Assessment of continuous positive airway pressure treatment in obstructive sleep apnea syndrome using 24-hour urinary catecholamines

Sleep apnea is a common and dangerous cardiovascular risk factor

Sleep apnea involves almost one billion individuals throughout the world, including 40 million Americans. Of major medical concern is the fact that the prevalence of sleep apnea is significantly increasing due to the epidemic of obesity, physical inactivity, and diabetes mellitus which are important risk factors for the development and persistence of sleep apnea in individuals. Sleep apnea is characterized by multiple episodes of apnea or hypopnea during sleep, which cause nocturnal arousals, gasping for breath during the night, daytime sleepiness, irritability, forgetfulness, fatigue and recurrent headaches. Obstructive sleep apnea occurs when upper airway obstruction occurs in an individual during sleep with absent or markedly reduced airflow in the presence of continued activity of inspiratory thoracic and diaphragmatic muscles. Central sleep apnea is defined as the absence or the significant reduction of naso-oral airflow due to the withdrawal during sleep of ponto-medullary respiratory center stimulation of the nerves of the inspiratory thoracic and diaphragmatic muscles and absence of contraction of these muscles during apnea. Complex sleep apnea occurs when an individual exhibits characteristics of both obstructive and central sleep apnea. The severity of sleep apnea is measured by polysomnography and the apnea hypopnea index (AHI), which is the average number of apneas and hypopneas per hour of sleep measured by polysomnography. Sleep apnea is mild if the AHI is 5-14/h with no or mild symptoms, moderate if the AHI is 15 to 30/h with occasional daytime sleepiness, and severe if the AHI is >30/h with frequent daytime sleepiness that interferes with the normal activities of daily life. Chronic sleep apneas and hypopneas followed by compensatory hyperpneas are associated with significant adverse cardiovascular consequences including: 1) recurrent hypoxemia and hypercarbia; 2) Increased sympathetic nerve activity and decreased parasympathetic nerve activity; 3) oxidative stress and vascular endothelial dysfunction; and 4) cardiac remodeling and cardiovascular disease. Moderate or severe sleep apnea significantly increases the risk of coronary artery disease, congestive heart failure, cerebral vascular events (strokes), and cardiac dysrhythmias, and also increase the morbidity and mortality of these diseases. Nevertheless, sleep apnea is currently underdiagnosed and untreated in many individuals due to the challenges in the prediction and detection of sleep apnea and a lack of well-defined optimal treatment guidelines. Chronic continuous positive airway pressure for ≥4 h/night for >70% of nights is beneficial in the treatment of patients with sleep apnea. CPAP Improves sleep quality, reduces the AHI, augments cardiac output and increases oxygen delivery to brain and heart, reduces resistant hypertension, decreases cardiac dysrhythmias, and reduces daytime sleepiness. The present article discusses the diagnosis of obstructive sleep apnea, central sleep apnea, and complex apnea. Thereafter the important pathophysiologic mechanisms in sleep apnea and the relationship of these pathophysiologic mechanics to atherosclerotic vascular disease are reviewed. Guidelines are then provided for the treatment of mild, moderate and severe sleep apnea. In order to reduce the cardiovascular morbidity and mortality caused by sleep apnea and facilitate the diagnosis and the long-term, effective treatment of sleep apnea in patients, the close cooperation is necessary of cardiovascular specialists, pulmonary specialists, and respiratory therapy/rehabilitation specialists.

Relevance Between Reduction of SpO2 and Parasympathetic Nervous Activity During Sleep

Sleep apnea syndrome (SAS) is associated with cardiopulmonary and dental nasopharyngeal diseases. The blood oxygen saturation (SpO2) detected using pulse oximetry is a diagnostic screening method for SAS. SAS severity is assessed using the oxygen desaturation index (ODI), which measures the number of times the SpO2 decreases by more than 3% for longer than 10 s. This study investigated the association between reduced SpO2 and parasympathetic nervous system activity (PSNA) during night sleep in young adults (n = 63; aged 20-32 years). Changes in PSNA were measured every minute for 24 h during a free-moving day using an ActiveTracer accelerometer. Pulse oximetry was performed simultaneously during sleep. All participants had significantly lower PSNA when the SpO2 decreased by 3% or more than when it did not. There were no significant differences in PSNA when an ODI cutoff of 5 events/h was used. However, participants with an ODI >5 events/h had significantly lower PSNA during normal SpO2 than those with an ODI <5 events/h, suggesting an association between SpO2 desaturation and PSNA decline during sleep. A high ODI may indicate reduced PSNA levels during sleep, affecting sleep efficiency. Treatment aimed at reducing the ODI may improve sleep quality, even in young adults.

