Obstructive sleep apnea leads to transient uncoupling of coronary blood flow and myocardial work in humans

Links Between Obstructive Sleep Apnea and Myocardial Blood Flow Changes Impacting Adverse Cardiovascular Disease-related Outcomes

PURPOSE OF REVIEW

Recent studies have demonstrated an association between obstructive sleep apnea (OSA) and abnormal myocardial blood flow (MBF), myocardial flow reserve (MFR), and coronary microvascular dysfunction (CMD). Here, we review the evidence and describe the potential underlying mechanisms linking OSA to abnormal MBF. Examining relevant studies, we assess the impact of OSA-specific therapy, such as continuous positive airway pressure (CPAP), on MBF.

RECENT FINDINGS

Recent studies suggest an association between moderate to severe OSA and abnormal MBF/MFR. OSA promotes functional and structural abnormalities of the coronary microcirculation. OSA also promotes the uncoupling of MBF to cardiac work. In a handful of studies with small sample sizes, CPAP therapy improved MBF/MFR. Moderate to severe OSA is associated with abnormal MFR, suggesting an association with CMD. Evidence suggests that CPAP therapy improves MBF. Future studies must determine the clinical impact of improved MBF with CPAP.

The impact of sleep disordered breathing on cardiac troponin in acutely decompensated heart failure

PURPOSE

Sleep disordered breathing in decompensated heart failure has physiological consequences (e.g., intermittent hypoxemia) that may predispose to subclinical myocardial injury, yet a temporal relationship between sleep apnea and troponin elevation has not been established.

METHODS

We assessed the feasibility of performing respiratory polygraphy and measuring overnight high-sensitivity cardiac troponin T change in adults admitted to the hospital with acutely decompensated heart failure. Repeat sleep apnea tests (SATs) were performed to determine response to optimal medical heart failure therapy. Multivariable logistic regression was used to identify associations between absolute overnight troponin change and sleep apnea characteristics.

RESULTS

Among the 19 subjects with acutely decompensated heart failure, 92% of SATs demonstrated sleep disordered breathing (apnea-hypopnea index [AHI] > 5 events/h). For those with repeat SATs, AHI increased in 67% despite medical management of heart failure. Overnight troponin increase was associated with moderate to severe sleep apnea (vs. no to mild sleep apnea, odds ratio (OR = 18.4 [1.51-224.18]), central apnea index (OR = 1.11 [1.01-1.22]), and predominantly central sleep apnea (vs. obstructive, OR = 22.9 [1.29-406.32]).

CONCLUSIONS

Sleep apnea severity and a central apnea pattern may be associated with myocardial injury. Respiratory polygraphy with serial biomarker assessment is feasible in this population, and combining this approach with interventions (e.g., positive airway pressure) may help establish if a link exists between sleep apnea and subclinical myocardial injury.

Comorbidity Profile and Predictors of Obstructive Sleep Apnea Severity and Mortality in Non-Obese Obstructive Sleep Apnea Patients

Backgrounds and Objectives: Obstructive sleep apnea (OSA) is associated with increased morbidity and mortality. OSA is an independent risk factor for many different conditions, especially cardiovascular diseases. The purpose of this study was to ascertain the comorbidity profile of non-obese patients with newly diagnosed OSA and evaluate the risk for cardiovascular disease and mortality. The present study also aimed to establish predictors for OSA severity. Materials and Methods: This study included 138 newly diagnosed patients who underwent polysomnographic analysis. The 10-year risk for cardiovascular disease was assessed using a newly validated prediction model: Systematic Coronary Risk Evaluation (SCORE-2). In addition, the Charlson Comorbidity Index (CCI) was assessed as a widely-used example of a mortality comorbidity index. Results: The study population included 138 patients: 86 males and 52 females. Patients were stratified, according to AHI (apnea/hypopnea index), into four groups: 33 patients had mild OSA (5 ≤ AHI < 15), 33 patients had moderate OSA (15 ≤ AHI < 30), 31 patients had severe OSA (AHI ≥ 30), and 41 individuals had AHI < 5, which were a part of the control group. SCORE-2 increased in line with OSA severity and was higher in OSA groups compared to the control group (H = 29.913; DF = 3; p < 0.001). Charlson Index was significantly higher in OSA patients compared to controls (p = 0.001), with a higher prevalence of total comorbidities in the OSA group of patients. Furthermore, CCI 10-year survival score was significantly lower in the OSA group, suggesting a shorter survival of those patients with a more severe form of OSA. We also examined the prediction model for OSA severity. Conclusions: Determining the comorbidity profile and estimation of the 10-year risk score of OSA patients could be used to classify these patients into various mortality risk categories and, according to that, provide them with adequate treatment.

