Cardiovascular disease and obstructive sleep apnea: implications for physicians

Obstructive sleep apnea (OSA) has been strongly associated with several cardiovascular disorders during the past decade, and studies suggested that there might be a causal relationship. Recent studies have described several pathophysiologic mechanisms that are active in OSA and may participate in the development of cardiovascular disorders. Primarily, the repetitive respiratory events that occur in OSA cause hypoxia, hypercapnea, arousals, or disrupted sleep singly or in combination. These abnormal physiologic events result in increased sympathetic outflow, alterations in blood pressure control mechanisms, dysfunctional ventilatory regulation, and vascular alterations. As a consequence of the relative impact and the genetic predisposition, these pathophysiologic alterations may lead to or complicate a wide variety of cardiovascular disorders. Frequently, patients who have OSA present with complaints of excessive daytime sleepiness, chronic fatigue, snoring, morning headache, and nocturnal arousals. Difficult-to-control hypertension, recurrent exacerbations of congestive heart failure, and nocturnal angina are common cardiovascular manifestations of undiagnosed OSA. This article reviews the major cardiovascular disorders associated with OSA and the pathophysiologic mechanisms associated with their development.     

Obstructive sleep apnea

Opinion statement Obstructive sleep apnea (OSA) is a major public health problem in the US that afflicts at least 2% to 4% of middle-aged Americans and incurs an estimated annual cost of 3.4 billion dollars. At Stanford, we utilize a multispecialty team approach combining the expertise of sleep medicine specialists (adult and pediatric), maxillofacial and ear, nose, and throat surgeons, and orthodontists to determine the most appropriate therapy for complicated OSA patients. The major treatment modality for children with OSA is tonsillectomy and adenoidectomy with or without radiofrequency treatment of the nasal inferior turbinate. Children with craniofacial anomalies resulting in maxillary or mandibular insufficiency may benefit from palatal expansion or more invasive maxillary/mandibular surgery. Continuous positive airway pressure (PAP) therapy is used in children with OSA who are not surgical candidates or have failed surgery. As a last resort, tracheotomy may be used in patients with persistent or severe OSA who do not respond to other measures. The cornerstone of treatment in adults utilizes PAP: continuous PAP, bilevel PAP, or auto PAP. Treatment of nasal obstruction, appropriate titration, attention to mask-fit issues, desensitization for claustrophobia, use of heated humidification for nasal dryness and nasal pain with continuous PAP, patient education, regular follow-up, use of compliance software (in selected individuals), and referral to support groups (AWAKE) are measures that can improve patient compliance. Adjunctive treatment modalities include lifestyle/behavioral/pharmacologic measures. Oral appliances can be used in patients with symptomatic mild sleep apnea or upper airway resistance syndrome. Patients who are unwilling or unable to tolerate continuous PAP or who have obvious upper airway obstruction may benefit from surgery. Surgical success depends on appropriate patient selection, the procedure performed, and the experience of the surgeon. Phase I surgeries have a success rate of 50% to 60%, whereas phase II surgeries have a success rate greater than 90%.     

Obstructive sleep apnea: Part II. Surgical approaches to sleep apnea

Successful surgical management of obstructive sleep apnea (OSAS) requires a thorough understanding of the pathophysiology and anatomical contributions to this widely variable disease. Early efforts to surgically correct OSAS involved bypassing the upper airway; thus, indirectly improving the symptoms without directly addressing the pathophysiology. Surgical procedures to treat OSAS have evolved over the past several decades as further understanding of the disease continues to be elicited.The surgical techniques employed in the treatment of OSAS are quite varied. Many surgical subspecialties have contributed to the understanding of the complexities of OSAS. Recent surgical management involves site-specific alterations of the upper airway to more directly address the disease process. In addition, current literature suggests an algorithmic and phased approach to the treatment of OSAS. Future technology offers the hope of better diagnostic and therapeutic options for the surgical management of OSAS.     

