Effect of Supplemental Oxygen on Blood Pressure in Obstructive Sleep Apnea (SOX). A Randomized Continuous Positive Airway Pressure Withdrawal Trial

Treatment of Sleep Apnea and Reduction in Blood Pressure: The Role of Heart Rate Response and Hypoxic Burden

BACKGROUND

Obstructive sleep apnea is associated with increased blood pressure (BP). Obstructive sleep apnea treatment reduces BP with substantial variability, not explained by the apnea-hypopnea index, partly due to inadequate characterization of obstructive sleep apnea's physiological consequences, such as oxygen desaturation, cardiac autonomic response, and suboptimal treatment efficacy. We sought to examine whether a high baseline heart rate response (ΔHR), a marker of high cardiovascular risk in obstructive sleep apnea, predicts a larger reduction in post-treatment systolic BP (SBP). Furthermore, we aimed to assess the extent to which a reduction in SBP is explained by a treatment-related reduction in hypoxic burden (HB).

METHODS

ΔHR and HB were measured from pretreatment and posttreatment polygraphy, followed by a 24-hour BP assessment in 168 participants treated with continuous positive airway pressure or nocturnal supplemental oxygen from the HeartBEAT study (Heart Biomarker Evaluation in Apnea Treatment). Multiple linear regression models assessed whether high versus mid (reference) ΔHR predicted a larger reduction in SBP (primary outcome) and whether there was an association between treatment-related reductions in SBP and HB.

RESULTS

A high versus mid ΔHR predicted improvement in SBP (adjusted estimate, 5.8 [95% CI, 1.0-10.5] mm Hg). Independently, a greater treatment-related reduction in HB was significantly associated with larger reductions in SBP (4.2 [95% CI, 0.9-7.5] mm Hg per 2 SD treatment-related reduction in HB). Participants with substantial versus minimal treatment-related reductions in HB had a 6.5 (95% CI, 2.5-10.4) mm Hg drop in SBP.

CONCLUSIONS

A high ΔHR predicted a more favorable BP response to therapy. Furthermore, the magnitude of the reduction in BP was partly explained by a greater reduction in HB.

The association between the effective apnea-hypopnea index and blood pressure reduction efficacy following CPAP/oxygen treatment

BACKGROUND

The effect of sleep apnea treatment on reducing cardiovascular disease risk remains inconclusive. This study aims to assess if the effective apnea hypopnea index (eAHI), a measure of residual sleep apnea burden post-treatment, is a factor in determining blood pressure (BP) response to continuous positive airway pressure therapy. The eAHI integrates time on therapy, residual apnea, and % of sleep time untreated.

METHODS

A secondary analysis of the Heart Biomarker Evaluation in Apnea Treatment (HeartBEAT) study, a randomized, controlled, parallel group assessment of continuous positive airway pressure (CPAP), oxygen and sleep hygiene. The Delta-AHI (▲AHI) was defined as the difference between baseline AHI and effective AHI at 12 weeks. Logistic and linear regression models estimated the predictors for nocturnal systolic BP change following sleep apnea therapy.

RESULTS

One hundred and sixty-nine subjects with a mean age of 62.82 ± 6.99 years were included in the final analysis. Fifty subjects had ▲AHI ≤8/hour of sleep and 119 subjects were higher. After adjustment, baseline mean nighttime systolic blood pressure (OR 1.036, 95% CI 1.015-1.058, p: 0.001) and ▲AHI ≥8/hour (OR 2.406, 95% CI 1.116-5.185, p:0.025) were independent predictors for mean nighttime systolic blood pressure change >3 mm Hg. The higher effective AHI was negatively related with BNP (β: -2.564, SE: 1.167, p: 0.029) and positively related with troponin change (β: 0.703, SE: 0.256, p: 0.007).

CONCLUSION

The ▲AHI was an independent predictor of the blood pressure response to sleep apnea treatment.

REGISTER NUMBER

NCT01086800.

Compliance and side effects of tongue stabilizing device in patients with obstructive sleep apnea

OBJECTIVE

To evaluate the long-term effectiveness, compliance, and side effects of tongue stabilizing devices (TSDs).

METHODS

Thirty-nine patients were followed up after 12 and 30 months. The subjective effectiveness was assessed using the Epworth Sleepiness Scale (ESS), the Functional Outcomes Sleep Questionnaire (FOSQ-10), the Chalder Fatigue Scale (CFQ), and a sleep-related quality of life questionnaire (QoL). Compliance and side effects were assessed.

RESULTS

At 12-months, 35.9% of patients confirmed continuing the therapy, compared to only 15.4% of patients at 30 months. At 30 months, a significant average improvement of ESS (2.0 ± 2.8) was observed compared to baseline levels in six patients. Six patients demonstrated an average increase in blood pressure. The most frequently reported side effects were mouth dryness and excessive salivation. The 3D analysis revealed small tooth movements.

CONCLUSION

The TSD therapy demonstrated a good long-term subjective effectiveness against OSA but had a relatively low treatment acceptance rate.

Nocturnal oxygen therapy in obstructive sleep apnoea: a systematic review and meta-analysis

Obstructive sleep apnoea is characterised by recurrent reduction of airflow during sleep leading to intermittent hypoxia. Continuous positive airway pressure is the first-line treatment but is limited by poor adherence. Nocturnal oxygen therapy may be an alternative treatment for obstructive sleep apnoea but its effects remain unclear. This meta-analysis evaluates the effects of nocturnal oxygen therapy on both obstructive sleep apnoea severity and blood pressure.A literature search was performed based on the Preferred Reporting Items for Systematic Review and Meta-analysis guidelines. Peer-reviewed, randomised studies that compared the effect of nocturnal oxygen therapy to sham in obstructive sleep apnoea patients were included. The main outcomes were the apnoea-hypopnoea index and systolic and diastolic blood pressure.The search strategy yielded 1295 citations. Nine studies with 502 participants were included. When nocturnal oxygen therapy was compared to sham/air, it significantly reduced the apnoea-hypopnoea index (mean difference (MD) -15.17 events·h-1, 95% CI -19.95- -10.38 events·h-1, p<0.00001). Nocturnal oxygen therapy had no significant effect on blood pressure at follow-up without adjustment for baseline values, but did, where available, significantly attenuate the change in blood pressure from baseline to follow-up for both systolic blood pressure (MD -2.79 mmHg, 95% CI -5.45- -0.14 mmHg, p=0.040) and diastolic blood pressure (MD -2.20 mmHg, 95% CI -3.83- -0.57 mmHg, p=0.008).Nocturnal oxygen therapy reduced the apnoea-hypopnoea index severity and the change in (but not absolute) systolic and diastolic blood pressure, compared to sham. This suggests that nocturnal oxygen therapy may be a treatment option for obstructive sleep apnoea. Further studies with longer-term follow-up and standardised measurements are needed.

