Inappropriate Timing of Swallow in the Respiratory Cycle Causes Breathing-Swallowing Discoordination

Comparative analysis of videofluoroscopy and pulse oximetry for aspiration identification in patients with dysphagia after stroke and non-dysphagics

PURPOSE

Dysphagia is a prevalent symptom observed in acute stroke. Several bedside screening tests are employed for the early detection of dysphagia. Pulse oximetry emerges as a practical and supportive method to augment the existing techniques utilized during bedside swallowing assessments. Desaturation levels, as measured by pulse oximetry, are acknowledged as indicative of aspiration by certain screening tests. However, the predictive capability of pulse oximetry in determining aspiration remains a subject of controversy. The objective of this study was to compare aspiration and oxygen desaturation levels by time and aspiration severity in dysphagic patients compared to healthy controls. It also aimed to evaluate the accuracy of pulse oximetry by comparing it with VFSS findings in detecting aspiration in both liquid (IDDSI-0) and semi-solid (IDDSI-4) consistencies.

MATERIALS AND METHODS

Eighty subjects (40 healthy and 40 acute stroke patients) participated. Patients suspected of dysphagia underwent videofluoroscopy as part of the stroke unit's routine procedure. Baseline SpO2 was measured before VFSS, and stabilized values were recorded. Sequential IDDSI-0 and IDDSI-4 barium tests were conducted with 5 ml boluses. Stabilized SPO2 values were recorded during swallowing and 3-min post-feeding. Patients with non-dysphagia received equal bolus monitoring. Changes in SPO2 during, before, and after swallowing were analyzed for each consistency in both groups.

RESULTS

The study revealed a statistically significant difference in SPO2 between patients with dysphagia and controls for IDDSI-4 and IDSSI-0. In IDDSI-4, 20% of patients experienced SpO2 decrease compared to 2.5% in control group (p = 0.013). For IDDSI-0, 35% of patients showed SpO2 decrease, while none in the control group did (p = 0.0001). Aspiration rates were 2.5% in IDDSI-4 and 57.5% in IDDSI-0. In IDDSI-0, SpO2 decrease significantly correlated with aspiration (p = 0.0001). In IDDSI-4, 20.5% had SpO2 decrease without aspiration, and showing no significant difference (p = 0.613). Penetration-Aspiration Scale scores had no significant association with SpO2 decrease (p = 0.602). Pulse oximetry in IDDSI-4 had limited sensitivity (0%) and positive predictive value, (0%) while in IDDSI-0, it demonstrated acceptable sensitivity (60.9%) and specificity (100%) with good discrimination capability (AUC = 0.83).

CONCLUSIONS

A decrease in SPO2 may indicate potential aspiration but is insufficient alone for detection. This study proposes pulse oximetry as a valuable complementary tool in assessing dysphagia but emphasizes that aspiration cannot be reliably predicted based solely on SpO2 decrease.

Identifying Non-Traditional Approaches to Swallowing Rehabilitation: A Scoping Review

In recent years, dysphagia care has shifted toward a more patient-centered approach. This means that dysphagia clinicians are considering more factors in the treatment process including the goals of care, quality of life, and cultural values. The purpose of this scoping review was to examine relevant research and identify dysphagia interventions outside of those traditionally used by dysphagia clinicians that may improve swallowing function. A review of relevant studies was conducted using search terms related to swallowing and treatment. The search yielded 8439 unique studies. Of the 283 articles that underwent a full-text review, 37 articles were included in the final review. These articles highlighted three potential areas of non-traditional dysphagia intervention that may serve to provide holistic care, while also aiming to improve swallowing mechanisms: acupuncture and Eastern medicine interventions, vocal exercises, and physical function exercises. The results suggest that dysphagia clinicians should work collaboratively with other allied health professionals and consider non-traditional approaches to dysphagia care. Through the identification of potentially effective but non-traditional or non-Eurocentric interventions for dysphagia care, clinicians may promote a culturally relevant, patient-centered approach, in turn increasing patient acceptance of treatment plans and compliance. Future research should explore the efficacy and feasibility of these interventions in dysphagia rehabilitation, as well as their effectiveness compared to more traditional approaches.

