The Combination of Atomoxetine and Oxybutynin Greatly Reduces Obstructive Sleep Apnea Severity. A Randomized, Placebo-controlled, Double-Blind Crossover Trial

Modulation of TASK-1/3 channels at the hypoglossal motoneuron pool and effects on tongue motor output and responses to excitatory inputs in vivo: implications for strategies for obstructive sleep apnea pharmacotherapy

Obstructive sleep apnea (OSA) occurs exclusively during sleep due to reduced tongue motor activity. Withdrawal of excitatory inputs to the hypoglossal motor nucleus (HMN) from wake to sleep contributes to this reduced activity. Several awake-active neurotransmitters with inputs to the HMN (e.g. serotonin [5-HT]) inhibit K+ leak mediated by TASK-1/3 channels on hypoglossal motoneurons, leading to increased neuronal activity in vitro. We hypothesize that TASK channel inhibition at the HMN will increase tongue muscle activity in vivo and modulate responses to 5-HT. We first microperfused the HMN of anesthetized rats with TASK channel inhibitors: doxapram (75 μM, n = 9), A1899 (25 μM, n = 9), ML365 (25 μM, n = 9), acidified artificial cerebrospinal fluid (ACSF, pH = 6.25, n = 9); and a TASK channel activator terbinafine (50 μM, n = 9); all with and without co-applied 5-HT (10 mM). 5-HT alone at the HMN increased tongue motor activity (202.8% ± 45.9%, p < 0.001). However, neither the TASK channel inhibitors, nor activator, at the HMN changed baseline tongue activity (p > 0.716) or responses to 5-HT (p > 0.127). Tonic tongue motor responses to 5-HT at the HMN were also not different (p > 0.05) between ChAT-Cre:TASKf/f mice (n = 8) lacking TASK-1/3 channels on cholinergic neurons versus controls (n = 10). In freely behaving rats (n = 9), microperfusion of A1899 into the HMN increased within-breath phasic tongue motor activity in wakefulness only (p = 0.005) but not sleep, with no effects on tonic activity across all sleep-wake states. Together, the findings suggest robust maintenance of tongue motor activity despite various strategies for TASK channel manipulation targeting the HMN in vivo, and thus currently do not support this target and direction for potential OSA pharmacotherapy.

A scalable method of determining physiological endotypes of sleep apnea from a polysomnographic sleep study

Sleep apnea is caused by several endophenotypic traits, namely pharyngeal collapsibility, poor muscle compensation, ventilatory instability (high loop gain), and arousability from sleep (low arousal threshold). Measures of these traits have shown promise for predicting outcomes of therapies (e.g. oral appliances, surgery, hypoglossal nerve stimulation, CPAP, and pharmaceuticals), which may become an integral part of precision sleep medicine. Currently, the methods Sands et al. developed for endotyping sleep apnea from polysomnography (PSG) are embedded in the original authors' code, which is computationally expensive and requires technological expertise to run. We present a reimplementation and validation of the integrity of the original authors' code by reproducing the endo-Phenotyping Using Polysomnography (PUP) method of Sands et al. The original MATLAB methods were reprogrammed in Python; efficient algorithms were developed to detect breaths, calculate normalized ventilation (moving time-average), and model ventilatory drive (intended ventilation). The new implementation (PUPpy) was validated by comparing the endotypes from PUPpy with the original PUP results. Both endotyping methods were applied to 38 manually scored polysomnographic studies. Results of the new implementation were strongly correlated with the original (p < 10-6 for all): ventilation at eupnea V̇ passive (ICC = 0.97), ventilation at arousal onset V̇ active (ICC = 0.97), loop gain (ICC = 0.96), and arousal threshold (ICC = 0.90). We successfully implemented the original PUP method by Sands et al. providing further evidence of its integrity. Additionally, we created a cloud-based version for scaling up sleep apnea endotyping that can be used more easily by a wider audience of researchers and clinicians.

Effects of hypnotics on obstructive sleep apnea endotypes and severity: Novel insights into pathophysiology and treatment

Impaired upper airway anatomy is the main cause of obstructive sleep apnea (OSA). However, there are other important non-anatomical contributors or "endotypes" including ventilatory control instability, poor pharyngeal dilator muscle responsiveness and waking up too easily to minor respiratory events (low arousal threshold). Recent studies have focused on the potential to target specific OSA causes with novel treatments to reduce OSA severity and improve efficacy with existing non-CPAP therapies which are often suboptimal (e.g., mandibular advancement splints). One novel target is pharmacotherapy with hypnotics to increase the threshold for arousal and reduce OSA severity in the approximately 30% of patients who have a low arousal threshold endotype. This increasing body of work has produced varied and at times unexpected findings which have challenged previous knowledge on the effects of hypnotics on upper airway physiology and breathing during sleep in people with OSA. This review provides a concise overview of the latest research that has investigated the effects of common hypnotics/sedative agents on upper airway physiology and OSA severity and potential implications for OSA pathophysiology, treatment and safety. This includes a summary of the latest knowledge on the effects of hypnotics on OSA endotypes. Priorities for future research are also highlighted.

