified ventilator allowing the patient to withhold ventilation as desired). Breathing-swallowing interactions were investigated by chin electromyography, cervical piezoelectric sensor, nasal flow recording and inductive plethysmography. Two water-bolus sizes (5 and 10ml) and a textured yogurt bolus were tested in a random order.

RESULTS

NIV use significantly improved swallowing fragmentation (defined as the number of respiratory interruption of the swallowing of a single bolus) (p = 0.003) and breathing-swallowing synchronization (with a significant increase of swallows followed by an expiration) (p <0.0001). Patient exhibited piecemeal swallowing which was not influenced by NIV use (p = 0.07). NIV use also significantly reduced dyspnea during swallowing (p = 0.04) while preserving swallowing comfort, regardless of bolus type.

CONCLUSION

The use of patient controlled NIV improves swallowing parameters in patients with severe neuromuscular respiratory failure requiring daytime NIV, without impairing swallowing comfort.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01519388.

Oral Alimentation in Neonatal and Adult Populations Requiring High-Flow Oxygen via Nasal Cannula

Use of high-flow oxygen via nasal cannula (HFO2-NC) is increasingly common in intensive care unit (ICU) settings. Despite the critical interface between respiration and swallowing, and the high acuity of patients in ICUs, the impact of HFO2-NC on feeding and swallowing is unknown. The present prospective, single-center, cohort study investigated the impact of HFO2-NC use on oral alimentation in neonatal and adult ICU patients. Oral alimentation status was evaluated in 100 consecutive ICU inpatients (50 neonatal and 50 adult) requiring HFO2-NC. Participant characteristics, respiratory support, successful initiation of oral feeding in neonates, and successful resumption of oral feeding in adults were recorded. Seventeen of 50 (34 %) neonates requiring HFO2-NC were deemed developmentally and medically appropriate by the neonatologist and nursing to begin oral alimentation. All 17 (100 %) were successful with initiation of oral feedings. Thirty-three of 50 (66 %) continued nil per os due to prematurity or medical conditions precluding oral alimentation at time of data collection. Thirty-nine of 50 (78 %) adults requiring HFO2-NC were deemed medically appropriate by the intensivist and nursing to resume oral alimentation (n = 34) or with a functional swallow without aspiration on FEES (n = 5). All 39 (100 %) resumed oral alimentation successfully. Eleven of 50 (22 %) continued nil per os due to severe respiratory issues precluding both swallow testing and oral alimentation at time of data collection. All developmentally and medically appropriate neonatal and adult patients requiring HFO2-NC were successful with either the introduction or resumption of oral alimentation. Patients requiring HFO2-NC who are identified as having feeding or swallowing issues should be referred for swallowing evaluations using the same criteria as patients who do not require HFO2-NC, as it is not the use of HFO2-NC but rather patient-specific determinants of feeding and swallowing readiness and their underlying medical conditions that impact readiness for oral alimentation status.

Dysphagia Screening: Contributions of Cervical Auscultation Signals and Modern Signal-Processing Techniques

Cervical auscultation is the recording of sounds and vibrations caused by the human body from the throat during swallowing. While traditionally done by a trained clinician with a stethoscope, much work has been put towards developing more sensitive and clinically useful methods to characterize the data obtained with this technique. The eventual goal of the field is to improve the effectiveness of screening algorithms designed to predict the risk that swallowing disorders pose to individual patients' health and safety. This paper provides an overview of these signal processing techniques and summarizes recent advances made with digital transducers in hopes of organizing the highly varied research on cervical auscultation. It investigates where on the body these transducers are placed in order to record a signal as well as the collection of analog and digital filtering techniques used to further improve the signal quality. It also presents the wide array of methods and features used to characterize these signals, ranging from simply counting the number of swallows that occur over a period of time to calculating various descriptive features in the time, frequency, and phase space domains. Finally, this paper presents the algorithms that have been used to classify this data into 'normal' and 'abnormal' categories. Both linear as well as non-linear techniques are presented in this regard.

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.

Noninvasive ventilation and breathing-swallowing interplay in chronic obstructive pulmonary disease*

OBJECTIVES

To investigate breathing-swallowing interactions in patients with chronic obstructive pulmonary disease requiring noninvasive mechanical ventilation and, if needed, to develop a technical modification of the ventilator designed to eliminate ventilator insufflations during swallowing.

DESIGN

We conducted a prospective, open-label, interventional study.

PATIENTS

Fifteen consecutive chronic obstructive pulmonary disease patients with exacerbations requiring ICU admission and NIV.

INTERVENTIONS

Swallowing performance and breathing-swallowing interactions were investigated noninvasively by chin electromyography, cervical piezoelectric sensor, and inductive respiratory plethysmography. Two water-bolus sizes (5 and 10 mL) were tested in random order. Swallowing was tested with and without noninvasive mechanical ventilation, in random order. First, a standard mechanical ventilator capable of delivering noninvasive mechanical ventilation was used. Second, a marketed device was equipped with an off-switch for use during swallowing.

