Upper airway muscles: influence on obstructive sleep apnoea pathophysiology and pharmacological and technical treatment options

Early-onset pharyngeal airway collapse in infants: a retrospective single-center study

BACKGROUND

Early-onset pharyngeal airway collapse (PAC) in infants, which presents with onset within 6-months old is relatively rare. This disease has not been given enough attention in clinic. The aim of this study was to explore the clinical features, endoscopic findings and outcomes of early-onset PAC in infants.

METHODS

The children of PAC with onset within 6-months old were included. A retrospective study was conducted.

RESULTS

(1) Total 26 cases were included. The age of onset was neonatal period in 20 cases, 1 to 3-months old in 5 cases, and 4 to 6-months old in 1 case. (2) The main clinical manifestations were noisy breathing (26/26), suprasternal retraction (18/26), snoring (14/26) and hypoxic episode (13/26). (3) Based on the endoscopic findings, collapse at the retropalatal level was most common (24/26). (4) Twelve cases underwent pharyngolaryngeal CT examination, which revealed abnormal findings in 7 cases. (5) Fifteen cases were accompanied with the other airway malformations. (6) In the group with comorbidities of cerebral impairment or craniofacial abnormalities, 1 case was lost to follow up, 4 cases died, and 10 cases survived, in which 9 cases had neurodevelopmental disorders. In the group without comorbidities, 2 cases were lost to follow up, 9 cases survived, in which 1 case had neurodevelopmental disorders. The incidence of poor prognosis including death and neurodevelopmental disorders was significantly higher in the group with comorbidities than that without comorbidities (P<0.01). (7) An symptomatic improvement of PAC was found in the majority of the survived cases (18/19) with age.

CONCLUSIONS

Early-onset PAC in infants usually exhibits varying degrees of relief with age, whereas the cases with comorbidities had a poor prognosis.

Mechanisms relating to sleeping position to the endotypes of sleep disordered breathing

PURPOSE

Obstructive sleep apnea (OSA) severity varies considerably depending on the body position during sleep in certain subjects. Such variability may be underpinned by specific, body position-related changes in OSA pathophysiological determinants, or endotypes. Also head position relative to trunk may influence OSA endotypes. However, no studies to our knowledge have reviewed the endotype variations according to head or body position up to now.

RECENT FINDINGS

Several findings illustrate that supine OSA is mostly attributable to unfavorable upper airway anatomy compared to lateral position. However, a reduced lung volume, with consequent ventilatory instability (or elevated loop gain), may also play a role. Furthermore, preliminary findings suggest that prone and reclined positions may have a beneficial effect on collapsibility and loop gain.

SUMMARY

Sleeping supine induces many unfavorable pathophysiological changes, especially in certain predisposed OSA patients. Little is known on the influence of other sleep positions on key endotypic traits.

Pharmacotherapy for obstructive sleep apnea: targeting specific pathophysiological traits

INTRODUCTION

The pathophysiology of obstructive sleep apnea (OSA) is multi-factorial and complex. Varying OSA's pathophysiological traits have been identified, including pharyngeal collapsibility, upper airway muscle reactivity, arousal threshold, and regulation of the ventilatory drive. Being CPAP of difficult tolerance and other interventions reserved to specific subpopulations new pharmacological treatments for OSA might be resolutive.

AREAS COVERED

Several existing and newly developed pharmacological drugs can impact one or more endotypes and could therefore be proposed as treatment options for sleep disordered breathing. With this review we will explore different pathophysiological traits as new targets for OSA therapy. This review will summarize the most promising pharmacological treatment for OSA accordingly with their mechanisms of action on upper airway collapsibility, muscle responsiveness, arousal threshold, and loop gain.

EXPERT OPINION

Only understanding the pathophysiological traits causing OSA in each patient and placing the disease in the framework of patient comorbidities, we will be able to evolve interventions toward OSA. The development of new drug's combinations will permit different approaches and different choices beside conventional treatments. In the next future, we hope that sleep specialists will select the treatment for a specific patient on the base of its pathophysiology, defining a precision medicine for OSA.