Cross-sectional case-control study of the relationships between pharyngeal compliance and heart rate variability indices in childhood obstructive sleep apnoea

A combination of noradrenergic and antimuscarinic agents reduces the apnea-hypopnea index (AHI) in adult patients with obstructive sleep apnoea (OSA) via reduced upper airway collapsibility, suggesting that a shift in the sympathovagal balance improves OSA. The objectives of our present case-control study were to assess heart rate variability (HRV) indices in the stages of sleep in children with and without OSA to evaluate OSA-induced sleep HRV modifications and to assess whether increased collapsibility measured during wakefulness is associated with reduced sympathetic activity during non-rapid eye movement (NREM) sleep. Three groups of 15 children were matched by sex, age, z-score of body mass index and ethnicity: non-OSA (obstructive AHI [OAHI] <2 events/hr), mild (OAHI ≥2 to <5 events/hr) or moderate-severe (OAHI ≥5 events/hr) OSA. Pharyngeal compliance was measured during wakefulness using acoustic pharyngometry. HRV indices (time and frequency domain variables) were calculated on 5-min electrocardiography recordings from polysomnography during wakefulness, NREM and REM sleep in periods free of any event. As compared to children without OSA, those with OSA (n = 30) were characterised by increased compliance and no physiological parasympathetic tone increase in REM sleep. Children with increased pharyngeal compliance (n = 21) had a higher OAHI due to higher AHI in NREM sleep, whereas their sympathetic tone was lower than that of those with normal compliance (n = 24). In conclusion, children with increased pharyngeal compliance exhibit decreased sympathetic tone associated with increased AHI in NREM sleep. Therapeutics directed at sympathovagal balance modifications should be tested in childhood OSA.

Orofacial Myofunctional Therapy in Obstructive Sleep Apnea Syndrome: A Pathophysiological Perspective

Obstructive sleep apnea (OSA) syndrome is a multi-factorial disorder. Recently identified pathophysiological contributing factors include airway collapsibility, poor pharyngeal muscle responsiveness, a low arousal threshold, and a high loop gain. Understanding the pathophysiology is of pivotal importance to select the most effective treatment option. It is well documented that conventional treatments (continuous positive airway pressure (CPAP), upper airway surgery, and dental appliance) may not always be successful in the presence of non-anatomical traits, especially in mild to moderate OSA. Orofacial myofunctional therapy (OMT) consists of isotonic and isometric exercises targeted to oral and oropharyngeal structures, with the aim of increasing muscle tone, endurance, and coordinated movements of pharyngeal and peripharyngeal muscles. Recent studies have demonstrated the efficacy of OMT in reducing snoring, apnea-hypopnea index, and daytime sleepiness, and improving oxygen saturations and sleep quality. Myofunctional therapy helps to reposition the tongue, improve nasal breathing, and increase muscle tone in pediatric and adult OSA patients. Studies have shown that OMT prevents residual OSA in children after adenotonsillectomy and helps adherence in CPAP-treated OSA patients. Randomized multi-institutional studies will be necessary in the future to determine the effectiveness of OMT in a single or combined modality targeted approach in the treatment of OSA. In this narrative review, we present up-to-date literature data, focusing on the role of OSA pathophysiology concepts concerning pharyngeal anatomical collapsibility and muscle responsiveness, underlying the response to OMT in OSA patients.

Paediatrics: how to manage obstructive sleep apnoea syndrome

Obstructive sleep apnoea syndrome (OSAS) is defined as the intermittent reduction or cessation of airflow due to partial or complete obstruction of the upper airway during sleep. Paediatric OSAS has specific contributing factors, presenting symptoms and management strategies in various age groups. Untreated OSAS can lead to detrimental effects on neurocognitive development and cardiovascular and metabolic functions of a growing child. In the past decade, practice guidelines have been developed to guide the evaluation and management of OSAS. This article provides a narrative review on the current diagnostic and treatment options for paediatric OSAS. Alternative diagnostic tools other than the standard polysomnography are discussed. Adenotonsillectomy is considered the first-line therapy yet it is not suitable for treatment of all OSAS cases. Nocturnal non-invasive positive airway pressure ventilation is effective and could be the priority treatment for patients with complex comorbidities, residual OSAS post-adenotonsillectomy or obesity. However, intolerance and non-adherence are major challenges of positive airway pressure therapy especially in young children. There is increasing evidence for watchful waiting and other gentler alternative treatment options in mild OSAS. The role of anti-inflammatory drugs as the primary or adjunctive treatment is discussed. Other treatment options, including weight reduction, orthodontic procedures and myofunctional therapy, are indicated for selected patients. Nevertheless, the successful management of paediatric OSAS often requires a multidisciplinary team approach.

Evaluation and Management of Adults with Obstructive Sleep Apnea Syndrome

Obstructive sleep apnea syndrome (OSAS) is a common and underdiagnosed medical condition characterized by recurrent sleep-dependent pauses and reductions in airflow. While a narrow, collapsible oropharynx plays a central role in the pathophysiology of OSAS, there are other equally important nonanatomic factors including sleep-stage dependent muscle tone, arousal threshold, and loop gain that drive obstructive apneas and hypopneas. Through mechanisms of intermittent hypoxemia, arousal-related sleep fragmentation, and intrathoracic pressure changes, OSAS impacts multiple organ systems. Risk factors for OSAS include obesity, male sex, age, specific craniofacial features, and ethnicity. The prevalence of OSAS is rising due to increasing obesity rates and improved sensitivity in the tools used for diagnosis. Validated questionnaires have an important but limited role in the identification of patients that would benefit from formal testing for OSA. While an in-laboratory polysomnography remains the gold standard for diagnosis, the widespread availability and accuracy of home sleep apnea testing modalities increase access and ease of OSAS diagnosis for many patients. In adults, the most common treatment involves the application of positive airway pressure (PAP), but compliance continues to be a challenge. Alternative treatments including mandibular advancement device, hypoglossal nerve stimulator, positional therapies, and surgical options coupled with weight loss and exercise offer possibilities of an individualized personal approach to OSAS. Treatment of symptomatic patients with OSAS has been found to be beneficial with regard to sleep-related quality of life, sleepiness, and motor vehicle accidents. The benefit of treating asymptomatic OSA patients, particularly with regard to cardiovascular outcomes, is controversial and more data are needed.

