Randomised sham-controlled trial of transcutaneous electrical stimulation in obstructive sleep apnoea

Combination of acute intermittent hypoxia and intermittent transcutaneous electrical stimulation in obstructive sleep apnea: a randomized controlled crossover trial

Intermittent hypoxia (IH) and intermittent transcutaneous electrical stimulation (ITES) might benefit patients with obstructive sleep apnea (OSA). However, the therapeutic value of combined IH and ITES in OSA is unknown. In this prospective, randomized, controlled crossover study, normoxia (air exposure for 50 min before sleep and sham stimulation for 6 h during sleep), IH (5 repeats of 5 min 10-12 % O2 alternating with 5 min air for 50 min, and sham stimulation for 6 h), ITES (air exposure for 50 min and 6 repeats of 30 min transcutaneous electrical stimulation alternating with 30 min of sham stimulation for 6 h), and IH&ITES (10-12 % O2 alternating with air for 50 min and transcutaneous electrical stimulation alternating with sham stimulation for 6 h) were administered to patients with OSA over four single-night sessions. The primary endpoint was difference in OSA severity between the interventions according to apnea-hypopnea index (AHI) and oxygen desaturation index (ODI). The efficacy was response to IH, ITES, IH&ITES defined as a ≥50 % reduction in AHI compared with normoxia. Twenty participants (17 male, 3 female) completed the trial. The median (IQR) AHI decreased from 14.5 (10.8, 17.5) events/h with normoxia to 6.9 (3.9, 14.8) events/h with IH (p=0.020), 5.7 (3.4, 9.1) events/h with ITES (p=0.001), and 3.5 (1.8, 6.4) events/h with IH&ITES (p=0.001). AHI was significantly different between IH and IH&ITES (p=0.042) but not between ITES and IH&ITES (p=0.850). For mild-moderate OSA (n=17), IH, ITES, and IH&ITES had a significant effect on AHI (p=0.013, p=0.001, p=0.001, respectively) compared with normoxia, but there were no differences in post hoc pairwise comparisons between intervention groups. No serious adverse events were observed. In conclusion, IH, ITES, and IH&ITES significantly reduced OSA severity. IH&ITES showed better efficacy in mild-moderate OSA than IH and was comparable to ITES. Our data do not support recommending IH&ITES over ITES for OSA.

A randomized controlled crossover trial of acute intermittent and continuous hypoxia exposure in mild-moderate obstructive sleep apnea: A feasibility study

In a prospective, randomized, controlled crossover study, we explored the effects of acute intermittent hypoxia and acute continuous hypoxia on patients with mild-moderate obstructive sleep apnea. Over three single-night sessions, subjects were alternately exposed to normoxia, acute continuous hypoxia and acute intermittent hypoxia before sleep. The apnea-hypopnea index and oxygen desaturation index were used to diagnose obstructive sleep apnea and evaluate efficacy. A responder was defined as a participant with a ≥ 50% reduction in apnea-hypopnea index between normoxia and hypoxia exposure. Sixteen participants with mild-moderate obstructive sleep apnea completed the study. Compared with normoxia, the mean apnea-hypopnea index decreased by 8.9 events per hr (95% confidence interval, 4.2-13.6, p = 0.001) with acute intermittent hypoxia and by 4.1 events per hr (95% confidence interval, 0.5-8.8, p = 0.082) with acute continuous hypoxia, equating to a mean decrease in apnea-hypopnea index of 4.8 events per hr (95% confidence interval, 0.1-9.5, p = 0.046) with acute intermittent hypoxia compared with acute continuous hypoxia. Compared with normoxia, the mean oxygen desaturation index decreased by 9.8 events per hr (95% confidence interval, 4.4-15.1, p = 0.001) with acute intermittent hypoxia but did not significantly decrease with acute continuous hypoxia; the mean oxygen desaturation index decreased by 7.2 events per hr (95% confidence interval, 1.8-12.6, p = 0.010) with acute intermittent hypoxia compared with acute continuous hypoxia. Of the 16 participants, 11 responded to acute intermittent hypoxia and four responded to acute continuous hypoxia (p = 0.032), of whom eight of 11 cases and all four cases had oxygen desaturation indexes <5 events per hr, respectively (p = 0.273). All participants tolerated acute intermittent hypoxia and there were no obvious adverse events during acute intermittent hypoxia exposure. In conclusion, acute intermittent hypoxia exposure improved apnea-hypopnea index and oxygen desaturation index in patients with mild-moderate obstructive sleep apnea, suggesting that further prospective validation of intermittent hypoxia exposure in patients with obstructive sleep apnea is needed to establish its clinical feasibility as a therapeutic modality.

Comparative effectiveness of hypoglossal nerve stimulation and alternative treatments for obstructive sleep apnea: a systematic review and meta-analysis

Continuous positive airway pressure (CPAP) is the primary therapeutic modality for obstructive sleep apnea (OSA) management. However, despite efforts to encourage patients to comply with CPAP usage, long-term adherence remains low. Consequently, surgical intervention for OSA is considered a secondary option for patients who exhibit non-compliance with CPAP. Therefore, we conducted systematic review and meta-analysis assessed the relative effectiveness of hypoglossal nerve stimulation (HNS) treatment and alternative surgical interventions for managing OSA. Five databases were searched. Studies were included if they measured polysomnography parameters and assessed sleep apnea-related quality of life (Epworth Sleepiness Scale [ESS]) both before and after HNS, and compared these outcomes with control, CPAP, or airway surgery (uvulopalatopharyngoplasty, expansion sphincter pharyngoplasty, or tongue base surgery) groups. A total of 10 studies (2209 patients) met the inclusion criteria. Compared to other airway surgeries, the rates of post-treatment apnea-hypopnea index (AHI) < 10 and < 15 events/h were significantly lower in the HNS group (odds ratio [OR] 5.33, 95% confidence interval [CI] 1.21-23.42; and 2.73, 95% CI 1.30-5.71, respectively). Additionally, postoperative AHI was significantly lower in the HNS group than in all other airway surgery groups (AHI: mean difference [MD] -8.00, 95% CI -12.03 to-3.97 events/h). However, there were no significant differences in the rate of post-treatment AHI < 5 events/h (OR 1.93, 95% CI 0.74-5.06) or postoperative ESS score (MD 0.40, 95% CI-1.52 to 2.32) between the two groups. HNS is an effective option for selected patients with moderate-to-severe OSA and CPAP intolerance.