Effect of yoga-based lifestyle and dietary modification in overweight individuals with sleep apnea: A randomized controlled trial (ELISA)

BACKGROUND

Obesity is recognised as an important risk factor for obstructive sleep apnea (OSA), with obese individuals at a four times higher risk of being diagnosed with the syndrome. Treating obesity with lifestyle modification is associated with a reduction in the severity of obstructive sleep apnea. Yoga comprises lifestyle modification that includes asana (postures), pranayama (breathing techniques), dhyana (meditation) and guideline principles for healthy living (Yama and Niyama). There is a scarcity of data to evaluate the effect of yoga on OSA. This study was conducted to evaluate the efficacy of Yoga based lifestyle modification on OSA.

METHODS

Consenting obese patients (BMI >23) diagnosed with obstructive sleep apnea (OSA) (AHI>5) on Polysomnography (PSG) were enrolled. Eligible patients were randomized into two groups. The control group received counselling for dietary modification (staple Indian) with regular exercise and the active intervention group received Yoga intervention as treatment (OSA module) in addition to similar dietary modification and regular exercise counselling. Polysomnography (PSG) was conducted at baseline and one year follow-up. All patients were evaluated at baseline, six months, and one year for compliance and anthropometric parameters. Additional assessment with Hamilton scales for depression and anxiety, SF-36, and the Pittsburgh sleep quality index was also conducted.

RESULTS

A total of 37 eligible patients (19 in the control group and 18 in the yoga group) were recruited for the study. The age [45.73 ± 10.71 vs. 46.22 ± 9.39 years, p = 0.88] and gender [15(78.95%) vs. 12(66.67%), p = 0.48 (males)] distribution was similar in both groups. After adjusting for age and gender, the percentage reduction in weight between the two groups did not reach statistical significance at one year. There was no significant difference in mean AHI between the two groups at one year. However, the number of patients with more than 40% AHI reduction [2/19 (10.52%) vs 8/18 (44.44%), p = 0.02] was significantly higher in the yoga group. Additionally, within the groups, the mean AHI at one year was significantly reduced in the yoga group [51.2 ± 28.0 to 36.8 ± 21.0/hour, p = 0.003], while no significant change was found in the control group [47.2 ± 23 to 38.8 ± 19.9/hour, p = 0.08].

CONCLUSIONS

Lifestyle alteration using Yoga intervention and modification of staple Indian diet may be effective in reducing OSA severity among obese patients.

CTRI NUMBER

CTRI/2017/05/008462.

Determinants of awake oropharyngeal volume reduction between sitting and supine positions in children evaluated for snoring

Pharyngeal collapsibility is a major determinant of obstructive sleep apnea (OSA) pathophysiology, but its anatomical predictors in children are largely unknown. We hypothesised that anatomical (tonsillar hypertrophy, narrow palate, nasal obstruction, dental/skeletal malocclusion, obesity) and OSA-related (apnea-hypopnea index, AHI) parameters could be related to a measure of awake pharyngeal collapsibility. We performed acoustic pharyngometry in children evaluated for suspected OSA, allowing us to measure the reduction of oropharyngeal volume in supine versus sitting position normalised for the volume in supine position (ΔV%), a measure of pharyngeal collapsibility. In addition to polysomnography and a clinical examination (anatomical parameters), acoustic rhinometry was used to assess nasal obstruction. A total of 188 snoring children were included, 118 (63%) of whom were obese and 74 (39%) of whom had moderate to severe OSA (AHI ≥5/h). The median (25th-75th percentiles) ΔV% in the whole population was 20.1% (4.7; 43.3). ΔV% was independently and positively associated with AHI (p = 0.023), z-score of BMI (p = 0.001), tonsillar hypertrophy (p = 0.007), narrow palate (p = 0.035), and African (p < 0.001) ancestry. By contrast, ΔV% was not modified by dental or skeletal malocclusion, Friedman palate position class or nasopharyngeal obstruction. Tonsillar hypertrophy, obesity, narrow palate and African ancestry are independently associated with an increase in pharyngeal collapsibility in snoring children, thus increasing the risk of OSA. Increased pharyngeal compliance in African children may explain the increased risk of residual OSA after adenotonsillectomy observed in this population.