Factors Influencing Early Diagnosis and Poor Prognosis of Dysphagia After Senile Ischemic Stroke

Dysphagia is often a long-term problem after ischemic stroke, which are often accompanied by complications and results in poor outcome. This study aimed to investigate the influencing factors associated with the prognosis of dysphagia after senile ischemic stroke and evaluate the diagnostic performance of crucial factors. A total of 192 elderly ischemic stroke patients (96 patients without dysphagia with average age of 69.81 ± 4.61 years and 96 patients with dysphagia with average of 70.00 ± 6.66 years) were enrolled in the retrospective study. The clinical factors of the patients were collected and recorded for chi-square analysis and logistic analysis. The receiver operating characteristic (ROC) curve was performed to evaluate the diagnostic performance of international normalized ratio (INR) and homocysteine (Hcy) in senile ischemic stroke patients. The age, cough reflex, history of stroke, mechanical ventilation, eating posture, insufficient elevation of the larynx, standard swallowing assessment (SSA) score, Hcy value, and INR were closely related to endpoint events of patients with dysphagia. The joint model (combined INR and Hcy value) can increase the area under the curve (AUC) value (0.948) with higher sensitivity and specificity for predicting patients with dysphagia occurred endpoint events. The influencing factors for older ischemic stroke patients with dysphagia include age, cough reflex, history of stroke, mechanical ventilation, eating posture, insufficient elevation of the larynx, SSA score, Hcy value, and INR. INR and Hcy were independent risk factors for prognosis and diagnostic markers for patients with dysphagia after senile ischemic stroke.

Tongue, palatal, hyoid and pharyngeal muscle activity during chewing, swallowing, and respiration

OBJECTIVE

Chewing, swallowing, and respiration are synchronized oropharyngeal functions. This study aimed to analyze the dynamics and coordination during natural chewing and swallowing in relation to respiratory phases.

DESIGN

Eight oropharyngeal muscles in minipigs were recorded using electromyography, X-ray fluoroscopy, and nasopharyngeal dynamics. Chewing cycles and swallowing episodes were analyzed for timing and activity amplitude along respiratory cycles. Digastric and middle pharyngeal constrictor were used as zero-points for timing analysis in chewing cycles and swallowing episodes, respectively. The beginning of these cycles and episodes were used as the zero-point for timing analysis in respiration during feeding.

RESULTS

The timing of jaw closing (57.8%) was longer than opening (42.2%) during chewing. Muscle activity occurred 20% later than digastric onsets and 15% earlier than jaw closing phase. Duration of muscle activity was shorter in ipsilateral than contralateral sides except for palatal muscles. Pharyngeal, palatal, and hyoid muscles showed longer durations than tongue muscles in jaw opening (p < 0.05). Palatal and hyoid muscles showed 2-phased activity in chewing while hyoid muscles showed higher amplitude in chewing and swallowing than other muscles. About 80% of the chewing cycles and swallowing episodes occurred in expiration. Nasopharyngeal airflow velocity increased from jaw opening to swallowing while airflow pressure decreased.

CONCLUSION

These findings indicate key activity of palatal and pharyngeal muscles mostly in chewing. The respiratory cycle changes in chewing and swallowing simultaneously with the activation of the tongue, palatal, and pharyngeal muscles. These findings will be useful for further understanding the mechanisms in swallowing and breathing disorders.

An automated respiratory data pipeline for waveform characteristic analysis

Comprehensive and accurate analysis of respiratory and metabolic data is crucial to modelling congenital, pathogenic and degenerative diseases converging on autonomic control failure. A lack of tools for high-throughput analysis of respiratory datasets remains a major challenge. We present Breathe Easy, a novel open-source pipeline for processing raw recordings and associated metadata into operative outcomes, publication-worthy graphs and robust statistical analyses including QQ and residual plots for assumption queries and data transformations. This pipeline uses a facile graphical user interface for uploading data files, setting waveform feature thresholds and defining experimental variables. Breathe Easy was validated against manual selection by experts, which represents the current standard in the field. We demonstrate Breathe Easy's utility by examining a 2-year longitudinal study of an Alzheimer's disease mouse model to assess contributions of forebrain pathology in disordered breathing. Whole body plethysmography has become an important experimental outcome measure for a variety of diseases with primary and secondary respiratory indications. Respiratory dysfunction, while not an initial symptom in many of these disorders, often drives disability or death in patient outcomes. Breathe Easy provides an open-source respiratory analysis tool for all respiratory datasets and represents a necessary improvement upon current analytical methods in the field. KEY POINTS: Respiratory dysfunction is a common endpoint for disability and mortality in many disorders throughout life. Whole body plethysmography in rodents represents a high face-value method for measuring respiratory outcomes in rodent models of these diseases and disorders. Analysis of key respiratory variables remains hindered by manual annotation and analysis that leads to low throughput results that often exclude a majority of the recorded data. Here we present a software suite, Breathe Easy, that automates the process of data selection from raw recordings derived from plethysmography experiments and the analysis of these data into operative outcomes and publication-worthy graphs with statistics. We validate Breathe Easy with a terabyte-scale Alzheimer's dataset that examines the effects of forebrain pathology on respiratory function over 2 years of degeneration.