Hypoglossal Nerve Stimulation Effects on Obstructive Sleep Apnea Over Time: A Systematic Review and Meta-analysis

OBJECTIVES

This study aimed to determine the efficacy of hypoglossal nerve stimulation (HGS) in the treatment of obstructive sleep apnea.

DATA SOURCES

PubMed, Cochrane database, Embase, Web of Science, SCOPUS, and Google Scholar.

REVIEW METHODS

Five databases were reviewed to identify relevant studies that measured polysomnography parameters such as the apnea-hypopnea index (AHI) and oxygen desaturation index, as well as quality of life and functional outcomes of sleep questionnaire scores, before and after HGS.

RESULTS

In total, 44 studies involving 8670 patients met the inclusion criteria. At 12 months after treatment, approximately 47%, 72%, and 82% of patients achieved AHI values of <5, < 10, and <15, respectively. The reported clinical success rates according to Sher criteria were 80% within 12 months and 73% between 12 and 36 months. While the favorable effects exhibited a gradual reduction up to 12 months postimplantation, they generally maintained a consistent level between the 12th and 36th months, as assessed by AHI < 5, <15, and success rate according to Sher criteria.

CONCLUSION

HGS can enhance quality of life scores and polysomnography outcomes in obstructive sleep apnea patients. Although the positive effects gradually decreased until 12 months after implantation, they generally remained consistent between 12 and 36 months.

Domiciliary transcutaneous electrical stimulation in patients with obstructive sleep apnoea and limited adherence to continuous positive airway pressure therapy: a single-centre, open-label, randomised, controlled phase III trial

Background

Hypoglossal nerve stimulation (HNS) for obstructive sleep apnoea (OSA) is a novel way to manage the condition. We hypothesised that in patients with OSA and limited adherence to continuous positive airway pressure (CPAP) therapy, domiciliary transcutaneous electrical stimulation (TESLA) would control sleep apnoea and provide health benefits.

Methods

We undertook a single-centre, open-label, randomised, controlled phase III trial in patients with OSA (apnoea-hypopnoea-index [AHI] 5-35 h-1), a BMI of 18.5-32 kg∗m-2, and a documented lack of adherence to CPAP therapy (<4 h∗night-1) at Guy's & St Thomas' NHS Foundation Trust (hospital), UK. Patients were randomly assigned (1:1) using minimisation (gender and OSA severity) to receive TESLA or usual care (CPAP) for at least 3 months; sleep study analysis was provided without knowledge of the assignment arm. The primary outcome was change in AHI at 3-months. The primary outcome and safety were analysed in the intention-to-treat population. Data are reported as median (interquartile range), unless otherwise explained. This trial is registered at ClinicalTrials.gov, NCT03160456.

Findings

Between 6 June 2018 and 7 February 2023, 56 participants were enrolled and randomly assigned (29 patients in the intervention group and 27 in the usual care group). Patients were followed up for a median of 3.0 months (IQR 3.0; 10.0). The groups were similar in terms of age (55.8 (48.2; 66.0) vs 59.3 (47.8; 64.4) years), gender (male:female, 19:10 vs 18:9) and BMI (28.7 (26.4; 31.9) vs 28.4 (24.4; 31.9) kg∗m-2). The unadjusted group difference in the Δ AHI was -11.5 (95% CI -20.7; -2.3) h-1 (p = 0.016). Adjusted for the baseline value, the difference was Δ AHI -7.0 (-15.7; 1.8) h-1 (p = 0.12), in favour of the intervention. Minor adverse events were found in one of the participants who developed mild headaches related to the intervention.

Interpretation

Domiciliary TESLA can be used safely and effectively in OSA patients with poor adherence to CPAP, with favourable impact on sleepiness and sleep fragmentation. Despite pandemic-related limitations of the amended protocol this trial provides the evidence that TESLA improves clinically meaningful outcomes over the observed follow up period, and the transcutaneous approach is likely to offer an affordable alternative for responders to electrical stimulation in clinical practice.

Funding

British Lung Foundation, United Kingdom Clinical Research Collaboration-registered King's Clinical Trials Unit at King's Health Partners.

Beyond CPAP: modifying upper airway output for the treatment of OSA

Obstructive Sleep Apnea (OSA) is exceedingly common but often under-treated. Continuous positive airway pressure (CPAP) has long been considered the gold standard of OSA therapy. Limitations to CPAP therapy include adherence and availability. The 2021 global CPAP shortage highlighted the need to tailor patient treatments beyond CPAP alone. Common CPAP alternative approaches include positional therapy, mandibular advancement devices, and upper airway surgery. Upper airway training consists of a variety of therapies, including exercise regimens, external neuromuscular electrical stimulation, and woodwind instruments. More invasive approaches include hypoglossal nerve stimulation devices. This review will focus on the approaches for modifying upper airway muscle behavior as a therapeutic modality in OSA.

Randomised, controlled crossover trial of intermittent and continuous transcutaneous electrical stimulation of the genioglossus muscle for obstructive sleep apnoea

PURPOSE

Continuous transcutaneous electrical stimulation (CTES) of the genioglossus muscle may benefit patients with obstructive sleep apnoea (OSA). However, the therapeutic value of intermittent transcutaneous electrical stimulation (ITES) for OSA is unclear.

METHODS

This was a randomised, controlled, crossover study to compare the effects of ITES and CTES of the genioglossus muscle. Over three single-night sessions, participants were alternately subjected to three genioglossus stimulation modalities during sleep (sham, CTES and ITES). The apnoea-hypopnoea index (AHI) and oxygen desaturation index (ODI) were used for OSA diagnosis and to evaluate efficacy. A responder was defined as an individual with a ≥50% reduction in AHI together with <10 AHI events per hour and/or an ODI reduction of ≥25% between sham stimulation and electrical stimulation nights.