Recognition of Patient Groups with Sleep Related Disorders using Bio-signal Processing and Deep Learning

Accurately diagnosing sleep disorders is essential for clinical assessments and treatments. Polysomnography (PSG) has long been used for detection of various sleep disorders. In this research, electrocardiography (ECG) and electromayography (EMG) have been used for recognition of breathing and movement-related sleep disorders. Bio-signal processing has been performed by extracting EMG features exploiting entropy and statistical moments, in addition to developing an iterative pulse peak detection algorithm using synchrosqueezed wavelet transform (SSWT) for reliable extraction of heart rate and breathing-related features from ECG. A deep learning framework has been designed to incorporate EMG and ECG features. The framework has been used to classify four groups: healthy subjects, patients with obstructive sleep apnea (OSA), patients with restless leg syndrome (RLS) and patients with both OSA and RLS. The proposed deep learning framework produced a mean accuracy of 72% and weighted F1 score of 0.57 across subjects for our formulated four-class problem.

Severe obstructive sleep apnea is associated with significant coronary artery plaque burden independent of traditional cardiovascular risk factors

Obstructive Sleep Apnea (OSA) is strongly associated with adverse cardiovascular events. In these patients, increased oxidative stress has been associated with accelerated coronary atherosclerosis. However, it is unclear if OSA is associated with significant coronary artery plaque burden. Our aim is to determine whether OSA and/or markers of hypoxemia are associated with coronary plaque burden (CPB). Patients who had coronary computed tomography angiography (CCTA) and a polysomnogram within 1 year of each other between 2011 and 2016 were analyzed. Apnea-Hypopnea Index (AHI) and hypoxemic burden (ODI3%, ODI4%, nadir SpO2, average spO₂ and time of spO₂ < 88%) were obtained from the polysomnogram. Total CPB was assessed using the prognostically validated CT-Leaman score (CT-LeSc). Significant CPB was defined as CT-LeSc ≥ 8.3. There were 119 patients with mean (± SD) age of 59 ± 12 years. Using logistical regression analysis; AHI, ODI4% and ODI3% were the only parameters associated with significant CPB. Severe OSA (AHI ≥ 30 events/h) was associated with significant CPB with adjusted OR of 3.21 (p = 0.010) independent of traditional cardiovascular risk factors. Mechanisms associated with apnea and hypopnea events (as measured by AHI, ODI3% and ODI4%), but not the severity of arterial desaturation (nadir SpO₂, burden of SpO₂ < 88%) were associated with significant CPB.

Sleep Disordered Breathing and Cardiovascular Diseases

Sleep disordered breathing (SDB), which causes sleep deprivation, intermittent hypoxia, and negative intrathoracic pressure swings, can be accompanied by other harmful pathophysiologies relating to cardiovascular diseases (CVD), including sudden death, atrial fibrillation, stroke, and coronary artery disease leading to heart failure. Continuous positive airway pressure (CPAP) therapy for SDB has been reported to provide favorable effects such as lowered systemic blood pressure and improved endothelial function. However, in recent randomized controlled trials, CPAP has failed to demonstrate its beneficial prognostic impact on the primary or secondary setting of CVD. In this review article, we describe the characteristics of SDB complicated with CVD, the prognostic impacts of SDB in CVD, and the beneficial effects of CPAP on CVD.

Obstructive sleep apnoea: from respiratory events to coronary microvascular dysfunction

Obstructive sleep apnoea (OSA) is an emerging and independent risk factor for cardiovascular diseases; coronary artery disease (CAD) is higher in OSA patients, even in the absence of other traditional cardiovascular risk factors. There is little evidence to show abnormalities in coronary blood flow (CBF) and disorders in coronary vascular resistance (CVR), occurring during the obstructive respiratory event, suggesting coronary microvascular dysfunction (CMD) as a potential mechanism of ischaemic heart disease (IHD) OSA-as a related consequence.