Treatment of sleep apnea syndromes

NECESSARY TREATMENT: Sleep apnea syndrome requires treatment because it affects cardiovascular and cerebrovascular morbidity and mortality and has important neuropsychological consequences with the risk of accidents due to impaired wakefulness. The patientís quality of life is greatly altered. GENERAL MEASURES: Patients should be informed of the risk due to the lack of sleep, advised that alcohol tranquilizers and hypnotic drugs are contraindicated, and counseled about loosing weight, the most difficult problem for obese patients. POSITIVE PRESSURE VENTILATION: Continuous positive pressure ventilation with a facial mask acts like a pneumatic prosthesis holding the airways open during sleep. Sleep can be reconstructed by eliminating the recorded pathological nocturnal events and thus reducing diurnal hypersomnia. Quality of life is improved and accidents related to diminished wakefulness are avoided. Death rate in treated patients is significantly lower than in non-treated patients. In France, the national health care system will reimburse positive pressure ventilation for sleep apnea syndromes recognized to cause more than 30 events per hour of recording or fragmented sleep due to respiratory impairment. OTHER TREATMENTS: Indications for other treatments in case of moderately severe sleep apnea syndrome (or if health care benefits are not recognized for positive pressure ventilation) are currently debated. No medication has been proven to be effective. Mandibular advancement ortheses are in the development stage and require multidisiplinary cooperation to verify their efficacy. Velar surgery has been proposed but is usually disappointing except for young patients actively participating in an integrated surgical treatment strategy.     

Pathophysiology of obstructive sleep apnea

This article explores the physiologic basis and symptoms of obstructive sleep apnea--a general term encompassing central sleep apnea and obstructive sleep apnea. The former is relatively uncommon while the latter is much more common. Episodic collapse and blockage of the upper airway occur during sleep despite continuous respiratory effort. Three types of sleep obstructive breathing--apnea, hypopnea, and airway resistance--are associated with respiratory-related arousals from sleep.     

Severity of obstructive sleep apnea

A four-level severity scale for obstructive sleep apnea is offered using four criteria: maximum oxygen desaturation, apnea/hyponea index, symptoms of excessive day-time sleepiness, and symptoms of related cardiac disease. Oxygen desaturation and the apnea/hyponea index for 175 patients, all having had uvulopalatopharyngoplasty surgery, showed 19% mild, 33% moderate, 17% moderately severe, and 31% severe obstructive sleep apnea. There was a very poor correlation between oxygen desaturations and number of obstructive events, which demands that both be used in any estimation of disease severity.     

Proteinuria in obstructive sleep apnea

BACKGROUND: Previous studies have reported an association between obstructive sleep apnea (OSA) and proteinuria, but are limited in their ability to assess proteinuria accurately, to adjust for confounders such as obesity, or to exclude confidently underlying renal disease in patients with OSA and nephrotic-range proteinuria. METHODS: The spot urine protein/creatinine ratio was measured in a prospective consecutive series of 148 patients referred for polysomnography who were not diabetic and had not been treated previously for OSA. The urine protein/creatinine ratio was compared across four levels of OSA severity, based on the frequency of apneas and hypopneas per hour: <5 (absent), 5 to 14.9 (mild), 15 to 29.9 (moderate), and > or =30 (severe). RESULTS: The median level of urine protein/creatinine ratio in all categories of OSA was <0.2 (range 0.03 to 0.69; median 0.06 in patients with normal apnea hypopnea index, 0.06, 0.07, 0.07 in patients with mild, moderate, and severe OSA, respectively). Eight subjects had a urine protein/creatinine ratio greater than 0.2. Univariate analysis showed a significant association between urine protein/creatinine ratio and older age (P < 0.0001), hypertension (P < 0.0001), coronary artery disease (P = 0.003), and arousal index (P = 0.003). Body mass index (P = 0.16), estimated creatinine clearance (P = 0.17), and apnea hypopnea index (P = 0.13) were not associated with the urine protein/creatinine ratio. In multiple regression analysis, only age and hypertension were independent positive predictors of the urine protein/creatinine ratio (P < 0.0001, R2 = 0.17). CONCLUSION: Clinically significant proteinuria is uncommon in sleep apnea. Nephrotic range proteinuria should not be ascribed to sleep apnea and deserves a thorough renal evaluation.     

