Obstructive sleep apnoea

Obstructive sleep apnoea is a disease of increasing importance because of its neurocognitive and cardiovascular sequelae. Abnormalities in the anatomy of the pharynx, the physiology of the upper airway muscle dilator, and the stability of ventilatory control are important causes of repetitive pharyngeal collapse during sleep. Obstructive sleep apnoea can be diagnosed on the basis of characteristic history (snoring, daytime sleepiness) and physical examination (increased neck circumference), but overnight polysomnography is needed to confirm presence of the disorder. Repetitive pharyngeal collapse causes recurrent arousals from sleep, leading to sleepiness and increased risk of motor vehicle and occupational accidents. The surges in hypoxaemia, hypercapnia, and catecholamine associated with this disorder have now been implicated in development of hypertension, but the association between obstructive sleep apnoea and myocardial infarction, stroke, and congestive heart failure is not proven. Continuous positive airway pressure, the treatment of choice for obstructive sleep apnoea, reduces sleepiness and improves hypertension.     

Obstructive sleep apnoea in Asia.

Obstructive sleep apnoea (OSA) syndrome is the commonest sleep-related breathing disorder worldwide. In Asia, the prevalence of symptomatic OSA in middle-aged men and women is 4.1-7.5% and 2.1-3.2%, respectively. These prevalence rates are similar to those reported in Caucasian populations. Obesity, an established major risk factor for OSA, is less common among Asians, and the reported values of body mass indices (BMIs) of Asians with OSA are lower than in their Caucasian counterparts. However, these population-based studies have consistently demonstrated that obesity is still the major risk factor for OSA in Asians, while other studies have suggested that craniofacial structural factors may make a greater contribution towards development of OSA in Asians than in Caucasians. Sleep medicine is in a developmental stage in many Asian countries, and the condition is likely under-recognised. Although sleep laboratories have been set up in various countries in Asia, the availability of this service is very limited. Continuous positive airway pressure is available in most parts of Asia, but financial constraints may limit its utility. Oral appliances have been postulated to have a greater role in the management of OSA in Asian patients, as they are likely to have more modifiable factors in their craniofacial structures, but this is yet to be proven. There is a great need for research and health care development on sleep disordered breathing in Asia, and the solution will only come with efforts towards promotion of awareness of this condition in both professional and lay communities.     

Obstructive sleep apnoea among HIV patients

The development of body weight gain and lipodystrophy due to antiretroviral therapy may lead to disturbances in sleep, particularly the obstructive sleep apnoea (OSA) syndrome. A retrospective review of the medical records of consecutively identified HIV-infected subjects who were diagnosed with OSA by overnight polysomnography between January 1, 2003 and December 31, 2004 was performed. Twelve HIV-infected subjects with OSA confirmed by polysomnography (total apnoea/hypopnoea index > or = 5) were identified. Daytime somnolence, fatigue, and snoring were the most common symptoms identified. Eleven (92%) subjects were overweight/obese, and seven (58%) had lipodystrophy. Eleven (92%) had a neck size > or =40.0 cm. Increased neck circumference, overweight or obese body mass index, and lipodystrophy are therefore potential risk factors for OSA among HIV patients. Clinicians caring for HIV patients with these characteristics should inquire about daytime somnolence, fatigue, and snoring and consider evaluation for a sleep-related disorder such as OSA. Overnight polysomnography can aid in the diagnosis of sleep disturbances.     

Obstructive sleep apnoea and cardiovascular disease

Obstructive sleep apnoea (OSA) leads to both acute and chronic physiological effects on the cardiovascular system. There is now a large amount of evidence showing that OSA is independently associated with a wide spectrum of clinical cardiovascular disease (CVD). Evidence for a causative effect of OSA is strongest for hypertension, but is weaker for other cardiovascular disorders. Large prospective trials are ongoing and when results become available the link between OSA and CVD is likely to be strengthened. Treatment of OSA with continuous positive airway pressure has been shown to improve blood pressure, particularly in those with hypertension, and also left ventricular ejection fraction in those with congestive heart failure. Given the high prevalence of OSA in the community and its effects on the cardiovascular system, symptoms of this disorder should be sought in patients being investigated or treated for CVD.     

Obstructive sleep apnoea syndrome and genes

Obstructive sleep apnoea (OSA) is a complex disease entity strongly influenced by genetic factors, especially those that affect obesity and fat distribution, upper airway muscle tone, craniofacial morphology, ventilatory control and sleep, giving rise to the OSA phenotype. OSA can also be considered a metabolic syndrome which adversely affects multiple organ systems, especially the cardiovascular system and the brain. The most widely used clinical marker for the diagnosis of OSA is the apnoea-hypopnoea index, calculated by polysomnography. A percentage of 35 to 40% of its variance can be attributed to genetic factors. Therefore, the identification and elucidation of the genes implicated in the pathogenesis of OSA becomes a matter of extensive research and could lead to the development of therapeutic agents that can have a beneficial effect on the natural course of OSA.     

Obstructive sleep apnoea syndrome promotes reversal albuminuria during sleep

Introduction  

Sleep apnoea syndrome (OSAS) may induce albuminuria during sleep which could reflect one of the possible pathogenetic mechanisms regarding cardiovascular risk.     

Obstructive sleep apnoea and plasma homocysteine.

We read with interest the recent article by Svatikova et al.,¹dealing with plasma homocysteine in obstructive sleep apnoea(OSA), and the accompanying editorial by Winnicki and Palatini.²Although both referred to our 2001 paper on the same subject,³our findings were not presented accurately. Similarly to Svatikovaet     

Obstructive sleep apnoea and plasma homocysteine.