New frontiers in pharmacologic obstructive sleep apnea treatment: A narrative review

Obstructive sleep apnea (OSA) is the most common form of sleep-disordered breathing characterized by intermittent partial or complete closure of the upper airway during sleep. If left untreated, OSA is associated with adverse cardiovascular outcomes such as hypertension, coronary heart disease, heart failure, cardiac arrhythmia, stroke, and death. Positive airway pressure (PAP) is often considered the first-line treatment for OSA. While PAP can be very effective in reducing the number of obstructive apneas and hypopneas, its impact on prevention of adverse cardiovascular consequences remains controversial, and treatment adherence is often poor. Hence, the necessity for novel treatment options to help those who cannot adhere to positive airway pressure treatment. Different classes of medications have been tested with regards to their effect on OSA severity. This review 1) provides an update on the epidemiology and pathophysiology of OSA, 2) outlines the mechanistic rationale for medication classes tested as OSA treatment and 3) discusses the effects of these medications on OSA. Several wake-promoting medications are approved for management of persistent sleepiness despite OSA treatment; discussion of these symptomatic treatments is outside the scope of this review. Herein, the authors review the current evidence for pharmacological management of OSA and provide future directions.

Gene delivery to the hypoglossal motor system: preclinical studies and translational potential

Dysfunction and/or reduced activity in the tongue muscles contributes to conditions such as dysphagia, dysarthria, and sleep disordered breathing. Current treatments are often inadequate, and the tongue is a readily accessible target for therapeutic gene delivery. In this regard, gene therapy specifically targeting the tongue motor system offers two general strategies for treating lingual disorders. First, correcting tongue myofiber and/or hypoglossal (XII) motoneuron pathology in genetic neuromuscular disorders may be readily achieved by intralingual delivery of viral vectors. The retrograde movement of viral vectors such as adeno-associated virus (AAV) enables targeted distribution to XII motoneurons via intralingual viral delivery. Second, conditions with impaired or reduced tongue muscle activation can potentially be treated using viral-driven chemo- or optogenetic approaches to activate or inhibit XII motoneurons and/or tongue myofibers. Further considerations that are highly relevant to lingual gene therapy include (1) the diversity of the motoneurons which control the tongue, (2) the patterns of XII nerve branching, and (3) the complexity of tongue muscle anatomy and biomechanics. Preclinical studies show considerable promise for lingual directed gene therapy in neuromuscular disease, but the potential of such approaches is largely untapped.

Considering the Role of Adherence in New and Emerging Sleep Treatments

There are several novel and emerging treatments for obstructive sleep apnea (OSA), including new devices and pharmacotherapies. Long-term efficacy and adherence data for these interventions in the sleep context are lacking. Future studies exploring the long-term adherence and efficacy in novel and emerging treatments of OSA are required to fully understand the place of these treatments in treatment hierarchies. Such research also should aim to evaluate the use of these novel therapies in real-world clinical settings, because many of the studies performed to date have been done under closely monitored research populations and relatively small sample sizes.

Designer Receptors Exclusively Activated by Designer Drugs Approach to Treatment of Sleep-disordered Breathing

Rationale: Obstructive sleep apnea is recurrent upper airway obstruction caused by a loss of upper airway muscle tone during sleep. The main goal of our study was to determine if designer receptors exclusively activated by designer drugs (DREADD) could be used to activate the genioglossus muscle as a potential novel treatment strategy for sleep apnea. We have previously shown that the prototypical DREADD ligand clozapine-N-oxide increased pharyngeal diameter in mice expressing DREADD in the hypoglossal nucleus. However, the need for direct brainstem viral injections and clozapine-N-oxide toxicity diminished translational potential of this approach, and breathing during sleep was not examined.Objectives: Here, we took advantage of our model of sleep-disordered breathing in diet-induced obese mice, retrograde properties of the adeno-associated virus serotype 9 (AAV9) viral vector, and the novel DREADD ligand J60.Methods: We administered AAV9-hSyn-hM3(Gq)-mCherry or control AAV9 into the genioglossus muscle of diet-induced obese mice and examined the effect of J60 on genioglossus activity, pharyngeal patency, and breathing during sleep.Measurements and Main Results: Compared with control, J60 increased genioglossus tonic activity by greater than sixfold and tongue uptake of 2-deoxy-2-[¹⁸F]fluoro-d-glucose by 1.5-fold. J60 increased pharyngeal patency and relieved upper airway obstruction during non-REM sleep.Conclusions: We conclude that following intralingual administration of AAV9-DREADD, J60 can activate the genioglossus muscle and improve pharyngeal patency and breathing during sleep.

Impact of cold and flu medication on obstructive sleep apnoea and its underlying traits: A pilot randomized controlled trial

BACKGROUND AND OBJECTIVE

Animal studies indicate that alpha-1 adrenergic receptor agonists and antimuscarinic agents improve genioglossus muscle activity during sleep and may be candidates for the pharmacological treatment of OSA. On the other hand, noradrenergic stimulants may be wake-promoting or cause insomnia symptoms if taken before bedtime, and the addition of a medication with sedative properties, such as an antihistaminic, may reduce these side effects. In this study, we aimed to determine the effects of the combination of an alpha-1 adrenergic agonist (pseudoephedrine) and an antihistaminic-antimuscarinic (diphenhydramine) on OSA severity (AHI), genioglossus responsiveness and other endotypic traits (V_passive , muscle compensation, LG and arousal threshold).

