Effect of reclining and chin-tuck position on the coordination between respiration and swallowing

The Masticatory Structure and Function in Children with Cerebral Palsy—A Pilot Study

(1) Background: Muscle tension around the head and neck influences orofacial functions. The data exist concerning head posture during increased salivation; however, little is known about muscle tightness during this process. This study aims to investigate whether or not any muscles are related to problems with eating, such as drooling in individuals with cerebral palsy; (2) Methods: Nineteen patients between the ages of 1 and 14 were examined prior to the physiotherapy intervention. This intervention lasted three months and consisted of: relaxing muscles via the strain-counterstrain technique, functional exercises based on the NeuroDevelopmental Treatment-Bobath method, and functional exercises for eating; (3) Results: the tone of rectus capitis posterior minor muscle on the left side (p = 0.027) and temporalis muscle on the right side (p = 0.048) before the therapy, and scalene muscle on the right side after the therapy (p = 0.024) were correlated with drooling behavior and were considered statistically significant. Gross motor function was not considered statistically significant with the occurrence of drooling behavior (p ≤ 0.05). Following the therapeutic intervention, the frequency of drooling during feeding decreased from 63.16% to 38.89% of the total sample of examined patients; (4) Conclusions: The tightness of the muscles in the head area can cause drooling during feeding.

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.

Effects of Chin-Down Maneuver on Pharyngeal Pressure Generation According to Dysphagia and Viscosity

Objective

To demonstrate the effects of chin-down maneuver on swallowing by using high-resolution manometry (HRM).

Methods

HRM data of 20 healthy subjects and 64 dysphagic patients were analyzed. Participants swallowed 5 mL of thin and honey-like liquids in neutral and chin-down positions. HRM was used to evaluate maximal velopharyngeal pressure/area, maximal tongue base pressure/area, maximal pharyngeal constrictor pressure, pre-/post-swallow upper esophageal sphincter (UES) peak pressure, minimal UES pressure, UES activity time, and nadir duration.

Results

Compared to the neutral position, the chin-down maneuver significantly increased tongue base pressure in both normal and dysphagic groups as well as for both honey-like and thin viscosities, although the honey-like liquid did not reach statistical significance in the dysphagic group. Regarding pharyngeal constrictors and pre-swallow peak UES pressure, the healthy group showed a significant decrease in thin liquid swallowing and decreasing tendency in honeylike liquid swallowing. UES nadir duration was significantly decreased for honey-like liquid swallowing in the dysphagic group and for both thin and honey-like liquids in the healthy group. UES nadir duration of honey-like and thin flow swallowing in the dysphagia group was 0.26 seconds after the chin-down maneuver, which was severely limited.

Conclusion

This study showed a different kinetic effect of the chin-down maneuver between the healthy and dysphagic groups, as well as between thin and honey-like viscosities. The chin-down maneuver increased tongue base pressure and decreased UES nadir duration, which the latter was severely limited in dysphagic patients. Therefore, appropriate application of the chin-down maneuver in clinical practice is required.

Effect of dexmedetomidine sedation on swallowing reflex: A pilot study

Background/purpose

Swallowing reflex depression during dental treatment or oral surgery may cause water to enter the lower respiratory tract, leading to coughing, thus hindering these procedures. Based on the hypothesis that dexmedetomidine (DEX) sedation may depress swallowing reflex, we aimed to characterize its effects on swallowing reflex and elucidate the affected functions.

Materials and methods

Swallowing reflex was induced in 9 young healthy male volunteers using a 5 mL-distilled water bolus injection over 3 s through a polyethylene catheter 3 times, both under wakefulness and DEX sedation. Swallowing EMG burst duration, pre-swallow EMG activity value, swallowing EMG burst peak value, latency time, and swallowing reflex timing in relation to the respiratory cycle were analyzed.

Results

The EMG burst duration was significantly prolonged with DEX sedation [206.9 ± 90.3% (1.20 ± 0.98 s)] compared to that with wakefulness [100 ± 00% (0.53 ± 0.28 s), P = 0.007]. No significant differences in the pre-swallow EMG activity value (P = 0.343), swallowing EMG burst peak value (P = 0.218), and latency times were apparent between wakefulness and DEX sedation (P = 0.793). Distributions of timing of the swallows in relation to the respiratory cycle did not significantly differ between the two conditions (P = 0.860).

