Putting sleep apnea to rest

Tailored therapy reduces fatigue-related risks

Aijaz Alvi, MD; Stella E. Lee, MD

WEB EXCLUSIVE / JANUARY 2005 / POSTGRADUATE MEDICINE

CME learning objectives

• To understand the various mechanisms of sleep apnea
• To learn how to identify patients at risk for sleep apnea
• To become familiar with treatment approaches to sleep apnea

The authors disclose no financial interests in this article and no unlabeled uses of any product mentioned.

Preview: Sleep apnea, the periodic cessation of breathing during sleep, is a common and underdiagnosed condition. Treatment can improve quality of life as well as reduce morbidity and mortality from sleep apnea-related hypertension, stroke, and traffic accidents. In this article, the authors discuss types of sleep apnea, diagnostic tools, and treatment strategies for both adults and children.
Alvi A, Lee SE. Putting sleep apnea to rest: tailored therapy reduces fatigue-related risks. Postgrad Med 2005;117(1) (online article)

Sleep apnea refers to the cessation of breathing during sleep for at least 10 seconds in adults or for two or more consecutive breaths in children. With a prevalence as high as 2% in women, 4% in men (1), and up to 10% in children (2), sleep apnea may be as common as diabetes in the general US population.

Frequent sleep apnea episodes, each followed by awakening, result in sleep fragmentation and daytime sleepiness. During discussion of sleep apnea, the term hypopnea is also used to describe a significant reduction in airflow due to partial obstruction. The apnea-hypopnea index is defined as the total number of episodes of apnea and hypopnea per hour of sleep. A value of 5 or greater is abnormal and may be associated with excessive daytime sleepiness (3).

In the long term, disturbed sleep may contribute to hypertension, right-sided heart failure, and even death. Fortunately, sleep apnea can be successfully treated with various approaches.

Types of sleep apnea

Disturbance of breathing can occur through several different mechanisms. Obstructive sleep apnea is an absence of airflow due to a closed or obstructed airway despite respiratory drive from the brain; central sleep apnea is the cessation of breathing due to the absence of this respiratory drive. Upper airway resistance involves the narrowing of the upper airway without obstruction.

Obstructive sleep apnea
The most common type of sleep apnea, obstructive sleep apnea often manifests as snoring that occurs when turbulent airflow through a narrowed upper airway causes vibration of pharyngeal structures. Snoring and obstructive sleep apnea can be thought of as being on either end of the obstruction spectrum, which begins with upper airway resistance and leads to narrowing and, finally, collapse of the upper airway. Obstructive sleep apnea results from narrowing or closure at any point in the airway, from the nose to the larynx. The obstruction most commonly occurs during rapid eye movement sleep, when relative relaxation of pharyngeal muscles leads to collapse of the upper airway.

Risk factors include male sex, obesity, increased neck circumference (measured at the cricothyroid membrane), craniofacial abnormalities, and acromegaly (4). However, a considerable proportion of women, children, and nonobese persons have undiagnosed obstructive sleep apnea (5).

Several studies suggest that obstructive sleep apnea plays a causal role in systemic hypertension independent of other risk factors, such as obesity (6,7), and is associated with increased morbidity and mortality in persons with cardiovascular or cerebrovascular disease (8). Possible mechanisms of this relationship include increased ventilatory and sympathetic responses to hypoxia (9), decreased cerebral perfusion, and increased coagulability (10). Although controversy exists about whether treatment of sleep apnea ameliorates hypertension, treatment with continuous positive airway pressure (CPAP) has been shown to cause small reductions in systolic and diastolic pressure (11).

A recent study (12) showed that patients with congestive heart failure and obstructive sleep apnea had improved cardiac function, sympathetic activity, and quality of life with CPAP treatment. Studies of the role of sleep apnea therapy in preventing cerebrovascular sequelae are limited, but CPAP treatment in patients who have had a stroke has been shown to improve depression (13).