MEASUREMENTS AND MAIN RESULTS

Swallowing performance and breathing-swallowing interactions were investigated noninvasively by chin electromyography, cervical piezoelectric sensor, and inductive respiratory plethysmography. Two water bolus sizes (5 and 10 mL) were tested in random order. Swallowing was tested with and without noninvasive mechanical ventilation in random order. First, a standard mechanical ventilator capable of delivering noninvasive mechanical ventilation was used. Swallowing efficiency, breathing-swallowing synchronization, and Borg Scale dyspnea scores improved significantly with noninvasive mechanical ventilation. However, swallowing induced ventilator triggering followed by autotriggering. To improve patient-ventilator synchrony, a marketed device was equipped with an off-switch for use during swallowing. This device completely eliminated swallowing-induced ventilator triggering and postswallow autotriggering.

CONCLUSION

Patients with chronic obstructive pulmonary disease admitted to the ICU for acute exacerbations had abnormal breathing-swallowing interactions and dyspnea, which improved with noninvasive mechanical ventilation. Furthermore, a ventilator device with a simple switch-off pushbutton to eliminate insufflations during swallows prevented swallowing-induced ventilator triggering and postswallow autotriggering.

The normal swallow: muscular and neurophysiological control

Swallowing is a complex physiologic function that involves precisely coordinated movements within the oral cavity, pharynx, larynx, and esophagus. This article reviews the anatomy, muscular control, and neurophysiological control of normal, healthy swallowing.

Symptoms of dysphagia in patients with COPD

OBJECTIVE

To identify symptoms of dysphagia in individuals with COPD, based on their responses on a self-perception questionnaire.

METHODS

The study comprised 35 individuals with COPD and 35 healthy individuals, matched for age and gender. The study group was assessed regarding COPD severity; sensation of dyspnea; body mass index (BMI); and symptoms of dysphagia. The control group was assessed regarding BMI and symptoms of dysphagia.

RESULTS

The most common symptoms of dysphagia in the study group were pharyngeal symptoms/airway protection (p < 0.001); esophageal symptoms/history of pneumonia (p < 0.001); and nutritional symptoms (p < 0.001). Positive correlations were found between the following pairs of variables: FEV₁ and BMI (r = 0.567; p < 0.001); pharyngeal symptoms/airway protection and dyspnea (r = 0.408; p = 0.015); and esophageal symptoms/history of pneumonia and pharyngeal symptoms/airway protection (r = 0.531; p = 0.001). There was a negative correlation between nutritional symptoms and BMI (r = -0.046; p < 0.008).

CONCLUSIONS

Our results show that the individuals with COPD presented with symptoms of dysphagia that were associated with the pharyngeal and esophageal phases of swallowing, as well as with the mechanism of airway protection, a history of pneumonia, and nutritional symptoms.

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.

Influence of experimental esophageal acidification on sleep bruxism: a randomized trial

The aim of this cross-over, randomized, single-blinded trial was to examine whether intra-esophageal acidification induces sleep bruxism (SB). Polysomnography with electromyogram (EMG) of masseter muscle, audio-video recording, and esophageal pH monitoring were performed in a sleep laboratory. Twelve healthy adult males without SB participated. Intra-esophageal infusions of 5-mL acidic solution (0.1 N HCl) or saline were administered. The frequencies of EMG bursts, rhythmic masticatory muscle activity (RMMA) episodes, grinding noise, and the RMMA/microarousal ratio were significantly higher in the 20-minute period after acidic infusion than after saline infusion. RMMA episodes including SB were induced by esophageal acidification. This trial is registered with the UMIN Clinical Trials Registry, UMIN000002923.

ABBREVIATIONS

ASDA, American Sleep Disorders Association; EMG, electromyogram; GER, gastroesophageal reflux; LES, lower esophageal sphincter; NREM, non-rapid eye movement; REM, rapid eye movement; RMMA, rhythmic masticatory muscle activity; SB, sleep bruxism; SD, standard deviation; UES, upper esophageal sphincter.

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.

The mandible advancement may alter the coordination between breathing and the non-nutritive swallowing reflex

The coordination between nasal breathing and non-nutritive swallowing serves as a protective reflex against potentially asphyxiating material, i.e. saliva and secretions, entering the respiratory tract. Although this protective reflex is influenced by positional changes in the head and body, the effect of mandible position on this reflex is not fully understood. We examined the effect of mandible advancement associated with mouth opening on the coordination between nasal breathing and non-nutritive swallowing induced by continuous infusion of distilled water into the pharyngeal cavity. The combination of mandible advancement and mouth opening increased the duration of swallowing apnoea and submental electromyographic burst duration. When the mandible was advanced with the mouth open, the duration of swallowing apnoea increased significantly compared with the centric position (0.79 +/- 0.23 vs. 0.64 +/- 0.12 s, P < 0.05, n = 12), and the duration of submental electromyographic activity increased significantly (2.11 +/- 0.63 vs. 1.46 +/- 0.25 s, P < 0.05, n = 12). Mandible advancement with mouth opening altered the respiratory phase resetting during swallowing and the timing of swallow in relation to respiratory cycle phase. We conclude that mandible re-positioning may strongly influence the coordination between nasal breathing and non-nutritive swallowing by altering respiratory parameters and by inhibiting movement of the tongue-jaw complex.

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.

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.