METHODS

Ten OSA patients performed a randomized, placebo-controlled, double-blind, crossover trial comparing one night of pseudoephedrine 120 mg plus diphenhydramine 50 mg (DAW1033D) to placebo administered prior to sleep. The AHI, genioglossus muscle responsiveness to negative oesophageal pressure and the endotypic traits were measured via PSG.

RESULTS

The participants' median (interquartile range) age was 50 (46-53) years and body mass index (BMI) was 34.3 (30.6-39.2) kg/m² . The drug combination had no effect on AHI (21.6 (9.1-49.8) on placebo vs 37.9 (5.1-55.4) events/h on DAW1033D, P > 0.5) or genioglossus responsiveness (6.0 (2.6-9.2) on placebo vs 4.0 (3.5-7.3) %/cm H₂ O). Amongst the phenotypic traits, only V_passive was improved by 29 (3-55) % eupnoea, P = 0.03 (mean (95% CI)).

CONCLUSION

The combination of pseudoephedrine and diphenhydramine did not improve OSA severity or genioglossus responsiveness but induced a small improvement in upper airway collapsibility, possibly due to the decongestant effect of the medications. The results of this study do not support the use of these medications for OSA treatment.

Positive Airway Pressure Therapy in Sleep-Disordered Breathing

Obstructive sleep apnea (OSA) is a highly prevalent condition with major neurocognitive and cardiovascular health effects. Positive airway pressure (PAP) therapy prevents the collapse of the pharyngeal airway to improve hypoxemia, hypercapnia, and sleep fragmentation caused by OSA. While adherence to PAP therapy has been thought to be a barrier to use, consistent usage is likely much higher than commonly thought. In addition, many strategies have been developed to assist providers in improving their patients' PAP adherence.

Trials in Sleep Apnea and Stroke: Learning From the Past to Direct Future Approaches

Few randomized controlled trials have evaluated the effectiveness of continuous positive airway pressure (CPAP) in reducing recurrent vascular events and mortality in poststroke obstructive sleep apnea (OSA). To date, results have been mixed, most studies were underpowered and definitive conclusions are not available. Using lessons learned from prior negative trials in stroke, we reappraise prior randomized controlled trials that examined the use of CPAP in treating poststroke OSA and propose the following considerations: (1) Intervention-based changes, such as ensuring that patients are using CPAP for at least 4 hours per night (eg, through use of improvements in CPAP technology that make it easier for patients to use), as well as considering alternative treatment strategies for poststroke OSA; (2) Population-based changes (ie, including stroke patients with severe and symptomatic OSA and CPAP noncompliers); and (3) Changes to timing of intervention and follow-up (ie, early initiation of CPAP therapy within the first 48 hours of stroke and long-term follow-up calculated in accordance with sample size to ensure adequate power). Given the burden of vascular morbidity and mortality in stroke patients with OSA, there is a strong need to learn from past negative trials and explore innovative stroke prevention strategies to improve stroke-free survival.

Journey towards a personalised medicine approach for OSA: Can a similar approach to adult OSA be applied to paediatric OSA?

The concept of personalised medicine is likely to revolutionise the treatment of adult obstructive sleep apnoea as a result of recent advances in the understanding of disease heterogeneity by identifying clinical phenotypes, pathophysiological endotypes, biomarkers and treatable traits. Children with the condition show a similar level of heterogeneity and paediatric obstructive sleep apnoea would also benefit from a more targeted approach to diagnosis and management. This review aims to summarise the adult literature on the phenotypes and endotypes of obstructive sleep apnoea and assess whether a similar approach may also be suitable to guide the development of new diagnostic and management approaches for paediatric obstructive sleep apnoea.

Zolpidem increases sleep efficiency and the respiratory arousal threshold without changing sleep apnoea severity and pharyngeal muscle activity

KEY POINTS

A decreased respiratory arousal threshold is one of the main contributors to obstructive sleep apnoea (OSA) pathogenesis. Several recent studies have sought to find a drug capable of increasing the respiratory arousal threshold without impairing pharyngeal muscle activity to reduce OSA severity, with variable success. Here we show that zolpidem increases the respiratory arousal threshold by ∼15%, an effect size which was insufficient to systematically decrease OSA severity as measured by the apnoea-hypopnoea index. Unlike recent physiological findings that showed paradoxical increases in pharyngeal muscle responsiveness during transient manipulations of airway pressure, zolpidem did not alter pharyngeal muscle responsiveness during natural sleep. It did, however, increase sleep efficiency without changing apnoea length, oxygen desaturation, next-day perceived sleepiness and alertness. These novel findings indicate that zolpidem was well tolerated and effective in promoting sleep in people with OSA, which may be therapeutically useful for people with OSA and comorbid insomnia.