Anthropometric Determinants of Autonomic Control in Obstructive Sleep Apnea: A Large-Scale Study

OBJECTIVE

Autonomic dysfunction is an independent risk factor for cardiovascular disease (CVD). Both obesity and obstructive sleep apnea (OSA) are associated with heart rate variability (HRV) (a hall marker of sympathetic arousal) and increased risk of CVD. This study aims to investigate whether anthropometric parameters could predict reduced HRV in adult OSA during wakefulness.

STUDY DESIGN

Cross-sectional study.

SETTING

Sleep center of Shanghai Jiao Tong University Affiliated Sixth Hospital from 2012 to 2017.

METHODS

Total of 2134 subjects (503 non-OSA and 1631 OSA) were included. Anthropometric parameters were recorded. HRV was recorded during a 5-minute wakefulness period and analyzed by using time-domain method and frequency-domain method. Multiple step-wise linear regressions were performed to determine significant predictors of HRV with and without adjustments. Multiplicative interactions between gender, OSA, and obesity on HRV were also determined and evaluated.

RESULTS

Waist circumference (WC) was significant negative determinant of root mean square of successive NN intervals (β = -.116, p < .001) and high-frequency power (β = -.155, p < .001). Age was the strongest determining factor of HRV. Significant multiplicative interactions between obesity and OSA on HRV, gender, and obesity on cardiovascular parameters were observed.

CONCLUSION

Anthropometric parameters could predict reduced HRV during wakefulness in patients with OSA, especially WC was the strongest influenceable factor. Obesity and OSA had significant multiplicative interaction on HRV. Gender and obesity had significant multiplicative interaction on cardiovascular parameters. Early intervention for obesity, especially centripetal obesity, may improve reduction of autonomic function and risk of CVD.

The effect of obstructive sleep apnea therapy on cardiovascular autonomic function: a systematic review and meta-analysis

STUDY OBJECTIVES

Autonomic function is impaired in obstructive sleep apnea (OSA) and may mediate the association between OSA and cardiovascular risk. We investigated the effect of OSA therapy on autonomic function through a systematic review and meta-analysis of intervention studies.

METHODS

A systematic search using three databases (Medline, Embase, and Scopus) was performed up to December 9, 2020. Studies of OSA patients ≥ 18 years with autonomic function assessed before and after treatment with positive airway pressure, oral appliance, positional therapy, weight loss, or surgical intervention were included for review. Random effects meta-analysis was carried out for five groups of autonomic function indices. Risk of bias was assessed using the Cochrane Collaboration tool.

RESULTS

Forty-three eligible studies were reviewed with 39 included in the meta-analysis. OSA treatment led to large decreases in muscle sympathetic nerve activity (Hedges' g = -1.08; 95% CI -1.50, -0.65, n = 8) and moderate decreases in catecholamines (-0.60; -0.94, -0.27, n = 3) and radio nucleotide imaging (-0.61; -0.99, -0.24, n = 2). OSA therapy had no significant effect on baroreflex function (Hedges' g = 0.15; 95% CI -0.09, 0.39, n = 6) or heart rate variability (0.02; -0.32, 0.36, n = 14). There was a significant risk of bias due to studies being primarily non-randomized trials.

CONCLUSIONS

OSA therapy selectively improves autonomic function measures. The strongest evidence for the effect of OSA therapy on autonomic function was seen in reduced sympathetic activity as assessed by microneurography, but without increased improvement in parasympathetic function. OSA therapy may reduce the risk of cardiovascular disease in OSA through reduced sympathetic activity.

Probable Change of Sleep Parameters after Resection and Reconstruction Surgeries in Patients with Oral Cavity or Oropharyngeal Cancers

In patients of oral cavity or oropharyngeal cancers, resection of the tumor and reconstruction of the defect may reduce the framework, add a bulky flap, alter the tissue flexibility, and contribute to postoperative obstructive sleep apnea (OSA). Postoperative OSA and the potential consequences may decrease the survival rate and reduce patients' quality of life. It is unclear whether the surgery is associated with postoperative OSA. Here, we compared the polysomnographies (PSGs) before and after the surgery in 15 patients of oral cavity or oropharyngeal cancers (out of 68 patients of head and neck cancers) without a chemo- or radio-therapy. Each patient received the second PSG before the start of any indicated adjuvant therapy to prevent its interference. There were 14 men and 1 woman, with a mean age and a standard deviation (SD, same in the following) of 56.2 ± 12.8 years. There were 6 tongue cancers, 5 buccal cancers, 2 tonsil cancer, 1 lower gum cancer, and 1 trigone cancer. The results show that the surgery changed sleep parameters insignificantly in apnea-hypopnea index (AHI), mean oxyhemoglobin saturation of pulse oximetry (SpO2), minimum SpO2, mean desaturation, and desaturation index but increased mean heart rate in the patients with free flaps. These results hint that the effect of surgery on developing OSA was small in this sample, with a longer plate or a larger framework for a bulkier free flap. It needs future studies with a large sample size to generalize this first observation.