Factors influencing new-onset hypertension in elderly patients with obstructive sleep apnea: A multicenter cohort study

Investigating the influencing factors of new-onset hypertension in the elderly with obstructive sleep apnea (OSA). 450 Chinese older patients with OSA who were non-hypertensive at baseline were enrolled. All patients had undergone polysomnography monitoring in the multicenter study. The primary endpoint was incident hypertension. Kaplan-Meier survival analysis was performed, and multivariate Cox proportional hazards models were generated to determine the factors influencing new-onset hypertension. A total of 176 (39.1%) patients developed hypertension. The hypertension group had older age, higher hemoglobin (Hb) level and apnea-hypopnea index (AHI) values than the non-hypertension group (all p < 0.05). During the median 33-month follow-up period, multivariate Cox analysis showed age (hazard ratio (HR) = 1.039, 95% confidence interval (95% CI): 1.016-1.062), AHI (HR = 1.015, 95% CI: 1.007-1.023) and Hb level (HR = 1.016, 95% CI: 1.008-1.025) were independent predictors of new-onset hypertension. However, continuous positive airway pressure (CPAP; HR = 0.508, 95% CI: 0.271-0.951) reduced the risk of developing hypertension. Notably, the subgroup analysis demonstrated that the plasma glucose level (HR = 1.168, 95% CI: 1.029-1.326) was a risk factor for male patients. Besides length of time with the pulse oxygen saturation less than 90% (Tsat90; HR = 1.005, 95% CI: 1.003-1.007), body mass index (BMI; HR = 1.170, 95% CI: 1.043-1.311), and dyslipidemia (HR = 2.335, 95% CI: 1.144-4.766) had statistically significant effects on the incidence of hypertension in certain subgroups. Although this study lacked analysis of items such as living habits and medication, it did show age, AHI, Hb and CPAP affected the development of hypertension in elderly OSA patients. These findings suggested that targeted interventions in specific populations may be more effective in preventing hypertension.

International Consensus Statement on Obstructive Sleep Apnea

BACKGROUND

Evaluation and interpretation of the literature on obstructive sleep apnea (OSA) allows for consolidation and determination of the key factors important for clinical management of the adult OSA patient. Toward this goal, an international collaborative of multidisciplinary experts in sleep apnea evaluation and treatment have produced the International Consensus statement on Obstructive Sleep Apnea (ICS:OSA).

METHODS

Using previously defined methodology, focal topics in OSA were assigned as literature review (LR), evidence-based review (EBR), or evidence-based review with recommendations (EBR-R) formats. Each topic incorporated the available and relevant evidence which was summarized and graded on study quality. Each topic and section underwent iterative review and the ICS:OSA was created and reviewed by all authors for consensus.

RESULTS

The ICS:OSA addresses OSA syndrome definitions, pathophysiology, epidemiology, risk factors for disease, screening methods, diagnostic testing types, multiple treatment modalities, and effects of OSA treatment on multiple OSA-associated comorbidities. Specific focus on outcomes with positive airway pressure (PAP) and surgical treatments were evaluated.

CONCLUSION

This review of the literature consolidates the available knowledge and identifies the limitations of the current evidence on OSA. This effort aims to create a resource for OSA evidence-based practice and identify future research needs. Knowledge gaps and research opportunities include improving the metrics of OSA disease, determining the optimal OSA screening paradigms, developing strategies for PAP adherence and longitudinal care, enhancing selection of PAP alternatives and surgery, understanding health risk outcomes, and translating evidence into individualized approaches to therapy.

Effectiveness of Continuous Positive Airway Pressure in Treating Hypertension in Obstructive Sleep Apnea: A Traditional Review

Almost one billion individuals worldwide suffer from obstructive sleep apnea (OSA). The most widely used treatment for OSA has been continuous positive airway pressure (CPAP), but its effect on blood pressure (BP) has been challenged. Our review aims to evaluate the effects of treating OSA with CPAP on BP and BP-related morbidities in adult hypertensive patients. Medical subject headings (MeSH) terminology was used to search the PubMed Central, MEDLINE, and PubMed databases for articles on the use of CPAP in OSA patients with hypertension. We selected various forms of academic writing, encompassing complete texts that were published in the English language. The study included a total of 21 papers. OSA is a serious health concern associated with a higher risk of cardiovascular disease, kidney disease, pulmonary hypertension, and aortic stiffness, which is brought on by the periodic hypoxia caused by nocturnal respiratory episodes. For individuals with moderate-to-severe OSA, CPAP therapy has been shown to have a considerable long-term benefit with a median drop of 11 mm Hg, and high adherence results in a decrease in diastolic BP. CPAP therapy directly lowers BP in OSA patients with a body mass index (BMI) of more than 30 kg/m2 and has also demonstrated improvement in early signs of atherosclerosis with lower nocturnal systolic BP levels. OSA patients with resistant hypertension also experienced lower BP after using CPAP for a year. Therefore, our findings suggest that obesity, hypersomnolence, high nocturnal BP, prolonged CPAP usage, and resistant hypertension may all have a major impact on the BP response to CPAP therapy in individuals with severe OSA.

The effectiveness of supplemental oxygen and high-flow nasal cannula therapy in patients with obstructive sleep apnea in different clinical settings: A systematic review and meta-analysis

STUDY OBJECTIVE

To evaluate the effectiveness of supplemental oxygen therapy and high-flow nasal cannula (HFNC) therapy in patients with obstructive sleep apnea (OSA) in different clinical settings to assess its application to surgical patients in the postoperative setting.

DESIGN

A systematic search was conducted on MEDLINE and other databases from 1946 to December 16th, 2021. Title and abstract screening were conducted independently, and the lead investigators resolved conflicts. Meta-analyses were performed using a random-effects model and are presented as mean difference and standardized mean difference with 95% confidence intervals. These were calculated using RevMan 5.4.

PATIENTS

1395 and 228 OSA patients underwent oxygen therapy and HFNC therapy respectively.

INTERVENTIONS

Oxygen therapy and HFNC therapy.

MEASUREMENTS

Apnea-hypopnea index (AHI), oxyhemoglobin saturation (SpO₂), cumulative time with SPO₂ < 90% (CT90).

MAIN RESULTS

Twenty-seven oxygen therapy studies were included in the review, with ten randomized controlled trials (RCT), seven randomized crossovers, seven non-randomized crossovers, and three prospective cohorts. Pooled analyses showed that oxygen therapy significantly reduced AHI by 31% and increased SpO₂ by 5% versus baseline, and CPAP significantly reduced AHI by 84%, and increased SpO₂ by 3% versus baseline. CPAP was 53% more effective in reducing AHI than oxygen therapy, but both treatments had similar effectiveness in increasing SpO₂. Nine HFNC studies were included in the review, with five prospective cohorts, three randomized crossovers, and one RCT. Pooled analyses showed that HFNC therapy significantly reduced AHI by 36% but did not substantially increase SpO₂.

CONCLUSIONS

Oxygen therapy effectively reduces AHI and increases SpO₂ in patients with OSA. CPAP is more effective in reducing AHI than oxygen therapy. HFNC therapy is effective in reducing AHI. Although both oxygen therapy and HFNC therapy effectively reduce AHI, more research is needed to draw conclusions on clinical outcomes.

