major findings is that OSA contributes an independent risk for the development of and after accounting for other known risk factors. Conse- disorders: the genesis quently, the identification of these dis- of obstructive sleep orders and their treatment may help to prevent morbidity and mortality. The prevalence of these disorders poses sig- BRIAN H. FORESMAN, DO nificant issues for the primary care physi- cians.

Sleep physiology Basic sleep physiology, although rarely Sleep encompasses approximately a third of our lives; however, sleep and the discussed in osteopathic medical schools, disorders of sleep are not widely understood. Data suggest that sleep plays a is essential in the understanding of OSA restorative role in physiologic mechanisms and that long-term disruption of sleep and related disorders. Sleep is classified may contribute to the development of disease. Nearly a third of the adult popu- in two major states: non–rapid-eye-move- lation is chronically afflicted by sleep disorders, and substantial economic loss is ment (non-REM) sleep and REM sleep. attributable to these disorders in terms of lost time, inefficiency, and accidents. Of Non-REM sleep comprises stages 1, 2, 3, the sleep disorders, obstructive (OSA) is one of the more common, clin- and 4. Stages 3 and 4 comprise slow- ically affecting up to 5% of the adult population. con- wave sleep and are characterized as deep tributes to the development of disease and has an adverse impact on daytime sleep. As one progresses from stage 1 to functioning in those affected by the disease. This article reviews basic sleep phys- stage 4, sleep becomes deeper and the iology, how these physiologic mechanisms are disrupted by OSA, and some of the number of slow waves increases. These techniques for treating patients with this disorder. stages give way to the development of (Key words: sleep disorders, obstructive sleep apnea, daytime sleepiness, REM sleep, that stage of sleep in which continuous positive airway pressure, circadian rhythm) the majority of dreams occur. During REM sleep, the stimuli that create dreams also cause signals to be gener- ated down the motor pathways of the leep encompasses approximately a gest that 10% to 15% of the general brainstem. Were it not for a secondary Sthird of our lives; however, the phys- population have frequent daytime sleepi- mechanism, these signals would initiate iologic processes active during sleep or ness, while some select groups may motor activity consistent with the dream sleep’s role in maintaining physiologic approach 35%.1 Sleep-related breathing content. The simultaneous activation of homeostasis is largely unknown. Until disorders are one of the most common an inhibitory pathway causes muscle the early 1980s, the physiologic need for disorders that may affect sleep and cause atonia in the majority of the skeletal sleep had not been convincingly estab- excessive daytime sleepiness; obstructive muscles and prevents people from acting lished. Now, data suggest that sleep plays sleep apnea (OSA) is the major disorder out their dreams. For individuals who a restorative role in physiologic mecha- in this class. In the general population, rely on the skeletal muscles, and espe- nisms and long-term disruption of sleep these disorders are not trivial and they are cially the accessory muscles, the muscle may contribute to the development of often complicated by other disorders, atonia compromises ventilation and may disease. Data regarding the prevalence medical conditions, or behavioral issues. result in hypoventilation or apnea. The of sleep disorders suggest that nearly a Symptomatic OSA affects between 2% characteristics of each of these sleep third or more of the adult population is and 4% of women and 5% to 9% of stages are briefly outlined in Table 1. chronically afflicted by sleep disorders men, depending on the criteria used.1 and a substantial loss in terms of time Although there appears to be an “at- Sleep architecture and accidents is related to these disorders. risk” population who is not symptomatic, The pattern of sleep stages that occurs Estimates from the United States sug- up to 9% of women and 24% of men during a night’s sleep constitutes the have the physiologic hallmarks. This may sleep architecture. Typically, an individ- be especially important as these individ- ual progresses from stage 1 to stage 2 Correspondence to Brian H. Foresman, DO, uals may be at risk for other disorders. to slow-wave sleep and then to REM Clinical Assistant Professor of Medicine, Medi- Recent studies conducted through the sleep in a recurring pattern. Each cycle, cal Director, Indiana University Center For Sleep National Institutes of Health have begun from the lighter stages of sleep through Disorders, Indiana University School of Medicine, Indianapolis, IN 46202-6602. to define the relationships between OSA the end of REM, typically takes 60 to 90 Email: [email protected] and cardiovascular disease.2 One of the minutes. As the night progresses, each

