Association of sleep-disordered breathing and the occurrence of stroke

Exposure to intermittent hypoxia inhibits allergic airway inflammation in a murine model of asthma

PURPOSE

Obesity increases the severity of asthma, and patients with severe asthma are often complicated with obstructive sleep apnea syndrome (OSAS), a concomitant disease of obesity. We investigated whether intermittent hypoxia (IH), which is a physiological feature of OSAS, modifies allergic airway inflammation in a murine model of asthma.

METHODS

Balb/c mice were sensitized by ovalbumin (OVA) intraperitoneally twice (days 1 and 14) and challenged with intranasal OVA three times (days 21, 22, and 23). The mice were exposed to IH either from days 1 to 24 (long exposure) or only from days 21 to 24 (short exposure). The impact of IH exposure to allergic airway inflammation was investigated using these mice models by histologic, morphometric, and molecular techniques. Additionally, the airway responsiveness to acetylcholine was also assessed.

RESULTS

OVA-sensitized and OVA-challenged mice exposed to room air (RA) showed increased total cell and eosinophil numbers in the BALF. The levels of interleukin (IL)-5 and IL-13 in the BALF also increased and goblet cell metaplasia was induced. In contrast, both long and short exposure to IH inhibited the increased total cell and eosinophil numbers. The levels of IL-5 and IL-13 in the BALF also decreased on exposure to IH. Moreover, the goblet cell hyperplasia and airway hyperresponsiveness were significantly reduced in mice exposed to IH compared to those exposed to RA.

CONCLUSIONS

These results suggest that IH may not deteriorate the asthmatic condition in a murine model of asthma.

Role of Obstructive Sleep Apnea in Cognitive Impairment

Obstructive sleep apnea (OSA) is a prevalent sleep related breathing disorder characterized by repetitive collapse of the upper airways leading to intermittent hypoxia and sleep disruption. Clinically relevant neurocognitive, metabolic and cardiovascular disease often occurs in OSA. Systemic hypertension, coronary artery disease, type 2 diabetes mellitus, cerebral vascular infarctions and atrial fibrillation are among the most often cited conditions with causal connections to OSA. Emerging science suggest that untreated and undertreated OSA increases the risk of developing cognitive impairment, including vascular dementia and neurodegenerative disorders, like Alzheimer’s disease. As with OSA, cardiovascular disease and type 2 diabetes mellitus, the incidence of dementia increases with age. Given our rapidly aging population, dementia prevalence will significantly increase. The aim of this treatise is to review current literature linking OSA to dementia and explore putative mechanisms by which OSA might facilitate the development and progression of dementia.

Is severe obstructive sleep apnea associated with less depressive symptoms?

PURPOSE

To investigate the relationship between obstructive sleep apnea (OSA) and symptoms of depression and anxiety in OSA patients.

METHODS

Symptoms were assessed using the Beck Depression Inventory (BDI) and the state part of the State-Trait Anxiety Inventory (STAI-S). BDI scores of ≥10 and STAI-S scores of ≥40 were considered to indicate the presence of depression and anxiety, respectively. Apnea severities measured using polysomnography were categorized into mild, moderate, and severe subgroups bounded by the 33rd and 66th percentiles of each polysomnographic parameter. Data were stratified by age, gender, and level of daytime sleepiness.

RESULTS

The study population comprised 795 adult patients (86.9% men). Symptoms of depression and anxiety were present in 46.2% and 49.2% of patients, respectively. Excessive daytime sleepiness was present in 40.0% of patients and did not differ depending on the level of apnea severity. Results of crude logistic regression analyses indicated that depressive symptoms were more prevalent in patients with mild OSA than those with severe OSA, regardless of the categorizing method. These results remained statistically significant following adjustment for several confounding factors. These relationships were similar but less prominent in measures of anxiety. In the sub-analyses, such negative associations between severity of OSA and depressive symptoms tended to be observed only in patients with daytime sleepiness.

CONCLUSIONS

Symptoms of depression and anxiety were found to be more prevalent in patients with mild OSA than those with severe OSA. Excessive daytime sleepiness was shown to affect the severity of depressive symptoms.

Sleep Disorders and Stroke: Does Treatment of Obstructive Sleep Apnea Decrease Risk of Ischemic Stroke?

PURPOSE OF REVIEW

This review aims to support obstructive sleep apnea (OSA) as a risk factor for ischemic stroke, review treatment strategies for OSA, provide a comprehensive review of clinical data on OSA treatment and ischemic stroke risk, and to critically assess if treatment of OSA decreases the risk of ischemic stroke and if treatment improves outcomes and subsequent ischemic stroke risk in post-stroke patients.

RECENT FINDINGS

Several observational studies, randomized controlled trials (RCTs), and meta-analyses have examined the risk of ischemic stroke and cardiovascular events in patients with OSA and have also examined continuous positive airway pressure (CPAP) treatment in these patients. Observational studies have shown an increased risk of ischemic stroke in patients with untreated OSA when compared with patients treated with CPAP; however, results are not statistically significant. RCTs and meta-analyses have shown no significant ischemic stroke risk reduction in CPAP treated patients with OSA. Several studies have shown improved outcomes in post-stroke patients with OSA treated with CPAP; however, few data is available for subsequent ischemic stroke risk reduction. Further research is needed for surgical treatment of OSA and assessment of ischemic stroke risk. OSA is associated with increased risk of ischemic stroke, and OSA should be treated with the appropriate therapy. While the current data is promising, more studies are necessary to state whether treatment of OSA reduces ischemic stroke risk and subsequent ischemic stroke risk. A practical approach to the sleep disorder evaluation and treatment of patients with cerebrovascular disease is outlined.

Effect of CPAP Treatment of Sleep Apnea on Clinical Prognosis After Ischemic Stroke: An Observational Study

STUDY OBJECTIVES

To evaluate continuous positive airway pressure (CPAP) treatment in patients with moderate to severe sleep-disordered breathing (SDB) after an ischemic stroke.

METHODS

We identified patients included in the Acute Stroke Registry and Analysis of Lausanne (ASTRAL) who underwent polysomnography after an ischemic stroke. We compared patients without significant SDB (apnea-hypopnea index [AHI] < 15 events/h: SDB-), with AHI ≥ 15 events/h who refused CPAP or with poor CPAP adherence (SDB+ CPAP-), and patients with SDB effectively treated by CPAP (SDB+ CPAP+).

RESULTS

We analyzed data from 101 patients (age 68.5 ± 11.1 years, 84.1% men). In multivariate analysis the SDB+ CPAP+ group was associated with a significant reduction of stroke recurrence and mortality (odds ratio 0.13, 95% confidence interval 0.00-0.86, P = .031), whereas atrial fibrillation was independently associated with a higher risk (odds ratio 4.32, 95% confidence interval 1.51-12.33, P = .006). Event-free survival analysis (stroke recurrence and death) after 2-year follow-up showed that those in the SDB+ CPAP+ group had significantly higher cardiovascular survival, and Cox proportion hazard model identified CPAP treatment as significantly associated with survival time (P = .025). The AHI and the National Institutes of Health Stroke Scale subacute score were independently associated with CPAP adherence among patients with SDB.

CONCLUSIONS

This observational study shows that CPAP treatment in stroke patients with moderate to severe SDB is associated with lower rates of stroke recurrence and death.

The Relationship between Obstructive Sleep Apnea and Alzheimer's Disease

Obstructive sleep apnea (OSA) and Alzheimer's disease (AD) are highly prevalent conditions with growing impact on our aging society. While the causes of OSA are now better characterized, the mechanisms underlying AD are still largely unknown, challenging the development of effective treatments. Cognitive impairment, especially affecting attention and executive functions, is a recognized clinical consequence of OSA. A deeper contribution of OSA to AD pathogenesis is now gaining support from several lines of research. OSA is intrinsically associated with disruptions of sleep architecture, intermittent hypoxia and oxidative stress, intrathoracic and hemodynamic changes as well as cardiovascular comorbidities. All of these could increase the risk for AD, rendering OSA as a potential modifiable target for AD prevention. Evidence supporting the relevance of each of these mechanisms for AD risk, as well as a possible effect of AD in OSA expression, will be explored in this review.