Proteomic Biomarkers of the Apnea Hypopnea Index and Obstructive Sleep Apnea: Insights into the Pathophysiology of Presence, Severity, and Treatment Response

Obstructive sleep apnea (OSA), a disease associated with excessive sleepiness and increased cardiovascular risk, affects an estimated 1 billion people worldwide. The present study examined proteomic biomarkers indicative of presence, severity, and treatment response in OSA. Participants (n = 1391) of the Stanford Technology Analytics and Genomics in Sleep study had blood collected and completed an overnight polysomnography for scoring the apnea−hypopnea index (AHI). A highly multiplexed aptamer-based array (SomaScan) was used to quantify 5000 proteins in all plasma samples. Two separate intervention-based cohorts with sleep apnea (n = 41) provided samples pre- and post-continuous/positive airway pressure (CPAP/PAP). Multivariate analyses identified 84 proteins (47 positively, 37 negatively) associated with AHI after correction for multiple testing. Of the top 15 features from a machine learning classifier for AHI ≥ 15 vs. AHI < 15 (Area Under the Curve (AUC) = 0.74), 8 were significant markers of both AHI and OSA from multivariate analyses. Exploration of pre- and post-intervention analysis identified 5 of the 84 proteins to be significantly decreased following CPAP/PAP treatment, with pathways involving endothelial function, blood coagulation, and inflammatory response. The present study identified PAI-1, tPA, and sE-Selectin as key biomarkers and suggests that endothelial dysfunction and increased coagulopathy are important consequences of OSA, which may explain the association with cardiovascular disease and stroke.

Sleep Apnea Syndrome (SAS) Clinical Practice Guidelines 2020

The prevalence of sleep disordered breathing (SDB) is reportedly very high. Among SDBs, the incidence of obstructive sleep apnea (OSA) is higher than previously believed, with patients having moderate-to-severe OSA accounting for approximately 20% of adult males and 10% of postmenopausal women not only in Western countries but also in Eastern countries, including Japan. Since 1998, when health insurance coverage became available, the number of patients using continuous positive airway pressure (CPAP) therapy for sleep apnea has increased sharply, with the number of patients about to exceed 500,000 in Japan. Although the "Guidelines for Diagnosis and Treatment of Sleep Apnea Syndrome (SAS) in Adults" was published in 2005, a new guideline was prepared in order to indicate the standard medical care based on the latest trends, as supervised by and in cooperation with the Japanese Respiratory Society and the "Survey and Research on Refractory Respiratory Diseases and Pulmonary Hypertension" Group, of Ministry of Health, Labor and Welfare and other related academic societies, including the Japanese Society of Sleep Research, in addition to referring to the previous guidelines. Because sleep apnea is an interdisciplinary field covering many areas, this guideline was prepared including 36 clinical questions (CQs). In the English version, therapies and managements for SAS, which were written from CQ16 to 36, were shown. The Japanese version was published in July 2020 and permitted as well as published as one of the Medical Information Network Distribution Service (Minds) clinical practice guidelines in Japan in July 2021.

Sleep Apnea Syndrome (SAS) Clinical Practice Guidelines 2020

The prevalence of sleep-disordered breathing (SDB) is reportedly very high. Among SDBs, the incidence of obstructive sleep apnea (OSA) is higher than previously believed, with patients having moderate-to-severe OSA accounting for approximately 20% of adult males and 10% of postmenopausal women not only in Western countries but also in Eastern countries, including Japan. Since 1998, when health insurance coverage became available, the number of patients using continuous positive airway pressure (CPAP) therapy for sleep apnea has increased sharply, with the number of patients about to exceed 500,000 in Japan. Although the "Guidelines for Diagnosis and Treatment of Sleep Apnea Syndrome (SAS) in Adults" was published in 2005, a new guideline was prepared to indicate the standard medical care based on the latest trends, as supervised by and in cooperation with the Japanese Respiratory Society and the "Survey and Research on Refractory Respiratory Diseases and Pulmonary Hypertension" Group, of Ministry of Health, Labor and Welfare and other related academic societies, including the Japanese Society of Sleep Research, in addition to referring to the previous guidelines. Since sleep apnea is an interdisciplinary field covering many areas, this guideline was prepared including 36 clinical questions (CQs). In the English version, therapies and managements for SAS, which were written from CQ16 to 36, were shown. The Japanese version was published in July 2020 and permitted as well as published as one of the Medical Information Network Distribution Service (Minds) clinical practice guidelines in Japan in July 2021.

Selective Continuous Positive Airway Pressure Withdrawal With Supplemental Oxygen During Slow-Wave Sleep as a Method of Dissociating Sleep Fragmentation and Intermittent Hypoxemia-Related Sleep Disruption in Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is considered to impair memory processing and increase the expression of amyloid-β (Aβ) and risk for Alzheimer’s disease (AD). Given the evidence that slow-wave sleep (SWS) is important in both memory and Aβ metabolism, a better understanding of the mechanisms by which OSA impacts memory and risk for AD can stem from evaluating the role of disruption of SWS specifically and, when such disruption occurs through OSA, from evaluating the individual contributions of sleep fragmentation (SF) and intermittent hypoxemia (IH). In this study, we used continuous positive airway pressure (CPAP) withdrawal to recapitulate SWS-specific OSA during polysomnography (PSG), creating conditions of both SF and IH in SWS only. During separate PSGs, we created the conditions of SWS fragmentation but used oxygen to attenuate IH. We studied 24 patients (average age of 55 years, 29% female) with moderate-to-severe OSA [Apnea-Hypopnea Index (AHI); AHI4% > 20/h], who were treated and adherent to CPAP. Participants spent three separate nights in the laboratory under three conditions as follows: (1) consolidated sleep with CPAP held at therapeutic pressure (CPAP); (2) CPAP withdrawn exclusively in SWS (OSA_SWS) breathing room air; and (3) CPAP withdrawn exclusively in SWS with the addition of oxygen during pressure withdrawal (OSA_SWS + O₂). Multiple measures of SF (e.g., arousal index) and IH (e.g., hypoxic burden), during SWS, were compared according to condition. Arousal index in SWS during CPAP withdrawal was significantly greater compared to CPAP but not significantly different with and without oxygen (CPAP = 1.1/h, OSA_SWS + O2 = 10.7/h, OSA_SWS = 10.6/h). However, hypoxic burden during SWS was significantly reduced with oxygen compared to without oxygen [OSA_SWS + O₂ = 23 (%min)/h, OSA_SWS = 37 (%min)/h]. No significant OSA was observed in non-rapid eye movement (REM) stage 1 (NREM 1), non-REM stage 2 (NREM 2), or REM sleep (e.g., non-SWS) in any condition. The SWS-specific CPAP withdrawal induces OSA with SF and IH. The addition of oxygen during CPAP withdrawal results in SF with significantly less severe hypoxemia during the induced respiratory events in SWS. This model of SWS-specific CPAP withdrawal disrupts SWS with a physiologically relevant stimulus and facilitates the differentiation of SF and IH in OSA.