Impact of reboxetine plus oxybutynin treatment for obstructive sleep apnea on cardiovascular autonomic modulation

The combination of noradrenergic (reboxetine) plus antimuscarinic (oxybutynin) drugs (reb-oxy) reduced obstructive sleep apnea (OSA) severity but no data are available on its effects on cardiac autonomic modulation. We sought to evaluate the impact of 1-week reb-oxy treatment on cardiovascular autonomic control in OSA patients. OSA patients were randomized to a double-blind, crossover trial comparing 4 mg reboxetine plus 5 mg oxybutynin to a placebo for OSA treatment. Heart rate (HR) variability (HRV), ambulatory blood pressure (BP) monitoring (ABPM) over 24 h baseline and after treatment were performed. Baroreflex sensitivity was tested over beat-to-beat BP recordings. 16 subjects with (median [interquartile range]) age 57 [51-61] years and body mass index 30 [26-36]kg/m² completed the study. The median nocturnal HR was 65 [60-69] bpm at baseline and increased to 69 [64-77] bpm on reb-oxy vs 66 [59-70] bpm on placebo (p = 0.02). The mean 24 h HR from ABPM was not different among treatment groups. Reb-oxy administration was not associated with any modification in HRV or BP. Reb-oxy increased the baroreflex sensitivity and did not induce orthostatic hypotension. In conclusion, administration of reb-oxy did not induce clinically relevant sympathetic overactivity over 1-week and, together with a reduction in OSA severity, it improved the baroreflex function.

Pharmacotherapy for Obstructive Sleep Apnoea and Coupled Life: A Descriptive Phenomenological Study of a Complex Interaction

BACKGROUND

Obstructive Sleep Apnoea (OSA) is a common chronic sleep-related breathing disorder. Drug therapy is a recent approach to treating OSA, and no data is available regarding its effects on a couple's life. The aim of this study was to investigate the impact on couples' lives of a novel drug treatment for OSA.

METHODS

Participants of a trial on new drug therapy (reboxetine plus oxybutynin) for OSA were interviewed. The study was conducted using a descriptive phenomenological approach by Sundler et al. Results: Ten patients and six of their partners were recruited through a purposive sampling between February and April 2021. The results indicate that drug treatment of OSA had a favourable impact on the couples' lives. Pharmacotherapy improved self-reported sleep quality, as the absence of CPAP allows people to sleep closer to the bed partner and because the patient does not have to sleep in a forced position. Moreover, the couples developed teamwork from the beginning which appeared to be crucial during the trial, especially when some difficulties and adverse events occurred.

CONCLUSIONS

This study presents the presence of a positive closed loop that could be considered a predictor of adherence to drug therapy.

The Different Effect of Tongue Motor Task Training (TTT) and Strength Training (ST) on the Modulation of Genioglossus Corticomotor Excitability and upper airway stability in Rats

STUDY OBJECTIVES

the mechanical efficiency of upper airway (UA) muscles are pivotal in maintaining UA stability. We aimed to investigate if different tongue training approaches could differently induce signs of neuroplastic in the corticomotor pathways and upper airway stability changes.

METHODS

36 Sprague-Dawley rats were trained daily for eight weeks to lick an isotonic force-sensing disc at targeting forces using 30-50% of maximal achieved lick force (MALF) for tongue task training (TTT) or targeting force set above 50%, 60% and 70% of MALF progressively for tongue strength training (TST). Corticomotor excitability was dynamically assessed by GG response to transcortical magnetic stimulation (TMS) at different sessions. GG EMG activity, GG ultrastructure and myosin heavy chain (MHC), UA dynamics were assessed after eight weeks.