We read with interest the recent article by Svatikova et al.,¹dealing with plasma homocysteine in obstructive sleep apnoea(OSA), and the accompanying editorial by Winnicki and Palatini.²Although both referred to our 2001 paper on the same subject,³our findings were not presented accurately. Similarly to Svatikovaet al.     

Obstructive sleep apnoea syndrome: current status

Introduction: Obstructive sleep apnoea syndrome (OSAS) is a prevalent condition that covaries with cardiovascular complications and most likely with arterial hypertension and diabetes mellitus. Objective: The present paper is a review of the current status of OSAS. Results: Definitions and diagnostic criteria as well as known risk factors, prevalence, symptoms, covariance with other diseases and consequences as traffic accidents are described. OSAS is characterised by daytime sleepiness symptoms that range from mild to severe. Risk factors such as anatomical upper airway abnormalities, overweight, smoking, excessive alcohol intake and use of muscle relaxants are related to the development of sleep apnoea. Various diagnostic procedures and treatment modalities are considered. Overnight polysomnography is the reference standard for sleep apnoea recording. Treatment modalities include mechanical [continuous positive airway pressure (CPAP), oral appliances], surgical, pharmacological and ‘conservative’ lifestyle modifications. Finally, Nordic accrediation guidelines for sleep medicine clinics and sleep medicine specialists are described. Conclusion: The diagnosis of OSAS should be performed with a polygraph, and the first‐line treatment of moderate to severe OSAS is CPAP. Lastly, compliance for this treatment should be optimised with regular clinical controls. Please cite this paper as: Berg S. Obstructive sleep apnoea syndrome: current status. The Clinical Respiratory Journal 2008; 2: 197–201.     

Obstructive sleep apnoea in a puerperal patient with Hallermann-Streiff syndrome.

A 26 yr old puerperal female with Hallermann-Streiff syndrome developed serious obstructive sleep apnoea syndrome during pregnancy. She underwent an elective Caesarean section delivery, but ending the pregnancy did not improve her clinical symptoms. By treating her with nasal continuous positive airway pressure, a worsening of her headaches and glaucoma was prevented. The administration of acetazolamide controlled all of her symptoms. Treatment with nasal ventilation is the best initial approach. It is also important to assure normal oxygenation before pregnancy since the foetus may suffer from the severe deprivation that may occur in these patients.     

Obstructive sleep apnoea and non-restorative sleep induced by the interface

Sleep and Breathing -     

Elevated plasma high-sensitivity C-reactive protein concentrations in Asian Indians living in the United States

Proinflammatory state may contribute to the excessive prevalence of type 2 diabetes and cardiovascular disease observed in populations originating from the Indian subcontinent (Asian Indians). This study was conducted to evaluate whether nondiabetic Asian Indian men living in the United States manifest a proinflammatory state when compared with Caucasians of similar age and body fat content. We also compared the relationships between plasma high-sensitivity C-reactive protein (hs-CRP), a marker of low-grade inflammation, and various parameters of body composition and fat distribution and insulin sensitivity in Asian Indians and Caucasians. For this purpose, plasma hs-CRP, oral glucose tolerance test, and anthropometric measurements were conducted in 82 Asian Indian men and 55 Caucasian men of similar age. The two groups had similar body fat content and truncal skinfolds thickness. Asian Indians had higher insulin areas under the curve during oral glucose tolerance tests, indicating a greater insulin resistance. Asian Indians also manifested a significant elevation of plasma hs-CRP. We conclude that young, overtly healthy Asian Indian men have both greater insulin resistance and higher hs-CRP levels than do Caucasians. This difference cannot be explained by greater adiposity in Asian Indians and suggests that many Asian Indians have an underlying proinflammatory state that may contribute to their increased risk for both type 2 diabetes and cardiovascular disease.     

Increased central adiposity in morbidly obese patients with obstructive sleep apnoea

Background: With the growing epidemic of obesity, few data are available regarding adipose distribution and the severity of sleep apnoea. Our aim was to measure precisely adipose distribution with dual‐energy X‐ray absorptiometry (DXA) in a morbidly obese population with and without obstructive sleep apnoea (OSA). Methods: Morbidly obese female subjects without a history of OSA underwent overnight polysomnography and DXA analysis. Subject demographics, DXA variables, serum laboratory markers and physical exam characteristics were compared between individuals with and without OSA. Results: For the study population (n= 26), mean body mass index (BMI) was 45.9 ± 7.8 kg/m²; mean age was 47.5 ± 10.2 years and all were female. The central adiposity ratio (CAR) was higher in individuals with OSA (apnoea–hypopnoea index > 5) than those without OSA (1.1 ± 0.05 vs 1.0 ± 0.04; P= 0.004). No difference was observed in Epworth Sleepiness Scale scores, body mass index (BMI) or neck circumference between groups. Conclusions: OSA is associated with increased central adipose deposition in patients with a BMI of >40 kg/m². These data may be helpful in designing future studies regarding the pathophysiology of OSA, and potential treatment options.     

Obstructive sleep apnoea,insulin resistance and adipocytokines

Obstructive sleep apnoea (OSA) is associated with multiple cardiometabolic abnormalities. Obesity is considered a major risk factor for the development of OSA, and it is also an established risk factor for insulin resistance and other cardiometabolic disorders. The enigma remains whether OSA has any causal role in the adverse metabolic profile, independent of or beyond that due to obesity. Sleep apnoeas and hypopnoeas result directly in intermittent hypoxaemia and cerebral arousals, both of which may evoke a cascade of downstream biologic responses in various body tissues and cells. Adipose tissue is a major source of adipocytokines many of which play important roles in the regulation of various metabolic functions. It is hypothesized that OSA may, through its unique pathophysiology, affect metabolic function through modulation of production or action of adipocytokines. This review focuses on insulin resistance, glucose metabolism and relevant adipocytokines in the context of OSA.