Association between self-reported snoring and hypertension: a systematic review and meta-analysis

OBJECTIVES

The purpose of this study is to summarize the evidence for the association between snoring and hypertension and the effect of snoring on hypertension in men and/or women.

METHODS

We searched the articles in the Cochrane Library, PubMed, Scopus, Web of Science and Embase published up to 12 November 2020 to evaluate the association between snoring and hypertension. Studies were selected according to the predefined screening criteria and their qualities were assessed by Newcastle-Ottawa Quality Evaluation Scale. The odds ratio and 95% confidence interval were used as effective indicators. It was registered in PROSPERO with the number: CRD42021224912.

RESULTS

According to the inclusion/exclusion criteria, 11 studies including eight prospective cohort studies and three cross-sectional studies were included. The results showed that compared with non-snoring participants, snoring significantly increased the risk of hypertension in both men and women [odds ratio (OR) = 1.32, 95% confidence interval (CI), 1.23-1.42; men: odds ratio (OR) = 1.32; 95% confidence interval (CI), 1.18-1.49; women: odds ratio (OR) = 1.26; 95% confidence interval (CI), 1.14-1.40]. Besides, the risk of hypertension was significantly increased when the snoring frequency was ≥4 nights/week [frequency≥4 nights/week: odds ratio (OR) = 1.42; 95% confidence interval (CI), 1.21-1.66; 4 nights/week >frequency>0: odds ratio (OR) = 1.23; 95% confidence interval (CI),1.13-1.34].

CONCLUSIONS

Snoring is considered as an independent predictor of hypertension in both men and women, which may play a role in the prevention and control of hypertension. People who snore frequently should pay close attention to their blood pressure levels to prevent hypertension.

Obstructive Sleep Apnea in Patients with Chronic Obstructive Pulmonary Disease: Facts and Perspectives

The co-occurrence of obstructive sleep apnea (OSA) and chronic obstructive pulmonary disease (COPD) in the same patient, named the overlap syndrome (OS), was first described in 1985. Although the American Thoracic Society underlined the limited knowledge of OS, stated research priorities for this condition, and recommended a "screening" strategy to identify OSA in COPD patients with chronic stable hypercapnia, research studies on OS remain scarce. This review aims to summarize the current knowledge and perspectives related to OSA in COPD patients. OS prevalence is 1.0-3.6% in the general population, 3-66% in COPD patients, and 7-55% in OSA patients. OS patients may have worse sleep quality than those with OSA or COPD alone. Scoring hypopneas may be difficult in COPD patients; desaturation episodes may have origins in these patients, namely upper airway obstruction, hypoventilation during paradoxical sleep, ventilation/perfusion mismatches, and obesity. The apnea-hypopnea index is similar in OSA and OS patients. Desaturations may be greater and more prolonged in OS patients than in patients with COPD or OSA alone. Low body mass index, hyperinflation, and less collapsible airways reduce the risk of OSA in COPD patients. OSA is a risk factor for pulmonary hypertension in COPD patients. Whether OS increases mortality and morbidity risks compared to COPD or OSA alone remains to be confirmed. No guidelines currently recommend specific approaches to the treatment of OSA in patients with COPD.

Influencing Factors of Daytime Sleepiness in Patients with Obstructive Sleep Apnea Hypopnea Syndrome and Its Correlation with Pulse Oxygen Decline Rate

Objective

To explore the influencing factors of daytime sleepiness in patients with obstructive sleep apnea hypopnea syndrome (OSAHS) and the correlation between daytime sleepiness and pulse oxygen decline rate in patients with severe OSAHS.

Methods

From January 2018 to April 2021, 246 consecutive patients with OSAHS diagnosed by polysomnography (PSG) in our hospital were selected. All patients were grouped according to the minimum nocturnal oxygen saturation and apnea hypopnea index (AHI). There were 33 cases in the no sleep hypoxia group, 34 cases in the mild hypoxia group, 119 cases in the moderate hypoxia group, and 60 cases in the severe hypoxia group. There were 30 cases in the simple snoring group, 55 cases in the mild OSAHS group, 48 cases in the moderate OSAHS group, and 113 cases in the severe OSAHS group. The Epworth Sleepiness Scale (ESS) scores of each group were compared. All patients were grouped according to ESS score. Those with score ≥9 were included in the lethargy group (n = 118), and those with score ≤10 were included in the no lethargy group (n = 128). Univariate and multivariate logistic regression analyses were used to explore the influencing factors of daytime sleepiness in OSAHS patients. Pearson correlation analysis showed the correlation between ESS score and pulse oxygen decline rate in patients with severe OSAHS.

Results

The ESS score of the severe hypoxia group > the moderate hypoxia group > the mild hypoxia group > the no sleep hypoxia group. There was significant difference among the groups (F = 19.700, P < 0.0001). There were significant differences between the severe hypoxia group and other groups and between the moderate hypoxia group and the no sleep hypoxia group and the mild hypoxia group (P < 0.05). The ESS score of the severe OSAHS group > the moderate OSAHS group > the mild OSAHS group > the simple snoring group. There was significant difference among the groups (F = 19.000, P < 0.0001). There were significant differences between the severe OSAHS group and other groups and between the moderate OSAHS group and the simple snoring group (P < 0.05). Univariate analysis showed that BMI, neck circumference, snoring degree, total apnea hypopnea time, AHI, micro arousal index (MAI), oxygen saturation (CT90%), lowest oxygen saturation (LSaO2), and mean oxygen saturation (MSaO2) were the influencing factors of daytime sleepiness in OSAHS patients (P < 0.05). Multiple logistic regression analysis showed that AHI and CT90% were independent risk factors for daytime sleepiness in OSAHS patients (P < 0.05). Pearson correlation analysis showed that there was a positive correlation between ESS score and pulse oxygen decline rate in patients with severe OSAHS (r = 0.765, P < 0.0001).

Conclusion

OSAHS patients may be accompanied by daytime sleepiness in varying degrees, which may be independently related to AHI and CT90%. The degree of daytime sleepiness in patients with severe OSAHS may be closely related to the decline rate of pulse oxygen, which should be paid great attention in clinic.

The efficacy of a titrated tongue-stabilizing device on obstructive sleep apnea: a quasi-experimental study

STUDY OBJECTIVES

To evaluate the short-term efficacy and self-reported outcomes of tongue-stabilizing device (TSD) therapy as compared to those of mandibular advancement device (MAD) therapy in an adult population diagnosed with obstructive sleep apnea.

METHODS

This study is a parallel, nonrandomized clinical trial of the TSD and MAD therapies. The efficacy of both interventions was evaluated objectively by level 3 home sleep apnea testing and by self-report using the Epworth Sleepiness Scale, the Functional Outcomes of Sleep Questionnaire, the Chalder Fatigue Scale, and the 36-Item Short-Form Health Survey. Adherence and adverse effects were self-reported.