Because of drowsiness and lack of concentration, persons with obstructive sleep apnea also are two to seven times more likely than healthy persons to have a traffic accident (14). A case-controlled study of 210 persons with sleep apnea (15) showed that treatment could decrease the auto collision rate of persons with obstructive sleep apnea to that of drivers in the general population.

Central sleep apnea
Central sleep apnea is a pattern of unstable breathing caused by various clinical states resulting from damage to the brainstem or cervical spine. Central sleep apnea can be classified as hypercapnic or hypocapnic. The hypercapnic form is seen mainly in patients with central nervous system disease that has caused loss of breathing control. It typically occurs in persons with encephalitis, neuromuscular disease, or abnormalities in thoracic anatomy, such as kyphoscoliosis. Hypocapnic central sleep apnea is seen mainly in patients with congestive heart failure. Cheyne-Stokes respirations involving crescendo-decrescendo alterations in tidal volume, separated by periods of apnea and hypopnea, may occur in up to 45% of persons with congestive heart failure (16).

Upper airway resistance
Upper airway resistance syndrome involves a decrease in airflow due to narrowing of the upper airway, causing arousal from sleep. Although no significant episodes of sleep apnea or oxyhemoglobin desaturation occur, sleep fragmentation still results, causing excessive daytime sleepiness.

Recognition of sleep apnea

The diagnosis of sleep apnea should be considered in patients who are obese, have hypertension, snore, or experience excessive daytime sleepiness.

Patient history
History taking should focus on breathing disturbances during sleep, sleep quality, daytime function, and risk factors. A history of hypothyroidism, craniofacial abnormality, Down syndrome, cardiovascular disease, a car accident, shift work, and sedative or alcohol use may indicate an increased risk of sleep apnea. The patient's bed partner may be able to provide information about snoring and episodes of breathing cessation, gasping, and snorting (17).

In addition to snoring, common symptoms during sleep may include restlessness, diaphoresis, nocturia, dry mouth, drooling, and gastroesophageal reflux. Although daytime sleepiness is the most common symptom, sleep apnea may interfere with several areas of daytime function and may cause headache, impaired memory and concentration, decreased dexterity, personality changes, irritability, aggressiveness, depression, anxiety, decreased libido, and erectile dysfunction.

Predictive models
A significant proportion of patients in the primary care setting may present with sleep apnea risk factors. However, diagnostic procedures such as a sleep study (polysomnography) can require considerable expense and time. To help select patients for further diagnostic testing with polysomnography, several screening models consisting of questionnaires and measurement of neck circumference have been proposed.

A study using the Berlin Questionnaire (18), a screening survey, found a high risk of sleep apnea in subjects who had two of the following three criteria: snoring, persistent daytime sleepiness or drowsiness while driving, and obesity or hypertension. The Berlin Questionnaire had a sensitivity of 86% in subjects with an apnea-hypopnea index greater than 5.

Another proposed predictive model uses neck circumference values to predict whether a sleep study will be positive for sleep apnea. The neck circumference is adjusted for hypertension (4 cm [1.6 in] added), snoring (3 cm [1.2 in] added), and bed partner reports of choking or gasping (3 cm added). A study of this model (19) showed that patients with an adjusted neck circumference of less than 43 cm (16.9 in) had a low probability of having a positive sleep study, those with a neck circumference of 43 to 48 cm (18.9 in) had an intermediate probability, and those with a value greater than 48 cm had a high probability. These values, when considered together with severity of daytime symptoms, were found to be more accurate than physician impression and useful in the selection of patients for polysomnography.

Because no consensus exists on the value of a clinical predictive model, neither of these models has been used extensively in practice. However, they may be useful in determining which patients should undergo further diagnostic testing.

