Chronic intermittent hypoxia leads to insulin resistance and impaired glucose tolerance through dysregulation of adipokines in non-obese rats

BACKGROUND AND OBJECTIVES

The aim of this study was to determine whether chronic intermittent hypoxia (CIH) could affect the secretion of adipokines, such as resistin, leptin, and adiponectin, in non-obese rats and to investigate the potential mechanisms.

METHODS

An established rodent model of CIH was utilized, in which rats were exposed to varying oxygen levels (7-21 %) respectively over a period of 5 weeks. The area under the curve (AUCG) and the insulin resistance index (homeostasis model of assessment for insulin resistance index, HOMA-IR) were calculated. The levels of several secretory factors in the blood were measured by enzyme-linked immunosorbent assay (ELISA). The mRNA levels and protein expression in adipose tissues was measured by reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

Glucose tolerance and the levels of adiponectin in non-obese rats were decreased in the CIH group both in the serum and adipose tissue compared with the controls, while the insulin resistance index and the levels of resistin and leptin were increased. Moreover, the expressions of hypoxia inducible factor-1α and lactate dehydrogenase A were significantly higher in chronic intermittent hypoxia rats than in control rats, suggesting the presence of adipose tissue hypoxia.

CONCLUSIONS

These results show that CIH leads to insulin resistance (IR) and impaired glucose tolerance (IGT) in a non-obese rodent model of obstructive sleep apnea-hypopnea syndrome, and these effects may be due to the dysregulation of adiponectin, resistin, and leptin.

Sleep disturbances and mild cognitive impairment: A review

OBJECTIVE

Mild cognitive impaired (MCI) is viewed as a transitional stage from normal to dementia. The aim of this study is analyze the sleep disturbances in subjects diagnosed as carries MCI.

METHODS

A review of the literature was conducted in order to document sleeps problems in the context of MCI.

RESULTS

Among the studies that compares the prevalence of sleep disturbances between subjects with MCI and those with normal cognition demonstrated that night time behaviors are more common in MCI patients (18.3-45.5%) than in normal population (10.9-23.3%).

CONCLUSIONS

Sleep disturbance is prevalent and predictive of cognitive decline in older people and in those with neurodegenerative disorders. The sleep problems have to be identified and treat to preserve the cognition and the MCI subjects with sleep disturbances have to be follow more closely to identify the initial signs of dementia.

An electrical cause of stridor: pediatric vagal nerve stimulators

Vagal nerve stimulators (VNS) are surgically implantable medical devices which are approved by the food and drug administration (FDA) for treatment of medically refractory epilepsy in children. Two children with seizures disorders presented to the pediatric otolaryngology clinic with complaints of stridor and sleep apnea following implantation of VNS devices. Both children were evaluated with flexible laryngoscopy, direct laryngoscopy and bronchoscopy. The children were noted to have contraction of their vocal folds and supraglottis and the settings of their VNS were adjusted until no further contractions were noted. Each child had resolution of their symptoms following adjustment.

Genetic variants associated with sleep disorders

OBJECTIVE

The diagnostic boundaries of sleep disorders are under considerable debate. The main sleep disorders are partly heritable; therefore, defining heritable pathophysiologic mechanisms could delineate diagnoses and suggest treatment. We collected clinical data and DNA from consenting patients scheduled to undergo clinical polysomnograms, to expand our understanding of the polymorphisms associated with the phenotypes of particular sleep disorders.

METHODS

Patients at least 21 years of age were recruited to contribute research questionnaires, and to provide access to their medical records, saliva for deoxyribonucleic acid (DNA), and polysomnographic data. From these complex data, 38 partly overlapping phenotypes were derived indicating complaints, subjective and objective sleep timing, and polysomnographic disturbances. A custom chip was used to genotype 768 single-nucleotide polymorphisms (SNPs). Additional assays derived ancestry-informative markers (eg, 751 participants of European ancestry). Linear regressions controlling for age, gender, and ancestry were used to assess the associations of each phenotype with each of the SNPs, highlighting those with Bonferroni-corrected significance.

RESULTS

In peroxisome proliferator-activated receptor gamma, coactivator 1 beta (PPARGC1B), rs6888451 was associated with several markers of obstructive sleep apnea. In aryl hydrocarbon receptor nuclear translocator-like (ARNTL), rs10766071 was associated with decreased polysomnographic sleep duration. The association of rs3923809 in BTBD9 with periodic limb movements in sleep was confirmed. SNPs in casein kinase 1 delta (CSNK1D rs11552085), cryptochrome 1 (CRY1 rs4964515), and retinoic acid receptor-related orphan receptor A (RORA rs11071547) were less persuasively associated with sleep latency and time of falling asleep.