Conclusion

Our data demonstrate that DEX sedation carries a potential risk of aspiration due to swallowing reflex depression during elevation of the larynx; therefore, suctioning of water and saliva should be rigorously performed. However, peripheral muscle contraction of the submental muscle complex, neural organization function, and timing of the swallowing reflex in relation to the respiratory cycle are not affected.

Head position classification of medical imaging studies: an assessment and development of a protocol

OBJECTIVES

To determine the optimal approach to reliably classify head position of head and neck medical imaging studies as flexion, neutral or extension for use in craniofacial and orthodontic research.

METHODS AND MATERIAL

A prospective study scanned six participants in flexed, neutral and extended head positions. Additionally, a retrospective dataset of 46 CT studies were visually classified into six categories: flexion, neutral-flexion, neutral, neutral-extension, extension and flexion-extension. 14 landmarks were placed in the head and neck region of all studies to calculate 17 head position angle and distance measurements. Assessment of head position classification was performed for each measure, as well as all measures together using GUIDE forest.

RESULTS

No single measure was sufficient to reliably classify head position in both retrospective and prospective imaging studies. Therefore, this study developed a head position protocol that considers multiple measures using two hybrid predictive models, to classify head position. Compared to visual assessment of head position, this protocol classified the imaging studies into the four head position categories with 82% neutral sensitivity and 100% neutral precision where the three neutral groups (neutral-flexion, neutral and neutral-extension) were grouped together.

CONCLUSION

This study established a novel head position classification protocol that uses multiple measures accounting for both head and neck positions to reliably classify head positions in imaging studies as: flexion, neutral or extension. Given the limitation that no single measure reliably classified head position, this protocol is strongly recommended to researchers who need to account for head position to reach valid conclusions.

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.

Effects of bolus consistency and reclining position on kinematic swallowing events in analysis using 320-row area detector computed tomography

This study used 320-row area detector computed tomography (320-ADCT) to determine whether kinematic swallowing events and bolus movement through the oropharynx are affected by bolus consistency and angle of recline. Fourteen healthy adults (4 men, 10 women; age, 22-90 years) underwent 320-ADCT assessment during three 10-mL barium swallow tests, with honey-thick liquid at 60° recline (60°thick), thin liquid at 60° recline (60°thin), and thin liquid at 45° recline (45°thin). The times of swallowing events were measured and compared among the different tests. Bolus propulsion, onset time of true vocal cord (TVC) closure, and upper esophageal sphincter opening were significantly earlier for 60°thin than for 60°thick. Onset time did not significantly differ between 60°thin and 45°thin; however, greater variability was noted for onset of TVC closure with 45°thin, as the TVC started to close before onset of swallowing in 30% of participants. Modulation of TVC closure depends on bolus transport in different reclining positions. The 45° reclining position elicited pre-swallow TVC closure in some participants, which suggests that excessive recline can increase perceived risk of airway invasion during 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.

Anatomical Directional Dissimilarities in Tri-axial Swallowing Accelerometry Signals