RESULTS

After 4 weeks, GG TMS latencies decreased in both tongue training groups when compared with the control group (p<0.05) and this excitability was more stable in TTT group. After 8 weeks, both GG TMS response and EMG activity revealed increased excitability in TTT and TST groups. The apoptotic pathological morphology changes of GG ultrastructure were observed in TST group, but not TTT. Percentage of GG MHC type I fibers in TST group was higher than the control and TTT groups (p<0.05). The UA Pcrit decreased significantly in TTT group (p<0.05) and tend to decrease in TST group (p=0.09).

CONCLUSION

TTT could improve the UA stability and induce the neuroplastic changes more efficiently without training-induced muscle injury, while TST revealed a fatigue-resistance change in GG.

Obstructive Sleep Apnea and Adherence to Continuous Positive Airway Pressure (CPAP) Treatment: Let's Talk about Partners!

BACKGROUND

Continuous positive airway pressure (CPAP) is the gold standard treatment for obstructive sleep apnea (OSA). The benefits of this therapy were studied and analyzed over time; patient adherence is often poor, as many factors negatively influence it. A topic that needs clarification is whether adherence to CPAP treatment in a patient with OSA is influenced by the behavior of a partner or spouse.

METHODS

A scoping review was conducted to evaluate the role of partner involvement in the CPAP treatment management in a patient with OSA. The research project was performed between August and September 2021 by consulting the main biomedical databases: CINHAL, Embase, PsycINFO, and PubMed.

RESULTS

Among 21 articles considered valid for our aim, 15 are qualitative studies, 5 are quantitative and 1 presents a mixed method. We identified several thematic areas and "key" elements, which are prevalent in the studies evaluated.

CONCLUSIONS

The presence of a partner promotes adherence to CPAP therapy in patients with OSA, resulting in ameliorating their overall quality of life. To increase CPAP adherence, a trained nurse could represent a reference figure to technically and emotionally support couples during the adaptation period and in the long term.

Comprehensive Analysis of N6-Methyladenosine Regulators in the Subcluster Classification and Drug Candidates Prediction of Severe Obstructive Sleep Apnea

Background: Obstructive sleep apnea (OSA) is the most common type of sleep apnea that impacts the development or progression of many other disorders. Abnormal expression of N6-methyladenosine (m6A) RNA modification regulators have been found relating to a variety of human diseases. However, it is not yet known if m6A regulators are involved in the occurrence and development of OSA. Herein, we aim to explore the impact of m6A modification in severe OSA.

Methods: We detected the differentially expressed m6A regulators in severe OSA microarray dataset GSE135917. The least absolute shrinkage and selection operator (LASSO) and support vector machines (SVM) were used to identify the severe OSA-related m6A regulators. Receiver operating characteristic (ROC) curves were performed to screen and verify the diagnostic markers. Consensus clustering algorithm was used to identify m6A patterns. And then, we explored the character of immune microenvironment, molecular functionals, protein-protein interaction networks and miRNA-TF coregulatory networks for each subcluster. Finally, the Connectivity Map (CMap) tools were used to tailor customized treatment strategies for different severe OSA subclusters. An independent dataset GSE38792 was used for validation.

Results: We found that HNRNPA2B1, KIAA1429, ALKBH5, YTHDF2, FMR1, IGF2BP1 and IGF2BP3 were dysregulated in severe OSA patients. Among them, IGF2BP3 has a high diagnostic value in both independent datasets. Furthermore, severe OSA patients can be accurately classified into three m6A patterns (subcluster1, subcluster2, subcluster3). The immune response in subcluster3 was more active because it has high M0 Macrophages and M2 Macrophages infiltration and up-regulated human leukocyte antigens (HLAs) expression. Functional analysis showed that representative genes for each subcluster in severe OSA were assigned to histone methyltransferase, ATP synthesis coupled electron transport, virus replication, RNA catabolic, multiple neurodegeneration diseases pathway, et al. Moreover, our finding demonstrated cyclooxygenase inhibitors, several of adrenergic receptor antagonists and histamine receptor antagonists might have a therapeutic effect on severe OSA.