Foresman • Sleep and breathing disorders: the genesis of obstructive sleep apnea JAOA • Vol 100 • No 8 • Supplement to August 2000 • S1 Table 1 Characteristics of Sleep Stages*

Background Special Stage EEG EMG EOG characteristics

Wake† Mixed frequency Relatively Eye movements May observe beta with more than 50% high tonic and blinks waves in EEG of the epoch alpha waves

Stage 1† Low voltage, Tonic EMG less SREMs in early Occasional vertex mixed frequency, than wake portion sharp waves in EEG; less than 50% alpha absence of spindles waves, predominance and K complexes of 2-Hz to 7-Hz activity

Stage 2 Low voltage, Similar to stage 1 Absence of REMs Intermittent mixed frequency tonic EMG or SREMs K complexes‡ and/or may have some slow- sleep spindles‡ wave activity

Stage 3 Slow-wave activity Similar to stage 1 Absence of REMs Sleep spindles and (2 Hz) of 75 V tonic EMG or SREMs K complexes may or amplitude in 20% to 50% may not be present of the epoch

Stage 4 Same as stage 3 Same as stage 3 Same as stage 3 Same as stage 3; but greater than 50% clearly identifiable of the epoch consists K complexes are rare of delta waves

Stage REM† Low voltage, mixed Low voltage, Episodic REMs Absence of sleep frequency,‡ tonic EMG, lower (Phasic REM)‡ spindles and K 5-Hz to 7-Hz “sawtooth” than preceding complexes; may see waves frequently seen stage‡ intermittent alpha but not required wave activity

Key: EEG electroencephalogram; EMG electromyogram; EOG electro-oculogram; REM rapid eye movement; SREM slow rolling eye movement. *A scoring epoch is typically 30 seconds. If paper systems are used, the paper speed is 10 mm/s. †For more details and exceptions see criteria in Rechtschaffen A, Kales A. A Manual of Standardized Terminology, Techniques and Scoring System for Sleep Stages of Human Subjects. Los Angeles, Calif: Brain Information Service/Brain Research Institute, University of California; 1968. ‡Characteristic that must be present.

cycle contains less slow-wave sleep and commonly, individuals who are getting ting occurs through a process of entrain- more REM sleep. The amount of each fewer than 6 hours of sleep each night are ing mediated by three primary processes. sleep stage and the amount of sleep sleep deprived. The first is exposure to light on awak- required by an individual changes with ening. The light stimulates neural signals age. Very young children require 14 to 16 Circadian patterns from the eye through the suprachiasmatic hours of sleep, with such requirement The timing of sleep is important in the nucleus that helps to regulate our internal declining to 8 to 10 hours for teenagers overall assessment of sleep disorders. “clock” and biologic rhythms. The sec- and young adults. Slow-wave sleep and Physiologic rhythms cycle across the ond mechanism is the pattern of daily REM sleep predominate. As individuals course of a single day. For most individ- activities. The stimulation arising from move into adulthood, their typical sleep uals, the duration of these rhythms, these activities and our interactions with requirement decreases into the range of 6 referred to as “circadian rhythms,” is other people reinforces the sleep-wake to 9 hours. Some individuals may require about 26 hours. These internal rhythms cycle. The final mechanism involves pat- more sleep or less sleep, but they represent must be reset each day to maintain con- terns of eating. Food is a very potent less than 5% of the population. Most sistency with the environment. This reset- stimulus with regard to our sleep-wake

S2 • JAOA • Vol 100 • No 8 • Supplement to August 2000 Foresman • Sleep and breathing disorders: the genesis of obstructive sleep apnea Table 2 Physiologic Changes in Respiratory Control With Sleep