REM obstructive sleep apnea: risk for adverse health outcomes and novel treatments

Rapid eye movement (REM) sleep was discovered nearly 60 years ago. This stage of sleep accounts for approximately a quarter of total sleep time in healthy adults, and it is mostly concentrated in the second half of the sleep period. The majority of research on REM sleep has focused on neurocognition. More recently, however, there has been a growing interest in understanding whether obstructive sleep apnea (OSA) during the two main stages of sleep (REM and non-REM sleep) leads to different cardiometabolic and neurocognitive risk. In this review, we discuss the growing evidence indicating that OSA during REM sleep is a prevalent disorder that is independently associated with adverse cardiovascular, metabolic, and neurocognitive outcomes. From a therapeutic standpoint, we discuss limitations of continuous positive airway pressure (CPAP) therapy given that 3 or 4 h of CPAP use from the beginning of the sleep period would leave 75% or 60% of obstructive events during REM sleep untreated. We also review potential pharmacologic approaches to treating OSA during REM sleep. Undoubtedly, further research is needed to establish best treatment strategies in order to effectively treat REM OSA. Moreover, it is critical to understand whether treatment of REM OSA will translate into better patient outcomes.

Coexistence of obstructive sleep apnea and telomerase activity, concentration of selected adipose tissue hormones and vascular endothelial function in patients with arterial hypertension

AIM

The aim of the present study was to determine the effect of obstructive sleep apnea (OSA) with hypertension on telomerase activity, visfatin and adipsine concentration in the blood and vascular endothelial function assessed by ultrasound measured flow-mediated dilatation of the brachial artery (FMD).

MATERIAL AND METHODS

The study involved a group of 106 people (average age: 54.79 years). The determination of telomerase activity and blood visfatin and adipsine concentrations, brachial artery ultrasound examination with endothelium-dependent dilatation evaluation (FMD) and polysomnography were carried out.

RESULTS

Patients with hypertension without OSA were characterized by significantly greater FMD in comparison to patients with arterial hypertension and OSA (8.13 ± 5.12 %vs. 6.82 ± 5.36%; p < 0.05). Negative linear relationship between apnea-hypopnea index (AHI) and FMD (r = -0.22, p < 0.05) has been demonstrated. Negative linear relationship between adipsine concentration in the blood and length of REM (Rapid Eye Movement) sleep (r = -0.21, p < 0.05) was found. Positive linear relationship between the concentration of visfatin in the blood and the length of REM sleep (r = 0.22, p < 0.05) was also observed. Higher body mass index, higher total cholesterol, triglyceride and glucose levels have been shown to be independent predictors of higher AHI values, while greater telomerase activity, greater FMD and use of angiotensin converting enzyme inhibitors are independent predicators for lower AHI values.

CONCLUSION

Higher values of AHI index in polysomnography in hypertensive patients can be related to lower telomerase activity in the blood and impaired function of vascular endothelial function assessed using ultrasound.

Association of Unrecognized Obstructive Sleep Apnea With Postoperative Cardiovascular Events in Patients Undergoing Major Noncardiac Surgery

Importance

Unrecognized obstructive sleep apnea increases cardiovascular risks in the general population, but whether obstructive sleep apnea poses a similar risk in the perioperative period remains uncertain.

Objectives

To determine the association between obstructive sleep apnea and 30-day risk of cardiovascular complications after major noncardiac surgery.

Design, Setting, and Participants

Prospective cohort study involving adult at-risk patients without prior diagnosis of sleep apnea and undergoing major noncardiac surgery from 8 hospitals in 5 countries between January 2012 and July 2017, with follow-up until August 2017. Postoperative monitoring included nocturnal pulse oximetry and measurement of cardiac troponin concentrations.

Exposures

Obstructive sleep apnea was classified as mild (respiratory event index [REI] 5-14.9 events/h), moderate (REI 15-30), and severe (REI >30), based on preoperative portable sleep monitoring.

Main Outcomes and Measures

The primary outcome was a composite of myocardial injury, cardiac death, heart failure, thromboembolism, atrial fibrillation, and stroke within 30 days of surgery. Proportional-hazards analysis was used to determine the association between obstructive sleep apnea and postoperative cardiovascular complications.

Results

Among a total of 1364 patients recruited for the study, 1218 patients (mean age, 67 [SD, 9] years; 40.2% women) were included in the analyses. At 30 days after surgery, rates of the primary outcome were 30.1% (41/136) for patients with severe OSA, 22.1% (52/235) for patients with moderate OSA, 19.0% (86/452) for patients with mild OSA, and 14.2% (56/395) for patients with no OSA. OSA was associated with higher risk for the primary outcome (adjusted hazard ratio [HR], 1.49 [95% CI, 1.19-2.01]; P = .01); however, the association was significant only among patients with severe OSA (adjusted HR, 2.23 [95% CI, 1.49-3.34]; P = .001) and not among those with moderate OSA (adjusted HR, 1.47 [95% CI, 0.98-2.09]; P = .07) or mild OSA (adjusted HR, 1.36 [95% CI, 0.97-1.91]; P = .08) (P = .01 for interaction). The mean cumulative duration of oxyhemoglobin desaturation less than 80% during the first 3 postoperative nights in patients with cardiovascular complications (23.1 [95% CI, 15.5-27.7] minutes) was longer than in those without (10.2 [95% CI, 7.8-10.9] minutes) (P < .001). No significant interaction effects on perioperative outcomes were observed with type of anesthesia, use of postoperative opioids, and supplemental oxygen therapy.

Conclusions and Relevance

Among at-risk adults undergoing major noncardiac surgery, unrecognized severe obstructive sleep apnea was significantly associated with increased risk of 30-day postoperative cardiovascular complications. Further research would be needed to assess whether interventions can modify this risk.

Positional therapy for obstructive sleep apnoea

BACKGROUND

The modalities of therapy for obstructive sleep apnoea (OSA) include behavioural and lifestyle modifications, positional therapy, oral appliances, surgery and continuous positive airway pressure therapy (CPAP). Though CPAP has proven efficacy in treating OSA, adherence with CPAP therapy is suboptimal. Positional therapy (to keep people sleeping on their side) is less invasive and therefore expected to have better adherence. This review considered the efficacy of positional therapy compared to CPAP as well as positional therapy against no positional therapy. Devices designed for positional therapy include lumbar or abdominal binders, semi-rigid backpacks, full-length pillows, a tennis ball attached to the back of nightwear, and electrical sensors with alarms that indicate change in position.

OBJECTIVES

To compare the efficacy of positional therapy versus CPAP and positional therapy versus inactive control (sham intervention or no positional therapy intervention) in people with OSA.

SEARCH METHODS

We identified studies from the Cochrane Airways' Specialised Register (including CENTRAL, MEDLINE, Embase, CINAHL, AHMED and PsycINFO), ClinicalTrials.gov, and the World Health Organization trials portal (ICTRP). It also contains results derived from handsearching of respiratory journals and abstract books of major annual meetings. We searched all databases from their inception to September 2018, with no restrictions on language of publication or publication type.

SELECTION CRITERIA

We included randomised controlled trials comparing positional therapy with CPAP and positional therapy with inactive control.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies and extracted the data. We used a random-effects model in the meta-analysis to estimate mean differences and confidence intervals. We assessed certainty of evidence using the GRADE approach.

MAIN RESULTS

We included eight studies. The studies randomised 323 participants into two types of interventions. The comparison between positional therapy and CPAP included 72 participants, while the comparison between positional therapy and inactive control included 251 participants. Three studies used supine vibration alarm devices, while five studies used physical positioning like specially designed pillows or semirigid backpacks.Positional therapy versus CPAPThe three studies included for this comparison were randomised cross-over trials. Two studies found that there was no difference in Epworth Sleepiness Scale (ESS) scores between CPAP and positional therapy. Two studies showed that CPAP produced a greater reduction in Apnoea-Hypopnoea Index (AHI) with a mean difference (MD) of 6.4 events per hour (95% CI 3.00 to 9.79; low-certainty evidence) compared to positional therapy. Subjective adherence, evaluated in one study, was found to be significantly greater with positional therapy (MD 2.5 hours per night, 95% CI 1.41 to 3.59; moderate-certainty evidence).In terms of secondary outcomes, one study each reported quality-of-life indices and quality-of-sleep indices with no significant difference between the two groups. One study reported cognitive outcomes using multiple parameters and found no difference between the groups. There were insufficient data to comment on other secondary outcomes like respiratory disturbance index (RDI), and frequency and duration of nocturnal desaturation. None of the studies clearly reported adverse effects.Positional therapy versus inactive controlThree studies of positional therapy versus no intervention were randomised cross-over trials, while two studies were parallel-arm studies. Data from two studies showed that positional therapy significantly improved ESS scores (MD -1.58, 95% CI -2.89 to -0.29; moderate-certainty evidence). Positional therapy showed a reduction in AHI compared with control (MD -7.38 events per hour, 95% CI -10.06 to -4.7; low-certainty evidence). One study reported adherence. The number of participants who continued to use the device at two months was no different between the two groups (odds ratio (OR) 0.80, 95% CI 0.33 to 1.94; low-certainty evidence). The same study reported adverse effects, the most common being pain in the back and chest, and sleep disturbance but there was no significant difference between the two groups in terms of device discontinuation (OR 1.25, 95% CI 0.5 to 3.03; low-certainty evidence). One study each reported quality-of-life indices and quality-of-sleep indices, with no significant difference between the two groups. One study reported cognitive outcome, and found no difference between the groups. There was insufficient evidence to comment on other secondary outcomes (RDI, frequency and duration of nocturnal desaturation).