Transadaptation and Validation of the Telugu Version of the Dysphagia Handicap Index

Dysphagia Handicap Index (DHI) is a clinically effective, concise, and user-friendly tool for assessing the functional impact of dysphagia in clinical populations. The present study aims to trans-adapt the DHI in the Telugu language and assesses its psychometric properties. The present study was conducted in two phases. The first phase includes translating and adapting the DHI tool into Telugu (T-DHI). The second phase includes an analysis of the psychometric properties of the trans-adapted Telugu version of the DHI. The DHI was translated into the Telugu language using the forward-backward translation method. The psychometric analysis was done on 100 participants. All the participants underwent a detailed clinical swallow examination after filling the T-DHI. The overall internal consistency and Guttmann split-half reliability for the Telugu version of the DHI were good. The correlation between the T-DHI subscales and the self-perceived severity of dysphagia was found to be high. The comparison of the T-DHI scores of the control and experimental groups revealed a significant difference. The T-DHI is a reliable and valid tool to assess the quality of life of the Telugu-speaking dysphagia population.

Diet and Nutritional Status of Polish Girls with Rett Syndrome-A Case-Control Study

(1) Background: Rett syndrome may be considered a disease strongly associated with nutritional disorders that are likely to require special management strategies, extending beyond what is usually required for children with other developmental disorders. The aim of the study was to assess the nutritional status and diet of Polish girls with Rett syndrome. (2) Methods: Each patient (study group = 49, control group = 22) underwent anthropometric measurements, including body weight and height, waist, hip and arm circumference, and skinfold measurement. The assessment of the diet was based on the analysis of 7-day menus and the Food Frequency Questionnaire (FFQ-6). Data were analyzed using Statistica 13.3. (3) Results: The majority of the girls with Rett syndrome were deficient in weight and height, and consumed fewer calories, less protein, dietary fiber, calcium, and iron than the control group. They also drank less fluid. Soft products that were easy to chew and considered to be high in energy value were significantly more common in the menus. (4) Conclusions: Girls with Rett syndrome are characterized by weight deficiencies, poor growth that deteriorates with age, and are at risk of food shortages. Various nutritional intervention strategies should be explored to reduce and, if possible, prevent malnutrition and cachexia in such patients.

Swallowing disorder - a possible therapeutic target for preventing COPD exacerbations

Dysphagia is a common comorbidity of chronic obstructive pulmonary disease (COPD). In this review article, we show that swallowing disorder can be detected at its early stage as a manifestation of breathing-swallowing discoordination. Furthermore, we provide evidence that low-pressure continuous airway pressure (CPAP) and transcutaneous electrical sensory stimulation using interferential current (IFC-TESS) counteract swallowing disorders and may reduce exacerbations in patients with COPD. Our first prospective study showed that inspiration immediately before or after swallowing is associated with COPD exacerbation. However, the inspiration before swallowing (I-SW) pattern could be interpreted as an airway-protecting behavior. Indeed, the second prospective study showed that the I-SW pattern is more frequently observed in patients who did not experience exacerbations. As potential therapeutic candidates, CPAP normalizes the timing of swallowing, and IFC-TESS applied to the neck acutely facilitates swallowing and chronically improves nutrition and airway protection. Further studies are necessary to elucidate whether such interventions reduce exacerbations in patients with COPD.

The Kuchi-kara Taberu index as a predictive marker of oral intake recovery in patients with aspiration pneumonia

AIM

In recent years, the Kuchi-kara Taberu (KT) index has been used as a new tool for the evaluation of dysphagia; however, its predictive ability remains unknown. This study was conducted to examine the validity of oral intake recovery prediction using the KT index in patients with aspiration pneumonia.

METHODS

The subjects were older inpatients admitted to an acute-care hospital for the treatment of aspiration pneumonia. A logistic regression analysis was conducted to clarify factors significantly associated with oral intake recovery. In addition, cut-off values of the predictors were calculated using a receiver operating characteristic curve analysis with the area under the curve (P < 0.05).

RESULTS

A total of 124 patients (mean age 84.3 ± 7.9 years old, 70 males, 54 females) were enrolled in this study and divided into two groups at discharge: the oral intake group (62.1%) and the non-oral intake group (37.9%). The significant predictors of the recovery of oral intake were the pre-treatment period, treatment period, and the total score of the KT index; the respective odds ratios were 1.082 (95% confidence interval [CI] 1.013-1.156), 1.018 (1.003-1.033) and 0.850 (0.780-0.927), and the respective areas under the curve were 0.407 (95% CI 0.300-0.515), 0.304 (0.208-0.399), and 0.732 (0.640-0.824). The cut-off value of the total score of the KT index was 30. The model showed 85.7% sensitivity and 57.4% specificity.

CONCLUSION

The KT index is suggested to be a valid variable for predicting whether or not a patient with aspiration pneumonia can recover their oral intake ability during acute-care hospitalization. Geriatr Gerontol Int 2023; 23: 221-226.