A Novel Sleep Respiratory Rate Detection Method for Obstructive Sleep Apnea Based on Characteristic Moment Waveform

Obstructive sleep apnea (OSA) affecting human's health is a kind of major breathing-related sleep disorders and sometimes leads to nocturnal death. Respiratory rate (RR) of a sleep breathing sound signal is an important human vital sign for OSA monitoring during whole-night sleeping. A novel sleep respiratory rate detection with high computational speed based on characteristic moment waveform (CMW) method is proposed in this paper. A portable and wearable sound device is used to acquire the breathing sound signal. And the amplitude contrast decreasing has been done first. Then, the CMW is extracted with suitable time scale parameters, and the sleep RR value is calculated by the extreme points of CMW. Experiments of one OSA case and five healthy cases are tested to validate the efficiency of the proposed sleep RR detection method. According to manual counting, sleep RR can be detected accurately by the proposed method. In addition, the apnea sections can be detected by the sleep RR values with a given threshold, and the time duration of the segmentation of the breath can be calculated for detailed evaluation of the state of OSA. The proposed method is meaningful for continued research on the sleep breathing sound signal.

Coronary flow reserve is impaired in patients with obstructive sleep apnea

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) is common in adult populations. Accumulating data indicate that it is independently associated with a variety of cardiovascular diseases and has prognostic importance in affected cases. In this study, we aimed to evaluate coronary flow reserve (CFR) in patients with OSA and controls.

METHODS

Sixty-one patients undergoing an overnight polysomnography were enrolled in this study. Patients with an apnea-hypopnea index (AHI) >5 were accepted as OSA group (n = 45) and those with an AHI <5 were taken as controls (n = 16). Using Doppler echocardiography at baseline and following dipyridamole infusion, coronary peak flow velocities were obtained. CFR was calculated as the ratio of peak diastolic flow to baseline diastolic flow. A CFR value <2 was accepted as impaired coronary microvascular function.

RESULTS

The mean age was 50.8 ± 10.8 years, of which 16 (26.2%) were female. Both groups had similar features with regard to demographic and clinical variables. The mean value of CFR was significantly lower in patients with OSA compared to those controls (2.24 ± 0.46 vs. 2.74 ± 0.62, respectively, P = 0.001). An abnormal CFR value was observed in 12 (26.7%) patients with OSA and in 1 (6.3%) participant in control group.

CONCLUSIONS

The findings of this study indicate that CFR, an indicator of coronary microvascular function, is significantly impaired in patients with OSA. Coronary microvascular function, an early sign of atherosclerosis, can be evaluated noninvasively in these patients might be used as a predictor of cardiovascular risk.

Impact of Continuous Positive Airway Pressure on Left Ventricular Systolic Loading and Coronary Flow Reserve in Healthy Young Men

BACKGROUND

Increased augmentation index (AIx) is accompanied by an elevated cardiovascular risk. A reduction of AIx is known for long-term continuous positive airway pressure (CPAP) therapy. We hypothesised that acute preload and left ventricular workload effects AIx and subendocardial viability ratio (SEVR) as a marker of coronary flow reserve.

METHODS

Increased augmentation index and central blood pressure parameters were measured by radial artery tonometry in 17 healthy men (32/±6years) at rest and during CPAP ventilation at pressures of 5, 10mbar and after recovery. In a subset of seven individuals, haemodynamic parameters and autonomic function were additionally examined using combined impedance cardiography and continuous noninvasive blood pressure monitoring.

RESULTS

Continuous positive airway pressure reduced heart rate corrected (AIx@75) (-2.8±8.1 [rest] to -10.7±11.3 [5mbar], p<0.01, to -12.2±10.5% [10mbar], p<0.01) and systolic time integral as a marker of left ventricular workload (2115±231 [rest] to 1978±290 [5mbar], p=0.02 to 1940±218 [10mbar], p<0.01 to 2013±241mmHg/s per min [recovery], p=0.03), while central systolic pressure did not change during CPAP. Total Peripheral Resistance Index increased reaching level of significance at 10mbar CPAP condition (1701±300 [rest] to 1850±301dyn*s*m²/cm⁵ [10mbar], p=0.04). There was a reversible increase of SEVR under CPAP conditions.