AUTHORS' CONCLUSIONS

The review found that CPAP has a greater effect on improving AHI compared with positional therapy in positional OSA, while positional therapy was better than inactive control for improving ESS and AHI. Positional therapy may have better adherence than CPAP. There were no significant differences for other clinically relevant outcomes such as quality of life or cognitive function. All the studies were of short duration. We are unable to comment on the long-term effects of the therapies. This is important, as most of the quality-of-life outcomes will be evident only when the therapies are given over a longer period of time. The certainty of evidence was low to moderate.

Prevalence, Clinical Profile, and In-Hospital Outcomes of Sleep-Disordered Breathing in Patients Undergoing Transcatheter Aortic Valve Implantation in Japan

Background: The prevalence, patient profile, and outcomes of sleep-disordered breathing (SDB) in aortic stenosis (AS) remain unknown, especially in East Asia.

Methods and Results: One hundred and eighty-one AS patients undergoing transcatheter aortic valve implantation (TAVI) were enrolled. Sixty-one patients (33.7%) had SDB, and lower stroke volume index was an independent determinant of SDB. Incidence of in-hospital stroke after TAVI was higher in the SDB group.

Conclusions: SDB is associated with left ventricular systolic dysfunction in Japanese AS patients referred for TAVI. SDB was highly associated with the incidence of stroke as a procedural complication.

A Global Comparison of Anatomic Risk Factors and Their Relationship to Obstructive Sleep Apnea Severity in Clinical Samples

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) is a global health issue and is associated with obesity and oropharyngeal crowding. Global data are limited on the effect of ethnicity and sex on these relationships. We compare associations between the apnea-hypopnea index (AHI) and these risk factors across ethnicities and sexes within sleep clinics.

METHODS

This is a cross-sectional, multicenter study of patients with OSA from eight sleep centers representing the Sleep Apnea Global Interdisciplinary Consortium (SAGIC). Four distinct ethnic groups were analyzed, using a structured questionnaire: Caucasians (Australia, Iceland, Germany, United States), African Americans (United States), Asians (Taiwan), and South Americans (Brazil). Regression analyses and interaction tests were used to assess ethnic and sex differences in relationships between AHI and anthropometric measures (body mass index [BMI], neck circumference, waist circumference) or Mallampati score.

RESULTS

Analyses included 1,585 individuals from four ethnic groups: Caucasian (60.6%), African American (17.5%), Asian (13.1%), and South American (8.9%). BMI was most strongly associated with AHI in South Americans (7.8% increase in AHI per 1 kg/m² increase in BMI; P < .0001) and most weakly in African Americans (1.9% increase in AHI per 1 kg/m² increase in BMI; P = .002). In Caucasians and South Americans, associations were stronger in males than females. Mallampati score differed between ethnicities but did not influence AHI differently across groups.

CONCLUSIONS

We demonstrate ethnic and sex variations in associations between obesity and OSA. For similar BMI increases, South American patients show greatest AHI increases compared to African Americans. Findings highlight the importance of considering ethnicity and sex in clinical assessments of OSA risk.

Effects of short-term continuous positive airway pressure withdrawal on cerebral vascular reactivity measured by blood oxygen level-dependent magnetic resonance imaging in obstructive sleep apnoea: a randomised controlled trial

Impaired cerebral vascular reactivity (CVR) increases long-term stroke risk. Obstructive sleep apnoea (OSA) is associated with peripheral vascular dysfunction and vascular events. The aim of this trial was to evaluate the effect of continuous positive airway pressure (CPAP) withdrawal on CVR.

41 OSA patients (88% male, mean age 57±10 years) were randomised to either subtherapeutic or continuation of therapeutic CPAP. At baseline and after 2 weeks, patients underwent a sleep study and magnetic resonance imaging (MRI). CVR was estimated by quantifying the blood oxygen level-dependent (BOLD) MRI response to breathing stimuli.

OSA did recur in the subtherapeutic CPAP group (mean treatment effect apnoea–hypopnoea index +38.0 events·h−1, 95% CI 24.2–52.0; p<0.001) but remained controlled in the therapeutic group. Although there was a significant increase in blood pressure upon CPAP withdrawal (mean treatment effect +9.37 mmHg, 95% CI 1.36–17.39; p=0.023), there was no significant effect of CPAP withdrawal on CVR assessedviaBOLD MRI under either hyperoxic or hypercapnic conditions.

Short-term CPAP withdrawal did not result in statistically significant changes in CVR as assessed by functional MRI, despite the recurrence of OSA. We thus conclude that, unlike peripheral endothelial function, CVR is not affected by short-term CPAP withdrawal.

Severe Obstructive Sleep Apnea With Imaged Carotid Plaque Is Significantly Associated With Systemic Inflammation

PURPOSE

Persons with obstructive sleep apnea (OSA) are at heightened risk of myocardial infarction (MI) and stroke caused by adiposity and intermittent hypoxia, which provoke proinflammatory cytokines to induce systemic and vascular inflammation, resulting in endothelial dysfunction and development of atherosclerotic plaque. This study compared levels of systemic inflammation, as indexed by the neutrophil-to-lymphocyte ratio (NLR), between groups of patients with severe OSA with and without carotid artery calcified plaque (CACP⁺ and CACP^-, respectively) on their panoramic image (PI).

MATERIALS AND METHODS

This study had a retrospective cross-sectional study design. Medical records and PIs of men with severe OSA treated by the dental service (January 1, 2017 to December 31, 2017) were reviewed. The predictor variable was the presence or absence of CACP on PIs and the outcome variable was NLR. The t test was used to analyze differences in mean NLRs between groups. Atherogenic risk factors (age, body mass index, hypertension, and diabetes) were assessed for independence by descriptive and logistic regression analyses. Significance set at .05 for all tests.

RESULTS

The study group (n = 39) of patients with CACP⁺ (mean age, 63 ± 7.4 yr) showed a mean NLR of 3.09 ± 1.42. The control group (n = 46) of patients with CACP^- (mean age, 62 ± 6.8 yr) showed a mean NLR of 2.10 ± 0.58. The difference between groups was significant (P < .001). Logistic regression for NLR and CACP failed to show meaningful correlations with covariates.

CONCLUSION

Older men with severe OSA and carotid atheromas on PIs show substantially greater systemic inflammation measured by NLRs. The combination of severe OSA, atheroma formation, and markedly increased NLR suggests a higher risk of MI and stroke and greater need for cardiovascular and cerebrovascular evaluation.

Cerebrovascular Disease in the Young Adult: Examining Melatonin's Possible Multiple Roles

In the last decade or more, there have been reports suggesting a rise in the incidence of stroke in young adults. Presently, it appears that the risk factors associated with the cause of stroke in young adults remain relatively constant across different geographic regions of the world. Moreover, the endogenous rhythm of a neurohormone such as melatonin is known to play certain roles in the modulation of some of the risk factors that are associated with an increased risk of stroke in young people. Whereas animal studies have shown that melatonin plays diverse roles in stroke, only a limited number of human studies examined the roles of exogenous melatonin administration in the prevention of stroke, attenuation of neuronal damage, and improving outcome or well-being in stroke patients. In this review, first we summarize existing studies of stroke in the young adult and then provide insights on melatonin and stroke. Thereafter, we discuss the role of melatonin in models of stroke and how melatonin can be regulated to prevent stroke in young adults. Finally, we highlight the possible roles of melatonin in the management and outcome of stroke, especially in the young adult stroke population.

Cerebral blood flow, oxygen metabolism, and lactate during hypoxia in patients with obstructive sleep apnea

Study Objectives

Obstructive sleep apnea (OSA) is associated with increased risk of stroke but the underlying mechanism is poorly understood. We suspect that the normal cerebrovascular response to hypoxia is disturbed in patients with OSA.