Dysphagia Management and Cervical Auscultation: Reliability and Validity Against FEES

This study investigated the reliability and validity (sensitivity and specificity) of cervical auscultation (CA) using both swallow and pre-post swallow-respiratory sounds, as compared with Flexible Endoscopic Evaluation of Swallowing (FEES). With 103 swallow-respiratory sequences from 23 heterogenic patients, these swallows sounds were rated by eight CA-trained Speech-Language Pathologists (SLPs) to investigate: (1) if the swallow was safe (primary outcome); (2) patient dysphagia status; (3) the influence of liquid viscosity on CA accuracy (secondary outcomes). Primary outcome data showed high CA sensitivity (85.4%), and specificity (80.3%) with all consistencies for the safe measurement, with CA predictive values of [Formula: see text] 90% to accurately detect unsafe swallows. Intra-rater reliability was good (Kappa [Formula: see text] 0.65), inter rater reliability moderate (Kappa [Formula: see text] 0.58). Secondary outcome measures showed high sensitivity (80.1%) to identify if a patient was dysphagic, low specificity (22.9%), and moderate correlation (r_s [Formula: see text] 0.62) with FEES. A difference across bolus viscosities identified that CA sensitivities (90.1%) and specificities ([Formula: see text] 84.7%) for thin liquids were greater than for thick liquids (71.0-77.4% sensitivities, 74.0-81.3% specificities). Results demonstrate high validity and moderate-good reliability of CA-trained SLPs to determine swallow safety when compared with FEES. Data support the use of CA as an adjunct to the clinical swallow examination. CA should include pre-post respiratory sounds and requires specific training. Clinical implications: The authors advocate for holistic dysphagia management including instrumental assessment and ongoing CSE/review [Formula: see text] CA. Adding CA to the CSE/review does not replace instrumental assessment, nor should CA be used as a stand-alone tool.

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.

Multiple intrinsic membrane properties are modulated in a switch from single- to dual-network activity

Neural network flexibility includes changes in neuronal participation between networks, such as the switching of neurons between single- and dual-network activity. We previously identified a neuron that is recruited to burst in time with an additional network via modulation of its intrinsic membrane properties, instead of being recruited synaptically into the second network. However, the modulated intrinsic properties were not determined. Here, we use small networks in the Jonah crab (Cancer borealis) stomatogastric nervous system (STNS) to examine modulation of intrinsic properties underlying neuropeptide (Gly1-SIFamide)-elicited neuronal switching. The lateral posterior gastric neuron (LPG) switches from exclusive participation in the fast pyloric (∼1 Hz) network, due to electrical coupling, to dual-network activity that includes periodic escapes from the fast rhythm via intrinsically generated oscillations at the slower gastric mill network frequency (∼0.1 Hz). We isolated LPG from both networks by pharmacology and hyperpolarizing current injection. Gly1-SIFamide increased LPG intrinsic excitability and rebound from inhibition and decreased spike frequency adaptation, which can all contribute to intrinsic bursting. Using ion substitution and channel blockers, we found that a hyperpolarization-activated current, a persistent sodium current, and calcium or calcium-related current(s) appear to be primary contributors to Gly1-SIFamide-elicited LPG intrinsic bursting. However, this intrinsic bursting was more sensitive to blocking currents when LPG received rhythmic electrical coupling input from the fast network than in the isolated condition. Overall, a switch from single- to dual-network activity can involve modulation of multiple intrinsic properties, while synaptic input from a second network can shape the contributions of these properties.NEW & NOTEWORTHY Neuropeptide-elicited intrinsic bursting was recently determined to switch a neuron from single- to dual-network participation. Here we identified multiple intrinsic properties modulated in the dual-network state and candidate ion channels underlying the intrinsic bursting. Bursting at the second network frequency was more sensitive to blocking currents in the dual-network state than when neurons were synaptically isolated from their home network. Thus, synaptic input can shape the contributions of modulated intrinsic properties underlying dual-network activity.

Comprehensive Approaches to Aspiration Pneumonia and Dysphagia in the Elderly on the Disease Time-Axis

Pneumonia in the elderly has been increasing on an annual basis. To a greater or lesser extent, aspiration is a major contributor to the development of pneumonia in the elderly. Antimicrobials alone are not sufficient for the treatment of pneumonia, and the condition may become intractable or even recur repeatedly. In addition, some patients with pneumonia may have no problems with eating, while others are unable to receive the necessary nutrition due to severe dysphagia. It has recently been found that pneumonia decreases both the muscle mass and strength of the swallowing and respiratory muscles, a condition named pneumonia-associated sarcopenia. This contributes to a pathophysiological time-axis of aspiration pneumonia and dysphagia in the elderly, in which silent aspiration leads to the development of pneumonia, and further to dysphagia, malnutrition, and low immunity. Therefore, it is recommended that the treatment and prevention of developing pneumonia should also differ according to an individual’s placement in the disease time-axis. In particular, approaches for preventing aspiration based on scientific findings are able to be implemented at home.