CONCLUSIONS

Continuous positive airway pressure ventilation acutely reduces AIx, heart rate and left ventricular workload in healthy young men. These effects seem to be mediated by left ventricular filling pressure, workload and reflection wave. Furthermore, we found an increase of subendocardial viability ratio as an indication for a rising coronary flow reserve by CPAP.

The Combination of Anatomy and Genioglossus Activity in Predicting the Outcomes of Velopharyngeal Surgery

Objective This study aims to evaluate the combination of genioglossus (GG) activity and anatomical characteristics in predicting outcomes of velopharyngeal surgery in patients with obstructive sleep apnea (OSA). Study Design Case series with planned data collection. Setting Sleep medical center. Subjects and Methods Forty patients with OSA underwent overnight polysomnography with synchronous genioglossus electromyography (GGEMG) using intraoral electrodes. The upper airway anatomy was evaluated by 3-dimensional computed tomography in patients with OSA. All patients received the same type of velopharyngeal surgery, consisting of revised uvulopalatopharyngoplasty with uvula preservation and concurrent transpalatal advancement pharyngoplasty. We followed up all patients using polysomnography for at least 3 months postoperatively. Results Twenty-five patients (62.50%) were responders, and 15 patients (37.50%) were nonresponders. The decreased apnea-hypopnea index was significantly positively correlated to the sleep onset GGEMG ( P = .006) but was negatively correlated to the change in GGEMG ( P = .013) and tonic GGEMG ( P = .018). Multiple regression analysis revealed that the minimal cross-sectional airway area at the velopharynx (VmCSA) (odds ratio [OR], 1.760; P = .019) and the sleep onset GGEMG (OR, 0.322; P = .043) were significant predictors for surgical outcomes. Combined the two predictors, the area under the ROC curve was 0.901 (OR, 0.789; P = .001) for surgical success, was more valuable than any one predictor. The area under the ROC curve with GGEMG was 0.843, VmCSA was 0.848. Conclusions The combination of sleep onset GGEMG and VmCSA can predict the outcome of velopharyngeal surgery in patients with OSA.

Sole effect of genioglossus advancement on apnea hypopnea index of patients with obstructive sleep apnea

CONCLUSION

Selected patients might have benefited from genioglossus advancement (GA), even it was applied solely. GA provided significant reduction on the apnea hypopnea index (AHI), with a 53% surgical success.

OBJECTIVES

The aim of this study was to evaluate the impact of GA on AHI of patients with obstructive sleep apnea (OSA).

METHOD

From January 2008 to April 2014 patients who underwent a genioglossus advancement procedure alone were included into the study and records of these cases were analyzed retrospectively. Pre-operative and post-operative values of body mass index (BMI), Epworth Sleepiness Scale (ESS), nocturnal polysomnographic data including AHI, mean, and minimum oxygen saturation were compared.

RESULTS

There were 16 males and one female patient with the mean age of 46 years. The AHI showed a significant reduction from 27.5 ± 8 pre-operatively to 17.3 ± 12.6 post-operatively. The pre-operative and post-operative mean O2 saturation value improved from 92.1 ± 2.4% to 93.4 ± 1.7%. Pre-operative ESS scores decreased significantly from 7.7 ± 1.6 to 4.8 ± 1.9. There were no significant difference between pre- and post-operative values of BMI and minimum O2 saturation. The success rate was found to be 53%, which was based on success criteria as an AHI of <20 with at least 50% reduction.

Acoustic Analysis of Snoring in the Diagnosis of Obstructive Sleep Apnea Syndrome: A Call for More Rigorous Studies

BACKGROUND

Snoring is a common symptom of obstructive sleep apnea syndrome (OSA) and has recently been considered for diagnosis of OSA.

OBJECTIVES

The goal of the current study was to systematically determine the accuracy of acoustic analysis of snoring in the diagnosis of OSA using a meta-analysis.