RESULTS

Of the 39 patients who received TSD therapy, 27 managed to adapt and complete the trial and were matched with 26 patients who received MAD therapy. At the 2-month follow-up, the acceptance rate of the TSD therapy was 53.8%. Both patients receiving TSD therapy and patients receiving MAD therapy showed significant improvements in their respiratory event index (P < .05), with no difference between the treatments (P > .05). In those receiving TSD therapy (n = 27), the only self-reported efficacy measure that significantly improved with TSD therapy was the Chalder Fatigue Scale (P < .05). In contrast, all 4 self-reported measures (Epworth Sleepiness Scale, Functional Outcomes of Sleep Questionnaire, 36-Item Short-Form Health Survey, and Chalder Fatigue Scale) showed a significant improvement with MAD therapy.

CONCLUSIONS

This study revealed similar improvements in apneas and oxygen saturation between TSD and MAD therapies. Whereas MAD therapy was a better treatment for obstructive sleep apnea in terms of daytime sleepiness and quality-of-life improvements, TSD therapy had a low treatment acceptance rate.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Name: The Efficacy of Tongue Stabilizing Device in Patients with Obstructive Sleep Apnea; URL: https://clinicaltrials.gov/ct2/show/NCT02329925; Identifier: NCT02329925; and Registry: ClinicalTrials.gov; Name: Adherence and Preference of Continuous Positive Airway Pressure vs Mandibular Advancement Splints in Obstructive Sleep Apnea Patients: A Randomized Trial (CHOICE); URL: https://clinicaltrials.gov/ct2/show/NCT02242617; Identifier: NCT02242617.

CITATION

Alshhrani WM, Hamoda MM, Okuno K, et al. The efficacy of a titrated tongue-stabilizing device on obstructive sleep apnea: a quasi-experimental study. J Clin Sleep Med. 2021;17(8):1607-1618.

Period-to-Period Variability of Moderate/Severe Obstructive Sleep Apnoea

INTRODUCTION

The severity of obstructive sleep apnoea (OSA) is highly variable on a night-to-night basis. Patients are commonly categorised based on the severity of their OSA, and this is then used to influence management and reimbursement, including continuous positive airway pressure (CPAP). We aimed to establish to what extent the OSA severity category changes during two periods of OSA, based on mean and maximum oxygen desaturation index (ODI).

METHODS

Patients with a diagnosis of moderate to severe OSA who had been on CPAP for greater than 1 year were included in this study. Subjects underwent two periods of CPAP withdrawal for four nights each.

RESULTS

Twenty-five patients completed the study. Based on the mean ODI of the four nights, 14 (56%) patients changed OSA severity categorisation, with three (12%) changing category to mild. Based on the maximum ODI of the four nights, nine (36%) patients changed OSA severity categorisation, with one (4%) changing category to mild. One third to a half of patients' OSA severity category changed between the two periods of four night's CPAP withdrawal.

CONCLUSIONS

OSA is highly variable on a period-to-period basis as well as on a night-to-night basis. We believe the concept of patients having a definable and 'real' level of OSA severity is therefore flawed. OSA severity should be based mainly on symptoms, as these are the dominant reasons for treatment, and the sleep study should be used qualitatively to ascertain whether respiratory events are the likely cause of the symptoms.

TRIAL REGISTRATION

ISRCTN17987510.

Cardiovascular Disorders Triggered by Obstructive Sleep Apnea-A Focus on Endothelium and Blood Components

Obstructive sleep apnea (OSA) is known to be an independent cardiovascular risk factor. Among arousal from sleep, increased thoracic pressure and enhanced sympathetic activation, intermittent hypoxia is now considered as one of the most important pathophysiological mechanisms contributing to the development of endothelial dysfunction. Nevertheless, not much is known about blood components, which justifies the current review. This review focuses on molecular mechanisms triggered by sleep apnea. The recurrent periods of hypoxemia followed by reoxygenation promote reactive oxygen species (ROS) overproduction and increase inflammatory response. In this review paper we also intend to summarize the effect of treatment with continuous positive airway pressure (CPAP) on changes in the profile of the endothelial function and its subsequent potential clinical advantage in lowering cardiovascular risk in other comorbidities such as diabetes, atherosclerosis, hypertension, atrial fibrillation. Moreover, this paper is aimed at explaining how the presence of OSA may affect platelet function and exert effects on rheological activity of erythrocytes, which could also be the key to explaining an increased risk of stroke.

Association of sleep-disordered breathing and wound healing in patients with diabetic foot ulcers

STUDY OBJECTIVES

Sleep-disordered breathing (SDB) is prevalent and associated with an increased risk of morbidity and mortality. However, whether SDB has an adverse impact on wound healing in patients with diabetic foot ulcers (DFUs) is uncertain. The purpose of this study was to investigate the association of SDB with wound healing in patients with DFUs.

METHODS

A total of 167 patients with DFUs were enrolled between July 2013 and June 2019 at West China Hospital (Chengdu, China) to assess the association of SDB with wound healing, ulcer recurrence, and all-cause mortality.

RESULTS

Whereas there was no significant association between apnea-hypopnea index (AHI) and wound healing, total sleep time (per hour: hazard ratio [HR], 1.15; 95% confidence interval [CI], 1.01-1.30; P = .029), sleep efficiency (per 10%: HR, 1.20; 95% CI, 1.04-1.37; P = .012), and wakefulness after sleep onset (per 30 minutes: HR, 0.89; 95% CI, 0.82-0.97; P = .008) were associated with wound healing. Total sleep time (per hour: odds ratio, 0.71; 95% CI, 0.51-0.97; P = .035) and sleep efficiency (per 10%: odds ratio, 0.68; 95% CI, 0.47-0.97; P = .033) were also associated with ulcer recurrence. Mean oxygen saturation (per 3%: HR, 0.68; 95% CI, 0.49-0.94; P = .021) and percentage of sleep time with oxygen saturation < 90% (per 10%: HR, 1.25; 95% CI, 1.03-1.53; P = .026) were significantly associated with mortality.

CONCLUSIONS

SDB is highly prevalent in patients with DFUs but its severity, as conventionally measured by AHI, is not associated with wound healing. Sleep fragmentation and hypoxemia are stronger predictors of poor wound healing, high ulcer recurrence, and increased risk of death in patients with DFUs.

Effect of One Night of Nocturnal Oxygen Supplementation on Highland Patients With OSA: A Randomized, Crossover Trial

BACKGROUND

The treatment of OSA in highland residents is not established.

RESEARCH QUESTIONS

Does nocturnal oxygen supplementation (NOS) improve sleep-related breathing disturbances, nocturnal oxygenation, and cognitive performance in patients with OSA living at 3,200 m?

STUDY DESIGN AND METHODS

Forty patients with OSA permanently living in Shangri-La, China at 3,200 m (median age [interquartile range], 47.0 [44.0-53.0] years; oxygen desaturation index, 38.4/h [34.2/h-52.3/h]), were randomly assigned to receive nasal NOS and sham oxygen (ambient air), for one night each, at 2 L/min, in a crossover design, separated by a washout period of 2 weeks. During treatment nights polysomnography was performed, and further outcomes were evaluated the next morning. The primary outcome was the difference in apnea-hypopnea index (AHI) between nights with NOS and nights with sham oxygen.