Obstructive sleep apnea in children

Opinion statement Despite increasing recognition of childhood obstructive sleep apnea syndrome (OSAS) as a significant public health problem, treatment of the condition remains inconsistent. Some children are screened using polysomnography and treated only when objective respiratory disturbances are identified. Many others receive adenotonsillectomy based only on signs and symptoms of upper airway obstruction without ever having a formal sleep study. Outcome-based data regarding the effectiveness of adenotonsillectomy, continuous positive airway pressure, and other treatments for childhood OSAS remain extremely limited. In this article, the major therapeutic options for treatment of childhood OSAS are reviewed. Adenotonsillectomy remains the most frequently used treatment for uncomplicated OSAS in children, but residual airway obstruction persists in a notable minority of patients. Nasal continuous positive airway pressure is used for children who are not good surgical candidates or who have failed previous surgical treatment, but is sometimes not tolerated by young children or their parents. Various alternative treatments are used on an individualized basis for children who cannot use the two first-line therapies for sleep apnea.     

Perioperative concerns in sleep apnea

Sleep apnea syndrome is one of a series of sleep-related breathing disorders, and is often under-diagnosed. Recent appreciation of the prevalence of sleep apnea and its physiologic effects has raised patient and caregiver awareness of the disorder. Few definitive data exist to guide perioperative management of patients with sleep apnea. Nevertheless, advances in the study of sleep apnea have served to highlight important aspects of anesthetic care for these patients. An improved understanding of the relationships between sleep apnea and comorbid conditions has better defined the role for preoperative treatment. Recent work has also clarified the impact of interactions between postoperative pain management strategies and sleep apnea, as well as the need for advanced postoperative monitoring. Finally, progress in our understanding of the relationship between sleep deprivation and the anesthesized state may provide new insights into relationships between the anesthetic and sleep states. The present review identifies important perioperative concerns in patients with sleep apnea and suggests management strategies.     

Treatment of complex sleep apnea syndrome

Patients with complex sleep apnea syndrome (CompSAS) present with features of obstructive sleep apnea syndrome but demonstrate not only instability of upper airway tone (leading to classic obstructive apneas and hypopneas) but also unstable, chemosensitive ventilatory control leading to repetitive central apneas or periodic breathing during sleep. The central apneas often become most apparent after application of continuous positive airway pressure (CPAP) to alleviate upper airway obstruction; patients continue to have fragmented sleep and repetitive desaturations as a result of central apneas and hypopneas. In some patients, central apneas appear to abate over time as a result of some form of adaptation to CPAP. How often this occurs is uncertain, however, and many patients with CompSAS require treatment that combines stabilization of the upper airway obstruction with treatment of respiratory center dysfunction. Adaptive servo-ventilation, which provides both a minimum pressure to hold the airway open and a precisely calculated ventilatory assist to minimize cyclic hypoventilation and hyperventilation, has emerged as a leading treatment. Noninvasive ventilation using bilevel positive airway pressure in the spontaneous-timed mode also may regulate ventilation in some patients with CompSAS. There is anecdotal evidence that CompSAS may be successfully treated using combined PAP therapy with oxygen, carbon dioxide, or the addition of dead space, but data are not sufficient to routinely recommend these methods.     

Management of sleep apnea in adults

Canadian Journal of Anesthesia/Journal canadien d'anesthésie - Sleep disordered breathing is increasingly being recognized in the surgical population. This morbidity modifies the...     

Central sleep apnea and hypoventilation syndrome

Opinion statement Central sleep apnea hypopnea syndrome (CSAHS) and sleep hypoventilation syndrome (SHVS) are two distinct clinical syndromes with clearly defined diagnostic criteria. It is important to distinguish between normo/hypocapnic and hypercapnic CSAHS prior to treatment. Nasal continuous positive airway pressure is currently considered the primary treatment of choice for normo/hypocapnic CSAHS. The initial management of hypercapnic CSAHS and SHVS should include identification of any treatable causes and discontinuation of any sedative medications. Medroxyprogesterone may be effective in the long term management of these patients. If pharmacologic therapy fails, assisted ventilation should be considered. Assisted ventilation during the night is usually sufficient to improve hypercapnia and hypoxemia both at night and during the day. Assisted ventilation is usually best administered through a tight fitting nasal mask.     