Physical examination
The physical examination should focus on craniofacial and soft tissue aspects of the oropharynx that may result in narrowing of the upper airway. These aspects include nasal obstruction caused by nasal septal deviation, allergies, enlarged turbinates, a nasal mass (figure 1), an enlarged uvula or low-lying soft palate, enlarged tonsils, retrognathia, and micrognathia.

Figure 1. Intranasal adenoids can contribute to obstructive sleep apnea.

Evidence suggests that obesity (body mass index >28 kg/m²) plays a causal role in obstructive sleep apnea. Of patients with obstructive sleep apnea, 75% are obese (20). Tonsillar enlargement and neck circumference of 43 cm or greater also have been shown to correlate with obstruction associated with sleep apnea (21). An otorhinolaryngoscopic examination with flexible endoscopy or nasal endoscopy is necessary to assess the site of obstruction.

The sleep study
Differential diagnostic considerations for patients who have excessive daytime sleepiness include primary snoring, sleep deprivation, narcolepsy, depression with insomnia, and sleep apnea. The "gold standard" for diagnosis of sleep disorders is polysomnography, which involves observation of a sleeping patient and analysis of sleep stage associated with oxygen saturation, oral and nasal airflow, respiratory effort, electrocardiographic pattern, body position, and limb movement.

Goals of the sleep study are to confirm the diagnosis of obstructive sleep apnea, assess the severity of apnea, select therapy, and evaluate response to treatment. Sleep stage is assessed with electroencephalography, electro-oculography, and electromyography. Comprehensive data on the pulmonary and nonpulmonary variables that may contribute to disordered sleep are collected. Other data collected include the distribution of sleep stages, presence of snoring, body position, decrements in oxygen saturation, periodic limb movements, and number of arousals, apneas, and hypopneas.

The severity of sleep apnea can be categorized as mild, moderate, or severe on the basis of the apnea-hypopnea index. Mild sleep apnea is defined by an apnea-hypopnea index from 5 to 14, an oxygen saturation of at least 86%, and minimal daytime disability. Moderate sleep apnea is defined by an index from 15 to 30 or an oxygen saturation of 80% to 85% and significant work or social dysfunction due to drowsiness and loss of concentration. Severe sleep apnea is defined by an index greater than 30 or an oxygen saturation of 79% or less and incapacitation due to the sleep disorder (3).

In addition to use in diagnosis of sleep disorders, polysomnography indicates the level of CPAP needed. Polysomnography is recommended before and after surgical procedures to correct abnormalities causing sleep apnea.

Management of sleep apnea

Treatment of sleep apnea must be tailored to individual patients, taking into account the severity of obstructive sleep apnea, the site of the obstruction, coexisting medical problems, and lifestyle. Treatment of severe obstructive sleep apnea is imperative because the associated mortality and morbidity are high. A hallmark study (8) showed that 40% of persons with an apnea-hypopnea index greater than 20 died over an 8-year period if untreated. Patients who have an apnea-hypopnea index of 5 or more may also benefit from treatment if they have excessive daytime sleepiness or medical conditions such as congestive heart failure and stroke.

Nonsurgical management
Conservative treatment may involve weight loss, exercise, and behavioral therapy. CPAP is the most widely used primary treatment for sleep apnea. Oral devices that facilitate mandibular and tongue advancement can be considered for patients with mild sleep apnea for whom CPAP treatment is not effective.

Conservative measures: Patients with mild sleep apnea diagnosed on the basis of polysomnography may respond best with conservative treatment that involves an adequate amount of sleep, good sleep hygiene, avoidance of the supine position during sleep, treatment of nasal obstruction, and weight loss.

Sleep deprivation is prevalent in US society and has been shown to contribute to increased snoring (22) as well as the obvious consequence of excessive daytime sleepiness. Physicians need to counsel patients with sleep apnea to avoid alcohol and other sedating agents that may exacerbate snoring or even precipitate sleep apnea because of relaxation of the tongue and pharynx. Nasal resistance due to conditions such as sinusitis can be treated with nasal corticosteroids, decongestants, or antihistamines. Finally, weight loss of as little as 10% has been shown to improve sleep apnea by decreasing fatty infiltration of the pharynx (23).