RESULTS

During nights with sham oxygen, the median (interquartile range) total AHI was 43.4/h (31.1/h-67.5/h), the obstructive AHI was 41.9/h (28.5/h-66.8/h), and the central AHI was 0.6/h (0.1/h-1.3/h); blood oxygenation as determined by pulse oximetry (Spo₂) was 87.0% (84.5%-89.0%). In intention-to-treat analysis, NOS decreased the total AHI by a median of 17.9/h (95% CI, 8.0/h-27.1/h; P < .001), through a reduction in obstructive AHI by 16.0/h (95% CI, 6.8/h-26.0/h; P < .001) and central AHI by 0.4/h (95% CI, 0.1/h-0.9/h; P < .001). NOS also increased Spo₂ by 7.0% (95% CI, 6.0%-8.0%; P < .001). Heart rate during sleep and pulse rate in the morning after NOS were significantly reduced, but subjective sleep quality and cognitive performance showed no changes.

INTERPRETATION

In highland residents with OSA, NOS significantly improved sleep-related breathing disturbances and nocturnal oxygenation. NOS also reduced heart rate during sleep and morning pulse rate. If these beneficial effects are confirmed in longer term studies, NOS may be a treatment option for highland patients with OSA who cannot be treated by CPAP.

TRIAL REGISTRY

Chinese Clinical Trial Registry; No.: ChiCTR1800017715; URL: http://www.chictr.org.cn/showproj.aspx?proj=29768.

Chronic intermittent hypoxia-induced mitochondrial dysfunction mediates endothelial injury via the TXNIP/NLRP3/IL-1β signaling pathway

Oxidative stress and inflammation induced by chronic intermittent hypoxia (CIH) are trigger factors of cardiovascular diseases in patients with obstructive sleep apnea (OSA). This study aimed to investigate the role of CIH-induced mitochondrial dysfunction in vascular endothelial injury both in vivo and in vitro. Human umbilical vein endothelial cells and Sprague Dawley rats were exposed to CIH. CIH promoted the production of intracellular reactive oxygen species, caused mitochondrial dysfunction, and induced cell apoptosis in human umbilical vein endothelial cells. RNA-Seq analysis revealed that the NOD-like receptor signaling pathway was involved in endothelial injury induced by CIH. TXNIP/NLRP3/IL-1β pathway was found to be upregulated by CIH. Knock-down of TNXIP rescued the endothelial cells from CIH-induced apoptosis, indicating that activation of the TXNIP/NLRP3/IL-1β pathway mediated the CIH-induced endothelial apoptosis. Administration of the mitochondria-targeted antioxidant mito-TEMPO improved mitochondrial function and suppressed upregulation of the TXNIP/NLRP3/IL-1β pathway, thereby alleviating CIH-induced endothelial apoptosis. In vivo experiments confirmed the results, where mito-TEMPO was found to ameliorate endothelial injury in rat aortas exposed to CIH. The results imply that CIH-induced mitochondrial dysfunction mediates endothelial injury implication of TXNIP/NLRP3/IL-1β signaling pathway.

Oxygen Therapy in Sleep-Disordered Breathing

Sleep-disordered breathing (SDB) is highly prevalent in adults and leads to significant cardiovascular and neurologic sequelae. Intermittent hypoxia during sleep is a direct consequence of SDB. Administration of nocturnal supplemental oxygen (NSO) has been used as a therapeutic alternative to positive airway pressure (PAP) in SDB. NSO significantly improves oxygen saturation in OSA but is inferior to PAP in terms of reducing apnea severity and may prolong the duration of obstructive apneas. The effect of NSO on daytime sleepiness remains unclear, but NSO may improve physical function-related quality of life in OSA. Its effects on BP reduction remain inconclusive. The effects of NSO vs PAP in OSA with comorbid COPD (overlap syndrome) are unknown. NSO is effective in reducing central sleep apnea related to congestive heart failure; however, its impact on mortality and cardiovascular clinical outcomes are being investigated in an ongoing clinical trial. In conclusion, studies are inconclusive or limited regarding clinical outcomes with oxygen therapy compared with sham or PAP therapy in patients with OSA and overlap syndrome. Oxygen does mitigate central sleep apnea. This review examines the crucial knowledge gaps and suggests future research priorities to clarify the effects of optimal dose and duration of NSO, alone or in combination with PAP, on cardiovascular, sleep, and cognitive outcomes.

Comparing the effects of supplemental oxygen therapy and continuous positive airway pressure on patients with obstructive sleep apnea: a meta-analysis of randomized controlled trials

BACKGROUND AND OBJECTIVE

Obstructive sleep apnea (OSA) is associated with hypertension, psychological impairment, neurocognitive dysfunction, and poor quality of sleep. Continuous positive airway pressure (CPAP) has been confirmed to effectively improve OSA, while the effects of supplemental oxygen therapy on OSA have still remained controversial. This meta-analysis aimed to compare the effects of supplemental oxygen therapy and CPAP on patients with OSA.

METHODS

PubMed, Cochrane library, EMBASE, and Web of Science databases were systematically searched from inception until April 2020. Randomized controlled trials (RCTs) that compared the effects of supplemental oxygen therapy and CPAP on patients with OSA were selected without language restriction.

RESULTS

In this meta-analysis, 8 RCTs that involved 887 patients were found eligible for further analyses. Pooled data showed that there was no significant difference in improving nocturnal oxygen saturation (SpO₂) level (95% confidence interval (CI) = - 1.17 to 1.53) or symptoms of depression (95%CI = - 0.69 to 1.19) between supplemental oxygen therapy and CPAP. Supplemental oxygen therapy was found less effective in reducing apnea-hypopnea index (AHI), time of SpO₂ < 90%, blood pressure, and improving quality of sleep compared with CPAP. A subgroup analysis based on flow rate of oxygen indicated that the effects of supplemental oxygen therapy on blood pressure significantly differed. Furthermore, an improvement in overall time of SpO₂ < 90% was correlated to duration of supplemental oxygen therapy.

CONCLUSIONS

CPAP is clinically effective for the treatment of patients with OSA. However, supplemental oxygen therapy can be cautiously used for improving nocturnal hypoxia and symptoms of depression when CPAP is not acceptable or not tolerated. Supplemental oxygen therapy is a promising option to alleviate partial disorders of OSA. Further studies need to focus on flow rate of oxygen and duration of supplemental oxygen therapy.

Acoustic stimulation time-locked to the beginning of sleep apnea events reduces oxygen desaturations: a pilot-study

STUDY OBJECTIVES

We aimed to determine whether bone-conducted acoustic stimulation could prematurely terminate sleep apnea events, thereby decreasing amplitude and duration of subsequent oxygen desaturation. As oxygen desaturation has been linked to cardiovascular consequences, we postulate this could be a viable therapy in some cases.