Treatment options for obstructive sleep apnea

Opinion statement  Sleep apnea is a major public health problem that afflicts 9% of women and 24% of men 30 to 60 years of age. It is highly treatable, but when untreated, it has been associated with (but not necessarily linked to) increased probability of cerebral and coronary vascular disease, congestive heart failure, metabolic dysfunction, cognitive dysfunction, excessive daytime sleepiness, motor vehicle accidents, reduced productivity, and decreased quality of life. The gold standard for treatment in adults is positive airway pressure (PAP) therapy: continuous PAP (CPAP), bilevel PAP, autotitrating CPAP, or autotitrating bilevel PAP. Measures to increase compliance with PAP therapy include medical or surgical treatment of any underlying nasal obstruction, setting appropriate pressure level and airflow, mask selection and fitting, heated humidification, desensitization for claustrophobia, patient and partner education, regular follow-up with monitoring of compliance software, and attendance of support groups (eg, AWAKE). Adjunctive treatment modalities include lifestyle or behavioral measures and pharmacologic therapy. Patients with significant upper airway obstruction who are unwilling or unable to tolerate PAP therapy may benefit from surgery. Multilevel surgery of the upper airway addresses obstruction of the nose, oropharynx, and hypopharynx. A systematic approach may combine surgery of the nose, pharynx, and hypopharynx in phase 1, whereas skeletal midface advancement or tracheotomy constitutes phase 2. Clinical outcomes are reassessed through attended diagnostic polysomnogram performed 3 to 6 months after surgery. Oral appliances can be used for patients with symptomatic mild or moderate sleep apnea who prefer them to PAP therapy or for whom PAP therapy has failed or cannot be tolerated. Oral appliances also may be used for patients with severe obstructive sleep apnea who are unable or unwilling to undertake PAP therapy or surgery. For children, the main treatment modality is tonsillectomy and adenoidectomy, with or without turbinate surgery. Children with craniofacial abnormalities resulting in maxillary or mandibular insufficiency may benefit from palatal expansion or maxillary/mandibular surgery. PAP therapy may be used for children who are not surgical candidates or if surgery fails.     

Nonhypersomnolent patients with obstructive sleep apnea

Until recently, snoring had been considered both a medical enigma and a psychosocial problem. Snoring is now considered to be an acoustic phenomenon produced by vibration of the soft palate and the tonsillar pillars. We describe 20 patients with a clinical complaint of excessive snoring who were referred to rule out obstructive sleep apnea. All patients were without symptoms of daytime sleepiness and failure of the right heart. Twenty subjects were studied, 18 of whom were males. All subjects were monitored for one full night in the Sleep Laboratory. The apnea rate ranged from 9.0 to 94.0 incidents an hour with a mean of 30.0. Eight of the 20 subjects had obstructive episodes longer than 1 minute and three others had episodes longer than 55 seconds. Hypersomnolence, long thought to be a cardinal symptom, is not present in all patients with an ostensibly significant degree of obstructive sleep apnea.     

Obstructive sleep apnea/ hypopnea syndrome

Opinion statement  

Obstructive sleep apnea syndrome in children

Obstructive sleep apnea syndrome is characterized by recurrent episodes of partial or complete obstruction of the upper airway during sleep. This results in the disruption of normal ventilation and sleep patterns. The symptoms, polysomnographic findings, pathophysiology, and treatment of obstructive sleep apnea syndrome are significantly different in children from those seen in adults.     

Obstructive sleep apnea patients voice analysis

It is generally considered that obstructive sleep apnea may associate larynx abnormalities--either anatomic or functional in nature; considering the vocal tract as a series of uniform loss cylindrical pipes the idea of non-invasively exploring this by means of spectral analysis emerged. The aim of our study is to evaluate potential changes in acoustic features of voice in sleep apnea patients as compared to matched controls in order to develop a potential screening test. Material and method: Sleep apnea subjects and controls were asked to produce sustained vowels such as "a" and "i" which were recorded and analyzed. Some parameters were estimated--average of fundamental frequency, peak amplitude variation and compared and others are still to be developed.