RESULTS

Fifteen men with OSA completed the study. Compared with sham, the median AHI with ITES decreased by 13.3 events/hour (95% CI 3.1 to 23.5, p=0.030) and by 7.3 events/hour (95% CI -3.9 to 18.5, p=0.825) with CTES. The median ODI was reduced by 9.25 events/hour (95% CI 0.5 to 18.0) with ITES and 3.3 events/hour (95% CI -5.6 to 12.2) with CTES; however, there was no significant difference between groups. Furthermore, ITES outperformed CTES with respect to longest apnoea duration (median (95% CI), 9.5 (0.0 to 19.0), p=0.011)) and the highest sleep efficiency (12.2 (2.7 to 21.7), p=0.009). Of the 15 participants, 8 responded to ITES and 3 responded to CTES (p=0.058), of whom all eight cases and two out of three cases had ODIs <5 events/hour, respectively. All participants tolerated ITES well.

CONCLUSIONS

ITES improved upper airway obstruction in patients with OSA, suggesting that further prospective validation of the intermittent approach is warranted.

TRIAL REGISTRATION NUMBER

ChiCTR2100050138.

The effect of transcutaneous electrical stimulation of the submental area on the cardiorespiratory response in normal and awake subjects

Background: Electrical stimulation has recently been introduced to treat patients with Obstructive sleep apnoea There are, however, few data on the effects of transcutaneous submental electrical stimulation (TES) on the cardiovascular system. We studied the effect of TES on cardiorespiratory variables in healthy volunteers during head-down-tilt (HDT) induced baroreceptor loading.

Method: Cardiorespiratory parameters (blood pressure, heart rate, respiratory rate, tidal volume, airflow/minute ventilation, oxygen saturation, and end-tidal CO2/O2 concentration) were recorded seated, supine, and during head-down-tilt (50) under normoxic, hypercapnic (FiCO2 5%) and poikilocapnic hypoxic (FiO2 12%) conditions. Blood pressure (BP) was measured non-invasively and continuously (Finapres). Gas conditions were applied in random order. All participants were studied twice on different days, once without and once with TES.

Results: We studied 13 healthy subjects (age 29 (12) years, six female, body mass index (BMI) 23.23 (1.6) kg·m−2). A three-way ANOVA indicated that BP decreased significantly with TES (systolic: p = 4.93E-06, diastolic: p = 3.48E-09, mean: p = 3.88E-08). Change in gas condition (systolic: p = 0.0402, diastolic: p = 0.0033, mean: p = 0.0034) and different postures (systolic: 8.49E-08, diastolic: p = 6.91E-04, mean: p = 5.47E-05) similarly impacted on BP control. When tested for interaction, there were no significant associations between the three different factors electrical stimulation, gas condition, or posture, except for an effect on minute ventilation (gas condition/posture p = 0.0369).

Conclusion: Transcutaneous electrical stimulation has a substantial impact on the blood pressure. Similarly, postural changes and variations in inspired gas impact on blood pressure control. Finally, there was an interaction between posture and inspired gases that affects minute ventilation. These observations have implications on our understanding of integrated cardiorespiratory control, and may prove beneficial for patients with SDB who are assessed for treatment with electrical stimulation.

Transcutaneous electrical stimulation in obstructive sleep apnoea: current developments and concepts of the TESLA-home programme

PURPOSE OF REVIEW

Obstructive sleep apnoea (OSA) is a highly prevalent condition affecting about 1 billion people worldwide. The first line therapy for most patients with OSA is continuous positive airway pressure (CPAP) therapy. However, there are significant limitations with long-term adherence to CPAP therapy, which may be as low as 30-60%.

RECENT FINDING

Electrical stimulation of the hypoglossal nerve has been studied in recent years. It achieves upper airway patency by causing a contraction of the genioglossus muscle, the strongest dilator of the upper airway, and by maintaining its neuromuscular tone in the asleep patient with OSA. Electrical stimulation can be delivered invasively, hypoglossal nerve stimulation (HNS), and noninvasively, transcutaneous electrical stimulation in OSA (TESLA). However, randomised controlled trials, the STAR and the TESLA trial, have provided promising results on efficacy and safety of the methods.

SUMMARY

Patient and public involvement underlines the interest in TESLA and HNS and highlights the need to provide non-CPAP therapeutic options to those who may find it difficult to cope with first line therapies. The relatively low costs and the favourable safety profile of the TESLA approach provide the chance to offer this treatment to patients with OSA following further development of the evidence.

Non-CPAP therapy for obstructive sleep apnoea

Treatment of obstructive sleep apnoea in adults is evolving, from a "one treatment fits all" to a more individualised approach. The spectrum of treatment options is broad and heterogeneous, including conservative, technological and pharmaceutical modalities. This raises the questions of which patients these modalities might be useful for, and if there are specific criteria for single or combined treatment. The most commonly used non-CPAP treatment is a mandibular advancement device. Furthermore, it appears from the available evidence that upper airway surgery, bariatric surgery, and maxillomandibular advancement can be effective in particular patient groups and should be indicated more readily in clinical practice. Technically, a tracheotomy is the most effective surgical treatment, but is not socially acceptable and is associated with major side-effects. Other treatment options are emerging, like positional therapy, hypoglossal nerve stimulation, and myofunctional exercises. Drug therapy is also promising when pathophysiological traits are considered. The range of currently available treatment options will be discussed in this review, with emphasis on the selection of appropriate patients, therapeutic efficacy and compliance, and reference to recent guidelines. In the selection process, routine application of drug-induced sleep endoscopy to assess the site(s) of collapse during sleep can increase the success rate of both surgical interventions and oral appliance therapy.