Methods

Global cerebral blood flow (CBF), cerebral metabolic rate of oxygen (CMRO2), and lactate concentration during hypoxia were measured in patients with OSA and matched controls. Twenty-eight patients (82.1% males, mean age 52.3 ± 10.0 years) with moderate-to-severe OSA assessed by partial polysomnography were examined and compared with 19 controls (73.7% males, mean age 51.8 ± 10.1 years). Patients and controls underwent magnetic resonance imaging (MRI) during 35 min of normoxia followed by 35 min inhaling hypoxic air (10%-12% O2). After 3 months of continuous positive airway pressure (CPAP) treatment, 22 patients were rescanned.

Results

During hypoxia, CBF significantly increased with decreasing arterial blood oxygen concentration (4.53 mL (blood)/100 g/min per -1 mmol(O2)/L, p < 0.001) in the control group, but was unchanged (0.89 mL (blood)/100 g/min per -1 mmol(O2)/L, p = 0.289) in the patient group before CPAP treatment. The CBF response to hypoxia was significantly weaker in patients than in controls (p = 0.003). After 3 months of CPAP treatment the CBF response normalized, showing a significant increase during hypoxia (5.15 mL (blood)/100 g/min per -1 mmol(O2)/L, p < 0.001). There was no difference in CMRO2 or cerebral lactate concentration between patients and controls, and no effect of CPAP treatment.

Conclusions

Patients with OSA exhibit reduced CBF in response to hypoxia. CPAP treatment normalized these patterns.

Using a modified version of the "STOP-BANG" questionnaire and nocturnal oxygen desaturation to predict obstructive sleep apnea after stroke or TIA

PURPOSE

Obstructive sleep apnea (OSA) is a risk factor and common morbidity for stroke and transient ischemic attack (TIA). However, screening for OSA in patients with stroke or TIA is uncommonly performed, due in part to difficulties associated with conducting polysomnography (PSG) and Home Sleep Apnea Tests (HSATs). The 8-point "STOP-BANG" questionnaire has been shown to have high methodological quality in screening for OSA. This study examined the clinical utility of a modified version of the "STOP-BANG" questionnaire, which removed neck circumference and included nocturnal oxygen desaturation in diagnosing OSA (ie, the "STOP-BAG-O" tool), with the goal of improving uptake and accuracy in diagnosing OSA.

METHODS

In total, 231 participants completed both the STOP-BAG questionnaire and PSG or HSAT within 12 months of stroke/TIA. Using receiver-operating curves, scores on the "STOP-BAG-O" and "STOP-BAG" questionnaires were assessed for their ability to predict a diagnosis of OSA and classify at least 50% of the study population.

RESULTS

Compared to an OSA diagnosis of AHI≥10, the STOP-BAG (using cut-offs of ≤3 and ≥4) had a sensitivity and specificity of 83.5% and 67.2%, respectively. The STOP-BAG-O (using cut-offs of ≤3 and ≥5) had a sensitivity and specificity of 95.9% and 78.4%, respectively. For all AHI cut-offs used, the area under the curve for the STOP-BAG-O was greater and statistically different (p < 0.001) than that for the STOP-BAG.

CONCLUSIONS

The STOP-BAG-O is a valid tool for identifying risk of OSA post-stroke/TIA. The simplicity of this tool and ease of assessing nocturnal oxygen desaturation makes it a feasible option for widespread use.

The Evolution of Sleep Apnea Six Months After Acute Ischemic Stroke and Thrombolysis

STUDY OBJECTIVES

Our goal was to investigate the evolution of prevalence, severity, and type of sleep apnea among patients who had an ischemic stroke, with or without treatment with thrombolysis after 6 months.

METHODS

We prospectively studied 204 patients who had an ischemic stroke (110 in the thrombolysis and 94 in the non-thrombolysis group). After follow-up, 177 patients were eligible for a final analysis (98 in the thrombolysis group and 79 in the non-thrombolysis group). An unattended sleep study with a three-channel portable device was performed both on admission and after the 6-month follow-up.

RESULTS

The patients receiving thrombolysis were younger than those in the non-thrombolysis group (mean 65.5 versus 69.6 years P = .039). Sleep apnea, defined as a respiratory event index (REI) ≥ 5 events/h, was diagnosed in 92.7% patients, 93.9% versus 91.1% (P = .488) in the thrombolysis and non-thrombolysis groups, respectively. The prevalence remained unchanged during follow-up. Mild sleep apnea progressed to moderate or severe sleep apnea in 69.2% of the patients. Globally, mean central apneas per hour increased by 2.2% (P = .002), whereas obstructive apneas declined by 1.7% (P = .014). The mean change of oxygen desaturation index was -6.1% (P < .001) in the thrombolysis group, -1.8% (P = .327) in the non-thrombolysis group, and 4.2% (P = .001) in the whole group. In the non-thrombolysis group, the risk for new sleep apnea incidence increased by 6.1-fold (P = .024) at follow-up when compared to the thrombolysis group.

CONCLUSIONS

Sleep apnea prevalence remained high in patients who had an ischemic stroke at 6 months post-stroke. The risk for developing sleep apnea after stroke was significantly lower among patients undergoing thrombolysis.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Title: Ischaemic Stroke and Sleep Apnea in Northern Part of Finland; Identifier: NCT01861275; URL: https://clinicaltrials.gov/ct2/show/NCT01861275.

Obstructive sleep apnea and stroke

Obstructive Sleep Apnea (OSA) is a common co-morbid condition in stroke patients. It represents a very important risk factor for stroke in addition to the other established ones such as hypertension, cardiovascular disease (CVD), hyperlipidemia, atrial fibrillation (AF), type 2 diabetes mellitus (T2DM), stress, smoking, and heavy drinking. Although in the United States the prevalence of OSA has somewhat decreased from the previous years, globally its prevalence remains constant, or in some cases, is on the rise. In this review we present the epidemiology for OSA in stroke populations and discuss the risk factors for stroke as well as the underlying pathogenetic mechanisms linking OSA, stroke and CVD. We also emphasize the more thorough evaluation and control of OSA in order to prevent the disabling side effects of a stroke, which not only compromises the physical and mental health of a person and increases the burden on families, but also adds a severe burden to national health economics. OSA should always be considered when assessing a patient with transient ischemic attacks (TIA). Work up and treatment for OSA will not only help prevent stroke with its devastating consequences, but will also help prevent CVD, and ameliorate co-morbid conditions such as diabetes and hypertension in these vulnerable populations.

Sleep Medicine: Stroke and Sleep

Cerebrovascular disease encompassing both ischemic and hemorrhagic strokes are among the leading causes of disability and mortality globally. The current evidence strongly suggests that identifying and addressing sleep disorders should be a part of both primary and secondary stroke prevention. Stroke and sleep are 'bedfellows' since sleep disorders, including sleep-disordered breathing, parasomnias, sleep-related movement disorders, insomnia, and hypersomnia are intimately intertwined with co-morbid cardiovascular conditions and increase stroke risk. Post-stroke sleep disorders also impact stroke rehabilitation, quality of life, and if left untreated can contribute to stroke recurrence.

Obstructive sleep apnea as a predictor of reduced heart rate variability

PURPOSE

This study aimed to analyze the relationship between the occurrence of obstructive sleep apnea (OSA) and heart rate variability (HRV) in a group of patients with clinical suggestion of OSA.

METHODS

104 patients with clinical suspicion of OSA were qualified to participate in the study (age: 53.15 ± 13.43 years). All participants took part in a survey and were subjected to laboratory tests, 24-hour ECG Holter monitoring, and polysomnography. The participants were divided into groups depending on the criterion of the presence of OSA.

RESULTS

The analysis of time HRV demonstrated lower parameters of SDNN for the entire recording and a 15-minute fragment of daily activity, as well as a lower pNN50 for the entire recording in those patients with diagnosed OSA. A statistically significant difference was observed for the spectral analysis of the LF/HF which was higher in the participants with OSA during the 15-minute fragment of N3 sleep. A negative correlation was observed between AHI and the following parameters: SDSD from the entire Holter recording (r = -0.21, p < 0.05) and from the 15-minute fragment of daily activity (r = -0.19, p < 0.05), mRR from the fragment of N3 sleep (r = -0.19, p < 0.05) and VLF from the entire Holter recording (r = -0.26, p < 0.05). A statistically significant positive correlation between AHI and LF/HF in 15-minute fragments of N3 sleep was found (r = 0.26, p < 0.05).