CONCLUSIONS

SNPs associated with several sleep phenotypes were suggested, but due to risks of false discovery, independent replications are needed before the importance of these associations can be assessed, followed by investigation of molecular mechanisms.

Biomarkers associated with obstructive sleep apnea and morbidities: a scoping review

OBJECTIVE

To map potential biomarkers of obstructive sleep apnea (OSA)-associated morbidities in both adults and children, to identify gaps in current evidence, and to determine the value of conducting a full systematic review.

METHODS

A scoping review was undertaken of studies in patients with OSA that evaluated the potential value of biological markers in identifying OSA-associated morbidities. Retained articles were only those studies whose main objective was to identify morbidity biomarkers in subjects with OSA, the latter being confirmed with a full overnight polysomnography (PSG) in a laboratory or at-home settings. The methodology of the selected studies was classified using an adaptation of the evidence quality criteria recommended by the American Academy of Pediatrics. Additionally the biomarkers were categorized according to their potential clinical applicability.

RESULTS

572 citations were identified of which 48 met inclusion criteria. Thirty-four studies were conducted in adults and 14 involved children. Most of the studies evaluated blood biomarkers, and presented 31 potential diagnostic biomarkers.

CONCLUSION

The majority of studies that performed explored blood-based biomarkers, with most not identifying definitive morbidity biomarkers. Of the potentially promising morbidity biomarkers, plasma IL-6 and high sensitivity C-reactive protein appear to exhibit a favorable profile, and may discriminate OSA patients with and without morbidities in both adults and children. MRP 8/14 was retained in children as well as cardiovascular morbidity-associated biomarker. Urinary neurotransmitters may also provide a good tool for screening OSA cognitive morbidity in children.

Hemoglobinopathies and sleep--The road less traveled

Sickle cell disease and thalassemia are common hereditary blood disorders associated with increased systemic inflammation, tissue hypoxia, endothelial dysfunction and end-organ damage, the latter accounting for the substantial morbidity and abbreviated lifespan associated with these conditions. Sleep perturbations in general, and sleep-disordered breathing in particular are also highly prevalent conditions and the mechanisms underlying their widespread end-organ morbidities markedly and intriguingly overlap with the very same pathways implicated in the hemoglobinopathies. However, little attention has been given to date to the potential contributing role of sleep disorders to sickle cell disease manifestations. Here, we comprehensively review the pathophysiological mechanisms and clinical manifestations linking disturbed sleep and hemoglobinopathies, with special emphasis on sickle cell disease. In addition to a broad summary of the available evidence, we identify many of the research gaps that require attention and future investigation, and provide the scientific contextual setting that should enable opportunities to investigate the intertwined pathophysiological mechanisms and clinical outcomes of sleep disorders and hemoglobinopathies.

Hypomyelination, memory impairment, and blood-brain barrier permeability in a model of sleep apnea

We investigated the effect of intermittent hypoxia, mimicking sleep apnea, on axonal integrity, blood-brain barrier permeability, and cognitive function of mice. Forty-seven C57BL mice were exposed to intermittent or sham hypoxia, alternating 30s of progressive hypoxia and 30s of reoxigenation, during 8h/day. The axonal integrity in cerebellum was evaluated by transmission electron microscopy. Short- and long-term memories were assessed by novel object recognition test. The levels of endothelin-1 were measured by ELISA. Blood-brain barrier permeability was quantified by Evans Blue dye. After 14 days, animals exposed to intermittent hypoxia showed hypomyelination in cerebellum white matter and higher serum levels of endothelin-1. The short and long-term memories in novel object recognition test was impaired in the group exposed to intermittent hypoxia as compared to controls. Blood-brain barrier permeability was similar between the groups. These results indicated that hypomyelination and impairment of short- and long-term working memories occurred in C57BL mice after 14 days of intermittent hypoxia mimicking sleep apnea.

Polysomnographic results of prone versus supine positioning in micrognathia

BACKGROUND

Children with micrognathia commonly present with upper airway symptoms and are at risk for developing obstructive sleep apnea (OSA). Prone positioning is widely used as first-line management for micrognathic children with obstructive symptoms. The aim of the present study was to document the effect of positioning on oxygenation and upper airway obstruction as measured by polysomnography (PSG).