ABSTRACT

A recent physiology study performed using continuous positive airway pressure (CPAP) manipulations indicated that the hypnotic zolpidem increases the arousal threshold and genioglossus responsiveness in people with and without obstructive sleep apnoea (OSA). Thus, zolpidem may stabilise breathing and reduce OSA severity without CPAP. Accordingly, we sought to determine the effects of zolpidem on OSA severity, upper airway physiology and next-day sleepiness and alertness. Nineteen people with OSA with low-to-moderate arousal threshold received 10 mg zolpidem or placebo according to a double-blind, randomised, cross-over design. Participants completed two overnight in-laboratory polysomnographies (1-week washout), with an epiglottic catheter, intramuscular genioglossus electromyography, nasal mask and pneumotachograph to measure OSA severity, arousal threshold and upper airway muscle responsiveness. Next-morning sleepiness and alertness were also assessed. Zolpidem did not change the apnoea-hypopnoea index versus placebo (40.6 ± 12.3 vs. 40.3 ± 16.4 events/h (means ± SD), p = 0.938) or nadir oxyhaemoglobin saturation (79.6 ± 6.6 vs. 79.7 ± 7.4%, p = 0.932), but was well tolerated. Zolpidem increased sleep efficiency by 9 ± 14% (83 ± 11 vs. 73 ± 17%, p = 0.010). Arousal threshold increased by 15 ± 5% with zolpidem throughout all sleep stages (p = 0.010), whereas genioglossus muscle responsiveness did not change. Next-morning sleepiness and alertness were not different between nights. In summary, a single night of 10 mg zolpidem is well tolerated and does not cause next-day impairment in alertness or sleepiness, or overnight hypoxaemia in OSA. However, despite increases in arousal threshold without any change in pharyngeal muscle responsiveness, zolpidem does not alter OSA severity. It does, however, increase sleep efficiency by ∼10%, which may be beneficial in people with OSA and insomnia.

Diagnosis and Management of Obstructive Sleep Apnea: A Review

IMPORTANCE

Obstructive sleep apnea (OSA) affects 17% of women and 34% of men in the US and has a similar prevalence in other countries. This review provides an update on the diagnosis and treatment of OSA.

OBSERVATIONS

The most common presenting symptom of OSA is excessive sleepiness, although this symptom is reported by as few as 15% to 50% of people with OSA in the general population. OSA is associated with a 2- to 3-fold increased risk of cardiovascular and metabolic disease. In many patients, OSA can be diagnosed with home sleep apnea testing, which has a sensitivity of approximately 80%. Effective treatments include weight loss and exercise, positive airway pressure, oral appliances that hold the jaw forward during sleep, and surgical modification of the pharyngeal soft tissues or facial skeleton to enlarge the upper airway. Hypoglossal nerve stimulation is effective in select patients with a body mass index less than 32. There are currently no effective pharmacological therapies. Treatment with positive airway pressure lowers blood pressure, especially in patients with resistant hypertension; however, randomized clinical trials of OSA treatment have not demonstrated significant benefit on rates of cardiovascular or cerebrovascular events.

CONCLUSIONS AND RELEVANCE

OSA is common and the prevalence is increasing with the increased prevalence of obesity. Daytime sleepiness is among the most common symptoms, but many patients with OSA are asymptomatic. Patients with OSA who are asymptomatic, or whose symptoms are minimally bothersome and pose no apparent risk to driving safety, can be treated with behavioral measures, such as weight loss and exercise. Interventions such as positive airway pressure are recommended for those with excessive sleepiness and resistant hypertension. Managing asymptomatic OSA to reduce cardiovascular and cerebrovascular events is not currently supported by high-quality evidence.

Effect of Venlafaxine on Apnea-Hypopnea Index in Patients With Sleep Apnea: A Randomized, Double-Blind Crossover Study

BACKGROUND

One of the key mechanisms underlying OSA is reduced pharyngeal muscle tone during sleep. Data suggest that pharmacologic augmentation of central serotonergic/adrenergic tone increases pharyngeal muscle tone.

RESEARCH QUESTION

We hypothesized that venlafaxine, a serotonin-norepinephrine reuptake inhibitor, would improve OSA severity.

STUDY DESIGN AND METHODS

In this mechanistic, randomized, double-blind, placebo-controlled crossover trial, 20 patients with OSA underwent two overnight polysomnograms ≥ 4 days apart, receiving either 50 mg of immediate-release venlafaxine or placebo before bedtime. Primary outcomes were the apnea-hypopnea index (AHI) and peripheral oxygen saturation (Spo₂) nadir, and secondary outcomes included sleep parameters and pathophysiologic traits with a view toward understanding the impact of venlafaxine on mechanisms underlying OSA.

RESULTS

Overall, there was no significant difference between venlafaxine and placebo regarding AHI (mean reduction, -5.6 events/h [95% CI, -12.0 to 0.9]; P = .09) or Spo₂ nadir (median increase, +1.0% [-0.5 to 5]; P = .11). Venlafaxine reduced total sleep time, sleep efficiency, and rapid eye movement (REM) sleep, while increasing non-REM stage 1 sleep (P_all < .05). On the basis of exploratory post hoc analyses venlafaxine decreased ("improved") the ventilatory response to arousal (-30%; P = .049) and lowered ("worsened") the predicted arousal threshold (-13%; [P = .02]; ie, more arousable), with no effects on other pathophysiologic traits (P_all ≥ .3). Post hoc analyses further suggested effect modification by arousal threshold (P = .002): AHI improved by 19% in patients with a high arousal threshold (-10.9 events/h [-3.9 to -17.9]) but tended to increase in patients with a low arousal threshold (+7 events/h [-2.0 to 16]). Other predictors of response were elevated AHI and less collapsible upper airway anatomy at baseline (|r| > 0.5, P ≤ .02).

INTERPRETATION

In unselected patients, venlafaxine simultaneously worsened and improved various pathophysiologic traits, resulting in a zero net effect. Careful patient selection based on pathophysiologic traits, or combination therapy with drugs countering its alerting effects, may produce a more robust response.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT02714400; URL: www.clinicaltrials.gov.

Risk of Alzheimer's Disease in Obstructive Sleep Apnea Patients With or Without Treatment: Real-World Evidence

OBJECTIVE

To assess the risk of Alzheimer's disease (AD) in patients with obstructive sleep apnea (OSA) with or without treatment based on real-world evidence.

STUDY DESIGN

Retrospective cohort study.