Slow-wave Stage 1 Stage 2 (stages 3 and 4) Rapid-eye- Variable sleep sleep sleep movement sleep

Source of control Metabolic Metabolic Metabolic Nonmetabolic

Respiratory pattern Periodic Regular Regular Irregular

Central /hypopneas Often Rare Absent Frequent

Response to metabolic stimuli Variable Mild decrease Mild decrease Moderate decrease

Chest wall movement Phasic Phasic Phasic Occasionally paradoxical

Table 3 Characteristics of Respiratory Events

Respiratory event Duration Airflow Effort Desaturation Arousal

Obstructive apnea At least 10 s Absent at Proportionately Not required Not required some point greater than in the event flow; crescendo effort common

Central apnea At least 10 s Proportional Absent or Common, but Not required to respiratory proportionally not required effort; absent decreased with at some point in airflow the event

Hypopnea 10 to 120 s, Decreased Proportionately Usually required Usually required longer should be by 50% relative greater than flow; if there is no if there is no hypoventilation to most recent crescendo arousal desaturation baseline airflow effort common

Respiratory event– At least 10 s; No significant Slight increase, Not required Required; related arousal* often several change from may crescendo usually cyclic minutes baseline to end of event

Cheyne-Stokes Series may last Varies Crescendo- Usually Not required 15 to 30 min proportionate with decrescendo mild cyclic or more the respiratory pattern desaturations, effort; may but not required include apnea at lowest point

*Associated with upper airways resistance syndrome (UARS).

Foresman • Sleep and breathing disorders: the genesis of obstructive sleep apnea JAOA • Vol 100 • No 8 • Supplement to August 2000 • S3 that occur with the onset of sleep and may be made worse by a supine position. Etiologic mechanisms include neuro- muscular weakness (eg, amyotrophic lat- eral sclerosis), abnormal control of res- piration (eg, congestive heart failure), partial or complete airway obstruction (eg, OSA), and disorders associated with airway disease (eg, asthma). The major disorder primarily associated with sleep is OSA. This disorder is characterized by recurrent narrowing or closure of the upper airway (Figure 1), leading to repeated apneas, hypopneas, or respira- tory arousals that are often associated with desaturations and fragmentation Velopharnyx of sleep. The source of the problem relates to Oropharnyx the structure of the oropharynx and func- Posterior nasopharnyx tional interrelationships involving the pharyngeal muscles. The pharyngeal muscles comprise two functional groups: Figure 1. Major sites of airway closure in obstructive sleep apnea. a pharyngeal dilator group and a pha- ryngeal constrictor group. At the initia- tion of each breath, the pharyngeal dila- tor mechanism is activated, thereby mechanisms. These three mechanisms increased sleep efficiency are character- maintaining the patency of the are often referred to as Zeitgebers, or istic of sleep deprivation. throughout inspiration. In the majority of “time givers.” These internal mechanisms cases of OSA, the pharyngeal dilator affect sleep onset, the patterns of sleep, Respiratory control mechanism is dysfunctional or there are and the timing of REM sleep. As an individual makes the transition physical impediments to airflow that from wake to sleep, the respiratory con- intermittently obstruct airflow during Sleep deprivation trol relationships change (Table 2). With sleep. Factors that limit sleep or fragment sleep the onset of sleep, the central mecha- Structural abnormalities such as functionally cause sleep deprivation. The nisms controlling blood levels of carbon micrognathia, macroglossia, and large major effect of sleep deprivation is to dioxide and oxygen allow functionally tonsils may also contribute to the devel- cause excessive sleepiness; however, stud- higher and lower levels, respectively. The opment of sleep apnea. The increase in ies by Rechtschaffen and colleagues3 theoretic reason for these changes is a body fat that is common in OSA results have shown that sleep is required for shift to metabolic control of respiration in airway narrowing, which may fur- maintenance of health. Individuals who and a change in the set points for both ther predispose to upper airway obstruc- are sleep deprived consistently show gases. The set point changes allow the tion. In this regard, obesity should be moodiness, decrements in memory, dif- carbon dioxide to rise by 2 torr to 3 torr considered a contributor to OSA, but ficulty in concentration, and progressive and the oxygen saturation to fall by 2% not a common etiologic mechanism. increases in sleepiness. Such changes are to 3%. Rapid transitions from wake to With sleep onset, the pharyngeal mus- often dependent on the type of sleep sleep can cause sleep-onset central cles relax, leading to an obstructive res- deprivation (total versus selective) and apneas. This form of central apnea piratory event (ie, apnea or hypopnea). the amount of sleep deprivation. Some should generally be considered a nor- Apneas may be categorized as obstructive disorders such as OSA may result in mal finding in the otherwise healthy apneas, mixed apneas, or central apneas selective REM deprivation. Over time, adult. (Table 3). Obstructive and central forms the tendency for REM to occur increas- of hypopneas may also be seen. Both es (so-called REM pressure), which may Etiology and pathophysiology of apneas and hypopneas must have a dura- result in an accentuated amount of REM obstructive sleep apnea tion of at least 10 seconds (Table 3). sleep during the recovery phase; this The pathophysiologic mechanisms that Reductions in airflow longer than 120 effect is commonly referred to as “REM account for sleep-related breathing dis- seconds are typically characterized as rebound.” A short sleep latency and orders result from physiologic changes hypoventilation. The exact amount of