Educational aims

To outline recommendations concerning the proper management of obstructive sleep apnoea (OSA) patients that cannot be treated adequately with continuous positive airway pressure (CPAP) due to intolerance, poor adherence or compliance, or CPAP refusal.To provide information about the selection of appropriate patients for alternative non-CPAP treatment options.To better understand the different aspects of OSA treatment with noninvasive approaches, such as oral appliances, positional therapy, drug treatment and myofunctional therapy, including indications, contraindications, and expected short- and long-term results.To discuss the different surgical options for the treatment of OSA and to provide information on the important issue of proper patient selection for surgery, as most OSA surgical outcomes are associated with the pre-operative assessment of the level(s) of upper airway collapse.

Current and Novel Treatment Options for OSA

Obstructive sleep apnoea is a challenging medical problem due to its prevalence, its impact on quality of life and performance in school and professionally, the implications for risk of accidents, and comorbidities and mortality. Current research has carved out a broad spectrum of clinical phenotypes and defined major pathophysiological components. These findings point to the concept of personalised therapy, oriented on both the distinct clinical presentation and the most relevant pathophysiology in the individual patient. This leads to questions of whether sufficient therapeutic options other than positive airway pressure (PAP) alone are available, for which patients they may be useful, if there are specific indications for single or combined treatment, and whether there is solid scientific evidence for recommendations. This review describes our knowledge on PAP and non-PAP therapies to address upper airway collapsibility, muscle responsiveness, arousability and respiratory drive. The spectrum is broad and heterogeneous, including technical and pharmaceutical options already in clinical use or at an advanced experimental stage. Although there is an obvious need for more research on single or combined therapies, the available data demonstrate the variety of effective options, which should replace the unidirectional focus on PAP therapy.

The analysis of individual pathophysiological composition opens new directions towards personalised treatment of OSA, focusing not only on pharyngeal dilation, but also on technical or pharmaceutical interventions on muscle function or breathing regulationhttps://bit.ly/3sayhkd

Beyond Usual Care: A Multidisciplinary Approach Towards the Treatment of Obstructive Sleep Apnoea

Obstructive Sleep Apnoea (OSA) is common and characterised by repeated apnoeas and hypopnoeas while asleep due to collapse of the upper airway. OSA can have a significant impact on physical and mental health and, when left untreated, is associated with increased risk of developing cardiovascular ill health. Besides cardiorespiratory implications excessive daytime sleepiness, morning headaches, limited memory function and lack of concentration are some further symptoms caused by OSA. Continuous Positive Airway Pressure (CPAP) therapy is the evidence-based treatment to maintain upper airway patency in patients with moderate to severe OSA. Proper adherence to CPAP therapy successfully abolishes nocturnal apnoeas and hypopnoeas, and diminishes consequences of uncontrolled OSA, such as treatment resistant hypertension. However, long term adherence to CPAP remains an unresolved limitation of this method. Although alternatives to CPAP therapy may be less efficacious, there is a variety of non-CPAP treatments that includes conventional lifestyle advice, postural advice, the use of mandibular advancement devices (MADs), surgical treatment options, such as uvulopalatopharyngoplasty, tonsillectomy, or maxillomandibular advancement, and the use of electrical stimulation of the upper airway dilator muscles. Hypoglossal Nerve Stimulation is available as an invasive (HNS) and a transcutaneous (TESLA) approach. For the management of “difficult-to-treat” patients with OSA, particularly in those in whom first line therapy proved to be unsuccessful, a multidisciplinary team approach may be helpful to incorporate the available options of non-CPAP therapy and provide appropriate choices. Symptom control, patient-related outcome measures and long-term cardiovascular health should be prioritised when choosing long-term therapies to treat OSA. The inclusion of patients in the choice of successful management options of their condition will facilitate better long-term adherence. Advancing clinical trials in the field will further help to resolve the relative lack of evidence for effective non-CPAP methods.

European Respiratory Society guideline on non-CPAP therapies for obstructive sleep apnoea

Treatment of obstructive sleep apnoea (OSA) in adults is evolving, as new therapies have been explored and introduced in clinical practice, while other approaches have been refined or reconsidered. In this European Respiratory Society (ERS) guideline on non-continuous positive airway pressure (CPAP) therapies for OSA, we present recommendations determined by a systematic review of the literature. It is an update of the 2011 ERS statement on non-CPAP therapies, advanced into a clinical guideline. A multidisciplinary group of experts, including pulmonary, surgical, dentistry and ear–nose–throat specialists, methodologists and patient representatives considered the most relevant clinical questions (for both clinicians and patients) relating to the management of OSA. Eight key clinical questions were generated and a systematic review was conducted to identify published randomised clinical trials that answered these questions. We used the GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach to assess the quality of the evidence and the strength of recommendations. The resulting guideline addresses gastric bypass surgery, custom-made dual-block mandibular advancement devices, hypoglossal nerve stimulation, myofunctional therapy, maxillo-mandibular osteotomy, carbonic anhydrase inhibitors and positional therapy. These recommendations can be used to benchmark quality of care for people with OSA across Europe and to improve outcomes.

OSA-patients who refuse/don't adhere to CPAP can profit from established/emerging treatment options. High scientific evidence is lacking. Patients’ values/preference may weigh heavy in the decision for non-CPAP options, while health inequity is a concern.https://bit.ly/3o0tJeP

Neuromodulation in Obstructive Sleep Apnea

Epidemiological studies show a steady rise in the prevalence of obstructive sleep apnea (OSA). Untreated OSA is responsible for numerous chronic health conditions, motor vehicle, and workplace-related accidents leading to substantial economic burden both to the individual and society. Multiple causes for OSA and a wide range of consequences has made its diagnosis and treatment difficult. Obstructive sleep apnea may be caused by anatomical variation, increased collapsibility of the upper airway, low sleep arousal threshold, and exaggerated response to desaturation. Lifestyle changes, anatomical corrective surgeries, and oral appliances have been used but patient compliance is poor as it interferes in the daily routine. Neuromodulation is a promising functional modifying option that addresses the cause of obstructive sleep apnea at multiple levels.