Obstructive Sleep Apnea-Induced Neurogenic Nocturnal Hypertension: A Potential Role of Renal Denervation?

There is a bidirectional, causal relationship between obstructive sleep apnea (OSA) and hypertension. OSA-related hypertension is characterized by high rates of masked hypertension, elevated nighttime blood pressure, a nondipper pattern of nocturnal hypertension, and abnormal blood pressure variability. Hypoxia/hypercapnia-related sympathetic activation is a key pathophysiological mechanism linking the 2 conditions. Intermittent hypoxia also stimulates the renin-angiotensin-aldosterone system to promote hypertension development. The negative and additive cardiovascular effects of OSA and hypertension highlight the importance of effectively managing these conditions, especially when they coexist in the same patient. Continuous positive airway pressure is the gold standard therapy for OSA but its effects on blood pressure are relatively modest. Furthermore, this treatment did not reduce the cardiovascular event rate in nonsleepy patients with OSA in randomized controlled trials. Antihypertensive agents targeting sympathetic pathways or the renin-angiotensin-aldosterone system have theoretical potential in comorbid hypertension and OSA, but current evidence is limited and combination strategies are often required in drug resistant or refractory patients. The key role of sympathetic nervous system activation in the development of hypertension in OSA suggests potential for catheter-based renal sympathetic denervation. Although long-term, randomized controlled trials are needed, available data indicate sustained and relevant reductions in blood pressure in patients with hypertension and OSA after renal denervation, with the potential to also improve respiratory parameters. The combination of lifestyle interventions, optimal pharmacological therapy, continuous positive airway pressure therapy, and perhaps also renal denervation might improve cardiovascular risk in patients with OSA.

Heart rate variability and obstructive sleep apnea: Current perspectives and novel technologies

Obstructive sleep apnea (OSA) is a highly prevalent condition, resulting in recurrent hypoxic events, sleep arousal, and daytime sleepiness. Patients with OSA are at an increased risk of cardiovascular morbidity and mortality. The mechanisms underlying the development of cardiovascular disease in OSA are multifactorial and cause a cascade of events. The primary contributing factor is sympathetic overactivity. Heart rate variability (HRV) can be used to evaluate shifts in the autonomic nervous system, during sleep and in response to treatment in patients with OSA. Newer technologies are aimed at improving HRV analysis to accelerate processing time, improve the diagnosis of OSA, and detection of cardiovascular risk. The present review will present contemporary understandings and uses for HRV, specifically in the realms of physiology, technology, and clinical management.

A Non-Framework Multilevel Surgery May Reduce Mean Heart Rate in Patients with Very Severe Obstructive Apnea Having Confined Retroglossal Space and Framework

An elevated mean heart rate in untreated patients of obstructive sleep apnea (OSA) may lead to a higher risk of mortality and the development of various cardiovascular diseases. The elevation may positively relate to the severity of OSA and present in both wakefulness and sleep. A reduction in heart rate has been presented in reports of treating OSA patients with continuous positive airway pressure (CPAP). However, patients with very severe OSA may refuse use of CPAP devices and advocated surgeries, such as direct skeletal surgery or tracheostomy. It is unclear whether the non-framework multilevel surgery we reported previously can overcome the unfavorable anatomy and reduce mean heart rate, which serves as a risk factor of mortality. Here, we show that multilevel surgery reduced the mean heart rate from 68.6 to 62.7 with a mean reduction of 5.9 beats/min. The results suggest that the surgery may reduce the risk of consequences and mortality associated with an elevated mean heart rate, such as various cardiovascular diseases. We disclose these findings, along with the variations and possible risks to our future patients with very severe OSA who refuse or cannot use a CPAP device or reject direct skeletal surgery.

Meta-analysis of changes in the levels of catecholamines and blood pressure with continuous positive airway pressure therapy in obstructive sleep apnea