METHODS

Patients newly diagnosed with OSA during 1997-2012 were identified using the National Health Insurance Research Database of Taiwan. Patients without OSA were randomly selected and matched in a 1:4 ratio by age, sex, urbanization level, and income. All patients were followed up until death or the end of 2013. The primary outcome was AD occurrence.

RESULTS

This study included 3,978 OSA patients and 15,912 non-OSA patients. OSA was independently and significantly associated with a higher incidence of AD in an adjusted Cox proportional hazard model (adjusted hazard ratio: 2.12; 95% confidence interval [CI], 1.27-3.56). The average period of AD detection from the time of OSA occurrence was 5.44 years (standard deviation: 2.96). Subgroup analyses revealed that the effect of OSA remained significant in patients aged ≥60 years, male subgroups, patients without CPAP or surgical treatment, and patients without pharmacological therapies. Patients with OSA who received treatment (continuous positive airway pressure or surgery) exhibited a significantly reduced risk of AD compared with those without treatment (incidence rate ratio 0.23, 95% CI, 0.06-0.98).

CONCLUSION

OSA is independently associated with an increased risk of AD. Treatment for OSA reduces the AD risk in OSA patients. AD irreversibility renders OSA as a potential modifiable target for slowing or preventing the process of AD development.

LEVEL OF EVIDENCE

IV Laryngoscope, 130:2292-2298, 2020.

Effects of the Combination of Atomoxetine and Oxybutynin on OSA Endotypic Traits

BACKGROUND

We recently showed that administration of the combination of the noradrenergic drug atomoxetine plus the antimuscarinic oxybutynin (ato-oxy) prior to sleep greatly reduced OSA severity, likely by increasing upper airway dilator muscle activity during sleep. In patients with OSA who performed the ato-oxy trial with an esophageal pressure catheter to estimate ventilatory drive, the effect of the drug combination (n = 17) and of the single drugs (n = 6) was measured on the endotypic traits over a 1-night administration and compared vs placebo. This study also tested if specific traits were predictors of complete response to treatment (reduction in apnea-hypopnea index [AHI] > 50% and < 10 events/h).

METHODS

The study was a double-blind, randomized, placebo-controlled trial. The arousal threshold, collapsibility (ventilation at eupneic drive [Vpassive]), ventilation at arousal threshold, and loop gain (stability of ventilatory control, LG1), were calculated during spontaneous breathing during sleep. Muscle compensation (upper airway response) was calculated as a function of ventilation at arousal threshold adjusted for Vpassive. Ventilation was expressed as a percentage of the eupneic level of ventilation (%_eupnea). Data are presented as mean [95% CI].

RESULTS

Compared with placebo, ato-oxy increased Vpassive by 73 [54 to 91]%_eupnea (P < .001) and muscle compensation by 29 [8 to 51]%_eupnea (P = .012), reduced the arousal threshold by -9 [-14 to -3]% (P = .022) and LG1 by -11 [-22 to 2]% (P = .022). Atomoxetine alone significantly reduced arousal threshold and LG1. Both agents alone improved collapsibility (Vpassive) but not muscle compensation. Patients with lower AHI, higher Vpassive, and higher fraction of hypopneas over total events had a complete response with ato-oxy.

FINDINGS

Ato-oxy markedly improved the measures of upper airway collapsibility, increased breathing stability, and slightly reduced the arousal threshold. Patients with relatively lower AHI and less severe upper airway collapsibility had the best chance for OSA resolution with ato-oxy.

A Review of Current Tools Used for Evaluating the Severity of Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is a common and heterogeneous disease characterized by episodic collapse within the upper airways, which leads to reduced ventilation and adverse consequences, including hypoxia, hypercapnia, sleep fragmentation, and long-term effects such as cardiovascular comorbidities. The clinical diagnosis of OSA and its severity classification are often determined based on the apnea-hypopnea index (AHI), defining the number of apneic and hypopnea events per hour of sleep. However, the limitations of the AHI to assess disease severity have necessitated the exploration of other metrics for additional information to reflect the complexity of OSA. Novel parameters such as the hypoxic burden have the potential to better capture the main features of OSA by maximizing the information available from the polysomnogram. These emerging measures have described multidimensional qualities of sleep-disordered breathing events and breathing irregularity and will ultimately result in better management of OSA.

Transition to Adult Care for Obstructive Sleep Apnea

Obstructive sleep apnea may occur throughout the lifespan, with peak occurrences in early childhood and during middle and older age. Onset in childhood is overwhelmingly due to adeno-tonsillar hypertrophy, while in adulthood, contributors include risk factors, such as obesity, male sex, and aging. More recently, there has been a precipitous increase in the prevalence of obstructive sleep apnea in youth. Drivers of this phenomenon include both increasing obesity and the survival of children with complex medical conditions into adulthood. Appropriate treatment and long-term management of obstructive sleep apnea is critical to ensure that these youth maintain well-being unfettered by secondary comorbidities. To this end, patient engagement and seamless transition of care from pediatric to adult health care systems is of paramount importance. To date, this is an unacknowledged and unmet need in most sleep programs. This article highlights the need for guideline-driven sleep disorder transition processes and illustrates the authors’ experience with the development of a program for sleep apnea.