METHODS

Three children with micrognathia from two institutions underwent PSG in both the prone and supine position.

RESULTS

Patient ages were 1 week, 3 months, and 7 months. Supine obstructive apnea-hypopnea indices (oAHI) were severe for all 3 children, with a mean of 21.9 events/hour (range 16.8 to 26.3). In the prone position, the oAHI significantly improved in 2 of 3 children, with a mean of 5.1 events/hour (range 0.3 to 10.3). The frequency of central apnea events increased in 1 child following supine positioning. Nadir oxygen saturation improved in 2 of 3 children and remained within normal limits in the third.

CONCLUSIONS

This is the first report of the effect of positioning on changes in PSG indices of micrognathic children. Improvement in obstructive PSG indices occurred with prone positioning, though OSA persisted in 2 of 3 children. The effect of positioning on central apnea was unclear. In light of these findings, we recommend that routine PSG be considered in micrognathic children undergoing prone positioning for definitive therapy of upper airway obstruction.

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.

Post analysis simulated correlation of the El-Ganzouri airway difficulty score with difficult airway

BACKGROUND

Difficult airway (DA) occurs frequently (5-15%) in clinical practice. The El-Ganzouri Risk Index (EGRI) has a high sensitivity for predicting a difficult intubation (DI). However difficult mask ventilation (DMV) was never included in the EGRI. Since DMV was not included in the EGRI assessment, and obstructive sleep apnea (OSA) is also correlated with DMV, a study correlating the prediction of DA and OSA (identified by STOP-Bang questionnaire, SB) seemed important.

METHODS

We accessed a database previously collected for a post analysis simulation of the airway difficulty predictivity of the EGRI, associated with normal and difficult airway, particularly DMV. As secondary aim, we measured the correlation between the SB prediction system and DA, compared to the EGRI.

RESULTS

A total of 2747 patients were included in the study. The proportion of patients with DI was 14.7% (95% CI 13.4-16) and the proportion of patients with DMV was 3.42% (95% CI 2.7-4.1). The incidence of DMV combined with DI was (2.3%). The optimal cutoff value of EGRI was 3. EGRI registered also an higher ability to predict DMV (AUC=0.76 (95% CI 0.71-0.81)). Adding the SB variables in the logistic model, the AUC increases with the inclusion of "observed apnea" variable (0.83 vs. 0.81, p=0.03). The area under the ROC curve for the patients with DI and DMV was 0.77 (95% CI 0.72-0.83).

CONCLUSIONS

This study confirms that the incidence of DA is not negligible and suggests the use of the EGRI as simple bedside predictive score to improve patient safety.

Obstructive sleep apnea is independently associated with worse diastolic function in coronary artery disease

BACKGROUND

Diastolic dysfunction is common in patients with coronary artery disease (CAD). We hypothesize that patients with CAD and preserved left ventricular ejection fraction (LVEF) and obstructive sleep apnea (OSA) will have worse diastolic function than similar patients without OSA.

MATERIAL AND METHODS

We analyzed sleep-study recordings and echocardiographic measurements obtained at baseline in a randomized controlled trial (RICCADSA) of revascularized patients with CAD who had LVEF of at least 50%. OSA was defined as an apnea-hypopnea-index (AHI) ≥15 events/h, and, no OSA, as an AHI <5. Worse diastolic function was defined as assumed elevated left ventricular filling pressure based on peak flow velocity in early diastole/Tissue Doppler of early diastolic ventricular filling (E/é) of >13 (or >9 in patients with an enlarged left atrial diameter [≥39 mm for women and ≥40 mm for men]).

RESULTS

Data from 431 patients were evaluated (mean age: 63.7 ± 8.8 y; men: 82.5%; OSA: n = 331). Worse diastolic function was more common among the patients with OSA than those without (54.4% vs 41.0%, p = 0.019). In multivariate analysis, OSA was associated with worse diastolic function (odds ratio [OR] 1.90, 95% confidence interval [CI] 1.13; 3.18) adjusted for female sex (OR 2.28, 95% CI 1.28; 4.07), hypertension (OR 1.84, 95% CI 1.20; 2.82), and diabetes mellitus (OR 2.45, 95% CI 1.42; 4.23). Age ≥60 years, obesity, and current smoking were nonsignificant.