Stress from obstructive sleep apnea (OSA) stimulates catecholamine release consequently exacerbating hypertension. However, different studies have shown a conflicting impact of continuous positive airway pressure (CPAP) treatment in patients with OSA on catecholamine levels and blood pressure. We aimed to examine changes to catecholamine levels and blood pressure in response to CPAP treatment. We conducted a meta‐analysis of data published up to May 2020. The quality of the studies was evaluated using standard tools for assessing the risk of bias. Meta‐analysis was conducted using RevMan (v5.3) and expressed in standardized mean difference (SMD) for catecholamines and mean difference (MD) for systolic (SBP) and diastolic blood pressure (DBP). A total of 38 studies met our search criteria; they consisted of 14 randomized control trials (RCT) totaling 576 participants and 24 prospective cohort studies (PCS) of 547 participants. Mean age ranged between 41 and 62 year and body mass index between 27.2 and 35.1 kg/m². CPAP treatment reduced 24‐hour urinary noradrenaline levels both in RCT (SMD = −1.1; 95% confidence interval (CI): −1.63 to − 0.56) and in PCS (SMD = 0.38 (CI: 0.24 to 0.53). SBP was also reduced by CPAP treatment in RCT (4.8 mmHg; CI: 2.0‐7.7) and in PCS (7.5 mmHg; CI: 3.3‐11.7). DBP was similarly reduced (3.0 mmHg; CI: 1.4‐4.6) and in PCS (5.1 mmHg; CI: 2.3‐8.0). In conclusion, CPAP treatment in patients with OSA reduces catecholamine levels and blood pressure. This suggests that sympathetic activity plays an intermediary role in hypertension associated with OSA‐related stress.

Sleep disturbances: one of the culprits of obesity-related cardiovascular risk?

Growing evidence suggested that Sleep Disorders (SD) could increase the risk of developing obesity and could contribute to worsen obesity-related cardiovascular risk. Further, obesity per se has been reported to blunt sleep homeostasis. This happens through several mechanisms. First of all, the excessive adipose tissue at neck and chest levels could represent a mechanical obstacle to breathe. Moreover, the visceral adipose tissue is known to release cytokines contributing to low-grade chronic inflammation that could impair the circadian rhythm. Also, nutrition plays an important role in sleep homeostasis. High fat and/or high carbohydrate diets are known to have a negative impact on both sleep quality and duration. In addition, obesity predisposes to a condition called "obstructive sleep apnea" that has a detrimental effect on sleep. SD could increase the risk and/or could contribute to worsen cardiovascular risk usually associated with obesity. The chronic low grade inflammation associated with obesity has been reported to increase the risk of developing hypertension, type 2 diabetes and dyslipidemia. In turn, improving quality of sleep has been reported to improve the management of these cardiovascular risk factors. Thus, the aim of this manuscript is to provide evidence on the association of obesity and SD and on how they could contribute to the risk of developing cardiovascular risk factors such as hypertension, dyslipidemia and type 2 diabetes in obesity.

Very low frequency component of heart rate variability as a marker for therapeutic efficacy in patients with obstructive sleep apnea: Preliminary study

BACKGROUND

Although positive airway pressure (PAP) therapy is effective for treating obstructive sleep apnea (OSA), some patients with severe OSA are intolerable to this treatment, which may lead to an increase in the mortality and morbidity of cardiovascular diseases. We investigated the relationship between heart rate variability (HRV) and sleep parameters during natural sleep and treatment of patients with OSA.

MATERIALS AND METHODS

This was the cross-sectional observation study. Patients were 17 males with severe OSA who were unable to accept continuous PAP. Standard polysomnography was performed for two consecutive nights, i.e., during natural sleep and following night with bilevel PAP (BiPAP) treatment. Time-dependent responses of the amplitudes of low frequency (LF), very low frequency (VLF), and high frequency components of HRV were assessed with the technique of complex demodulation.

RESULTS

Apnea-hypopnea index, oxygen desaturation time, and percentage of stage 1 sleep were significantly reduced, whereas the percentages of rapid eye movement and stages 3 + 4 sleep were increased, by BiPAP treatment. Therapy also reduced the amplitudes of VLF and LF components of HRV. Difference in amplitudes of VLF during natural sleep and treatment with BiPAP was significantly correlated with difference in percentages of stage 1 and stages 3 + 4 sleep.

CONCLUSION

Therapy-induced amelioration of OSA and sleep quality was accompanied by decrease in the amplitudes of VLF components of HRV. The VLF component may thus reflect physiological changes in both autonomic activity and sleep structure and serve as an objective marker for therapeutic efficacy in patients with severe OSA.

Blood pressure response to treatment of obese vs non-obese adults with sleep apnea

Many patients with obstructive sleep apnea (OSA), but not all, have a reduction in blood pressure (BP) with positive airway pressure (PAP) treatment. Our objective was to determine whether the BP response following PAP treatment is related to obesity. A total of 188 adults with OSA underwent 24-hour BP monitoring and 24-hour urinary norepinephrine collection at baseline. Obesity was assessed by waist circumference, body mass index, and abdominal visceral fat volume. Participants adherent to PAP treatment were reassessed after 4 months. Primary outcomes were 24-hour mean arterial pressure (MAP) and 24-hour urinary norepinephrine level. Obstructive sleep apnea participants had a significant reduction in 24-hour MAP following PAP treatment (-1.22 [95% CI: -2.38, -0.06] mm Hg; P = .039). No significant correlations were present with any of the 3 obesity measures for BP or urinary norepinephrine measures at baseline in all OSA participants or for changes in BP measures in participants adherent to PAP treatment. Changes in BP measures following treatment were not correlated with baseline or change in urinary norepinephrine. Similar results were obtained when BP or urinary norepinephrine measures were compared between participants dichotomized using the sex-specific median of each obesity measure. Greater reductions in urinary norepinephrine were correlated with higher waist circumference (rho = -0.21, P = .037), with a greater decrease from baseline in obese compared to non-obese participants (-6.26 [-8.82, -3.69] vs -2.14 [-4.63, 0.35] ng/mg creatinine; P = .027). The results indicate that the BP response to PAP treatment in adults with OSA is not related to obesity or urinary norepinephrine levels.