Noninvasive electrical stimulation of oropharyngeal muscles in obstructive sleep apnea

Introduction: Continuous positive airway pressure (CPAP) therapy remains the standard treatment for obstructive sleep apnea. However, its proven effect is useless if the patient does not tolerate the treatment. The electrical stimulation approach has been investigated for several decades now and it seems that the implantable devices for invasive electrical stimulation of hypoglossal nerve are viewed as effective with some of them already approved for human use.Areas covered: in this review, we intent to summarize the existing records of noninvasive stimulation in sleep apnea to make the scientific community aware of the details before deciding on its future. We believe that this is a battle still to fight and more could be done bearing in mind the safety of this method.Expertopinion: noninvasive electrical stimulation has been left behind based on few, small and inconsistent studies using different stimulation parameters. These studies are difficult to compare and to draw conclusions.Electrical stimulation is a field for research in the treatment of obstructive sleep apnea, with many aspects still to be discovered, and which may become a therapeutic alternative to the use of CPAP in certain patients.

The combination of intermittent electrical stimulation with acute intermittent hypoxia strengthens genioglossus muscle discharge in chronic intermittent hypoxia-pretreated rats

OBJECTIVE

Exploring whether the genioglossus discharge in chronic intermittent hypoxia(CIH) - pretreated rats could be enhanced by intermittent electrical stimulation combined with acute intermittent hypoxia(AIH).

METHODS

Rats were pretreated with CIH for 4 weeks and then were randomly divided into 6 groups: time control, intermittent electric stimulation, AIH, intermittent electric stimulation + AIH, continuous electric stimulation and continuous hypoxia exposure. The genioglossus discharges were recorded and compared before and after stimulation. Normoxic-treated rats were grouped and treated with the same stimulation protocols.

RESULTS

Intermittent electrical stimulation or AIH temporarily increased the activity of the genioglossus discharge, in which the degree of the increase was significantly higher in CIH-pretreated rats than in normoxic rats.After intermittent electrical stimulation, AIH evoked a sustained elevation of genioglossus discharge activities in CIH-pretreated rats, in which the degree of the increase was significantly higher than in rats induced by a single intermittent electric stimulation.

CONCLUSION

Intermittent electrical stimulation combined with AIH strengthens the genioglossus plasticity in CIH-pretreated rats.

Clinical and Research Solutions to Manage Obstructive Sleep Apnea: A Review

Obstructive sleep apnea (OSA), a common sleep disorder disease, affects millions of people. Without appropriate treatment, this disease can provoke several health-related risks including stroke and sudden death. A variety of treatments have been introduced to relieve OSA. The main present clinical treatments and undertaken research activities to improve the success rate of OSA were covered in this paper. Additionally, guidelines on choosing a suitable treatment based on scientific evidence and objective comparison were provided. This review paper specifically elaborated the clinically offered managements as well as the research activities to better treat OSA. We analyzed the methodology of each diagnostic and treatment method, the success rate, and the economic burden on the world. This review paper provided an evidence-based comparison of each treatment to guide patients and physicians, but there are some limitations that would affect the comparison result. Future research should consider the consistent follow-up period and a sufficient number of samples. With the development of implantable medical devices, hypoglossal nerve stimulation systems will be designed to be smart and miniature and one of the potential upcoming research topics. The transcutaneous electrical stimulation as a non-invasive potential treatment would be further investigated in a clinical setting. Meanwhile, no treatment can cure OSA due to the complicated etiology. To maximize the treatment success of OSA, a multidisciplinary and integrated management would be considered in the future.

Emerging Technologies and Indications of Neuromodulation and Increasing Role of Non Invasive Neuromodulation

Altering the enormous complex connectivity and output of the central nervous system is one of the most fascinating development in medical technologies. It harbors the ability to treat and modulate different neurological disorders and diseases such as Parkinson's disease, Alzheimer's disease and even help with drug delivery to treat unreachable areas of brain via opening of the blood brain barrier. Evolution of neuromodulation techniques has been significant in last few years. They have become less invasive and more focused. Newer neuromodulation techniques consist of invasive, minimally invasive and non-invasive technologies. The decision to use one of these technologies depends on the indication and the targeted area within the central or peripheral nervous system. In the last decade technological advances and the urge to minimize the surgical and the long term complications of hardware implantation, have pushed the neurosurgical community to increase the use of non-invasive neuromodulation technics. In this article, we will discuss the different emerging technologies in neuromodulation and the increasing role of non-invasive neuromodulation.

Practice Recommendations for Diagnosis and Treatment of the Most Common Forms of Secondary Hypertension

The vast majority of hypertensive patients are never sought for a cause of their high blood pressure, i.e. for a 'secondary' form of arterial hypertension. This under detection explains why only a tiny percentage of hypertensive patients are ultimately diagnosed with a secondary form of arterial hypertension. The prevalence of these forms is, therefore, markedly underestimated, although, they can involve as many as one-third of the cases among referred patients and up to half of those with difficult to treat hypertension. The early detection of a secondary form is crucial, because if diagnosed in a timely manner, these forms can be cured at long-term, and even when cure cannot be achieved, their diagnosis provides a better control of high blood pressure, and allows prevention of hypertension-mediated organ damage, and related cardiovascular complications. Enormous progress has been made in the understanding, diagnostic work-up, and management of secondary hypertension in the last decades. The aim of this minireview is, therefore, to provide updated concise information on the screening, diagnosis, and management of the most common forms, including primary aldosteronism, renovascular hypertension, pheochromocytoma and paraganglioma, Cushing's syndrome, and obstructive sleep apnea.

Ultrasound assessment of upper airway dilator muscle contraction during transcutaneous electrical stimulation in patients with obstructive sleep apnoea

Background

Electrical current can be used to stimulate upper airway dilator muscles to treat obstructive sleep apnoea (OSA). Ultrasound devices are widely available and may be used to detect contraction of the upper airway dilator muscles assessing the functionality of electrical stimulation (ES) used for this treatment.