CONCLUSIONS

The study group of patients with OSA is characterized by reduced HRV. The higher AHI constitutes an independent predictor of reduced HRV, both in the sympathetic and parasympathetic components, and the sympathetic-parasympathetic balance.

Models of intermittent hypoxia and obstructive sleep apnea: molecular pathways and their contribution to cancer

Obstructive sleep apnea (OSA) is common and linked to a variety of poor health outcomes. A key modulator of this disease is nocturnal intermittent hypoxia. There is striking epidemiological evidence that patients with OSA have higher rates of cancer and cancer mortality. Small-animal models demonstrate an important role for systemic intermittent hypoxia in tumor growth and metastasis, yet the underlying mechanisms are poorly understood. Emerging data indicate that intermittent hypoxia activates the hypoxic response and inflammatory pathways in a manner distinct from chronic hypoxia. However, there is significant heterogeneity in published methods for modeling hypoxic conditions, which are often lacking in physiological relevance. This is particularly important for studying key transcriptional mediators of the hypoxic and inflammatory responses such as hypoxia-inducible factor (HIF) and NF-κB. The relationship between HIF, the molecular clock, and circadian rhythm may also contribute to cancer risk in OSA. Building accurate in vitro models of intermittent hypoxia reflective of OSA is challenging but necessary to better elucidate underlying molecular pathways.

Exosomal Cargo Properties, Endothelial Function and Treatment of Obesity Hypoventilation Syndrome: A Proof of Concept Study

STUDY OBJECTIVES

Longitudinal studies support the usage of positive airway pressure (PAP) therapy in treating obstructive sleep apnea (OSA) to improve cardiovascular disease. However, the anticipated benefit is not ubiquitous. In this study, we elucidate whether PAP therapy leads to immediate improvements on endothelial function, a subclinical marker of cardiovascular status, by examining the effect of circulating exosomes, isolated from patients before and after PAP therapy, on naive endothelial cells.

METHODS

We isolated plasma-derived circulating exosomes from 12 patients with severe OSA and obesity hypoventilation syndrome (OHS) before and after 6 weeks of PAP therapy, and examined their effect on cultured endothelial cells using several in vitro reporter assays.

RESULTS

We found that circulating exosomes contributed to the induction and propagation of OSA/OHS-related endothelial dysfunction (ie, increased permeability and disruption of tight junctions along with increased adhesion molecule expression, and reduced endothelial nitric oxide synthase expression), and promoted increased monocyte adherence. Further, when comparing exosomes isolated before and after PAP therapy, the disturbances in endothelial cell function were attenuated with treatment, including an overall cumulative decrease in endothelial permeability in all 12 subjects by 10.8% (P = .035), as well as detection of a subset of 4 differentially expressed exosomal miRNAs, even in the absence of parallel changes in systemic blood pressure or metabolic function.

CONCLUSIONS

Circulating exosomes facilitate important intercellular signals that modify endothelial phenotype, and thus emerge as potential fundamental contributors in the context of OSA/OHS-related endothelial dysfunction. Exosomes may not only provide candidate biomarkers, but are also a likely and plausible mechanism toward OSA/OHS-induced cardiovascular disease.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov, Title: AVAPS-AE Efficacy Study, URL: https://clinicaltrials.gov/ct2/show/NCT01368614, Identifier: NCT01368614.

Association of sleep-disordered breathing with severe chronic vascular disease in patients with type 2 diabetes

BACKGROUND

Severe chronic vascular disease (CVD) is a major cause of co-morbidity and mortality in patients with type 2 diabetes (DM2). Sleep-disordered breathing (SDB) has been linked to CVD in the general population due to enhanced sympathetic activation, oxidative stress, endothelial dysfunction, and hypertension; however data for DM2 patients is scarce. Therefore, the aim of the present analysis to assess whether SDB is associated with CVD in patients with DM2, independent of other known associated factors.

METHODS

We analyzed cross-sectional data of 679 patients with DM2 from the DIACORE-SDB sub-study for association of SDB with CVD. SDB was assessed with a validated 2-channel ambulatory monitoring device. CVD was ascertained as a previous diagnosis of peripheral artery disease (PAD), coronary artery disease (CAD), or stroke via medical records and general practitioners.

RESULTS

Of the analyzed 679 patients, 228 (34%) had SDB (respiratory event index [REI] ≥15/hour); and were significantly more often affected by CVD than patients without SDB (38% vs. 23%, p < 0.01; PAD 7% vs. 2%, p = 0.01; CAD 27% vs. 18%, p = 0.01; stroke 11% vs. 6%, p = 0.07). Regression analysis accounting for known modulators of CVD, such as age, body-mass index, systolic blood pressure, duration of DM2, HbA1c, smoking status, and low-density lipoprotein showed that the REI was independently associated with CVD (OR 1.099 per 5 REI points; 95%CI = [1.024, 1.179]).

CONCLUSIONS

In patients with DM2, SDB is significantly associated with CVD, independent of other known modulators of atherosclerosis.

Continuous Positive Airway Pressure Reduces Night-Time Blood Pressure and Heart Rate in Patients With Obstructive Sleep Apnea and Resistant Hypertension: The RHOOSAS Randomized Controlled Trial

Objective

Most patients with resistant hypertension (RH) have obstructive sleep apnea (OSA). We aimed to determine the impact of OSA and continuous positive airway pressure (CPAP) treatment on the leptin profile and blood pressure (BP) in patients with RH.

Methods

After an initial case-control study (RH with and without OSA), we performed a randomized, single blind study in OSA + RH patients receiving either sham CPAP (3 months) followed by active CPAP (6 months) or 6 months of active CPAP. The primary outcome was the comparison of leptin levels between groups of RH patients with or without OSA. Secondary outcomes were the comparison of metabolic parameters, biomarkers of sympathetic activity, and BP indices between the two groups of RH patients with or without OSA. The same outcomes were then evaluated and compared before and after sham and effective CPAP intervention.

Results

Sixty-two patients (60 ± 10 years; 77% men) with RH (24-h daytime systolic BP (SBP)/diastolic BP: 145 ± 13/85 ± 10 mmHg, 3.7 antihypertensive drugs) were included. The 37 RH patients exhibiting OSA (60%) were predominantly men (87 vs 64% for non-OSA patients), with a greater prevalence of metabolic syndrome and higher creatininemia. Their leptin concentrations were significantly lower than in non-OSA patients [9 (6; 15) vs 17 (6; 29) ng/mL] but increased after 6 months of CPAP. Three months of effective CPAP significantly decreased night-time SBP by 6.4 mmHg and heart rate (HR) by 6.0 bpm, compared to sham CPAP.

Conclusion

The association between OSA and RH corresponds to a specific, predominately male phenotype with a higher burden of metabolic syndrome and higher creatininemia but there was no significant difference between OSA and non-OSA patients regarding BP indices, and the number of antihypertensive drugs used. Active CPAP could be efficient at decreasing night-time BP and HR, but there was no difference between CPAP and sham CPAP groups for all metabolic and SNS markers (NCT00746902 RHOOSAS).

Diagnostic accuracy of a two-stage model for detecting obstructive sleep apnoea in chronic tetraplegia

BACKGROUND

Obstructive sleep apnoea (OSA) is highly prevalent in people with spinal cord injury (SCI). Polysomnography (PSG) is the gold-standard diagnostic test for OSA, however PSG is expensive and frequently inaccessible, especially in SCI. A two-stage model, incorporating a questionnaire followed by oximetry, has been found to accurately detect moderate to severe OSA (MS-OSA) in a non-disabled primary care population. This study investigated the accuracy of the two-stage model in chronic tetraplegia using both the original model and a modified version for tetraplegia.

METHODS

An existing data set of 78 people with tetraplegia was used to modify the original two-stage model. Multivariable analysis identified significant risk factors for inclusion in a new tetraplegia-specific questionnaire. Receiver operating characteristic (ROC) curve analyses of the questionnaires and oximetry established thresholds for diagnosing MS-OSA. The accuracy of both models in diagnosing MS-OSA was prospectively evaluated in 100 participants with chronic tetraplegia across four international SCI units.

RESULTS

Injury completeness, sleepiness, self-reported snoring and apnoeas were included in the modified questionnaire, which was highly predictive of MS-OSA (ROC area under the curve 0.87 (95% CI 0.79 to 0.95)). The 3% oxygen desaturation index was also highly predictive (0.93 (0.87-0.98)). The two-stage model with modified questionnaire had a sensitivity and specificity of 83% (66-93) and 88% (75-94) in the development group, and 77% (65-87) and 81% (68-90) in the validation group. Similar results were demonstrated with the original model.