METHODS

PubMed, Cochrane Library database, and EMBASE were searched up to July 15, 2014. A systematic review and meta-analysis of sensitivity, specificity, and other measures of accuracy of acoustic analysis of snoring in the diagnosis of OSA were conducted. The median of apneahypopnea index threshold was 10 events/h, range: 5-15 or 10-15 if aforementioned suggestion is adopted.

RESULTS

A total of seven studies with 273 patients were included in the meta-analysis. The pooled estimates were as follows: sensitivity, 88% (95% confidence interval [CI]: 82-93%); specificity, 81% (95% CI: 72-88%); positive likelihood ratio (PLR), 4.44 (95% CI: 2.39-8.27); negative likelihood ratio (NLR), 0.15 (95% CI: 0.10-0.24); and diagnostic odds ratio (DOR), 32.18 (95% CI: 13.96-74.81). χ(2) values of sensitivity, specificity, PLR, NLR, and DOR were 2.37, 10.39, 12.57, 3.79, and 6.91 respectively (All p > 0.05). The area under the summary receiver operating characteristic curve was 0.93. Sensitivity analysis demonstrated that the pooled estimates were stable and reliable. The results of publication bias were not significant (p = 0.30).

CONCLUSIONS

Acoustic analysis of snoring is a relatively accurate but not a strong method for diagnosing OSA. There is an urgent need for rigorous studies involving large samples and single snore event tests with an efficacy criterion that reflects the particular features of snoring acoustics for OSA diagnosis.

Sleep-disordered breathing and resistant hypertension

Hypertension is a highly prevalent problem worldwide, affecting at least one third of the adult general population. Although the exact prevalence is uncertain, it is estimated that at least 15% to 20% of individuals with hypertension have resistant hypertension. Resistant hypertension has been shown to predict more adverse cardiovascular and renal outcomes. In 2003, the Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure recognized obstructive sleep apnea (OSA) as an important cause of secondary hypertension. A large body of epidemiologic evidence has linked OSA to resistant hypertension, nondipping nocturnal blood pressure, as well as target organ damage, including left ventricular hypertrophy, arterial stiffness, and microalbuminuria. The importance of OSA as a risk factor for the development of hypertension independent of other confounding factors also was observed in a prospective longitudinal study. More importantly, OSA predicts an increased risk of adverse cardiovascular outcomes, mortality, and sudden cardiac death. This article discusses the associations between OSA and resistant hypertension and reviews the latest understanding on the pathophysiologic mechanisms of hypertension in OSA. Nocturnal continuous positive airway pressure therapy is regarded as the standard treatment for OSA. Prospective randomized controlled trials and meta-analyses of prospective randomized controlled trials within the past 10 years that have examined the effects of continuous positive airway pressure therapy on blood pressure control in patients with OSA with or without hypertension are reviewed and summarized. The majority of the trials suggest a modest but significant benefit on blood pressure control with continuous positive airway pressure therapy. Whether continuous positive airway pressure therapy may improve hard outcomes of patients with OSA and resistant hypertension warrants further investigation.

Obstructive sleep apnea and acute coronary syndromes: etiology, risk, and management

Obstructive sleep apnea (OSA) is characterized by upper airway collapse and airflow reduction despite respiratory effort, resulting in intermittent hypoxia and arousals, leading to a cascade of hemodynamic, autonomic, inflammatory, and metabolic effects, responsible for its adverse cardiovascular effect. OSA is an independent risk factor for cardiovascular disease, and its prevalence in patients presenting with acute coronary syndromes is up to 69%. Furthermore, OSA has been associated with increased risk of adverse events after an acute coronary syndrome. Continuous positive airway pressure is considered the mainstay of treatment of OSA and has been shown to reduce the risk of cardiovascular events. However, the proper time to start treatment in the acute setting is unknown. A prospective randomized clinical trial is currently underway to answer this question.

Obstructive sleep apnea and risk of cardiovascular disease and all-cause mortality: a meta-analysis of prospective cohort studies

BACKGROUND

The association between obstructive sleep apnea (OSA) and the incidence of cardiovascular disease (CVD) has been examined in many studies. However, the findings are not entirely consistent across studies. Our goal was to evaluate the association between OSA and risk of CVD and all-cause mortality by performing a meta-analysis of prospective cohort studies.