Methods

In a physiological sub-study of a randomised controlled trial, patients with OSA underwent ultrasound examination to assess contraction of the upper airway dilator muscles in response to transcutaneous ES. Ultrasound scans were scored according to the picture quality (poor = '0', acceptable = '1' and good = '2'). Tongue base thickness was assessed in mid-sagittal and coronal planes with (D2, A2) and without ES (D1, A1), while awake and seated. The primary outcome was to determine the increase in tongue thickness during ES in both views (D2 - D1 = ΔD), as well as any increase in the cross-sectional area (CSA) in the coronal view (A2 - A1 = ΔA). Data were presented as mean and standard deviation (SD).

Results

Fourteen patients [eight male, age 57.5 (9.8) years, body mass index (BMI) 29.5 (2.8) kg/m²] with OSA [Apnea-Hypopnea Index (AHI) 19.5 (10.6) × hour^-1] were studied. Quality of the ultrasound scans was acceptable or good with 1.5 (0.5) points. In the mid-sagittal plane, ΔD was +0.17 (0.07) cm in midline and +0.21 (0.09) cm in the widest diameter, a percentual change of 12.2% (4%) and 12.8% (5.2%) (P<0.001, respectively). In the coronal plane, ΔD was +0.17 (0.04) cm, an increase of 12.3% (4.6%) (P<0.001, respectively), ΔA in the CSA increased by +18.9% (3.0%) with stimulation (P<0.001). There was a negative correlation between age and ΔA (r= -0.6, P=0.03), but no significant associations were found with gender, BMI, neck circumference, Epworth Sleepiness Scale (ESS), AHI, skin and subcutaneous tissue in the submental area.

Conclusions

Ultrasound can visualise upper airway dilator muscle contraction during transcutaneous ES in awake patients with OSA. Contraction is best detected in the CSA of the tongue base in the coronal plane.

Electrical stimulation as a therapeutic approach in obstructive sleep apnea - a meta-analysis

PURPOSE

Electrical stimulation of the upper airway dilator muscles is an emerging treatment for obstructive sleep apnea (OSA). Invasive hypoglossal nerve stimulation (HNS) has been accepted as treatment alternative to continuous positive airway pressure (CPAP) for selected patients, while transcutaneous electrical stimulation (TES) of the upper airway is being investigated as non-invasive alternative.

METHODS

A meta-analysis (CRD42017074674) on the effects of both HNS and TES on the apnea-hypopnea index (AHI) and the Epworth Sleepiness Scale (ESS) in OSA was conducted including published evidence up to May 2018. Random-effects models were used. Heterogeneity and between-study variance were assessed by I² and τ², respectively.

RESULTS

Of 41 identified clinical trials, 20 interventional trials (n = 895) could be pooled in a meta-analysis (15 HNS [n = 808], 5 TES [n = 87]). Middle-aged (mean ± SD 56.9 ± 5.5 years) and overweight (body mass index 29.1 ± 1.5 kg/m²) patients with severe OSA (AHI 37.5 ± 7.0/h) were followed-up for 6.9 ± 4.0 months (HNS) and 0.2 ± 0.4 months (TES), respectively. The AHI improved by - 24.9 h^-1 [95%CI - 28.5, - 21.2] in HNS (χ² 79%, I² 82%) and by - 16.5 h^-1 [95%CI - 25.1, - 7.8] in TES (χ² 7%, I² 43%; both p < 0.001). The ESS was reduced by - 5.0 (95%CI - 5.9, - 4.1) (p < 0.001).

CONCLUSION

Both invasive and transcutaneous electrical stimulation reduce OSA severity by a clinically relevant margin. HNS results in a clinically relevant improvement of symptoms. While HNS represents an invasive treatment for selected patients with moderate to severe OSA, TES should be further investigated as potential non-invasive approach for OSA.

Transcutaneous Electrical Stimulation Therapy in Obstructive Sleep Apnea: A Systematic Review and Meta-analysis

OBJECTIVE

To evaluate the treatment efficacy of transcutaneous electrical nerve stimulation (TENS) in patients with obstructive sleep apnea (OSA).

DATA SOURCES

Primary studies were identified though PubMed, Scopus, OVID, and Cochrane Library.

REVIEW METHODS

Systematic review was conducted by querying databases for articles published through July 2019. The search identified randomized controlled trial, randomized comparison, or observational studies pertaining to TENS treatment for OSA. Meta-analysis was performed on pre- and posttreatment apnea-hypopnea index (AHI), mean oxygen saturation (SaO₂), lowest oxygen saturation (LSAT), and arousal index (AI).

RESULTS

Literature search identified 10 studies that reported sufficient outcome measures to be considered for analysis. A total of 198 patients were identified with a mean age of 50.9 years with a male to female ratio of 1.6:1. Average body mass index (BMI) of the cohort was 29.8 kg/m². Treatment with TENS demonstrated reduction in AHI by 12.9 points (95% confidence interval, -22.3 to -3.43; P = .008). The mean differences in SaO₂, LSAT, and AI did not reach statistical significance.

CONCLUSION

The TENS treatment of upper airway dilator muscles resulted in reduction of AHI in patients with OSA. However, its effects on SaO₂, LSAT, and AI were equivocal. Its impact on patients' quality of life could not be assessed due to heterogeneity in outcome measures. Future randomized controlled trials with generalizable standardized outcome measures are needed to assess the efficacy and compliance of TENS.