CONCLUSION

Implementation of this simple alternative to full PSG could substantially increase the detection of OSA in patients with tetraplegia and improve access to treatments.

TRIAL REGISTRATION NUMBER

Results, ACTRN12615000896572 (The Australian and New Zealand Clinical Trials Registry) and pre-results, NCT02176928 (clinicaltrials.gov).

Nocturnal cerebral hypoxia in obstructive sleep apnoea: a randomised controlled trial

Cerebral hypoxia may promote cerebral damage in patients with obstructive sleep apnoea (OSA). We investigated whether OSA patients experience nocturnal cerebral hypoxia that is prevented by continuous positive airway pressure (CPAP).

OSA patients using CPAP underwent sleep studies including pulse oximetry (arterial oxygen saturation (SpO2)) and near-infrared spectroscopy to monitor cerebral tissue oxygenation (CTO) at baseline and after 2 weeks on either subtherapeutic or therapeutic CPAP according to randomised allocation. Changes in oxygenation at end of the 2-week intervention were compared between groups.

Among 21 patients (mean apnoea/hypopnoea index 50.3 events·h−1), OSA recurred in all nine patients using subtherapeutic CPAP and in none of the patients using therapeutic CPAP: mean (95% CI) between-group differences in changes of oxygen desaturation index from baseline to 2 weeks +40.7 (31.1–50.4) events·h−1 for SpO2 and +37.0 (25.3–48.7) events·h−1 for CTO (both p<0.001). Mean nocturnal SpO2 and CTO decreased more in patients using subtherapeutic versus therapeutic CPAP: −2.4 (−3.4–−1.1)% and −3.8 (−7.4–−0.1)%, respectively; both p<0.03. Severe CTO drops ≥13% associated with cerebral dysfunction in previous studies occurred in four out of nine patients using subtherapeutic CPAP, but in none out of 12 patients using therapeutic CPAP (p=0.01).

In patients with OSA, CPAP withdrawal resulted in nocturnal cerebral deoxygenation, suggesting a role of cerebral hypoxia in predisposing untreated OSA patients to cerebral damage.

Portable Sleep Monitoring for Diagnosing Sleep Apnea in Hospitalized Patients With Heart Failure

BACKGROUND

Sleep apnea is an underdiagnosed condition in patients with heart failure. Efficient identification of sleep apnea is needed, as treatment may improve heart failure-related outcomes. Currently, use of portable sleep monitoring in hospitalized patients and those at risk for central sleep apnea is discouraged. This study examined whether portable sleep monitoring with respiratory polygraphy can accurately diagnose sleep apnea in patients hospitalized with decompensated heart failure.

METHODS

Hospitalized patients with decompensated heart failure underwent concurrent respiratory polygraphy and polysomnography. Both recordings were scored for obstructive and central disordered breathing events in a blinded fashion, using standard criteria, and the apnea-hypopnea index (AHI) was determined. Pearson's correlation coefficients and Bland-Altman plots were used to examine the concordance among the overall, obstructive, and central AHI values derived by respiratory polygraphy and polysomnography.

RESULTS

The sample consisted of 53 patients (47% women) with a mean age of 59.0 years. The correlation coefficient for the overall AHI from the two diagnostic methods was 0.94 (95% CI, 0.89-0.96). The average difference in AHI between the two methods was 3.6 events/h. Analyses of the central and obstructive AHI values showed strong concordance between the two methods, with correlation coefficients of 0.98 (95% CI, 0.96-0.99) and 0.91 (95% CI, 0.84-0.95), respectively. Complete agreement in the classification of sleep apnea severity between the two methods was seen in 89% of the sample.

CONCLUSIONS

Portable sleep monitoring can accurately diagnose sleep apnea in hospitalized patients with heart failure and may promote early initiation of treatment.

Association of vasomotor symptoms and sleep apnea risk in midlife women

OBJECTIVE

The aim of the study was to determine the association between self-reported vasomotor symptoms (VMS) and obstructive sleep apnea (OSA) risk.

METHODS

The STOP-BANG to evaluate OSA and Menopause Rating Scale (MRS) were administered to 2,935 women seen in the Women's Health Clinic at Mayo Clinic in Rochester, MN, between May 2015 and December 2016. Of these, 1,691 women were included in the analysis. Total MRS and VMS ratings were compared using logistic regression, with age, smoking, and body mass index (BMI) included as covariates between women at intermediate/high risk versus low risk for OSA.

RESULTS

Total MRS scores were significantly higher in women with intermediate/high-risk OSA scores versus those with low-risk scores [mean (SD): 16.8 (8.0) vs 12.9 (7.0), P < 0.001]. Women at intermediate/high OSA risk were older, had more education, self-reported hypertension, BMI >35 kg/m, and were less likely to be married or employed. Self-reported severe/very severe VMS were significantly associated with intermediate/high risk versus low risk for OSA (26.6% vs 15.0%; P < 0.001). After adjusting for age, BMI, smoking status, and self-reported hypertension, the odds of having intermediate/high risk for OSA were 1.87 times higher for those with severe/very severe VMS compared with those with none/mild/moderate VMS (95% CI, 1.29-2.71, P < 0.001). This association persisted upon subgroup analysis based on BMI <25 kg/m (odds ratio 2.15; 95% CI, 1.12-4.16, P = 0.022).

CONCLUSIONS

Self-reported severe/very severe VMS were associated with intermediate/high risk for OSA in midlife women, even in women with BMI <25 kg/m. Given the limitations of the STOP-BANG tool, OSA risk may, however, have been overestimated.

Sleep Apnea in Heart Failure

PURPOSE OF REVIEW

In this review, we discuss the current treatment options for sleep-disordered breathing (SDB) in patients with heart failure (HF). We address the role of positive airway pressure (PAP) devices and other emerging therapies. The review includes discussion of recent trials that reported negative consequences for the PAP devices in patients with heart failure.

RECENT FINDINGS

Optimal guideline-directed medical therapies of HF and PAP devices have been the mainstay treatments for HF patients with SDB. Recently, randomized controlled trials (RCTs) evaluated the effect of PAP on clinical outcomes in patients with cardiovascular (CV) disease and heart failure and found no benefit in decreasing fatal and non-fatal CV events. The Sleep Apnea Cardiovascular Endpoints (SAVE) trial evaluated continuous positive airway pressure (CPAP) ventilation in patients with CV disease and obstructive sleep apnea (OSA) and did not observe any improvement in CV effect. In patients with HF and central sleep apnea (CSA), adaptive servo-ventilation (ASV) was hypothesized to help HF outcomes, but the Adaptive Servo-Ventilation for Central Sleep Apnea in Systolic Heart Failure (SERVE-HF) trial did not show any mortality benefit. Instead, the trial suggested an increase in all-cause and CV mortality in the treatment arm. currently, studies have not shown the use of PAP therapy to improve any risks of CV outcomes or death in HF patients with sleep apnea, but some associations with improvements in symptoms from OSA have been observed.

Prevalence, Risk Factors, Outcomes, and Treatment of Obstructive Sleep Apnea in Patients with Cerebrovascular Disease: A Systematic Review

BACKGROUND

Obstructive sleep apnea (OSA) is known to increase the risk of cerebrovascular disease (CVD), and patients with CVD have high incidence of OSA. The study aimed to systematically evaluate the prevalence of OSA in patients with CVD.

MATERIALS AND METHODS

Medline, Embase, Science Citation Index, Wanfang, CNKI, and Wiley Online Library were thoroughly searched to identify relevant studies. Random-effects models were used to calculate the pooled rate estimates. Meta-regression and subgroup analysis were performed to explore potential sources of heterogeneity.

RESULTS

Thirty-seven studies with 3242 patients were analyzed. The prevalence of OSA (apnea hypopnea index [AHI] >10) ranged from 34.5% to 92.3%, the random-effects pooled prevalence was 61.9%. Furthermore, the prevalence of sleep disordered breathing (SDB) with AHI  greater than  5 was 70.4%, with AHI greater than 20 was 39.5%, and with AHI greater than 30 was 30.1%. Only 8.3% of the SDB was primarily central apnea. Seventeen studies reported risk factors for OSA, 6 of which used multivariate analyses to extract risk factors. In univariate meta-regression analysis, male had higher prevalence than female (P = .041). OSA was associated with increased length of hospitalization in 2 studies, and 1 long-term study reported severe sleep apnea was associated with poor functional outcome. Among the 5 studies on treatment, 3 indicated that early treatment with CPAP was effective; the remaining studies did not find benefit from CPAP treatment and reported the CPAP acceptance was poor.