METHODS

Eight patients with severe Obstructive Sleep Apnea (2 women, 45 [20-68] y.o. Apnea-Hypopnea Index: 77.7 ± 22.3/h) underwent polysomnography at the Lausanne University Sleep Center. Short acoustic stimulations were administered by bone conduction every second event of sleep apnea. Sounds were remotely administered using a Dreem® headband worn by patients while undergoing nocturnal polysomnography. Amplitude (%) and duration(s) of oxygen desaturations following terminated apneas were compared to that of non-stimulated previous and subsequent events.

RESULTS

549 stimulations (68.6 ± 38 sounds per patient) in N1 (16.2%), N2 (69.9%), N3 (4.2%), and REM(9.6%) were conducted. Compared to the previous and subsequent non-stimulated apnea, stimulations reduced event duration by 21.4% (-3.4 ± 7.2 s, p < 0.0001) while oxygen desaturation amplitude and duration were reduced by 30.4% (mean absolute difference ± SD: -1.9 ± 2.8%, p < 0.0001), and 39.6% (-5.7 ± 9.2 s, p < 0.0001) respectively. For these variables, each patient showed a significant improvement following acoustic stimulation. Sound-associated discomfort was rated 1.14 ± 1.53 on an 8 points scale (8 = worst) and only 6.8% of emitted sounds were perceived by the patients, suggesting a well-tolerated intervention.

CONCLUSIONS

Bone-conducted sound stimuli decreased apnea events duration as well as duration and amplitude of associated oxygen desaturations. Stimulations were well tolerated and rarely perceived by patients. This therapeutic approach deserves further investigation, with monitoring of effects on sleep quality, daytime function/sleepiness and cardiovascular parameters.

Nocturnal heart rate variability in obstructive sleep apnoea: a cross-sectional analysis of the Sleep Heart Health Study

Background

Obstructive sleep apnoea (OSA) results in sympathetic overdrive. Increased nocturnal heart rate variability (HRV) is a surrogate marker of autonomic disturbance. The aim was to study the association of the apnoea-hypopnea index (AHI), nocturnal hypoxaemia, and sleep fragmentation with nocturnal HRV to address the pathophysiological mechanisms underlying autonomic disturbance in OSA.

Methods

Participants of the Sleep Hearth Health Study with available data on nocturnal HRV and an AHI ≥10/h have been included in this cross-sectional analysis. The main outcome of interest was the association of sleep fragmentation, nocturnal hypoxaemia, and the AHI with nocturnal HRV. Multivariate regression modelling with the mean of the standard deviations of normal-sinus-to-normal-sinus-interbeat intervals in all 5-minute segments (SDNNIDX) and with low to high frequency power-ratio (LF/HF) as dependent variables controlling for prespecified confounders (age, sex, cups of coffee, beta blocker, nocturnal heart rate) was used to assess the contribution of the arousal index, total sleep time with an oxygen saturation <90% (TST90) and the AHI not due to arousals to HRV. The significance level was set at P<0.01.

Results

In 258 patients with OSA (mean ± SD age 62±10 years, BMI 29±4 kg/m², median (IQR) AHI 18.6/h (14.0-25.6), the arousal index (coef =0.42, P=0.002) was independently positively associated with SDNNIDX also after having controlled for potential confounders, whereas the AHI (coef =0.22, P=0.030) and TST90 (coef =0.36, P=0.054) were not. The arousal index-but not TST and AHI-was also independently associated with LF/HF.

Conclusions

In OSA, pronounced sleep fragmentation is associated with higher nocturnal HRV and a sympatho-vagal imbalance with sympathetic dominance. OSA severity and nocturnal hypoxaemia did not independently predict nocturnal HRV.

Obstructive sleep apnea and pulmonary hypertension: a bidirectional relationship

Mesarwi O, Malhotra A. Obstructive sleep apnea and pulmonary hypertension: a bidirectional relationship. J Clin Sleep Med . 2020;16(8):1223–1224.

Understanding the pathophysiological mechanisms of cardiometabolic complications in obstructive sleep apnoea: towards personalised treatment approaches

In January 2019, a European Respiratory Society research seminar entitled "Targeting the detrimental effects of sleep disturbances and disorders" was held in Dublin, Ireland. It provided the opportunity to critically review the current evidence of pathophysiological responses of sleep disturbances, such as sleep deprivation, sleep fragmentation or circadian misalignment and of abnormalities in physiological gases such as oxygen and carbon dioxide, which occur frequently in respiratory conditions during sleep. A specific emphasis of the seminar was placed on the evaluation of the current state of knowledge of the pathophysiology of cardiovascular and metabolic diseases in obstructive sleep apnoea (OSA). Identification of the detailed mechanisms of these processes is of major importance to the field and this seminar offered an ideal platform to exchange knowledge, and to discuss pitfalls of current models and the design of future collaborative studies. In addition, we debated the limitations of current treatment strategies for cardiometabolic complications in OSA and discussed potentially valuable alternative approaches.

Increased sympathetic responses induced by chronic obstructive sleep apnea are caused by sleep fragmentation

Obstructive sleep apnea (OSA) is often associated with sympathetic overactivity and hypertension. These associations are mainly attributed to hypoxia acting on arterial chemoreceptors. However, the contribution of arousal from sleep is unclear. We measured the effect of OSA and sleep fragmentation on cardiovascular and sympathetic function and gene expression in the brain in rats. Male Wistar rats were fitted with a tracheal balloon and EEG and electromyogram electrodes and assigned to control (n = 6), OSA (n = 9), or arousal (n = 8) treatments. The OSA group was subjected to obstructive apnea, each time the rat entered sleep, for 8 h/day for 15 days. The arousal group was similarly exposed to vibration, which was produced with a miniature vibration motor mounted on the rat's head. Vibration intensity slowly increased until the rat awoke. One day after the last apnea or arousal, rats were anesthetized and arterial blood pressure and splanchnic sympathetic nerve activity (SSNA) were recorded. Baseline mean and diastolic pressure were increased after OSA. Resting SSNA was similar in the three groups, but both OSA and sleep fragmentation increased sympathetic activation in response to airway obstruction and chemoreflex activation by cyanide. OSA increased superoxide dismutases 1 and 2 in the brainstem, whereas sleep fragmentation did not. Our results suggest that sympathetic overactivity to chemoreceptor stimulation was a consequence of arousal from sleep. Our study suggests that sleep disruption may have an important role in the development of apnea-related sympathetic activation.NEW & NOTEWORTHY Obstructive sleep apnea causes a hyperactive chemoreflex, with increased sympathetic activation. However, it is not clear whether this pathophysiologic mechanism is due to repeated hypoxia or to sleep disruption. The present study suggests that sleep fragmentation contributes importantly to increased sympathetic activation after chemoreceptor stimulation. This suggests that sleep fragmentation has an important role in the sympathetic activation seen in sleep apnea patients.

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.