Hypoglossal Nerve Stimulation in the Treatment of Obstructive Sleep Apnea: Patient Selection and New Perspectives

Hypoglossal nerve stimulation (HNS) is an increasingly widespread OSA treatment. It is a non-anatomical modifying surgery able to achieve an adequate objective and subjective result with a reasonable complication rate. HNS exploits the neurostimulation to reduce upper airway collapsibility providing a multilevel upper airway improvement within a single procedure. Proper patient selection has a fundamental role in determining an adequate long-term clinical outcome. All patient candidates for HNS undergo a standard comprehensive sleep medicine assessment and upper airway surgical examination. Several features should be assessed preoperatively in order to predict patients' response to HNS treatment. In particular, the assessment of OSA severity, BMI > 32 Kg/m², collapse pattern during drug-induced sleep endoscopy (DISE), and many other parameters, is central for a good patient selection and customization of OSA treatment. HNS is indeed one of the most promising tools in the widespread context of personalized sleep medicine. HNS is an adjustable medical device that could be titrated in order to improve HNS effectiveness, maintaining patient comfort. Moreover, HNS provides the opportunity for patients to play an active role in their own care, with a potential improvement in therapy adherence and efficacy. This review summarizes the current evidence in patient selection for HNS, highlighting the reasons behind the optimistic future of this OSA treatment in the context of personalized medicine.

The specific branches leading to the genioglossus muscle: three-dimensional localisation using skin reference points

INTRODUCTION

Supra-selective stimulation of the branches destined for the horizontal part of genioglossus muscle (GGh) could be a target of choice in the treatment of mild-to-severe obstructive sleep apnea syndrome. The main aim of our study was to assess a percutaneous method for the three-dimensional localisation of the terminal branches destined to GGh.

MATERIALS AND METHODS

Twenty cadaveric hypoglossal nerves were dissected and included in the injection protocol. The distance between the posterior edge of the mandibular symphysis and the hyoid bone on the sagittal midline as the approximated distance of the geniohyoid muscle (dGH) was measured before any dissection. Methylene blue mixed with a thickening agent, was injected. The injection point was defined in relation to dGH, in an orthonormal coordinate system. For each dissection, we recorded the theoretical and the real (X, Y, Z) coordinates of GGh motor points and measured their distance to each other.

RESULTS

X was accurately estimated. Y and Z were overestimated by + 5.34 ± 5.21 mm ([Formula: see text]) and + 4.79 ± 3.99 mm ([Formula: see text]) on average, respectively. We found a more significant difference between the theoretical and real Y and Z coordinates in the subgroup BMI < 25 kg/m² (8.6 ± 4.5 mm and 6.9 ± 2.5 mm, respectively, p = 0.0009), and of Z in subgroup with dGH ≥ 50 mm (6.89 ± 3.26 mm, p = 0.0494).

CONCLUSIONS

X can be estimated accurately using the relationship [Formula: see text]. Y seems to be related to BMI and Z may be estimated with the relationship [Formula: see text]. This three-dimensional localisation could be very helpful to facilitate placement of cuff electrodes to manage refractory sleep apnea.

Domiciliary use of transcutaneous electrical stimulation for patients with obstructive sleep apnoea: a conceptual framework for the TESLA home programme

Obstructive sleep apnoea (OSA) is a global health problem of increasing prevalence. Effective treatments are available with continuous positive airway pressure (CPAP) therapy and mandibular advancement devices (MAD). However, there is limited long-term adherence to therapy, as CPAP and MAD require permanent usage to avoid recurrence of the symptoms and adverse ill health. Alternative treatments would aid in the treatment cascade to manage OSA effectively whenever standard therapy has been trialled and failed. Hypoglossal nerve stimulation (HNS), an invasive approach to stimulate the pharyngeal dilator muscles of the upper airway during sleep, has been approved for the treatment of OSA by several healthcare systems in recent years. In parallel to the development of HNS, a non-invasive approach has been developed to deliver electrical stimulation. Transcutaneous electrical stimulation in obstructive sleep apnoea (TESLA) uses non-invasive electrical stimulation to increase neuromuscular tone of the upper airway dilator muscles of patients with OSA during sleep. Data from previous feasibility studies and randomised controlled trials have helped to identify a subgroup of patients who are "responders" to this treatment. However, further investigations are required to assess usability, functionality and task accomplishment of this novel treatment. Consideration of these factors in the study design of future clinical trials will strengthen research methodology and protocols, improve patient related outcome measures and assessments, to optimise this emerging therapeutical option. In this review, we will introduce a conceptual framework for the TESLA home programme highlighting qualitative aspects and outcomes.

Kinesthetic stimulation for obstructive sleep apnea syndrome: An "on-off" proof of concept trial

Obstructive sleep apnea (OSA) occurs when the upper airway narrows or collapses due to the loss of upper airway muscle activation at sleep onset. This study investigated the effectiveness of triggered kinesthetic stimulation in patients with OSA. This proof-of-concept, open-label, multicenter prospective study was conducted on 24 patients with severe OSA. During a one night evaluation, kinesthetic stimulation was intermittently delivered in 30 minute periods. The duration of apneas and hypopneas during Stim _on and Stim _off periods were compared. Five hospital-based university centers in France participated. Sleep studies were evaluated by a single scorer at a core laboratory (CHU Grenoble). Results show that during the Stim _on phases, statistically significant decreases in durations of apneas and hypopneas were observed in 56% and 46% of patients, respectively. Overall, 75% of patients showed an improvement in apneas or hypopneas durations. The mean reduction in durations for patients with a significant decrease was 4.86 seconds for apneas and 6.00 seconds for hypopneas. This proof of concept study is the first to identify kinesthetic stimulation as a potentially effective therapy for OSA. These data justify evaluation in a controlled study.

Phenotyping the pathophysiology of obstructive sleep apnea using polygraphy/polysomnography: a review of the literature

Continuous positive airway pressure (CPAP) is the first-line treatment for the majority of patients affected by obstructive sleep apnea syndrome (OSA). However, long-term compliance with CPAP therapy may result limited and alternatives to CPAP therapy are required to address the increasing need to provide tailored therapeutic options. Understanding the pathophysiological traits (PTs) of OSA patients [upper airway (UA) anatomical collapsibility, loop gain (LG), arousal threshold (AT), and UA gain (UAG)] lies at the heart of the customized OSA treatment. However, sleep research laboratories capable to phenotype OSA patients are sparse and the diagnostic procedures time-consuming, costly, and requiring significant expertise. The question arises whether the use of routine clinical polysomnography or nocturnal portable multi-channel monitoring (PSG/PM) can provide sufficient information to characterize the above traits. The aim of the present review is to deduce if the information obtainable from the clinical PSG/PM analysis, independently of the scope and context of the original studies, is clinically useful to define qualitatively the PTs of individual OSA patients. In summary, it is possible to identify four patterns using PSG/PM that are consistent with an altered UA collapsibility, three that are consistent with altered LG, two with altered AT, and three consistent with flow limitation/UA muscle response. Furthermore, some PSG/PM indexes and patterns, useful for the suitable management of OSA patient, have been discussed. The delivery of this clinical approach to phenotype pathophysiological traits will allow patients to benefit in a wider range of sleep services by facilitating tailored therapeutic options.