CONCLUSIONS

In this cohort with CAD and preserved LVEF, OSA was associated with worse diastolic function independent of the traditionally recognized risk indicators.

Sleep disorders associated with primary mitochondrial diseases

STUDY OBJECTIVES

Primary mitochondrial diseases are caused by heritable or spontaneous mutations in nuclear DNA or mitochondrial DNA. Such pathological mutations are relatively common in humans and may lead to neurological and neuromuscular complication that could compromise normal sleep behavior. To gain insight into the potential impact of primary mitochondrial disease and sleep pathology, we reviewed the relevant English language literature in which abnormal sleep was reported in association with a mitochondrial disease.

DESIGN

We examined publication reported in Web of Science and PubMed from February 1976 through January 2014, and identified 54 patients with a proven or suspected primary mitochondrial disorder who were evaluated for sleep disturbances.

MEASUREMENTS AND RESULTS

Both nuclear DNA and mitochondrial DNA mutations were associated with abnormal sleep patterns. Most subjects who underwent polysomnography had central sleep apnea, and only 5 patients had obstructive sleep apnea. Twenty-four patients showed decreased ventilatory drive in response to hypoxia and/ or hyperapnea that was not considered due to weakness of the intrinsic muscles of respiration.

CONCLUSIONS

Sleep pathology may be an underreported complication of primary mitochondrial diseases. The probable underlying mechanism is cellular energy failure causing both central neurological and peripheral neuromuscular degenerative changes that commonly present as central sleep apnea and poor ventilatory response to hyperapnea. Increased recognition of the genetics and clinical manifestations of mitochondrial diseases by sleep researchers and clinicians is important in the evaluation and treatment of all patients with sleep disturbances. Prospective population-based studies are required to determine the true prevalence of mitochondrial energy failure in subjects with sleep disorders, and conversely, of individuals with primary mitochondrial diseases and sleep pathology.

Intermittent but not sustained hypoxia activates orexin-containing neurons in mice

Hypothalamic orexin-containing neurons are activated by CO2 and contribute to hypercapnic ventilatory activation. However, their role in oxygen-related regulation of breathing is not well defined. In this study, we examined whether an experimental model mimicking apnea-induced repetitive hypoxemia (intermittent hypoxia [IH]) activates orexin-containing neurons. Mice were exposed to IH (5×5min at 10% O2), intermittent hyperoxia (IO; 5×5min at 50% O2), sustained hypoxia (SH; 25min at 10% O2), or sham stimulation. Their brains were examined using double immunohistochemical staining for orexin and c-Fos. The results indicated that IH (25.8±3.0%), but not SH (9.0±1.5%) activated orexin-containing neurons when compared to IO (5.5±0.6%) and sham stimulation (5.9±1.4%). These results correlate with those of our previous work showing that IH-induced respiratory long-term facilitation is dependent on orexin-containing neurons. Taken together, orexin contributes to repetitive hypoxia-induced respiratory activation and the hypoxic activation of orexin-containing neurons is pattern dependent.

Glucose, insulin, and insulin resistance in normal-weight, overweight and obese children with obstructive sleep apnea

BACKGROUND

Obstructive sleep apnea (OSA) is associated with components of metabolic syndrome. Both body weight and OSA independently influence metabolic measurements. The goal of this study was to determine whether OSA in normal-weight, overweight or obese children, compared to matched control groups, was associated with increased levels of glucose, insulin and insulin resistance (IR).

METHODS

Age- and gender-specific body mass index (BMI) percentiles were determined and used to categorize subjects into normal-weight (BMI<85%) and overweight-obese (BMI≥85%) groups. In addition, subjects were divided into normal-weight (BMI<85%), overweight (BMI≥85% and <95%) and obese (BMI≥95%) groups. Polysomnography was conducted and morning levels of glucose and insulin were measured and IR was determined from the blood samples collected early in the morning after overnight fast. Results were compared between the subject groups. Effects of severity of OSA defined by apnea hypopnea index (AHI) and oxygen desaturation index (ODI) on glucose, insulin, and HOMA-IR were analyzed.

RESULTS

Glucose, insulin, and HOMA-IR in OSA and matched control groups were not significantly different for normal-weight, overweight and obese subjects. The ODI was significantly associated with elevated levels of glucose and HOMA-IR after adjustment for age, gender, race, and BMI Z-score.