Conclusion: Our study presents an overview of the expression pattern and crucial role of m6A regulators in severe OSA, which may provide critical insights for future research and help guide appropriate prevention and treatment options.

Multiple Sclerosis and related disorders

Multiple Sclerosis (MS) is a common neuroinflammatory disorder which is associated with disabling clinical consequences. The MS disease process may involve neural centers implicated in the control of breathing, leading to ventilatory disturbances during both wakefulness and sleep. In this chapter, a brief overview of MS disease mechanisms and clinical sequelae including sleep disorders is provided. The chapter then focuses on obstructive sleep apnea-hypopnea (OSAH) which is the most prevalent respiratory control abnormality encountered in ambulatory MS patients. The diagnosis, prevalence, and clinical consequences as well as data on effects of OSAH treatment in MS patients are discussed, including the impact on the disabling symptom of fatigue and other clinical sequelae. We also review pathophysiologic mechanisms contributing to OSAH in MS, and in turn mechanisms by which OSAH may impact on the MS disease process, resulting in a bidirectional relationship between these two conditions. We then discuss central sleep apnea, other respiratory control disturbances, and the pathogenesis and management of respiratory muscle weakness and chronic hypoventilation in MS. We also provide a brief overview of Neuromyelitis Optica Spectrum Disorders and review current data on respiratory control disturbances and sleep-disordered breathing in that condition.

High-Fat Diet-Induced Mitochondrial Dysfunction Promotes Genioglossus Injury - A Potential Mechanism for Obstructive Sleep Apnea with Obesity

PURPOSE

Obesity is a worldwide metabolic disease and a critical risk factor for several chronic conditions. Obstructive sleep apnea (OSA) is an important complication of obesity. With the soaring morbidity of obesity, the prevalence of OSA has markedly increased. However, the underlying mechanism of the high relevance between obesity and OSA has not been elucidated. This study investigated the effects of obesity on the structure and function of the genioglossus to explore the possible mechanisms involved in OSA combined with obesity.

METHODS

Six-week-old male C57BL/6J mice were fed high-fat diet (HFD, 60% energy) or normal diet (Control, 10% energy) for 16 weeks. The muscle fibre structure and electromyography (EMG) activity of genioglossus were measured. The ultrastructure and function of mitochondrial, oxidative damage and apoptosis in genioglossus were detected by transmission electron microscopy (TEM), qPCR, Western blotting, immunohistochemistry and TUNEL staining. We further studied the influence of palmitic acid (PA) on the proliferation and myogenic differentiation of C2C12 myoblasts, as well as mitochondrial function, oxidative stress, and apoptosis in C2C12 myotubes.

RESULTS

Compared with the control, the number of muscle fibres was decreased, the fibre type was remarkably changed, and the EMG activity had declined in genioglossus. In addition, a HFD also reduced mitochondria quantity and function, induced excessive oxidative stress and increased apoptosis in genioglossus. In vitro, PA treatment significantly inhibited the proliferation and myogenic differentiation of C2C12 myoblasts. Moreover, PA decreased the mitochondrial membrane potential, upregulated mitochondrial reactive oxygen species (ROS) levels, and activated the mitochondrial-related apoptotic pathway in myotubes.

CONCLUSION

Our findings suggest that a HFD caused genioglossus injury in obese mice. The mitochondrial dysfunction and the accompanying oxidative stress were involved in the genioglossus injury, which may provide potential therapeutic targets for OSA with obesity.