Non-surgical treatment of obstructive sleep apnea syndrome

Obstructive sleep apnea syndrome (OSAS), a pervasive disease, is closely associated with complications such as cardiovascular diseases, neurocognitive diseases, and metabolic syndromes. Continuous positive airway pressure (CPAP) is the standard treatment for OSAS, with low compliance due to multifarious factors. The two other modes of ventilation, bi-level positive airway pressure (BPAP) and autotitrating positive airway pressure (APAP), which were developed from CPAP, are slightly different from CPAP in specific groups, as well as the corresponding treatment effect and compliance. The compliance of traditional positional therapy is not high, but with the emergence of the neck-based position treatment device, its compliance and indications have changed. Although CPAP is superior to mandibular advancement device (MAD) in improving AHI, MAD seems to be comparable to CPAP in improving other indicators. Corticosteroids and leukotriene receptor antagonists are effective treatments for mild OSAS children. Whether corticosteroids can be used in other OSAS groups and their adjunctive functions to CPAP remains unclear. The combination of these two kinds of drugs appears to be more effective than single drug. Researches on transcutaneous electrical stimulation are still not enough. Its effectiveness and stimulation settings still need further study. This review summarized the various OSAS non-surgical treatments from indications, treatment outcomes, compliance, adverse reactions, and recent progress.

Personalised medicine in sleep respiratory disorders: focus on obstructive sleep apnoea diagnosis and treatment

In all fields of medicine, major efforts are currently dedicated to improve the clinical, physiological and therapeutic understanding of disease, and obstructive sleep apnoea (OSA) is no exception. The personalised medicine approach is relevant for OSA, given its complex pathophysiology and variable clinical presentation, the interactions with comorbid conditions and its possible contribution to poor outcomes. Treatment with continuous positive airway pressure (CPAP) is effective, but CPAP is poorly tolerated or not accepted in a considerable proportion of OSA patients. This review summarises the available studies on the physiological phenotypes of upper airway response to obstruction during sleep, and the clinical presentations of OSA (phenotypes and clusters) with a special focus on our changing attitudes towards approaches to treatment. Such major efforts are likely to change and expand treatment options for OSA beyond the most common current choices (i.e CPAP, mandibular advancement devices, positional treatment, lifestyle changes or upper airway surgery). More importantly, treatment for OSA may become more effective, being tailored to each patient's need.

Treating OSA: Current and emerging therapies beyond CPAP

Continuous positive airway pressure (CPAP) is the standard treatment for moderate-to-severe obstructive sleep apnoea (OSA). However, adherence to CPAP is limited and non-CPAP therapies are frequently explored. Oral appliance (OA) therapy is currently widely used for the treatment of snoring, mild, moderate and severe OSA. The most commonly used and studied OA consists of a maxillary and mandibular splint which hold the lower jaw forward during sleep. The efficacy of OA is inferior to CPAP; however, the effectiveness as measured by sleepiness, quality of life, endothelial function and blood pressure is similar likely due to higher acceptance and subjective adherence. Upper airway stimulation augments neural drive by unilaterally stimulating the hypoglossal nerve. The Stimulation Therapy for Apnea Reduction (STAR) study enrolled 126 patients and demonstrated a 68% reduction in OSA severity. A high upfront cost and variable response are the main limitations. Oropharyngeal exercises consist of a set of isometric and isotonic exercises involving the tongue, soft palate and lateral pharyngeal wall. The collective reported trials (n = 120) showed that oropharyngeal exercises can ameliorate OSA and snoring (~30-40%). Nasal EPAP devices consist of disposable one-way resister valve. A systematic review (n = 345) showed that nasal EPAP reduced OSA severity by 53%. The Winx device consists of a mouthpiece placed inside the oral cavity that is connected by tubing to a console that generates negative pressure. Winx may provide successful therapy for ~30-40% of OSA patients. In conclusion, several non-CPAP therapies to treat OSA are currently available.

Electrical stimulation for the treatment of obstructive sleep apnoea: a review of the evidence

INTRODUCTION

Obstructive sleep apnoea is an increasingly prevalent clinical condition with significant impact on individuals and public health. Continuous positive airway pressure therapy is the standard treatment, but adherence is limited and alternative treatments are needed. In this context, non-invasive and invasive methods for the electrical stimulation of upper airway dilator muscles have been demonstrated to be effective in selected patients. Areas covered: This review will cover investigations on the clinical effects, safety, and tolerability of non-invasive and invasive electrical stimulation of the upper airway for the management of obstructive sleep apnoea. Following a search of the relevant literature published on PubMed this review is focused mainly on data obtained from randomized clinical trials and clinical studies. Expert commentary: The available evidence provides a rationale to consider upper airway electrical stimulation as treatment for selected patients with obstructive sleep apnoea, who have poor adherence or experience difficulties with continuous positive airway pressure therapy. Non-invasive stimulation using transcutaneous electrodes and implantable hypoglossal nerve stimulator technologies may provide an alternative to continuous positive airway pressure for the treatment of obstructive sleep apnoea via restoration of neuromuscular tone and improved upper airway patency.

Review of the British Thoracic Society Winter Meeting 2016, 7-9 December, London, UK

This article reviews the British Thoracic Society Winter Meeting 2016 and highlights the new developments in scientific and clinical research across the breadth of respiratory medicine.