Temporal variations in the pattern of breathing: techniques, sources, and applications to translational sciences

The breathing process possesses a complex variability caused in part by the respiratory central pattern generator in the brainstem; however, it also arises from chemical and mechanical feedback control loops, network reorganization and network sharing with nonrespiratory motor acts, as well as inputs from cortical and subcortical systems. The notion that respiratory fluctuations contain hidden information has prompted scientists to decipher respiratory signals to better understand the fundamental mechanisms of respiratory pattern generation, interactions with emotion, influences on the cortical neuronal networks associated with cognition, and changes in variability in healthy and disease-carrying individuals. Respiration can be used to express and control emotion. Furthermore, respiration appears to organize brain-wide network oscillations via cross-frequency coupling, optimizing cognitive performance. With the aid of information theory-based techniques and machine learning, the hidden information can be translated into a form usable in clinical practice for diagnosis, emotion recognition, and mental conditioning.

Sarcopenic Dysphagia, Malnutrition, and Oral Frailty in Elderly: A Comprehensive Review

Frailty is a highly prevalent condition in the elderly that has been increasingly considered as a crucial public health issue, due to the strict correlation with a higher risk of fragility fractures, hospitalization, and mortality. Among the age-related diseases, sarcopenia and dysphagia are two common pathological conditions in frail older people and could coexist leading to dehydration and malnutrition in these subjects. “Sarcopenic dysphagia” is a complex condition characterized by deglutition impairment due to the loss of mass and strength of swallowing muscles and might be also related to poor oral health status. Moreover, the aging process is strictly related to poor oral health status due to direct impairment of the immune system and wound healing and physical and cognitive impairment might indirectly influence older people’s ability to carry out adequate oral hygiene. Therefore, poor oral health might affect nutrient intake, leading to malnutrition and, consequently, to frailty. In this scenario, sarcopenia, dysphagia, and oral health are closely linked sharing common pathophysiological pathways, disabling sequelae, and frailty. Thus, the aim of the present comprehensive review is to describe the correlation among sarcopenic dysphagia, malnutrition, and oral frailty, characterizing their phenotypically overlapping features, to propose a comprehensive and effective management of elderly frail subjects.

Singing Experience Influences RSST Scores

It has recently been shown that the aging population is refractory to the maintenance of swallowing function, which can seriously affect quality of life. Singing and vocal training contribute to mastication, swallowing and respiratory function. Previous studies have shown that singers have better vocal cord health. No consensus has been reached as to how vocal training affects swallowing ability. Our study was designed to establish evidence that singers are statistically superior at inducing the swallowing reflex. To test our hypothesis, we undertook a clinical trial on 55 singers and 141 non-singers (mean age: 60.1 ± 11.7 years). This cross-sectional study with propensity score matching resulted in significant differences in a repetitive saliva swallowing test among singers: 7.1 ± 2.4, n = 53 vs. non-singers: 5.9 ± 1.9, n = 53, p < 0.05. We conclude that singing can serve an important role in stabilizing the impact of voluntary swallowing on speech.

Conditional loss of Engrailed1/2 in Atoh1-derived excitatory cerebellar nuclear neurons impairs eupneic respiration in mice

Evidence for a cerebellar role during cardiopulmonary challenges has long been established, but studies of cerebellar involvement in eupneic breathing have been inconclusive. Here we investigated temporal aspects of eupneic respiration in the Atoh1-En1/2 mouse model of cerebellar neuropathology. Atoh1-En1/2 conditional knockout mice have conditional loss of the developmental patterning genes Engrailed1 and 2 in excitatory cerebellar nuclear neurons, which leads to loss of a subset of medial and intermediate excitatory cerebellar nuclear neurons. A sample of three Atoh1-derived extracerebellar nuclei showed no cell loss in the conditional knockout compared to control mice. We measured eupneic respiration in mutant animals and control littermates using whole-body unrestrained plethysmography and compared the average respiratory rate, coefficient of variation, and the CV2, a measure of intrinsic rhythmicity. Linear regression analyses revealed that Atoh1-En1/2 conditional knockouts have decreased overall variability (p = 0.021; b = -0.045) and increased intrinsic rhythmicity compared to their control littermates (p < 0.001; b = -0.037), but we found no effect of genotype on average respiratory rate (p = 0.064). Analysis also revealed modestly decreased respiratory rates (p = 0.025; b = -0.82), increased coefficient of variation (p = 0.0036; b = 0.060), and increased CV2 in female animals, independent of genotype (p = 0.024; b = 0.026). These results suggest a cerebellar involvement in eupneic breathing by controlling rhythmicity. We argue that the cerebellar involvement in controlling the CV2 of respiration is indicative of an involvement of coordinating respiration with other orofacial rhythms, such as swallowing.