CONCLUSIONS

There is high prevalence of OSA in patients with CVD (61.9%). Therefore, accurate diagnosis and treatment to OSA is very important so as to prevent CVD.

Continuous Positive Airway Pressure Therapy in Gestational Diabetes With Obstructive Sleep Apnea: A Randomized Controlled Trial

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) is associated with gestational diabetes mellitus (GDM). This study assessed the effects of continuous positive airway pressure (CPAP) in obese pregnant females with GDM and OSA.

METHODS

A randomized controlled trial was conducted (April 2014 - June 2016). Obese females at 24 to 34 weeks gestation and with diet-controlled GDM were screened for OSA. Those with OSA were randomly assigned to receive 2 weeks nightly CPAP or be part of a waitlist control group. After 2 weeks, all patients were offered CPAP. The primary outcome was glucose metabolism, obtained from an oral meal tolerance test (MTT) at baseline and 2 weeks. Pregnancy outcomes were collected.

RESULTS

Eighteen patients were randomized to CPAP and 18 to control groups. There were no significant changes between groups in fasting glucose, glucose response to MTT, and insulin sensitivity or secretion after 2 weeks. Those adherent to CPAP had significantly improved insulin secretion (P = .016) compared to the control group. When a counterfactual instrumental variable approach was applied to deal with nonadherence, the CPAP group had significantly improved insulin secretion (P = .002) and insulin sensitivity (P = .015). Lower rates of preterm delivery (P = .002), unplanned cesarean section (P = .005), and neonatal intensive care unit admissions (P < .001) were observed among those who used CPAP longer than 2 weeks.

CONCLUSIONS

Two weeks of CPAP in females with GDM and OSA did not result in improved glucose levels, but insulin secretion improved in those adherent to CPAP. Continued CPAP use was possibly associated with improved pregnancy outcomes.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Title: Obstructive Sleep Apnea and Gestational Diabetes: Incidence and Effects of Continuous Positive Airway Pressure Treatment on Glucose Metabolism; Identifier: NCT02108197; URL: https://clinicaltrials.gov/ct2/show/NCT02108197.

Sleep-Related Leg Movements in Patients with Transient Ischemic Attack and Controls

Background: Periodic leg movements during sleep (PLMS) have been associated with an increased risk for cardiovascular diseases and there is a high prevalence of PLMS found in patients with obstructive sleep apnea syndrome (OSAS). We evaluated patients with transient ischemic attack (TIA) for PLMS and respiratory related leg movements (RRLM), versus a control group without TIA. Methods: Twenty-five patients with TIA and 34 patients with no vascular diagnosis were referred for polysomnography. Diagnosis of PLMS was made if the periodic leg movement index (PLMI) was ≥5 and clinical significant as PLMI ≥15. Results: There was no significant difference in PLMI ≥5 and ≥15 between patients with and without TIA. In the absence of OSAS, 2 out of 5 TIA patients (40%) had a PLMI ≥15 compared to 1 of the 19 patients without TIA (5%; p = 0.037). There was no increase in RRLMs when OSAS was present. Conclusions: TIA patients did not have higher PLMI compared to controls, and in the presence of OSAS, there was no increase in RRLMs compared to patients without TIA. In selective patients, PLMS could be associated with cardiovascular diseases, since PLMS was clinically more often found in the TIA group without OSAS.

Obstructive Sleep Apnea-a Perioperative Risk Factor

BACKGROUND

Obstructive sleep apnea (OSA) is a common disorder of breathing but is probably underappreciated as a perioperative risk factor.

METHODS

This review is based on pertinent articles, published up to 15 August 2015, that were retrieved by a selective search in PubMed based on the terms "sleep apnea AND anesthesia" OR "sleep apnea AND pathophysiology." The guidelines of multiple specialty societies were considered as well.

RESULTS

OSA is characterized by phases of upper airway obstruction accompanied by apnea/hypoventilation, with hypoxemia, hypercapnia, and recurrent overactivation of the sympathetic nervous system. It has been reported that 22% to 82% of all adults who are about to undergo surgery have OSA. The causes of OSA are multifactorial and include, among others, an anatomical predisposition and /or a reduced inspiratory activation of the bronchodilator muscles, particularly when the patient is sleeping or has taken a sedative drug, anesthetic agent, or muscle relaxant. OSA is associated with arterial hypertension, coronary heart disease, and congestive heart failure. It can be assessed before the planned intervention with polysomnography and structured questionnaires (STOP/STOP-BANG), with sensitivities of 62% and 88%. The utility of miniaturized screening devices is debated. Patients with OSA are at risk for perioperative problems including difficult or ineffective mask ventilation and/or intubation, postoperative airway obstruction, and complications arising from other comorbid conditions. They should be appropriately monitored postoperatively depending on the type of intervention they have undergone, and depending on individually varying, patient-related factors; postoperative management in an intensive care unit may be indicated, although no validated data on this topic are yet available.

CONCLUSION

OSA patients need care by specialists from multiple disciplines, including anesthesiologists with experience in recognizing OSA, securing the airway of OSA patients, and managing them postoperatively. No randomized trials have yet compared the modalities of general anesthesia for OSA patients with respect to postoperative complications or phases of apnea or hypopnea.

Sleep Disturbances as a Risk Factor for Stroke

Sleep, a vital process of human being, is carefully orchestrated by the brain and consists of cyclic transitions between rapid eye movement (REM) and non-REM (NREM) sleep. Autonomic tranquility during NREM sleep is characterized by vagal dominance and stable breathing, providing an opportunity for the cardiovascular-neural axis to restore homeostasis, in response to use, distress or fatigue inflicted during wakefulness. Abrupt irregular swings in sympathovagal balance during REM sleep act as phasic loads on the resting cardiovascular system. Any causes of sleep curtailment or fragmentation such as sleep restriction, sleep apnea, insomnia, periodic limb movements during sleep, and shift work, not only impair cardiovascular restoration but also impose a stress on the cardiovascular system. Sleep disturbances have been reported to play a role in the development of stroke and other cardiovascular disorders. This review aims to provide updated information on the role of abnormal sleep in the development of stroke, to discuss the implications of recent research findings, and to help both stroke clinicians and researchers understand the importance of identification and management of sleep pathology for stroke prevention and care.

Sleep Apnea in Patients Hospitalized With Acute Ischemic Stroke: Underrecognition and Associated Clinical Outcomes

STUDY OBJECTIVES

To evaluate clinical recognition of sleep apnea and related outcomes in patients hospitalized with acute ischemic stroke.

METHODS

A retrospective study of all patients hospitalized with acute ischemic stroke from April 2008 to December 2014. The primary predictor and outcome variables were sleep apnea and hospital mortality, respectively. Secondary outcomes were mechanical ventilation, hospital length of stay, and the survivor's functional level by the modified Rankin scale. A sensitivity multivariate regression analysis included the propensity score for cardiovascular comorbidities and sleep apnea.

RESULTS

Of 989 patients, 190 (19%) were considered to have sleep apnea. Only 42 patients (22%) received any treatment for sleep apnea during the hospital stay. Despite higher prevalence of cardiovascular comorbidities, the patients with sleep apnea had lower hospital mortality, 1% versus 5.6% in patients without sleep apnea (odds ratio [OR] 0.18; 95% confidence interval [CI], 0.03-0.58, P = .002). Only the National Institutes of Health Stroke Scale (NIHSS) and the Glasgow coma scale (GCS) were significant predictors of adjusted hospital mortality (OR 1.06, 95% CI 1.01-1.11, P = .01 and OR 0.61, 95% CI 0.51-0.69, P ≤ .001, respectively). A composite clinical propensity score for sleep apnea and cardiovascular comorbidities was significantly associated with decreased mortality, independent to either NIHSS (OR 0.11, 95% CI 0.017-0.71; P = .02) or GCS (OR 0.07, 95% CI 0.01-0.52; P = .01).

CONCLUSIONS

Prevalence of sleep apnea in our study was low, likely because of clinical underrecognition. Despite having more cardiovascular disease, the patients with acute stroke and sleep apnea had less severe neurological injury and lower unadjusted mortality than those without a history of sleep apnea.

Obstructive sleep apnoea-hypopnoea and arrhythmias: new updates

AIMS

Obstructive sleep apnoea-hypopnoea (OSAH) is a prevalent condition characterized by repetitive pharyngeal collapse during sleep, leading to hypoxemia, hypercapnia, and persistent inspiratory efforts against an occluded airway until arousal. Several studies demonstrated that OSAH exerts acute and chronic effects on the cardiovascular system. Thus, although being a respiratory problem, the most important consequences of OSAH are cardiovascular, among which there are arrhythmias. The purpose of this review is to systematically analyse what has been recently published about the relationship between OSAH and every cardiac arrhythmia separately.