CPAP therapy: Considered the first-line treatment of choice for obstructive sleep apnea, CPAP prevents collapse of the pharyngeal airway by providing air under positive pressure through a nasal or facial mask. Randomized controlled studies with placebo (sham CPAP) (24,25) have shown that CPAP treatment decreases sleepiness and improves quality of life.

Although CPAP therapy is effective for improving sleep apnea symptoms, the compliance rates have been reported to be as low as 50%; many patients abandon treatment within the first 2 to 4 weeks (26). Low compliance may be due to patient discomfort, including nasal congestion and dryness, skin abrasions, claustrophobia, difficulty adjusting to air pressure, and frustration with mask leaks. Improvement in long-term maintenance of CPAP therapy has occurred with intensive patient support, education, and consistent follow-up by healthcare professionals (27).

Additional strategies to improve compliance include heated humidification of CPAP air, use of nasal corticosteroid sprays to reduce nasal symptoms, use of a full-face mask or nasal pillows to prevent air leaks, and adjustment of pressure through a pressure ramp, autoadjusting, or bilevel positive-pressure therapy to meet patient needs. Patients who have difficulty exhaling against the consistent pressure of CPAP may benefit from therapy with bilevel positive airway pressure. Various mask interfaces ranging from full-face masks (for patients who prefer to breathe through their mouth) to nasal prongs (which may reduce claustrophobia) are available. Alternating the use of nasal pillows one night with a mask the next night may prevent skin abrasions.

Oral devices: Data suggest that oral devices designed to stabilize the airway by moving the mandible or tongue forward should be reserved for patients with mild sleep apnea who snore and those who cannot tolerate CPAP therapy. In the long term, CPAP has been shown to be more effective than an adjustable oral appliance in patients with mild to moderate obstructive sleep apnea, although the oral appliance is better tolerated (28). Two randomized controlled studies (29,30) have shown that a mandibular advancement splint is effective in resolving symptoms of sleep apnea through a significant reduction in the apnea-hypopnea index.

Contraindications to oral devices include a diagnosis of central sleep apnea, temporomandibular joint disease, or nasal obstruction. Current guidelines suggest that physicians treating patients who are considering an oral appliance should first obtain an initial sleep study to ensure an accurate diagnosis and assess the severity of sleep apnea and then obtain a follow-up sleep study after fitting of the oral appliance (3). More research is needed in this area to determine specific recommendations for the use of oral devices in obstructive sleep apnea.

Surgical management
Patients with discrete craniofacial abnormalities and inadequate relief of obstructive sleep apnea with conservative measures and CPAP therapy may benefit from more invasive treatments. Surgical management, which typically includes orthopharyngeal and maxillofacial surgery, should be individualized to the site and degree of obstruction.

Before deciding whether surgery is appropriate, the physician needs to conduct a thorough evaluation, including history taking and a complete physical examination with a focus on the airway. A sleep study and, possibly, imaging studies should be obtained. In rare instances, tracheostomy may be required to maintain the airway in patients who cannot tolerate CPAP therapy or other interventions.

Oropharyngeal surgery: Several types of oropharyngeal surgery, including uvulopalatopharyngoplasty, laser-assisted uvulopalatoplasty, and radiofrequency ablation, are available. Uvulopalatopharyngoplasty may be useful in patients with palatal elongation or tonsil hypertrophy, or both. The procedure consists of reduction of excess tissue in the palate, uvula, and posterior and lateral pharyngeal walls and, in some cases, the tonsils. It reduces snoring by 85% and improves the apnea-hypopnea index by 50% in 40% to 50% of patients with obstructive sleep apnea (31). Depending on the site of obstruction, success rates as high as 80% can be achieved; however, some symptoms may resurface in the years after surgery. Complications of uvulopalatopharyngoplasty include pharyngeal discomfort, dryness, and disturbances in taste and speech.