Sarcopenic Dysphagia: A Narrative Review from Diagnosis to Intervention

Sarcopenia, defined as a decline in muscle mass and function related to aging, affects both limb and swallowing-related muscles. Sarcopenic dysphagia is characterized by decreased swallowing function; therefore, early detection of subclinical dysphagia and subsequent intervention appear to be crucial in the elderly. Numerous tools have been employed to measure the function, strength, and mass of swallowing-related muscles in sarcopenic elderly. The swallowing function can be evaluated by questionnaires like Eating Assessment Tool, Functional Oral Intake Scale, and Food Intake Level Scale, and tests such as the modified water swallowing test and videofluoroscopic swallowing study. Surface electromyography and high-resolution manometry can be applied for quantifying swallowing-related muscle strength. Modalities such as ultrasonography and magnetic resonance imaging are capable of estimating the swallowing muscle mass. In patients with sarcopenic dysphagia, a thorough assessment should be given followed by an integrated intervention combining swallowing muscle strengthening, nutrition support, food texture modification, physical, and occupational therapies. This article aimed to comprehensively summarize the diagnostic criteria/tools as well as their associations/performance in sarcopenic dysphagia. The intervention strategy will also be narrated in this review.

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.

Molecular and Neural Mechanism of Dysphagia Due to Cancer

Cancer is one of the most common causes of death worldwide. Along with the advances in diagnostic technology achieved through industry–academia partnerships, the survival rate of cancer patients has improved dramatically through treatments that include surgery, radiation therapy, and pharmacotherapy. This has increased the population of cancer “survivors” and made cancer survivorship an important part of life for patients. The senses of taste and smell during swallowing and cachexia play important roles in dysphagia associated with nutritional disorders in cancer patients. Cancerous lesions in the brain can cause dysphagia. Taste and smell disorders that contribute to swallowing can worsen or develop because of pharmacotherapy or radiation therapy; metabolic or central nervous system damage due to cachexia, sarcopenia, or inflammation can also cause dysphagia. As the causes of eating disorders in cancer patients are complex and involve multiple factors, cancer patients require a multifaceted and long-term approach by the medical care team.

Laryngeal Sarcoidosis and Swallowing: What Do We Know About Dysphagia Assessment and Management in this Population?

Introduction

Sarcoidosis is a chronic granulomatous disease of unknown aetiology and laryngeal involvement is seen in a small percentage of cases. Dysphagia is a common but under-reported symptom. Little is known about how dysphagia typically presents or is managed in the context of this fluctuating disease. We present our case series using an SLT-led model of assessment and management.

Methods

A literature search was conducted for any articles that reported both laryngeal sarcoidosis and dysphagia. We then analysed a case series of laryngeal sarcoidosis patients treated at Charing Cross Hospital. We report on multidimensional swallowing evaluation and rehabilitative interventions.

Results

Seventeen papers report both laryngeal sarcoidosis and dysphagia, with only one paper giving details on the nature of the dysphagia and the treatment provided.

In our case series (n = 7), patients presented with FOIS Scores ranging from 5 to 7 pre-operatively (median = 6). Aspiration (median PAS Score = 6 and Range = 3–8) and pharyngeal residue were common. Sensory issues were also prevalent with most unaware of the extent of their difficulties. Management interventions included safe swallowing advice, compensatory strategies, exercises and close surveillance given their potential for repeated surgical interventions.

Conclusion

Laryngeal sarcoidosis is a rare condition. Dysphagia is under-reported and our experience highlights the need for specialist dysphagia intervention. Further research is required to understand dysphagia management requirements in the context of this fluctuating disease process.

The modified water swallowing test score is the best predictor of postoperative pneumonia following extubation in cardiovascular surgery: A retrospective cohort study