Swallowing accelerometry is a noninvasive approach currently under consideration as an instrumental screening test for swallowing difficulties, with most current studies focusing on the swallowing vibrations in the anterior-posterior (A-P) and superior-inferior (S-I) directions. However, the displacement of the hyolaryngeal structure during the act of swallowing in patients with dysphagia involves declination of the medial-lateral (M-L), which suggests that the swallowing vibrations in the M-L direction have the ability to reveal additional details about the swallowing function. With this motivation, we performed a broad comparison of the swallowing vibrations in all three anatomical directions. Tri-axial swallowing accelerometry signals were concurrently collected from 72 dysphagic patients undergoing videofluoroscopic evaluation of swallowing (mean age: 63.94 ± 12.58 years period). Participants swallowed one or more thickened liquids with different consistencies including thin-thick liquids, nectar-thick liquids, and pudding-thick liquids with either a comfortable self-selected volume from a cup or a controlled volume by the examiner from a 5-ml spoon. Swallows were grouped based on the viscosity of swallows and the participant's stroke history. Then, a comprehensive set of features was extracted in multiple signal domains from 881 swallows. The results highlighted inter-axis dissimilarities among tri-axial swallowing vibrations including the extent of variability in the amplitude of signals, the degree of predictability of signals, and the extent of disordered behavior of signals in time-frequency domain. First, the upward movement of the hyolaryngeal structure, representing the S-I signals, were actually more variable in amplitude and showed less predictable behavior than the sideways and forward movements, representing the A-P and M-L signals, during swallowing. Second, the S-I signals, which represent the upward movement of the hyolaryngeal structure, behaved more disordered in the time-frequency domain than the sideways movement, M-L signals, in all groups of study except for the pudding swallows in the stroke group. Third, considering the viscosity and the participant's pathology, thin liquid swallows in the nonstroke group presented the most directional differences among all groups of study. In summary, despite some directional dissimilarities, M-L axis accelerometry characteristics are similar to those of the two other axes. This indicates that M-L axis characteristics, which cannot be observed in videofluoroscopic images, can be adequately derived from the A-P and S-I axes.

Effect of body posture on involuntary swallow in healthy volunteers

Clinically, reclining posture has been reported to reduce risk of aspiration. However, during involuntary swallow in reclining posture, changes in orofacial and pharyngeal movement before and during pharyngeal swallow should be considered. Further, the mechanisms underlying the effect of body posture on involuntary swallow remain unclear. The aim of the present study was to determine the effect of body posture on activity patterns of the suprahyoid muscles and on patterns of bolus transport during a natural involuntary swallow. Thirteen healthy male adults participated in a water infusion test and a chewing test. In the water infusion test, thickened water was delivered into the pharynx at a very slow rate until the first involuntary swallow was evoked. In the chewing test, subjects were asked to eat 10 g of gruel rice. In both tests, the recording was performed at four body postures between upright and supine positions. Results showed that reclining changed the location of the bolus head at the start of swallow and prolonged onset latency of the swallowing initiation. Muscle burst duration and whiteout time measured by videoendoscopy significantly increased with body reclining and prolongation of the falling time. In the chewing test, reclining changed the location of the bolus head at the start of swallow, and the frequency of bolus residue after the first swallow increased. Duration and area of EMG burst and whiteout time significantly increased with body reclining. These data suggest that body reclining may result in prolongation of pharyngeal swallow during involuntary swallow.

Immediate effects of Kinesio Taping on the movement of the hyoid bone and epiglottis during swallowing by stroke patients with dysphagia

[Purpose] The purpose of this study was to identify the effects of Kinesio Taping (KT) on the swallowing function of stroke patients. [Subjects and Methods] Twenty-two stroke patients were randomly assigned to two groups; an experimental group which received KT, and a control group which received no taping intervention. Two-dimensional kinematic analysis was used to determine the displacement of the hyoid bone and the angular variation of the epiglottis using human anatomy-based coordinates. The functional dysphagia scale (FDS) was determined by a videofluoroscopic study (VFSS). [Results] The experimental group presented statistically significant improvements in kinematic changes of the vertical excursion of the hyoid bone and epiglottal rotation. [Conclusion] Clinical use of KT for dysphagia patients should be considered as a treatment approach. In future research, more subjects and more diverse patterns should be studied to accumulate further evidence.

Effectiveness of Chin-tuck Maneuver to Facilitate Swallowing in Neurologic Dysphagia

Introduction The chin-tuck maneuver is the most frequently employed postural maneuver in the treatment of neurogenic oropharyngeal dysphagia caused by encephalic vascular strokes and degenerative diseases.

Objective The purpose of this study was to investigate the effectiveness of this maneuver in patients with neurogenic dysphagia and factors that could interfere in it.

Methods In this retrospective cohort, we analyzed the medical files and videofluoroscopy exams of 35 patients (19 male – 54% and 16 female – 46%; age range between 20 and 89 years old; mean = 69 years).

Results The results suggest that the effectiveness of chin-tuck maneuver is related to the overall degree of dysphagia: the more severe the dysphagia, the less effective the maneuver.

Conclusion Chin-tuck maneuver should benefit dysphagic patients with delay in the swallowing trigger, reduced laryngeal elevation, and difficulties to swallow liquids, but is not the best compensatory strategy for patients with severe dysphagia.