[The contribution of orofacial myofunctional reeducation to the treatment of obstructive sleep apnoea syndrome (OSA): a systematic review of the literature]

Obstructive sleep apnoea syndrome (OSA) is a widespread and under-diagnosed condition, making it a major public health and safety problem. Orofacial myofunctional reeducation (OMR) has been shown to be effective in the multidisciplinary treatment of OSA in children, adolescents and adults and is prescribed at several stages of OSA management. The main objective of this systematic literature review was to evaluate the effectiveness of active or passive orofacial myofunctional reeducation (OMR) in the treatment of obstructive sleep apnoea syndrome in children, adolescents and adults. The systematic literature review was undertaken from the three electronic databases: Medline (via PubMed), Cochrane Library, Web of Science Core Collection, and supplemented by a limited grey literature search (Google Scholar) in order to identify the studies evaluating the effectiveness of the OMR on OSA. The primary outcome of interest was a decrease in the Apnea-Hypopnea Index (AHI) of at least five episodes per hour compared to the baseline state. Secondary outcomes were an improvement in subjective sleep quality, sleep quality measured by night polysomnography and subjectively measured quality of life. Only ten studies met all the inclusion criteria. Eight were randomized controlled clinical trials, one was a prospective cohort study and another was a retrospective cohort study. Six studies were devoted to adult OSA and four to pediatric OSA. All included studies were assessed as "low risk of bias" based on the 12 bias risk criteria of the Cochrane Back Review Group. Based on the available evidence, RMO allows a significant reduction in AHI, up to 90.6% in children and up to 92.06% in adults. It significantly reduces the intensity and frequency of snoring, helps reduce daytime sleepiness, limits the recurrence of OSA symptoms after adenoamygdalectomy in children and improves adherence to PPC therapy. Passive RMO, with the assistance provided to the patient by wearing a custom orthosis, increases adherence to reeducation, significantly improves snoring intensity, AHI and significantly increases the upper airway. Published data show that orofacial myofunctional rééducation is effective in the multidisciplinary treatment of OSA in children, adolescents and adults and should be widely prescribed at several stages of OSA management. Passive RMO, with the pearl mandibular advancement orthosis designed by Michèle Hervy-Auboiron, helps to compensate for the frequent non-compliance observed during active RMO treatments.

[Non-surgical treatment of the sleep related breathing disorders in adults]

The treatment of obstructive sleep apnoea/hypopnoea syndrome (OSAHS) must allow for the suppression of symptoms and also prevent its immediate and long-term consequences. The evaluation of the effectiveness of treatments is now based on a normal apnea/hypopnea index, a normal oxygen saturation and the disappearance of sleep fragmentation. Clinical and biological follow-up of co-morbidities must be ensured. Compliance with treatment, a major element of success, must be monitored. Continuous Positive Airway Pressure (CPAP) is still the most effective and widely used treatment. However, mandibular advancement orthosis is now recommended as a first-line treatment in moderate forms in the absence of severe cardiovascular comorbidities (CV) and remains a therapeutic alternative in the event of refusal or intolerance to CPAP. Nutritional management in cases of obesity and a physical activity program must be systematically offered. A reduction in nocturnal breathing disorders can also be achieved by using a device in the event of positional OSAHS, or by limiting fluid movements. The contribution of myofunctional therapy is currently being evaluated. Very recently, a study testing the efficiency of pharmacological treatment on the severity of OSAHS and the reactivity of geniogloss appears to be promising. The evaluation of these different treatments and their combination should make it possible to evolve towards a personalised management adapted to each patient.

The Role of Animal Models in Developing Pharmacotherapy for Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is a highly prevalent disease characterized by recurrent closure of the upper airway during sleep. It has a complex pathophysiology involving four main phenotypes. An abnormal upper airway anatomy is the key factor that predisposes to sleep-related collapse of the pharynx, but it may not be sufficient for OSA development. Non-anatomical traits, including (1) a compromised neuromuscular response of the upper airway to obstruction, (2) an unstable respiratory control (high loop gain), and (3) a low arousal threshold, predict the development of OSA in association with anatomical abnormalities. Current therapies for OSA, such as continuous positive airway pressure (CPAP) and oral appliances, have poor adherence or variable efficacy among patients. The search for novel therapeutic approaches for OSA, including pharmacological agents, has been pursued over the past years. New insights into OSA pharmacotherapy have been provided by preclinical studies, which highlight the importance of appropriate use of animal models of OSA, their applicability, and limitations. In the present review, we discuss potential pharmacological targets for OSA discovered using animal models.

Critical Issues in Dental and Medical Management of Obstructive Sleep Apnea

This critical review focuses on obstructive sleep apnea (OSA) and its management from a dental medicine perspective. OSA is characterized by ≥10-s cessation of breathing (apnea) or reduction in airflow (hypopnea) ≥5 times per hour with a drop in oxygen and/or rise in carbon dioxide. It can be associated with sleepiness and fatigue, impaired mood and cognition, cardiometabolic complications, and risk for transportation and work accidents. Although sleep apnea is diagnosed by a sleep physician, its management is interdisciplinary. The dentist’s role includes 1) screening patients for OSA risk factors (e.g., retrognathia, high arched palate, enlarged tonsils or tongue, enlarged tori, high Mallampati score, poor sleep, supine sleep position, obesity, hypertension, morning headache or orofacial pain, bruxism); 2) referring to an appropriate health professional as indicated; and 3) providing oral appliance therapy followed by regular dental and sleep medical follow-up. In addition to the device features and provider expertise, anatomic, behavioral, demographic, and neurophysiologic characteristics can influence oral appliance effectiveness in managing OSA. Therefore, OSA treatment should be tailored to each patient individually. This review highlights some of the putative action mechanisms related to oral appliance effectiveness and proposes future research directions.