No guidelines have been established for the evaluation of swallowing function following extubation. The factors of bedside swallowing evaluations (BSEs) that are associated with the development of pneumonia have not been fully elucidated. This study aimed to retrospectively investigate the most appropriate measurements of BSEs for predicting pneumonia.The study subjects were 97 adults who underwent BSEs following cardiovascular surgery. Patients were divided into the pneumonia onset group (n = 21) and the non-onset group (n = 76). Patient characteristics, intraoperative characteristics, complications, BSE results, and postoperative progress were compared between the groups. BSEs were composed of consciousness level, modified water swallowing test (MWST) score, repetitive saliva swallowing test score, speech intelligibility score, and risk of dysphagia in the cardiac surgery score. Univariate and multivariate analyses with the BSE as the independent variable and pneumonia onset as the dependent variable were also performed to identify factors that predict pneumonia. For factors that became significant in univariate analysis, the incidence of pneumonia was shown using the Kaplan-Meier curve.No significant differences were found in patient characteristics, intraoperative characteristics, and complications between the 2 groups. The postoperative progress was significantly different between the 2 groups, the pneumonia-onset group had a significantly longer time until the start of oral intake and a significantly lower median value of Food Intake Level Scale at the time of discharge. According to univariate and multivariate analyses, MWST score was a significant factor for predicting the onset of pneumonia even after adjusting for patient characteristics and surgical factors, and the incidence of pneumonia increased approximately 3 times when the MWST score was 3 points or less.The MWST score after extubation in cardiovascular surgery was the strongest predictor of postoperative pneumonia in BSEs. Furthermore, the incidence of pneumonia increased approximately 3 times when the MWST score was 3 points or less. Predicting cases with a high risk of developing pneumonia allows nurses and attending physicians to monitor the progress carefully and take aggressive preventive measures.

Breathing-Swallowing Discoordination and Inefficiency of an Airway Protective Mechanism Puts Patients at Risk of COPD Exacerbation

Introduction

Dysphagia is a newly acknowledged multifactorial risk factor for the exacerbation of chronic obstructive pulmonary disease (COPD). Effective screening methods are awaited. We performed a prospective study to evaluate the impact of musculature and breathing-swallowing discoordination on the exacerbation of COPD with a novel swallowing monitor using a piezoelectric sensor.

Patients and Methods

This was the second part of a prospective study of patients with COPD from the Iizuka COPD cohort. Seventy patients with stable COPD underwent dysphagia screening, skeletal muscle mass index (SMI) and tongue pressure measurements, and swallowed 3 mL and 30 mL of water while wearing a swallowing monitor. Patients were followed for one year.

Results

During the follow-up period, 28 patients experienced exacerbations (E group), and 42 had none (non-E group). There was no significant difference in tongue pressure measurements between the two groups. The SMI in the E group was significantly lower than that in the non-E group. Among the swallowing monitor measurements, the 3 mL I-SW% (the percentage of swallows in which inspiration preceded the swallow [out of ten 3 mL swallows]) was significantly lower in the E group than in the non-E group.

Conclusion

Breathing-swallowing coordination is an independent factor related to the exacerbation of COPD. Not only the presence of discoordination but also the inability to produce an airway protection mechanism may contribute to more frequent aspiration and exacerbations.

Loss of cerebellar function selectively affects intrinsic rhythmicity of eupneic breathing

Respiration is controlled by central pattern generating circuits in the brain stem, whose activity can be modulated by inputs from other brain areas to adapt respiration to autonomic and behavioral demands. The cerebellum is known to be part of the neuronal circuitry activated during respiratory challenges, such as hunger for air, but has not been found to be involved in the control of spontaneous, unobstructed breathing (eupnea). Here we applied a measure of intrinsic rhythmicity, the CV2, which evaluates the similarity of subsequent intervals and is thus sensitive to changes in rhythmicity at the temporal resolution of individual respiratory intervals. The variability of intrinsic respiratory rhythmicity was reduced in a mouse model of cerebellar ataxia compared to their healthy littermates. Irrespective of that difference, the average respiratory rate and the average coefficient of variation (CV) were comparable between healthy and ataxic mice. We argue that these findings are consistent with a proposed role of the cerebellum in modulating the duration of individual respiratory intervals, which could serve the purpose of coordinating respiration with other rhythmic orofacial movements, such as fluid licking and swallowing.

Effects of noninvasive ventilation on the coordination between breathing and swallowing in patients with chronic obstructive pulmonary disease

Purpose

As shown in our previous study, inspiration after swallowing (SW-I) increases during the bi-level positive airway pressure ventilation (BiPAP) in healthy subjects because swallowing-associated non-inspiratory flow (SNIF) triggers inspiratory support, while SW-I during continuous positive pressure ventilation (CPAP) is rare. In the present study, we evaluated the coordination between breathing and swallowing during spontaneous breathing, BiPAP, and CPAP in patients with chronic obstructive pulmonary disease (COPD).

Patients and methods

This study is a prospective intervention study at the Hoshigaoka Medical Center (November 01, 2015–April 30, 2018). We simultaneously recorded the respiratory flow, laryngeal motion, and swallowing sounds during saliva swallowing in patients with COPD. We estimated the respiratory phase after swallowing, frequency of SNIF, the duration of the respiratory pause during swallowing, and timing of swallowing in the respiratory cycle and compared these parameters among control, CPAP, and BiPAP conditions.