METHODS

We searched Pubmed, Scopus, Web of Science and Cochrane Collaboration databases for 'OSAHS arrhythmias', 'OSAH arrhythmias' and 'OSA arrhythmias'. We analyse 1298 articles and meta-analyses, excluding already edited reviews.

RESULTS

Arrhythmias, especially of ventricular origin, are frequent in OSAH. Ventricular premature beats, couplets and ventricular tachycardia runs are even more frequent in patients suffering from heart failure. They may be due to left heart remodelling, overwork and ischaemia and can explain at least some sudden deaths occurring between midnight and 6 a.m. Sinus pauses and atrioventricular blocks are increased according to the severity of the disturbance and may be reduced by continuous positive airway pressure therapy, preventing pace-maker implantation. Finally, atrial fibrillation, resistance against antiarrhythmic drugs and recurrences after surgical procedures are strongly related to OSAH.

CONCLUSION

Arrhythmias are frequent in OSAH. Treatment of OSAH may reduce some of them. An implantable cardioverter-defibrillator and continuous positive airway pressure should be considered in some patients.

Reproducibility and predictors of the apnea hypopnea index across multiple nights

BACKGROUND

Attended polysomnography (PSG) is the standard diagnostic test for sleep apnea (SA). However, due to internight variability in SA, a single night PSG may not accurately reflect the true severity of SA. Although internight variability is a well-known phenomenon, its root causes have not been fully elucidated. The objective of this study was to determine factors associated with internight variability in the apnea-hypopnea index (AHI) and its magnitude in the home environment.

METHODS

Each participant had a full overnight PSG simultaneous with a validated portable sleep apnea monitoring device (BresoDx®) followed by two overnight home tests using the portable monitor only. Patients were stratified into those with variable AHI and consistent AHI (AHI difference ≥10 or <10 between any 2 nights, respectively). Demographics, sleepiness, sleep test variable, and supine-predominant SA (supine-SA) were examined for any association with variable AHI.

RESULTS

Forty patients completed the protocol. The correlation between PSG and simultaneous BresoDx derived AHIs was 93.4%. Inter-class correlation between the three nights' AHIs was 89.2%. Over two-thirds (67.5%) of patients had consistent AHIs across the three nights while 32.5% had variable AHI. AHI variability was significantly associated with supine-SA (p=0.0014) and correlated with first night's AHI (r=0.664, p<0.001). None of the other variable, including BMI, sleepiness, gender, or test duration were associated with internight variability.

CONCLUSION

Although portable monitoring was highly reproducible over three nights in the majority of participants, one third had a variable AHI. Supine-SA and high AHI on the first night were predictors of high internight variability.

Access to CPAP treatment in patients with moderate to severe sleep apnea in a Latin American City

Introduction:

The most effective treatment for moderate to severe obstructive sleep apnea (OSA) is continuous positive airway pressure (CPAP) but adherence may be a limiting factor. Most compliance studies often only include patients under CPAP treatment, neglecting the importance of access to treatment. The aim of this study was to evaluate CPAP access and compliance in OSA patients, after CPAP indication and titration.

Methods:

We included moderate to severe OSA patients, diagnosed by in-lab polysomnography (PSG), with CPAP indication and effective pressure titration. Between 12 to 18 months after treatment was indicated a telephone questionnaire was administered including questions about access to CPAP, reasons of no access, reported adherence and symptoms improvement.

Results:

A total of 213 patients responded to the survey (171 males, mean age 53.4±13.5 and BMI 34.02±8.8 kg/m²). Almost a third of the patients (28.2%) did not initiate CPAP treatment. Out of 213, 153 patients (71.8%) started treatment with CPAP and 120 (56.3%) reported still being under treatment a year after indication, additionally, 85.8% reported that they were using it =4hs/night. Those who accessed to CPAP were on average, older age, had full coverage of treatment by their medical insurance, required lower effective pressure and experienced more severe sleepiness compared to those individuals who did not accessed to CPAP.

Discussion:

A significant proportion of OSA patients with CPAP indication did not initiate and/or eventually abandoned CPAP. Approximately only 50% of the patients were still under treatment, with acceptable self-reported adherence rate and clinical response, one year after the initial treatment indication. Additional measures are necessary to increase access to CPAP and improve long-term compliance.

Utility of Acoustic Pharyngometry for the Diagnosis of Obstructive Sleep Apnea

RATIONALE

Owing to resource limitations, the testing of patients for obstructive sleep apnea (OSA) is often delayed. There is a need to accurately triage and expedite testing in those with a high pretest probability of OSA. Acoustic pharyngometry is a simple, noninvasive technique used to assess the upper airway cross-sectional area (UA-XSA), which is known to be reduced in those with OSA.

OBJECTIVES

To determine the discriminative ability and predictive value of UA-XSA measurements by acoustic pharyngometry for OSA.

METHODS

We conducted a cross-sectional study with a clinical cohort of consecutive adults with suspected OSA who had undergone both polysomnography and acoustic pharyngometry. OSA was defined as an apnea-hypopnea index greater than or equal to 5. Multivariable logistic regression analyses and receiver operating characteristic curves were used.

MEASUREMENTS AND MAIN RESULTS

The cohort included 576 subjects, 87% of whom had OSA and 64% of whom were men. The subjects' median body mass index (BMI) was 30.3 kg/m², and their median age was 57 years. The median UA-XSA at FRC when sitting was significantly smaller in those with OSA compared with those without OSA (3.3 cm² [interquartile range, 2.7-3.8] vs. 3.7 cm² [interquartile range, of 2.9-4.2]). When the analysis was controlled for age, sex, BMI, and comorbidities, the odds of OSA increased for every 1-cm² decrease in the mean UA-XSA FRC when sitting (odds ratio, 1.62; 95% confidence interval, 1.23-2.13). The mean UA-XSA provided fair discrimination for OSA (area under the curve, 0.60). A cutoff value of 3.75 cm², the point with the best sum of sensitivity and specificity, had sensitivity of 73% and specificity of 46%. The magnitude of the incremental discriminative value of UA-XSA over clinical variables (age, sex, BMI, and comorbidities) was small and nonsignificant (P = 0.5).

CONCLUSIONS

The mean UA-XSA at FRC when sitting or supine provided no further significant advantage over clinical variables for the discernment of OSA.

Association of obstructive sleep apnoea with the risk of vascular outcomes and all-cause mortality: a meta-analysis

OBJECTIVE

This study aimed to conduct a meta-analysis to explore and summarise the evidence regarding the association between obstructive sleep apnoea (OSA) and the subsequent risk of vascular outcomes and all-cause mortality.

METHODS

Electronic databases PubMed, Embase and the Cochrane Library were searched to identify studies conducted through May 2016. Prospective cohort studies that reported effect estimates with 95% CIs of major adverse cardiac events (MACEs), coronary heart disease (CHD), stroke, cardiac death, all-cause mortality and heart failure for different levels versus the lowest level of OSA were included.

RESULTS

A total of 16 cohort studies reporting data on 24 308 individuals were included. Of these, 11 studies reported healthy participants, and the remaining five studies reported participants with different diseases. Severe OSA was associated with an increased risk of MACEs (relative risk (RR): 2.04; 95% CI 1.56 to 2.66; P<0.001), CHD (RR: 1.63; 95% CI 1.18 to 2.26; P=0.003), stroke (RR: 2.15; 95% CI 1.42 to 3.24; P<0.001), cardiac death (RR: 2.96; 95% CI 1.45 to 6.01; P=0.003) and all-cause mortality (RR: 1.54; 95% CI 1.21 to 1.97; P<0.001). Moderate OSA was also significantly associated with increased risk of MACEs (RR: 1.16; 95% CI 1.01 to 1.33; P=0.034) and CHD (RR: 1.38; 95% CI 1.04 to 1.83; P=0.026). No significant association was found between mild OSA and the risk of vascular outcomes or all-cause mortality (P>0.05). Finally, no evidence of a factor-specific difference in the risk ratio for MACEs among participants with different levels of OSA compared with those with the lowest level of OSA was found.

CONCLUSIONS

Severe and moderate OSAs were associated with an increased risk of vascular outcomes and all-cause mortality. This relationship might differ between genders. Therefore, further large-scale prospective studies are needed to verify this difference.