Direct effects of Facio-Oral Tract Therapy(®) on swallowing frequency of non-tracheotomised patients with acute neurogenic dysphagia

OBJECTIVES

The aim of this study was to investigate the direct effect of Facio-Oral Tract Therapy(®) on swallowing frequency of non-tracheotomised patients with acute neurogenic dysphagia.

METHODS

Within a pre-, post-/during and follow-up study design, 19 non-tracheotomised dysphagic patients were included consecutively and treated according to three specific preselected Facio-Oral Tract Therapy stimulation techniques.

RESULTS

The primary outcome was the direct effect of the three different Facio-Oral Tract Therapy stimulation techniques on the number of swallows. We found a significant effect of Facio-Oral Tract Therapy on swallowing frequency as compared to baseline with an increase by 65.63% and medium effect size of D = 0.62. No significant difference could be demonstrated when comparing baseline to follow-up.

CONCLUSION

For the first time, this positive therapy effect could be demonstrated on a population of non-tracheotomised patients. Facio-Oral Tract Therapy seems to be an appropriate means for improving effectiveness and safety of swallowing. Since improvement was not long lasting, it appears to be reasonable to apply therapy frequently during the day with the plausible result of minimising the amount of aspirated saliva and thereby reducing the risk of aspiration pneumonia. Further studies may consider choosing a randomised controlled trial design to demonstrate that change in swallow frequency is related to the target intervention only.

Impact of lingual plates on the interocclusal free way space: a pilot study

Palatal augmentation prostheses are commonly used in the treatment for dysphagia. By lowering the palatal contours, the tongue contact is increased and thus the bolus propulsion facilitated. However, the unfavourable weight of such appliances may be avoided when using lingual plates. Hence, the aim of this study is to investigate the effect of two different types of lingual plates on the vertical dimension in rest position. Eleven healthy dentate subjects with an average age of 35.5 years (26-60 years) volunteered in this pilot study. The vertical overbites were measured on plaster models. Two different designs of the experimental lingual plates were tested in this pilot study (P-type & D-type). The inter-occlusal freeway space was measured using the electromagnetic K7 jaw-tracking system (Myotronics, U.S.A.), while the subjects were seated in an upright position. They were asked to close from rest position into maximum intercuspation for about 2 s. Recordings were performed without the plates and subsequently with each of the two plate designs in situ. All recordings were performed three times and the second closing movement of each recording was used for the analysis. After averaging the repetitions without experimental lingual plates, with P-type and D-type plates, the differences were analysed using a Kruskall-Wallis test. The results showed no significantly increased freeway space while using both types of lingual plates. Hence, it can be concluded that any altered tongue pressure during swallowing with lingual plates is not related to an increase in vertical dimension.

A decision-algorithm defining the rehabilitation approach: 'Facial oral tract therapy'

AIM

The aim of this study was to describe and define the rehabilitation approach: 'Facial Oral Tract Therapy' (F.O.T.T.).

METHOD

We defined the content and process of the rehabilitation approach (F.O.T.T.) in a decision-algorithm supported by a manual with supplementary material. The algorithm was developed by a research occupational therapist and an F.O.T.T. senior instructor. We used an inductive approach combining existing knowledge from: F.O.T.T. instructors, therapists trained in using the F.O.T.T. approach, and existing literature. A group of F.O.T.T. instructors and the originator of the treatment approach Mrs. Kay Coombes has given comments to and approved the algorithm.

RESULT

The algorithm consist of five flowcharts: 'one assessment' chart guiding the therapist in the examination of the patient and four 'treatment charts', one for each of the four areas of F.O.T.T.: swallowing and eating; oral hygiene; breathing, voice, and speech articulation; facial expression, giving guidance on interventions. The algorithm outlines all important components in the treatment that the therapist should decide to use or not to use in the intervention. The algorithm is supported by a manual with criteria of when to use which components.

CONCLUSION

This algorithm is designed to be a practical guideline to therapists using F.O.T.T. in clinical practice and in educational settings. The use of this algorithm may support standardization of F.O.T.T. and thereby promote and maintain the quality in the treatment. This in turn will facilitate research that addresses F.O.T.T. and outcomes.