Results

The expiration after swallowing (SW-E) frequency was associated with the occurrence of SNIF (p<0.01), pause duration ≤0.8 s (p<0.01), and timing of swallowing at the intermediate respiratory phase (50–80% of the respiratory cycle from the onset of inspiration) (p<0.01). In particular, the occurrence of SNIF most substantially affected the SW-E frequency. The SW-I frequencies under the control, CPAP, and BiPAP conditions were 35.0%, 3.0%, and 37.7%, respectively. The pause durations were shorter during CPAP and BiPAP than under the control condition (p<0.01). During CPAP, the occurrence rates of SW-E. Residual denotes the percentage difference between observed and expected values (residual =10.8: p<0.01) and SNIF (residual =9.1: p<0.01) were significantly increased, and timing of swallowing shifted toward the intermediate respiratory phase (residual=3.5: p<0.01).

Conclusion

CPAP decreases the SW-I frequency, increases the SNIF occurrence, and normalizes the timing of swallowing, all of which suggest that CPAP alleviates the risk of aspiration in patients with COPD.

Using Machine Learning and a Combination of Respiratory Flow, Laryngeal Motion, and Swallowing Sounds to Classify Safe and Unsafe Swallowing

OBJECTIVE

The aim of this research was to develop a swallowing assessment method to help prevent aspiration pneumonia. The method uses simple sensors to monitor swallowing function during an individual's daily life.

METHODS

The key characteristics of our proposed method are as follows. First, we assess swallowing function by using respiratory flow, laryngeal motion, and swallowing sound signals recorded by simple sensors. Second, we classify whether the recorded signals correspond to healthy subjects or patients with dysphagia. Finally, we analyze the recorded signals using both a feature extraction method (linear predictive coding) and a machine learning method (support vector machine).

RESULTS

Based on our experimental results for 140 healthy subjects (54.5 32.5 years old) and 52 patients with dysphagia (75.5 20.5 years old), our proposed method could achieve 82.4% sensitivity and 86.0% specificity.

CONCLUSION

Although 20% of testing sample sets were erroneously classified, we conclude that our proposed method may facilitate screening examinations of swallowing function.

SIGNIFICANCE

In combination with the portable sensors, our proposed method is worth utilizing for noninvasive swallowing assessment.

Central Respiration and Mechanical Ventilation in the Gating of Swallow With Breathing

Swallow-breathing coordination safeguards the lower airways from tracheal aspiration of bolus material as it moves through the pharynx into the esophagus. Impaired movements of the shared muscles or structures of the aerodigestive tract, or disruptions in the interaction of brainstem swallow and respiratory central pattern generators (CPGs) result in dysphagia. To maximize lower airway protection these CPGs integrate respiratory rhythm generation signals and vagal afferent feedback to synchronize swallow with breathing. Despite extensive study, the roles of central respiratory activity and vagal feedback from the lungs as key elements for effective swallow-breathing coordination remain unclear. The effect of altered timing of bronchopulmonary vagal afferent input on swallows triggered during electrical stimulation of the superior laryngeal nerves or by injection of water into the pharyngeal cavity was studied in decerebrate, paralyzed, and artificially ventilated cats. We observed two types of single swallows that produced distinct effects on central respiratory-rhythm across all conditions: post-inspiratory type swallows disrupted central-inspiratory activity without affecting expiration, whereas expiratory type swallows prolonged expiration without affecting central-inspiratory activity. Repetitive swallows observed during apnea reset the E2 phase of central respiration and produced facilitation of swallow motor output nerve burst durations. Moreover, swallow initiation was negatively modulated by vagal feedback and was reset by lung inflation. Collectively, these findings support a novel model of reciprocal inhibition between the swallow CPG and inspiratory or expiratory cells of the respiratory CPG where lung distension and phases of central respiratory activity represent a dual peripheral and central gating mechanism of swallow-breathing coordination.

Strategies for the Integration of Cough and Swallow to Maintain Airway Protection in Humans

PURPOSE

Airway protective behaviors, like cough and swallow, deteriorate in many populations suffering from neurologic disorders. While coordination of these behaviors has been investigated in an animal model, it has not been tested in humans.

METHODS

We used a novel protocol, adapted from previous work in the cat, to assess cough and swallow independently and their coordination strategies in seven healthy males (26 ± 6 years). Surface electromyograms of the submental complex and external oblique complex, spirometry, and thoracic and abdominal wall kinematics, were used to evaluate the timing of swallow, cough, and breathing as well as lung volume (LV) during these behaviors.

RESULTS

Unlike the cat, there was significant variability in the cough-swallow phase preference; however, there was a targeted LV range in which swallow occurred.

CONCLUSION

These results give insight into the differences between the cat and human models in airway protective strategies related to the coordination of cough and swallow behaviors, allowing for better understanding of dystussia and dysphagia.