The Association Between Obstructive Sleep Apnea Characterized by a Minimum 3 Percent Oxygen Desaturation or Arousal Hypopnea Definition and Hypertension

STUDY OBJECTIVES

The association between obstructive sleep apnea (OSA) and hypertension in prior studies has been determined using a definition of hypopnea requiring a 4% O₂ desaturation. However, the American Academy of Sleep Medicine (AASM) recommends using a 3% O₂ desaturation or an arousal. This analysis assesses the relationship between OSA and hypertension utilizing the AASM recommended definition and the 2018 American College of Cardiology/American Heart Association hypertension guidelines.

METHODS

Data from 6113 participants from the Sleep Heart Health Study were analyzed. The AASM recommended apnea-hypopnea index (AHI) was classified into 4 categories of OSA severity: < 5, 5 to < 15, 15 to < 30 and ≥ 30 events/h. Three definitions of hypertension were used: elevated (> 120/< 80 or use of hypertension medications [meds]), stage 1/stage 2 (> 130/80 or meds), stage 2 (> 140/90 or meds). Data were analyzed using logistic regression controlling for demographics, smoking and body mass index. Multiple linear regression analysis assessed the relationship between natural log AHI, and systolic and diastolic blood pressure controlling for the same covariates.

RESULTS

For all definitions of blood pressure elevation, increasing OSA severity was associated with greater likelihood of an elevated or hypertensive status in fully adjusted models (odds ratio [95% confidence interval]): elevated 1.30 (1.09-1.54), 1.39 (1.13-1.70) 1.69 (1.29-2.13); stage 1/2: 1.25 (1.06-1.47), 1.32 (1.10-1.59), 1.53 (1.23-1.91); stage 2: 1.07 (0.91-1.25), 1.21 (1.01-1.44), 1.37 (1.11-1.69) for AHI 5 to < 15, 15 to < 30 and > 30 events/h (< 5 events/h reference). Linear regression found that AHI was associated with both systolic and diastolic blood pressure in fully adjusted models.

CONCLUSIONS

Use of the AASM recommended definition of hypopnea as a component of the AHI is associated with the presence of hypertension.

CITATION

Budhiraja R, Javaheri S, Parthasarathy S, Berry RB, Quan SF. The association between obstructive sleep apnea characterized by a minimum 3 percent oxygen desaturation or arousal hypopnea definition and hypertension. J Clin Sleep Med. 2019;15(9):1261-1270.

Oxygen for the treatment of obstructive sleep apnoea hypopnoea syndrome

Oxygen, in the form of diatomic oxygen (O₂), comprises 20.8% of the Earth's atmosphere and is essential to most life forms on the planet. In 1777, Lavoisier was the first to name oxygen and recognise that it was a chemical element involved in combustion.

Nocturnal oxygen therapy cannot currently be recommended as a sole treatment for obstructive sleep apnoeahttp://bit.ly/2kuAsPU

Association of novel measures of sleep disturbances with blood pressure: the Multi-Ethnic Study of Atherosclerosis

BACKGROUND

Mechanisms underlying blood pressure (BP) changes in obstructive sleep apnoea (OSA) are incompletely understood. We assessed the associations between BP and selected polysomnography (PSG) traits: sleep depth, airflow limitation measurements and OSA-specific hypoxic burden.

METHODS

This cross-sectional analysis included 2055 participants from the Multi-Ethnic Study of Atherosclerosis who underwent PSG and BP measurements in 2010-2013. Sleep depth was assessed using the 'OR product', a continuous measure of arousability. Airflow limitation was assessed by duty cycle (T_i/T_t) and % of breaths with flow limitation, and hypoxia by 'hypoxic burden'. Primary outcomes were medication-adjusted systolic BP (SBP) and diastolic BP (DBP). We used generalised linear models adjusted for age, sex, race/ethnicity, smoking, education, body mass index, alcohol use, periodic limb movements and alternative physiological disturbances.

RESULTS

The sample had a mean age of 68.4 years and apnoea-hypopnoea index of 14.8 events/hour. Sleep depth was not significantly associated with BP. Every 1 SD increment in log-transformed non-rapid eye movement duty cycle was associated with 0.9% decrease in SBP (95% CI: 0.1% to 1.6%), even after adjusting for sleep depth and hypoxic burden. Every 1 SD increment in log-transformed hypoxic burden was associated with a 1.1% increase in SBP (95% CI: 0.1% to 2.1%) and 1.9% increase in DBP (95% CI: 1.0% to 2.8%) among those not using hypertension medications.

CONCLUSIONS

Higher duty cycle was associated with lower SBP overall and hypoxic burden with higher SBP and DBP among non-BP medication users. These findings suggest changes in both respiratory effort and oxygenation during sleep influence BP.

Obstructive sleep apnoea and coronary artery disease

Obstructive sleep apnoea (OSA) is a highly prevalent disorder, which causes significant nocturnal and daytime symptoms, reduced quality of life, and impaired functional capacity. Importantly, however, OSA also appears to predispose to the development of a number of cardiovascular and metabolic diseases, including diabetes, hypertension, and stroke. In this review we explore its relationship with coronary artery disease (CAD), discussing mechanisms whereby it may promote the development of atherosclerosis, evidence of its effect on CAD incidence and outcomes, and coronary imaging studies in subjects with OSA. Finally, we shall evaluate the current evidence regarding the impact of continuous positive airway pressure therapy on CAD outcomes in OSA patients.

Comorbid obstructive sleep apnoea and chronic obstructive pulmonary disease and the risk of cardiovascular disease

Chronic obstructive pulmonary disease (COPD) and obstructive sleep apnoea (OSA) syndrome are both highly prevalent, affecting at least 10% of the general adult population, and each has been independently associated with an increased risk of cardiovascular disease. The presence of both disorders together, commonly referred to as the overlap syndrome, is also highly prevalent, although various clinical and pathophysiological factors associated with COPD may increase or decrease the likelihood of OSA. Lung hyperinflation reduces the likelihood of obstructive apnoea, whereas right heart failure increases the likelihood as a result of rostral fluid shift causing upper airway narrowing in the supine position while asleep. Furthermore, upper airway inflammation associated with OSA may aggravate lower airway inflammation in COPD. The proposed mechanisms of cardiovascular disease in each disorder are similar and include systemic inflammation, oxidative stress, and sympathetic excitation. Thus, one could expect that the prevalence of co-morbid cardiovascular disease would be higher in the overlap syndrome but, with the exception of pulmonary hypertension, there are few published reports that have explored this aspect in depth. Hypoxia is more pronounced in patients with the overlap syndrome, especially during sleep, which is likely to be the principal factor accounting for the recognised higher prevalence of pulmonary hypertension in these patients. Cardiac sympathetic activity is increased in patients with the overlap syndrome when compared to each disorder alone, but echocardiographic evidence of left ventricular strain is no greater in overlap patients when compared to COPD alone. While survival might be expected to be worse in overlap patients, recent evidence surprisingly indicates that the incremental contribution of lung function to mortality diminishes with increasing severity of OSA. Identification of co-morbid OSA in patients with COPD has practical clinical significance as appropriate positive airway pressure therapy in COPD patients with co-existing OSA is associated with improved morbidity and mortality.