METHODS

We used generalized least squares regression models to estimate the dose-response relationship. Heterogeneity, subgroup, and sensitivity analyses and publication bias were performed.

RESULTS

Twelve prospective cohort studies involving 25,760 participants were included in the meta-analysis. The overall combined relative risks for individuals with severe OSA compared with individuals with an AHI of <5 were 1.79 (95% confidence interval [CI]: 1.47 to 2.18) for CVD, 1.21 (95% CI: 0.75 to 1.96) for incident fatal and non-fatal coronary heart disease, 2.15 (95% CI: 1.42 to 3.24) for incident fatal and non-fatal stroke, and 1.92 (95% CI: 1.38 to 2.69) for deaths from all-causes. A positive association with CVD was observed for moderate OSA but not for mild OSA. The results of the dose-response relationship indicated that per 10-unit increase in the apnea-hypopnea index was associated with a 17% greater risk of CVD in the general population.

CONCLUSIONS

This meta-analysis of prospective cohort studies suggests that severe OSA significantly increases CVD risk, stroke, and all-cause mortality. A positive association with CVD was observed for moderate OSA but not for mild OSA.

Cardiac workload in patients with sleep-disordered breathing early after acute myocardial infarction

BACKGROUND

Sleep-disordered breathing (SDB) may promote an increase in cardiac workload early after acute myocardial infarction (AMI). We tested the hypothesis that in the early phase after AMI, SDB is associated with increased 24-h arterial BP, heart rate (HR), and, thus, cardiac workload.

METHODS

In this prospective study, 55 consecutive patients with AMI and subsequent percutaneous coronary intervention (78% men; mean age, 54 ± 10 y; mean BMI, 28.3 ± 3.6 kg/m²; mean left ventricular ejection fraction [LVEF], 47% ± 8%) underwent polysomnography and 24-h ambulatory BP and heart rate monitoring within 5 days after MI. Cardiac workload was calculated as systolic BP multiplied by HR. The presence of SDB was defined as ≥ 10 apneas and hypopneas per hour of sleep.

RESULTS

Fifty-five percent of the patients had SDB, of which 40% was predominantly central in nature. Patients with SDB had higher 24-h HR and systolic and diastolic BP compared with those without SDB (115 vs 108 mm Hg, P = .029; 71 vs 67 mm Hg, P = .034; 69 vs 64 beats/min, P = .050, respectively). Use of antihypertensive medication and β-receptor blockers was similar in both groups. In a multivariate linear regression analysis, SDB was significantly associated with an increased 24-h cardiac workload (β-coefficient, 0.364; 95% CI, 0.071-0.657; P = .016), independently of age, sex, BMI, LVEF, and antihypertensive medication.

CONCLUSION

Patients with AMI and SDB have significantly increased 24-h BP, HR, and cardiac workload. Treatment of SDB may be a valuable nonpharmacologic approach to lower cardiac workload in these patients.

Severe obstructive sleep apnea increases mortality in patients with ischemic heart disease and myocardial injury

OBJECTIVES

We hypothesized that obstructive sleep apnea(OSA) has a dose-dependent impact on mortality in those with ischemic heart disease or previous myocardial injury.

METHODS

We performed a retrospective cohort study of 281 consecutive OSA patients with a history of myocardial injury as determined by elevated troponin levels or with known existing ischemic heart disease. We compared survival between those with severe OSA [apnea–hypopneaindex (AHI) ≥30] and those with mild to moderate OSA(AHI >5 and <30).

RESULTS

Of the 281 patients (mean age 65 years, mean BMI34, 98% male, 58% with diabetes), 151 patients had mild moderate OSA and 130 had severe OSA. During a mean follow-up of 4.1 years, there were significantly greater deaths in the severe OSA group compared to the mild moderate OSA group [53 deaths (41%) vs. 44 deaths(29%), respectively, p00.04]. The adjusted hazard ratio for mortality with severe OSA was 1.72 (95% confidence interval1.01–2.91, p00.04).