Targeting Endotypic Traits with Medications for the Pharmacological Treatment of Obstructive Sleep Apnea. A Review of the Current Literature

Obstructive sleep apnea (OSA) is a highly prevalent condition with few therapeutic options. To date there is no approved pharmacotherapy for this disorder, but several attempts have been made in the past and are currently ongoing to find one. The recent identification of multiple endotypes underlying this disorder has oriented the pharmacological research towards tailored therapies targeting specific pathophysiological traits that contribute differently to cause OSA in each patient. In this review we retrospectively analyze the literature on OSA pharmacotherapy dividing the medications tested on the basis of the four main endotypes: anatomy, upper airway muscle activity, arousal threshold and ventilatory instability (loop gain). We show how recently introduced drugs for weight loss that modify upper airway anatomy may play an important role in the management of OSA in the near future, and promising results have been obtained with drugs that increase upper airway muscle activity during sleep and reduce loop gain. The lack of a medication that can effectively increase the arousal threshold makes this strategy less encouraging, although recent studies have shown that the use of certain sedatives do not worsen OSA severity and could actually improve patients' sleep quality.

Obstructive Sleep Apnea: Emerging Treatments Targeting the Genioglossus Muscle

Obstructive sleep apnea (OSA) is characterized by repetitive episodes of upper airway obstruction caused by a loss of upper airway dilator muscle tone during sleep and an inadequate compensatory response by these muscles in the context of an anatomically compromised airway. The genioglossus (GG) is the main upper airway dilator muscle. Currently, continuous positive airway pressure is the first-line treatment for OSA. Nevertheless, problems related to poor adherence have been described in some groups of patients. In recent years, new OSA treatment strategies have been developed to improve GG function. (A) Hypoglossal nerve electrical stimulation leads to significant improvements in objective (apnea-hypopnea index, or AHI) and subjective measurements of OSA severity, but its invasive nature limits its application. (B) A recently introduced combination of drugs administered orally before bedtime reduces AHI and improves the responsiveness of the GG. (C) Finally, myofunctional therapy also decreases AHI, and it might be considered in combination with other treatments. Our objective is to review these therapies in order to advance current understanding of the prospects for alternative OSA treatments.

Sleep Pharmacotherapy for Common Sleep Disorders in Pregnancy and Lactation

Sleep disturbances are common in pregnancy, and sleep disorders may worsen or present de novo in the course of gestation. Managing a pregnant patient is complicated by the risk of teratogenicity, pharmacokinetic changes, and the dynamic nature of pregnancy. Although nonpharmacologic interventions are likely safest, they are often ineffective, and a patient is left dealing with frustrations of the sleep disturbance, as well as the negative outcomes of poor sleep in pregnancy. As with any other condition in pregnancy, management requires an understanding of pregnancy physiology, knowledge of the impact of a given condition on pregnancy or fetal and neonatal outcomes, and an ability to weigh the risk of the exposure to an untreated, or poorly treated condition, against the risk of a given drug. In partnership with the pregnant patient or couple, options for therapy should be reviewed in the context of the impact of the condition on pregnancy and offspring outcomes, while understanding that data (positive or negative) on the impact of therapy on perinatal outcomes are lacking. This article reviews the epidemiology of sleep disorders in pregnancy, general principles of prescribing in pregnancy and lactation, and safety surrounding therapeutic options in pregnancy.

Muscarinic Inhibition of Hypoglossal Motoneurons: Possible Implications for Upper Airway Muscle Hypotonia during REM Sleep

Proper function of pharyngeal dilator muscles, including the genioglossus muscle of the tongue, is required to maintain upper airway patency. During sleep, the activity of these muscles is suppressed, and as a result individuals with obstructive sleep apnea experience repeated episodes of upper airway closure when they are asleep, in particular during rapid-eye-movement (REM) sleep. Blocking cholinergic transmission in the hypoglossal motor nucleus (MoXII) restores REM sleep genioglossus activity, highlighting the importance of cholinergic transmission in the inhibition of hypoglossal motor neurons (HMNs) during REM sleep. Glutamatergic afferent input from neurons in the parahypoglossal (PH) region to the HMNs is critical for MoXII respiratory motor output. We hypothesized that state-dependent cholinergic regulation may be mediated by this pathway. Here we studied the effects of cholinergic transmission in HMNs in adult male and female mice using patch-clamp recordings in brain slices. Using channelrhodopsin-2-assisted circuit mapping, we first demonstrated that PH glutamatergic neurons directly and robustly activate HMNs (PH^Glut → HMNs). We then show that carbachol consistently depresses this input and that this effect is presynaptic. Additionally, carbachol directly affects HMNs by a variable combination of muscarinic-mediated excitatory and inhibitory responses. Altogether, our results suggest that cholinergic signaling impairs upper airway dilator muscle activity by suppressing glutamatergic input from PH premotoneurons to HMNs and by directly inhibiting HMNs. Our findings highlight the complexity of cholinergic control of HMNs at both the presynaptic and postsynaptic levels and provide a possible mechanism for REM sleep suppression of upper airway muscle activity.SIGNIFICANCE STATEMENT Individuals with obstructive sleep apnea can breathe adequately when awake but experience repeated episodes of upper airway closure when asleep, in particular during REM sleep. Similar to skeletal postural muscles, pharyngeal dilator muscles responsible for maintaining an open upper airway become hypotonic during REM sleep. Unlike spinal motoneurons controlling postural muscles that are inhibited by glycinergic transmission during REM sleep, hypoglossal motoneurons that control the upper airway muscles are inhibited in REM sleep by the combination of monoaminergic disfacilitation and cholinergic inhibition. In this study, we demonstrated how cholinergic signaling inhibits hypoglossal motoneurons through presynaptic and postsynaptic muscarinic receptors. Our results provide a potential mechanism for upper airway hypotonia during REM sleep.