CONCLUSIONS

IR levels between OSA and control for both normal-weight, overweight and obese subjects were not significantly different. The ODI was associated with increased IR in children with OSA. OSA-induced hypoxic events during sleep may be a potential mechanism of increased IR in children with OSA, independent of body weight.

Self-reported remission of obstructive sleep apnea following bariatric surgery: cohort study

BACKGROUND

Evidence on remission of obstructive sleep apnea (OSA) after bariatric surgery and its relation to weight loss is conflicting. We sought to identify factors associated with successful self-reported OSA remission in a large cohort of bariatric surgery patients.

METHODS

We analyzed data from the statewide, prospective clinical registry of the Michigan Bariatric Surgery Collaborative and identified 3,550 patients with OSA who underwent a primary bariatric procedure between June 2006 and October 2011 and had at least 1 year of follow-up data. We used multivariate logistic regression to identify preoperative factors associated with successful self-reported OSA remission, defined as discontinuation of continuous positive airway pressure or bilevel positive airway pressure at 1 year. Our regression model also included procedure type and weight loss at 1 year, divided into equal quintiles, as covariates.

RESULTS

The overall 1-year self-reported OSA remission rate was 60%. Significant predictors of remission included age category (per 10 yr) (OR .73, CI .69-.78), body mass index category (per 10 units) (OR .57, CI .54-.62), male gender (OR .58, CI .52-.69), hypertension (OR .83, CI .74-.99), depression (OR .78, CI .69-.88), pulmonary disease (OR .88, CI .78-.98), and baseline Health and Activities Limitations Index score (OR 1.70, CI 1.32-2.23). Relative to gastric banding, the adjusted odds of OSA remission were greater with gastric bypass (OR 2.38, CI 1.89-3.08), sleeve gastrectomy (OR 2.01, CI 1.44-2.55), and duodenal switch (OR 2.57, CI 1.02-7.26). The odds ratio of OSA remission increased stepwise through quintiles of 1-year weight loss. Relative to the lowest quintile, the odds ratios of remission in the 2(nd) through 5(th) quintiles were 1.44 (CI 1.11-1.84), 2.03 (CI 1.48-2.57), 2.47 (1.85-3.40), and 3.53 (CI 2.56-4.85).

CONCLUSIONS

Weight loss is an important predictor of self-reported OSA remission after bariatric surgery. However, independent of weight loss, there remain significant differences in the likelihood of remission between gastric banding and other bariatric procedures. This suggests that there may be metabolic, weight-independent effects of procedure type on self-reported OSA remission.

Intensive care unit and hospital mortality in patients with obstructive sleep apnea

INTRODUCTION

Obstructive sleep apnea (OSA) is a common disorder affecting between 5% and 24% of men and women. The prevalence of OSA in the intensive care unit (ICU) population is unknown. This study was undertaken to determine the prevalence of OSA in patients admitted to the ICU and to determine if OSA is an independent predictor of mortality.

METHODS

This is a retrospective study using an Acute Physiology and Chronic Health Evaluation III database cross-referenced to a comprehensive clinical database to identify patients with and without OSA admitted to medical, surgical, and mixed ICUs at a large academic medical center.

RESULTS

Between January 2003 and December 2005, 15077 patients were admitted to the ICUs; and of these, 1183 (7.8%) had a physician-documented diagnosis of OSA. Eight hundred thirty-five (71%) patients had polysomnographic testing at our institution with a documented apnea-hypopnea index more than 5 per hour. Patients with OSA were younger (59.1 ± 14.0 vs 62.3 ± 18.0), male (58.9% vs 53.7%), and had lower Acute Physiology and Chronic Health Evaluation III scores (45.3 ± 24.1 vs 54.9 ± 27.7). Predicted mortality (10.3% ± 16.4% vs 16.3 ± 21.7), median ICU length of stay (1.13 vs 1.50 days), ICU mortality (2.4% vs 6.2%), and hospital mortality (3.9% vs 11.4%) were all reduced in patients with OSA, P values < .001. When adjusted for the severity of illness, OSA was independently associated with decreased hospital mortality, (0.408; 95% confidence interval, 0.298-0.557).

CONCLUSIONS

Obstructive sleep apnea is common in patients admitted to the ICU. Obstructive sleep apnea was associated with a reduction in both ICU and hospital mortality.