CONCLUSIONS

The severity of obstructive sleep apnea is associated with increased risk of death, and risk stratification based on OSA severity is relevant even in the diseased cardiac patient.

Acute cardiopulmonary failure from sleep-disordered breathing

Sleep-disordered breathing (SDB) comprises a diverse set of disorders marked by abnormal respiration during sleep. Clinicians should realize that SDB may present as acute cardiopulmonary failure in susceptible patients. In this review, we discuss three clinical phenotypes of acute cardiopulmonary failure from SDB: acute ventilatory failure, acute congestive heart failure, and sudden death. We review the pathophysiologic mechanisms and recommend general principles for management. Timely recognition of, and therapy for, SDB in the setting of acute cardiopulmonary failure may improve short- and long-term outcomes.

Links between sleep disordered breathing, coronary atherosclerotic burden, and cardiac biomarkers in patients with stable coronary artery disease

BACKGROUND

Sleep disordered breathing (SDB) is highly prevalent in patients with cardiovascular disease, although it is not clear whether SDB has any link to coronary atherosclerotic burden in patients with stable coronary artery disease (CAD). This study sought to analyze the links between SDB, coronary atherosclerotic burden, and cardiac biomarkers in stable CAD patients.

METHODS AND RESULTS

We studied 83 consecutive patients who underwent coronary angiography or scheduled percutaneous coronary intervention. SDB was evaluated by an ambulatory polysomnographic monitoring device. Coronary atherosclerotic burden was evaluated by the Gensini score, and myocardial stress/injury were assessed by measuring plasma levels of N-terminal pro-B-type natriuretic peptide (NT-proBNP) and high sensitivity troponin T (hs-TnT). Patients with an apnea hypopnea index (AHI)≧15 events/h (n=32) showed significantly higher Gensini score (35.7±38.0 vs 20.1±19.7, p=0.033) than those with AHI<15. The higher AHI group showed significantly higher NT-proBNP (275.8±402.6 pg/ml vs 131.9±146.3 pg/ml, p=0.047) and hs-TnT levels (0.011±0.005 ng/ml vs 0.008±0.003 ng/ml, p=0.015). Furthermore it was revealed that AHI significantly correlated with the Gensini score (r=0.253, p=0.036), NT-proBNP (r=0.266, p=0.027), and hs-TnT (r=0.274, p=0.023), and multiple stepwise linear regression analysis revealed that AHI (β=0.257, p=0.029) and history of smoking (β=0.244, p=0.038) were independently correlated with Gensini score among clinical and SDB-related parameters.

CONCLUSIONS

Severity of SDB has a significant link to the severity of coronary atherosclerotic burden, which also reflected elevated NT-proBNP and hs-TnT as silent myocardial ischemia and minute myocardial injury even in stable CAD patients.

Practice parameters for the surgical modifications of the upper airway for obstructive sleep apnea in adults

BACKGROUND

Practice parameters for the treatment of obstructive sleep apnea syndrome (OSAS) in adults by surgical modification of the upper airway were first published in 1996 by the American Academy of Sleep Medicine (formerly ASDA). The following practice parameters update the previous practice parameters. These recommendations were reviewed and approved by the Board of Directors of the American Academy of Sleep Medicine.

METHODS

A systematic review of the literature was performed, and the GRADE system was used to assess the quality of evidence. The findings from this evaluation are provided in the accompanying review paper, and the subsequent recommendations have been developed from this review. The following procedures have been included: tracheostomy, maxillo-mandibular advancement (MMA), laser assisted uvulopalatoplasty (LAUP), uvulopalatopharyngoplasty (UPPP), radiofrequency ablation (RFA), and palatal implants.