Laser-assisted uvulopalatoplasty is indicated for treatment of primary snoring and mild obstructive sleep apnea. It is usually performed under local anesthesia, unlike uvulopalatopharyngoplasty, which requires general anesthesia. The procedure consists of removal of part of the uvula and soft palate. Recent studies have shown elimination of snoring in 80% to 90% of cases (32), as well as improvement in obstructive sleep apnea in 40% to 50% of patients with the mild form (33).

Radiofrequency ablation has been useful in reducing soft tissue in the palate with less postoperative pain than that with laser-assisted uvulopalatoplasty. Complications may include postoperative hemorrhage and bacterial infection.

Two procedures, genioglossal and hyoid advancement, are under investigation and may be alternatives to major surgical interventions in the future. They both involve placement of suspension sutures to relieve obstruction at or below the base of the tongue. In genioglossal advancement, the anterior tip of the mandible and its attachment to the tongue is moved forward. One retrospective nonrandomized study (34) showed a 90% improvement in collapse at the base of the tongue after genioglossal advancement. In hyoid advancement, the hyoid bone is brought forward to further open the airway at the base of the tongue and vallecula. Complications may include hematoma and transient numbness of the teeth.

Maxillofacial surgery: Maxillomandibular advancement surgery may be considered for patients with craniofacial abnormalities, such as a receding chin and jaw, that predispose them to obstructive sleep apnea. The goal is to move both the maxilla and the mandible forward to establish an open airway. Success rates of 90% to 100% with maxillomandibular advancement surgery as the primary procedure have been reported (35,36). Although more definitive than other treatments, maxillomandibular advancement surgery is major surgery and requires lengthy recovery time, during which the jaws are fixed with wires or other stabilization measures. Complications include transient numbness of the chin and cheek and malocclusion of the jaw.

Sleep apnea in children

Obstructive sleep apnea is common in children and has been associated with failure to thrive, behavior problems (eg, attention-deficit/hyperactivity disorder), developmental delays, nocturnal enuresis, and pulmonary hypertension leading to cor pulmonale. The disorder is often associated with adenotonsillar hypertrophy (figure 2), neuromuscular problems, and craniofacial abnormalities. Contributing risk factors include obesity, black race, family history of the disorder, and sinus or respiratory problems (eg, bronchitis, asthma) (37).

Figure 2. Obstructive sleep apnea in children is often associated with adenotonsillar hypertrophy.

The American Academy of Pediatrics recommends that all children be screened for snoring (38). If a child has a history of snoring, the physician needs to obtain a more detailed history of labored breathing during sleep, observed apnea, restless sleep, diaphoresis, enuresis, cyanosis, excessive daytime sleepiness, and behavior or learning problems. Polysomnography is the most effective means for diagnosing sleep apnea and should be obtained in children at risk for sleep apnea.

Adenotonsillectomy is first-line treatment for most children with obstructive sleep apnea, resolving the disorder in 75% to 100% of cases (38). Several recent studies have shown that this procedure significantly improves long-term quality of life and ameliorates behavior problems in children with obstructive sleep apnea (39,40).

Conclusion

Obstructive sleep apnea is a pervasive, debilitating, and often unrecognized disorder in both adults and children. However, it can be readily diagnosed and treated successfully through a variety of approaches. Treatment of sleep apnea has been shown to significantly improve quality of life as well as ameliorate cardiovascular disease and prevent traffic accidents related to excessive daytime sleepiness. The disorder is broad in spectrum, and treatment is most beneficial if individualized.

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Dr Alvi is an otolaryngologist, Mercy Health System, Crystal Lake, Illinois. Dr Lee is affiliated with Mount Sinai Hospital, Chicago. Correspondence: Stella E. Lee, MD, PO Box 804891, Chicago, IL 60680.

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