Ventricular Arrhythmias in Patients with Obstructive Sleep Apnea

Obstructive Sleep Apnea (OSA) is a prevalent condition thought to increase in the future. Being mostly undiagnosed, the most serious complications are cardiovascular diseases, among which are arrhythmias. Controversy remains as to whether OSA is a primary etiologic factor for ventricular arrhythmias, because of the high incidence of cardiovascular comorbidities in OSA patients. Howev-er, there is mostly a strong evidence of a relation between OSA and ventricular arrhythmias. A few mechanisms have been proposed to be responsible for this association and some electrocardiographic changes have also been demonstrated to be more frequent in OSA patients. Treatment of OSA with Continuous Positive Airway Pressure (CPAP) has the potential to reduce arrhythmias and confer a mortality benefit.

"BROAD Effect: Bradycardia in Obstructive Airway Disease"An Unusual Phenomenon: A Case Report

Non Invasive Ventilation (NIV) is frequently used in Obstructive Airway Disease (OAD) especially COPD (Chronic Obstructive Pulmonary Disease). Patients often get hypoxic or retain carbon dioxide during attempts to feed the patient orally or trial of intermittent support. However, patient developing sudden bradycardia by mere taking off the mask and reverting to sinus rhythm as soon as mask is put back is extremely rare. We present one such case that was also a treatment challenge for us. Recurrent bradycardia in COPD, with repeatability on discontinuation of Non Invasive Ventilation (NIV) is an extremely rare condition with not much reports/studies in the medical literature. The mechanisms leading to such an event are poorly understood. To the best of our knowledge, it's the first case to be reported from India.

Interactions between and Shared Molecular Mechanisms of Diabetic Peripheral Neuropathy and Obstructive Sleep Apnea in Type 2 Diabetes Patients

Type 2 diabetes (T2D) accounts for about 90% of all diabetes patients and incurs a heavy global public health burden. Up to 50% of T2D patients will eventually develop neuropathy as T2D progresses. Diabetic peripheral neuropathy (DPN) is a common diabetic complication and one of the main causes of increased morbidity and mortality of T2D patients. Obstructive sleep apnea (OSA) affects over 15% of the general population and is associated with a higher prevalence of T2D. Growing evidence also indicates that OSA is highly prevalent in T2D patients probably due to diabetic peripheral neuropathy. However, the interrelations among diabetic peripheral neuropathy, OSA, and T2D hitherto have not been clearly elucidated. Numerous molecular mechanisms have been documented that underlie diabetic peripheral neuropathy and OSA, including oxidative stress, inflammation, endothelin-1, vascular endothelial growth factor (VEGF), accumulation of advanced glycation end products, protein kinase C (PKC) signaling, poly ADP ribose polymerase (PARP), nitrosative stress, plasminogen activator inhibitor-1, and vitamin D deficiency. In this review, we seek to illuminate the relationships among T2D, diabetic peripheral neuropathy, and OSA and how they interact with one another. In addition, we summarize and explain the shared molecular mechanisms involved in diabetic peripheral neuropathy and OSA for further mechanistic investigations and novel therapeutic strategies for attenuating and preventing the development and progression of diabetic peripheral neuropathy and OSA in T2D.

The sympathetic nervous system and catecholamines metabolism in obstructive sleep apnoea

Obstructive sleep apnoea (OSA) is the most common sleep disorder of breathing in middle-aged and overweight subjects. It features recurrent episodes of upper airway total (apnoea) o partial (hypopnea) collapse during sleep, which are associated with a reduction in blood oxygen saturation and with arousal from sleep to re-establish airway patency. An association of OSA with dysregulation of the autonomous nervous system (ANS) and altered catecholamines (CAs) metabolism has been contended for years. However, the pathophysiology mechanisms underlying these alterations remain to be fully clarified. Nonetheless, these alterations are deemed to play a key pathogenic role in the established association of OSA with several conditions besides arterial hypertension (HT), including coronary artery disease, stroke, and, more in general, with increased risk of cardiovascular (CV) events. Hence, in this review we will analyse the relationship between the sleep disturbances associated with OSA and the altered function of the ANS, including CAs metabolism.