Secondary hypertension, issues in diagnosis and treatment

Secondary hypertension (SH) often implies a correctable form of nonessential hypertension. Often certain clinical clues prompt a more extensive evaluation of the causes of the hypertension. Renovascular disease, intrinsic renal disease, primary hyperaldosteronism, and obstructive sleep apnea represent the most common causes of SH. This article defines the disorder and details its epidemiology, prevalence, pathophysiology, physical findings, and treatment strategies.

Prevalence of pre-stroke sleep apnea risk and short or long sleep duration in a bi-ethnic stroke population

BACKGROUND

The ethnic disparity in ischemic stroke between Mexican Americans (MAs) and non-Hispanic whites (NHWs) may be partly attributable to disparities in sleep and its disorders. We therefore assessed whether pre-stroke sleep apnea symptoms (SA risk) and pre-stroke sleep duration differed between MAs and NHWs.

METHODS

MA and NHW ischemic stroke survivors in the Brain Attack Surveillance in Corpus Christi (BASIC) project reported sleep duration and SA symptoms on the validated Berlin questionnaire, both with respect to their pre-stroke baseline. Log binomial and linear regression models were used to test the unadjusted and adjusted (demographics and vascular risk factors) associations of high-risk Berlin scores and sleep duration with ethnicity.

RESULTS

Among 862 subjects, 549 (63.7%) were MA and 514 (59.6%) had a high risk of pre-stroke SA. The MA and NHW subjects showed no ethnic difference, after adjustment for potential confounders, in pre-stroke SA risk (risk ratio (95% confidence interval (CI)): 1.06 (0.93, 1.20)) or in pre-stroke sleep duration (on average MAs slept 2.0 fewer minutes than NHWs, 95% CI: -18.8, 14.9 min).

CONCLUSIONS

Pre-stroke SA symptoms are highly prevalent, but ethnic differences in SA risk and sleep duration appear unlikely to explain ethnic stroke disparities.

Prosthodontic approach to treat obstructive sleep apnea

Sleep disordered breathing represents a continuum, ranging from simple snoring sans sleepiness, upper-airway resistance syndrome, obstructive sleep apnea (OSA) syndrome, to hypercapnic respiratory failure. Fifty seven articles formed the initial database and a final total of 50 articles were selected to form this review report. Four months were spent on the collection and retrieval of the articles. Articles were selected based on accuracy and evidence in the scientific literature. Oral appliances (OAs) are indicated for use in patients with mild to moderate OSA who prefer them to continuous positive airway pressure (CPAP) therapy, or for those who do not respond to, are not appropriate candidates for, or for those who have failed treatment attempts with CPAP. OAs protrude the mandible and hold it in a forward and downward position. As a consequence, the upper airway enlarges antero-posteriorly and laterally, improving its stability. Although OA are effective in some patients with OSA, they are not universally suitable. Compliance with OAs depends mainly on the balance between the perception of benefit and the side effects. In conclusion, marked variability is illustrated in the individual response to OA therapy and hence the treatment outcome is subjective.

Neck circumference and lowest oxygen saturation are independently associated with high coexistence of hypertension in obstructive sleep apnea

PURPOSE

Obstructive sleep apnea (OSA) is considered an independent risk factor for hypertension. However, it is still not clear which clinical factors are related with the presence of hypertension in OSA patients. We aimed to find different physical features and compare the sleep study results which are associated with the occurrence of hypertension in OSA patients.

MATERIALS AND METHODS

Medical records were retrospectively reviewed for patients diagnosed with OSA at Severance Cardiovascular Hospital between 2010 and 2013. Males with moderate to severe OSA patients were enrolled in this study. Clinical and polysomnographic features were evaluated to assess clinical variables that are significantly associated with hypertension by statistical analysis.

RESULTS

Among men with moderate to severe OSA, age was negatively correlated with hypertension (odds ratio=0.956), while neck circumference was positively correlated with the presence of hypertension (odds ratio=1.363). Among the polysomnographic results, the lowest O₂ saturation during sleep was significantly associated with the presence of hypertension (odds ratio=0.900).

CONCLUSION

Age and neck circumference should be considered as clinically significant features, and the lowest blood O₂ saturation during sleep should be emphasized in predicting the coexistence or development of hypertension in OSA patients.

Extraction of respiratory myogram interference from the ECG and its application to characterize sleep-related breathing disorders in atrial fibrillation

BACKGROUND AND PURPOSE

Present methods to extract respiratory myogram interference (RMI) from the Holter-ECG and assess effect of supraventricular arrhythmias (SVAs) onto ECG-based detection of sleep-related breathing disorders (SRBDs) and AHI estimation.