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.

Relationship between ease of swallowing and deglutition-related muscle activity in various postures

The purpose of this study was to investigate the relationship between the ease of swallowing and the deglutition-related muscle activity in various body and head postures by surface electromyography (EMG). Bipolar surface electrodes were placed on the right suprahyoid and infrahyoid muscles of nine healthy adults (19-28 years) while swallowing jelly. Ten postures per subject were examined: five body angulations (0 degrees [supine], 30 degrees, 60 degrees, 90 degrees [upright] and 120 degrees from the horizontal) and two head positions (chin-up and chin-down). The duration and amplitude of suprahyoid and infrahyoid muscle activity were measured by an electromyograph, and the ease of swallowing was subjectively determined by using a rating scale (0 = difficult to swallow, 10 = easy to swallow). The group-average duration and amplitude of muscle activity and the group-average rating scales mostly showed insignificant changes with the body angulations independent of the head positions. Interestingly, the duration and amplitude of muscle activity during swallowing were negatively correlated with the rating scales, indicating that a shorter duration and smaller activity of muscle activity corresponds to easier swallowing. Consequently, the duration and amplitude of suprahyoid and infrahyoid muscle activity measured by surface EMG would be a useful indicator of the easy-to-swallow performance.

Effect of wearing a palatal plate on swallowing function

PURPOSE

The purpose of this study was to determine the effect of wearing a palatal plate on swallowing function.

METHODS

The subject group consisted of 10 healthy, fully dentate males. Two experimental palatal plates (EPP) were used in this study: one was 1.4mm thick (EPP1), and the other was 2.8mm thick (EPP2). Tongue movements and swallowing sounds were simultaneously recorded. The position of the surface of the tongue was recorded by using ultrasound diagnostic equipment in the sagittal plane. Swallowing tests were performed under three conditions: without EPP (WOE), with EPP1 (WP1), and with EPP2 (WP2). Swallowing index (SI) and tongue contact time (TCT) was calculated.

RESULTS

The value of SI was lowest under WOE, and highest under WP2, with a statistically significant difference. There was no statistical significance, however, between SI under WOE and that under WP1. The value of TCT was longest under WOE, and shortest under WP2, with a statistically significant difference.

CONCLUSIONS

This investigation suggests that the thickness of a palatal plate influences SI and TCT, which correlate with swallowing function.

The videofluorographic swallowing study

This article describes the evidence for the physiologic foundation and interpretation of the videofluorographic swallowing study (VFSS). The purpose and clinical efficacy of VFSS are explained. Standardization of the VFSS procedure, protocol, interpretation, and reporting is highlighted as a critical step in future clinical practice and research. Individualized evidenced-based rehabilitation strategies are presented as key components that are systematically applied during the VFSS procedure and integrated into the swallowing management plan. A new tool that has been developed and tested for the quantification of swallowing impairment is introduced.

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.

Influences of body posture on duration of oral swallowing in normal young adults

The primary purpose of this study was to determine whether body posture altered the duration of oral swallowing. To answer this question, we recorded electromyograms (EMGs) from the anterior tongue and suprahyoid (SH) muscles as well as laryngeal movement associated with swallowing in nine normal young subjects. The subjects swallowed a test food after receiving a signal while in four randomly set postures: upright, two inclined (60 degrees and 30 degrees to the horizontal), and supine positions. We measured the durations from the start to the peak and from the peak to the end of the integrated tongue and SH EMGs. We assumed that the duration from the start to the peak of the integrated SH EMG would correspond to the duration of oral swallowing. The average duration from the start to the peak of the integrated SH EMG decreased after moving from the upright to the inclined and supine positions. The decrease in the duration was statistically significant and consistent for three experimental sessions. The duration from the start to the peak of the integrated tongue EMG during swallowing tended to decrease after lying down, but not significantly. The postural changes did not affect the remaining four durations. The decrease in the duration of oral swallowing induced by lying down suggests that the gravitational force placed on the test food facilitates the swallowing reflex. Large variation in the tongue activity during swallowing among the subjects can probably be attributed to the lack of a significant decrease in the duration of the tongue activity.

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.