Diagnostic capability of biological markers in assessment of obstructive sleep apnea: a systematic review and meta-analysis

OBJECTIVE

The purpose of this systematic review is to evaluate the diagnostic value of biological markers (exhaled breath condensate, blood, salivary and urinary) in the diagnosis of OSA in comparison to the gold standard of nocturnal PSG.

METHODS

Studies that differentiated OSA from controls based on PSG results, without age restriction, were eligible for inclusion. The sample of selected studies could include studies in obese patients and with known cardiac disease. A detailed individual search strategy for each of the following bibliographic databases was developed: Cochrane, EMBASE, MEDLINE, PubMed, and LILACS. The references cited in these articles were also crosschecked and a partial grey literature search was undertaken using Google Scholar. The methodology of selected studies was evaluated using the 14-item Quality Assessment Tool for Diagnostic Accuracy Studies.

RESULTS

After a two-step selection process, nine articles were identified and subjected to qualitative and quantitative analyses. Among them, only one study conducted in children and one in adults found biomarkers that exhibit sufficiently satisfactory diagnostic accuracy that enables application as a diagnostic method for OSA.

CONCLUSION

Kallikrein-1, uromodulin, urocotin-3, and orosomucoid-1 when combined have enough accuracy to be an OSA diagnostic test in children. IL-6 and IL-10 plasma levels have potential to be good biomarkers in identifying or excluding the presence of OSA in adults.

Biomarkers associated with obstructive sleep apnea: A scoping review

The overall validity of biomarkers in the diagnosis of obstructive sleep apnea (OSA) remains unclear. We conducted a scoping review to provide assessments of biomarkers characteristics in the context of obstructive sleep apnea (OSA) and to identify gaps in the literature. A scoping review of studies in humans without age restriction that evaluated the potential diagnostic value of biological markers (blood, exhaled breath condensate, salivary, and urinary) in the OSA diagnosis was undertaken. Retained articles were those focused on the identification of biomarkers in subjects with OSA, the latter being confirmed with a full overnight or home-based polysomnography (PSG). Search strategies for six different databases were developed. The methodology of selected studies was classified using an adaptation of the evidence quality criteria from the American Academy of Pediatrics. Additionally the biomarkers were classified according to their potential clinical application. We identified 572 relevant studies, of which 117 met the inclusion criteria. Eighty-two studies were conducted in adults, 34 studies involved children, and one study had a sample composed of both adults and children. Most of the studies evaluated blood biomarkers. Potential diagnostic biomarkers were found in nine pediatric studies and in 58 adults studies. Only nine studies reported sensitivity and specificity, which varied substantially from 43% to 100%, and from 45% to 100%, respectively. Studies in adults have focused on the investigation of IL-6, TNF-α and hsCRP. There was no specific biomarker that was tested by a majority of authors in pediatric studies, and combinatorial urine biomarker approaches have shown preliminary promising results. In adults IL-6 and IL-10 seem to have a favorable potential to become a good biomarker to identify OSA.

Mean platelet volume in patients with obstructive sleep apnea and its relationship with simpler heart rate derivatives

Some studies show increased mean platelet volume (MPV) in obstructive sleep apnea (OSA). The aim of this study was to evaluate MPV in OSA patients without cardiovascular risk factors and the possible association of heart rate derivatives with MPV. A total of 82 patients (aged 30–70 years) were divided into 2 groups according to the presence of either OSA or non-OSA as the control group. The OSA group consisted of 52 patients and the control group consisted of 30 subjects. Neither group was significantly different in terms of MPV values as well as heart rate (HR) derivatives such as minimum HR, maximum HR, the difference between maximum HR and minimum HR, mean HR, and heart rate performance index (HRPI) [(HR max. − HR min.)/HR mean] (P > 0.05 for all variables). In multivariate analysis, platelet count and percentages of recording time spent at arterial oxygen saturation < 90% significant variables are associated with MPV (β ± SE: −0.004 ± 0.002, 95% CI, −0.008 to −0.001; P = 0.034) and (β ± SE: 2.93 ± 1.93, 95% CI, 0.167 to 5.69; P = 0.038). Consequently, our findings predominantly suggest that there is a casual and reciprocal interaction between MPV and autonomic activation.