METHODS

RMI was quantified as residual energy after ECG cancellation or high-pass filtering for different windowing constellations. In 140 cases without (SET_A) and 10 cases with persistent SVAs (SET_B), respiratory polysomnogram annotations served as reference for SRDB detection from Holter-ECGs. We applied our previously published method to identify SRDBs in 1-min epochs and estimate the AHI based on joint modulations in RMI and QRS-area.

RESULTS

Sensitivity and specificity of 0.855/0.860 in SET_A dropped to 0.831/0.75 in SET_B. A significantly higher number of wake events in SET_B likely contribute to the asymmetric decrease and is consistent with a tendency to overestimate the AHI.

CONCLUSIONS

Despite reduced accuracy, RMI and QRS-area appear relatively robust against SVA and promise Holter-based detection at least of medium to severe SRBDs also in patients with SVAs.

The effect of adrenal medullectomy on metabolic responses to chronic intermittent hypoxia

Obstructive sleep apnea causes intermittent hypoxia (IH) and is associated with insulin resistance and type 2 diabetes. IH increases plasma catecholamine levels, which may increase insulin resistance and suppress insulin secretion. The objective of this study was to determine if adrenal medullectomy (MED) prevents metabolic dysfunction in IH. MED or sham surgery was performed in 60 male C57BL/6J mice, which were then exposed to IH or control conditions (intermittent air) for 6 weeks. IH increased plasma epinephrine and norepinephrine levels, increased fasting blood glucose and lowered basal and glucose-stimulated insulin secretion. MED decreased baseline epinephrine and prevented the IH induced increase in epinephrine, whereas the norepinephrine response remained intact. MED improved glucose tolerance in mice exposed to IH, attenuated the impairment in basal and glucose-stimulated insulin secretion, but did not prevent IH-induced fasting hyperglycemia or insulin resistance. We conclude that the epinephrine release from the adrenal medulla during IH suppresses insulin secretion causing hyperglycemia.

Sleep apnea-hypopnea syndrome and type 2 diabetes. A reciprocal relationship?

Epidemiological data suggest that sleep apnea-hypopnea syndrome (SAHS) is independently associated with the development of insulin resistance and glucose intolerance. Moreover, despite significant methodological limitations, some studies report a high prevalence of SAHS in patients with type 2 diabetes mellitus (DM2). A recent meta-analysis shows that moderate-severe SAHS is associated with an increased risk of DM2 (relative risk=1.63 [1.09 to 2.45]), compared to the absence of apneas and hypopneas. Common alterations in various pathogenic pathways add biological plausibility to this relationship. Intermittent hypoxia and sleep fragmentation, caused by successive apnea-hypopnea episodes, induce several intermediate disorders, such as activation of the sympathetic nervous system, oxidative stress, systemic inflammation, alterations in appetite-regulating hormones and activation of the hypothalamic-pituitary-adrenal axis which, in turn, favor the development of insulin resistance, its progression to glucose intolerance and, ultimately, to DM2. Concomitant SAHS seems to increase DM2 severity, since it worsens glycemic control and enhances the effects of atherosclerosis on the development of macrovascular complications. Furthermore, SAHS may be associated with the development of microvascular complications: retinopathy, nephropathy or diabetic neuropathy in particular. Data are still scant, but it seems that DM2 may also worsen SAHS progression, by increasing the collapsibility of the upper airway and the development of central apneas and hypopneas.

Guidelines (short version) of the French Oto-Rhino-Laryngology--Head and Neck Surgery Society (SFORL) for the management of post-tonsillectomy pain in adults

OBJECTIVES

The present clinical practice guidelines cover the entire field of management of post-tonsillectomy pain. Given the French and European regulatory restrictions on the use of codeine, an update appears necessary to clarify the management of post-tonsillectomy pain in adults.

METHOD

A work group approached the issue of pain management, following the chronological pathway from initial consultation to postoperative period. As exhaustive a study of the literature as possible assessed the pain impact of the various surgical techniques and the efficacy of the various analgesia schedules.

RESULTS

Guidelines on the management of post-tonsillectomy pain in adults were drawn up and graded, based on the levels of evidence of selected articles and on work group consensus. The guidelines stress the importance of patient information and seek to harmonize practice, reduce the risk of postoperative complications and above all improve control of post-tonsillectomy pain in adults.