RECOMMENDATIONS

The presence and severity of obstructive sleep apnea must be determined before initiating surgical therapy (Standard). The patient should be advised about potential surgical success rates and complications, the availability of alternative treatment options such as nasal positive airway pressure and oral appliances, and the levels of effectiveness and success rates of these alternative treatments (Standard). The desired outcomes of treatment include resolution of the clinical signs and symptoms of obstructive sleep apnea and the normalization of sleep quality, the apnea-hypopnea index, and oxyhemoglobin saturation levels (Standard). Tracheostomy has been shown to be an effective single intervention to treat obstructive sleep apnea. This operation should be considered only when other options do not exist, have failed, are refused, or when this operation is deemed necessary by clinical urgency (Option). MMA is indicated for surgical treatment of severe OSA in patients who cannot tolerate or who are unwilling to adhere to positive airway pressure therapy, or in whom oral appliances, which are more often appropriate in mild and moderate OSA patients, have been considered and found ineffective or undesirable (Option). UPPP as a sole procedure, with or without tonsillectomy, does not reliably normalize the AHI when treating moderate to severe obstructive sleep apnea syndrome. Therefore, patients with severe OSA should initially be offered positive airway pressure therapy, while those with moderate OSA should initially be offered either PAP therapy or oral appliances (Option). Use of multi-level or stepwise surgery (MLS), as a combined procedure or as stepwise multiple operations, is acceptable in patients with narrowing of multiple sites in the upper airway, particularly if they have failed UPPP as a sole treatment (Option). LAUP is not routinely recommended as a treatment for obstructive sleep apnea syndrome (Standard). RFA can be considered as a treatment in patients with mild to moderate obstructive sleep apnea who cannot tolerate or who are unwilling to adhere to positive airway pressure therapy, or in whom oral appliances have been considered and found ineffective or undesirable (Option). Palatal implants may be effective in some patients with mild obstructive sleep apnea who cannot tolerate or who are unwilling to adhere to positive airway pressure therapy, or in whom oral appliances have been considered and found ineffective or undesirable (Option). Postoperatively, after an appropriate period of healing, patients should undergo follow-up evaluation including an objective measure of the presence and severity of sleep-disordered breathing and oxygen saturation, as well as clinical assessment for residual symptoms. Additionally, patients should be followed over time to detect the recurrence of disease (Standard).

CONCLUSIONS

While there has been significant progress made in surgical techniques for the treatment of OSA, there is a lack of rigorous data evaluating surgical modifications of the upper airway. Systematic and methodical investigations are needed to improve the quality of evidence, assess additional outcome measures, determine which populations are most likely to benefit from a particular procedure or procedures, and optimize perioperative care.

Formant analysis of breath and snore sounds

Formant frequencies of snore and breath sounds represent resonance in the upper airways; hence, they change with respect to the upper airway anatomy. Therefore, formant frequencies and their variations can be examined to distinguish between snore and breath sounds. In this paper, formant frequencies of snore and breath sounds are investigated and automatically grouped into 7 clusters based on K-Means clustering. First, formants clusters of breath and snore sounds of all subjects were investigated together and their union were calculated as the most probable ranges of the formants. The ranges for the first four formants which span the main frequency components of breath and snore sounds were found to be [20-400]Hz, [270-840]Hz, [500-1380]Hz and [910-1920]Hz. These ranges were then used as priori information to recalculate the formants of snore and breath sounds separately. Statistical t-test showed the 1(st) and 3(rd) formants to be the most characteristic features in distinguishing the breath and snore sounds from each other.

Acoustic obstructive sleep apnea detection

Obstructive sleep apnea (OSA) is a common respiratory disorder during sleep, in which the airways are collapsed and impair the respiration. Apnea is s cessation of airflow to the lungs which lasts at least for 10s. The current gold standard method for OSA assessment is full night polysomnography (PSG); however, its high cost, inconvenience for patients and immobility have persuaded researchers to seek simple and portable devices to detect OSA. In this paper, we report on developing a new system for OSA detection and monitoring, which only requires two data channels: tracheal breathing sounds and the blood oxygen saturation level (S(a)O(2)). A fully automated method was developed that uses the energy of breathing sounds signals to segment the signals into sound and silent segments. Then, the sound segments are classified into breath, snore (if exists) and noise segments. The S(a)O(2) signal is analyzed to find the rises and drops in the S(a)O(2) signal. Finally, a fuzzy algorithm was developed to use this information and detect apnea and hypopnea events. The method was evaluated on the data of 40 patients simultaneously with full night PSG study, and the results were compared with those of the PSG. The results show high correlation (96%) between our system and PSG. Also, the method has been found to have sensitivity and specificity values of more than 90% in differentiating simple snorers from OSA patients.