Hypertension and sleep: overview of a tight relationship

Autonomic cardiovascular control changes across sleep stages. Thus, blood pressure (BP), heart rate and peripheral vascular resistance progressively decrease in non-rapid eye movement sleep. Any deterioration in sleep quality or quantity may be associated with an increase in nocturnal BP which could participate in the development or poor control of hypertension. In the present report, sleep problems/disorders, which impact either the quality or quantity of sleep, are reviewed for their interaction with BP regulation and their potential association with prevalent or incident hypertension. Obstructive sleep apnea syndrome, sleep duration/deprivation, insomnia, restless legs syndrome and narcolepsy are successively reviewed. Obstructive sleep apnea is clearly associated with the development of hypertension that is only slightly reduced by continuous positive airway pressure treatment. Shorter and longer sleep durations are associated with prevalent or incident hypertension but age, gender, environmental exposures and ethnic differences are clear confounders. Insomnia with objective short sleep duration, restless legs syndrome and narcolepsy may impact BP control, needing additional studies to establish their impact in the development of permanent hypertension. Addressing sleep disorders or sleep habits seems a relevant issue when considering the risk of developing hypertension or the control of pre-existent hypertension. Combined sleep problems may have potential synergistic deleterious effects.

CPAP therapy prevents increase in blood pressure after upper airway surgery for obstructive sleep apnoea

OBJECTIVE

The aim of this study was to investigate the efficacy of continuous positive airway pressure (CPAP) therapy following uvulopalatopharyngoplasty (UPPP) to prevent blood pressure (BP) elevation during sleep.

METHODS

Sixteen normotensive patients with OSA were subjected to UPPP with or without septoplasty. These patients were instrumented for 24 h of ambulatory BP recording, polysomnography, nocturnal urinary catecholamine and pain evaluation using a visual analogue scale in the day prior to surgery (D-1), following the surgery (D+1) and 30 days later (D+30). For the D+1, the patients were divided into two groups: the without CPAP therapy group and the with CPAP therapy group.

RESULTS

The apnoea-hypopnoea index (AHI) significantly increased in the patients without CPAP therapy compared with the D-1 (74 ± 23 vs. 35 ± 6 times/h, p < 0.05), and in the CPAP group, there was a significant reduction in the average AHI value to 14 ± 6 times/h, p < 0.01. During D+1, we observed an increase in the nocturnal systolic BP (10 %), diastolic BP (12 %) and heart rate (14 %) in the group without CPAP. These metrics were re-established in the CPAP group to values that were similar to those that were observed on the D-1. The absence of nocturnal dipping in the group without CPAP was followed by a significant increase in nocturnal norepinephrine (42 ± 12 μg/l/12 h) and epinephrine (8 ± 2 μg/l/12 h) levels compared with the D-1 (norepinephrine 17 ± 3; epinephrine 2 ± 0.3 μg/l/12 h, p < 0.001). In the patients who used the CPAP treatment, the nocturnal catecholamine levels were similar to D-1. The effectiveness of intravenous analgesic therapy was verified by a significant decrease in the pain scores in patients both with and without CPAP therapy.

CONCLUSION

These data confirm an increase in the AHI on the night following UPPP with or without septoplasty. This increase promotes an absence of nocturnal dipping and a significant increase in urinary catecholamine levels. CPAP therapy was effective to prevent the transitory increase in BP.

Effects of CPAP on nitrate and norepinephrine levels in severe and mild-moderate sleep apnea

BACKGROUND

Reduced plasma nitrate (NO(x)) levels and increased urinary norepinephrine (U-NE) levels have been described in severe obstructive sleep apnea (OSA), and are reverted by continuous positive airway pressure (CPAP). The effect of CPAP on these biomarkers in mild-moderate OSA is not well understood. The aim of this study was to compare NO(x) and U-NE levels and blood pressure (BP) between male patients with mild-moderate and severe OSA and determine the impact of 1 month of CPAP therapy on these parameters.

METHODS

We undertook a prospective study of 67 consecutive OSA patients (36 mild-moderate, 31 severe). Measurements of plasma NO(x) at 11 pm, 4 am and 7 am, 24-h U-NE and ambulatory BP were obtained at baseline and after 1 month of CPAP.

RESULTS

At baseline, NO(x) levels showed a significant decrease during the night in both groups (p < 0.001). U-NE level and BP were significantly higher in the severe OSA group. After 1 month of CPAP, there was a significant increase in NO(x) levels and a reduction in U-NE level and BP only in patients with severe OSA.

CONCLUSIONS

One month of CPAP results in significant improvements in NO(x) levels, 24-h U-NE level and BP in patients with severe OSA, but not in patients with mild-moderate OSA.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01769807.

Obstructive sleep apnea and severe mental illness: evolution and consequences

Sleep complaints are commonly encountered in psychiatric clinics. Underlying medical disorders or sleep disorders need to be identified and treated to optimize treatment of the mental illness. Excessive daytime sleepiness, which is the main symptom of obstructive sleep apnea (OSA), overlaps with those of many severe mental illnesses. Medication side effects or the disorder itself maybe account for daytime sleepiness but comorbid OSA is a possibility that should not be overlooked. The diagnosis of OSA is straightforward but treatment compliance is problematic in psychiatric patients. This article summarizes studies concerning comorbid OSA in patients with severe mental illness and includes suggestions for future investigations.

Coagulability in obstructive sleep apnea

BACKGROUND

Obstructive sleep apnea (OSA) is a common disorder that affects both quality of life and cardiovascular health. The causal link between OSA and cardiovascular morbidity⁄mortality remains elusive. One possible explanation is that repeated episodes of nocturnal hypoxia lead to a hypercoagulable state that predisposes patients to thrombotic events. There is evidence supporting a wide array of hematological changes that affect hemostasis (eg, increased hematocrit, blood viscosity, platelet activation, clotting factors and decreased fibrinolytic activity).

OBJECTIVE

To provide a comprehensive review of the current evidence associating OSA with increased coagulability, and to highlight areas for future research.

METHODS

Keyword searches in Ovid Medline were used to identify relevant articles; all references in the articles were searched for relevant titles. The Web of Science was used to identify articles citing the relevant articles found using the Ovid Medline search. All original peer-reviewed articles, meta-analyses and systematic reviews regarding the pertinent topics between 1990 and present were selected for review.

RESULTS

Hematocrit, blood viscosity, certain clotting factors, tissue factor, platelet activity and whole blood coagulability are increased in patients with OSA, while fibrinolysis is impaired.

CONCLUSION

There is considerable evidence that OSA is associated with a procoagulant state. Several factors are involved in the procoagulant state associated with OSA. There is a need for adequately powered clinical studies involving well-matched control groups to address potential confounding variables, and to accurately delineate the individual factors involved in the procoagulant state associated with OSA and their response to treatment.

Sympathetic and catecholaminergic alterations in sleep apnea with particular emphasis on children

Sleep is involved in the regulation of major organ functions in the human body, and disruption of sleep potentially can elicit organ dysfunction. Obstructive sleep apnea (OSA) is the most prevalent sleep disorder of breathing in adults and children, and its manifestations reflect the interactions between intermittent hypoxia, intermittent hypercapnia, increased intra-thoracic pressure swings, and sleep fragmentation, as elicited by the episodic changes in upper airway resistance during sleep. The sympathetic nervous system is an important modulator of the cardiovascular, immune, endocrine and metabolic systems, and alterations in autonomic activity may lead to metabolic imbalance and organ dysfunction. Here we review how OSA and its constitutive components can lead to perturbation of the autonomic nervous system in general, and to altered regulation of catecholamines, both of which then playing an important role in some of the mechanisms underlying OSA-induced morbidities.

Profound bradycardia associated with NIV removal

A patient with lower-limb onset ALS presented with a one-month history of vasovagal episodes and a one-week history of cough productive of green sputum and lethargy. She was drowsy and in acute on chronic type-two respiratory failure. She responded to non-invasive ventilation, however she suffered recurrent episodes of profound bradycardia on removal of the mask, which gradually resolved over ten days. We have reviewed the literature and offer a potential explanation for these events.

Nocturnal intermittent serious hypoxia and reoxygenation in proliferative diabetic retinopathy cases

PURPOSE

To clarify the relationship between evaluation items of sleep-disordered breathing and diabetic retinopathy in detail.

DESIGN

Cross-sectional comparative study.

METHODS

Sixty-eight consecutive nonproliferative diabetic retinopathy and 151 proliferative diabetic retinopathy (PDR) cases who had undergone surgeries in our department were included in this study. Pulse oximetry was conducted overnight and mean oxygen saturation by pulse oximeter (SpO(2); %), the sleeping 4% oxygen desaturation index (4% ODI times/hour), lowest SpO(2) (%), and the cumulative percent time spent at SpO(2) < 90% (CT 90%) were calculated. The results were evaluated and compared between the 2 groups. In addition, these results and preoperative patient background factors were analyzed using logistic regression analysis to clarify risk factor of PDR.

RESULTS

4% ODI and CT 90% in the PDR group were significantly higher than in the nonproliferative diabetic retinopathy group (4% ODI, 7.8 vs. 4.9; P = .007; CT 90%, 2.2 vs 0.8; P = .0006). Lowest SpO(2) was significantly lower in the PDR group than in the nonproliferative diabetic retinopathy groups (82.4 vs 87.0; P = .0006). Logistic regression analysis identified being younger, having a lower value for the lowest SpO(2), and a high hemoglobin A1c value to be risk factors for PDR (age: odds ratio, 0.90; 95% confidence interval, -0.86 to -0.94; P < .0001; lowest SpO(2): odds ratio, 0.93; 95% confidence interval, 0.88 to 0.99; P = .02; hemoglobin A1c: odds ratio, 1.00 to 1.69; P = .047).

CONCLUSIONS

This study indicated that PDR cases had episodes of nocturnal intermittent hypoxia and reoxygenation as a result of sleep-disordered breathing and that low-value lowest SpO(2) were the risk factors for PDR development.