S4 • JAOA • Vol 100 • No 8 • Supplement to August 2000 Foresman • Sleep and breathing disorders: the genesis of obstructive sleep apnea the decrease in airflow necessary to iden- Severe obstructive sleep tify the reduction varies; however, a min- apnea–hypopnea syndrome imum reduction of 30% to 50% is nec- Habitual essary in most circumstances because of technical limitations of the equipment ➤ used to measure airflow. In some sleep laboratories, the reduction in airflow Obstructive events Central and obstructive must be coupled with a desaturation or Respiratory event– events arousal in order to score the event. The related arousals choice of criteria for scoring respiratory Frequent arousals Arousals require events varies widely, and no one defini- Mild stimulus needed significant stimulus tion has been accepted as a universal standard.4 Figure 2. Progression of obstructive sleep apnea. The number of apneas that occurs per hour of sleep is referred to as the apnea index (AI). The number of apneas plus hypopneas that occurs per hour of Clinical features breathing when supine. Further physi- sleep is referred to as the apnea-hypop- The most common features of OSA are cal examination often reveals evidence of nea index (AHI). In some instances, the excessive daytime sleepiness, loud snor- lower extremity edema and hyperten- respiratory-disturbance index (RDI) may ing, witnessed apneas, morning sion. Cardiovascular disease, diabetes, be substituted for the AHI; however, the headaches, frequent nocturnal arousals, or hyperlipidemia is frequently noted in criteria for respiratory events has changed and weight gain. Usually, patients present these patients. The family medical history during the past 10 years,4 and proposed with the history of increasing daytime frequently reveals that other family mem- changes in the definition will likely alter sleepiness present for the past 2 to 5 bers have either OSA or a history of the validity of such substitutions in the years, increasing weight, and decreasing excessive sleepiness and snoring. future. Typically, an AHI or an RDI ability to perform typical activities. greater than 5 is abnormal. In the past, Patients or their significant other often Typical laboratory findings some authors suggested that this number reports that sleep is quite restless and The definitive test for suspected sleep did not become clinically significant until associated with frequent arousals relat- apnea usually involves polysomnogra- the RDI was greater than 20. More ed to snorting or snoring. They usually phy. Polysomnography is performed to recent data from the Sleep Heart Health awaken unrefreshed and often take naps verify the diagnosis of OSA and to rule Study,2 however, has provided other during the day or fall asleep sponta- out other disorders.5 These studies findings that support this contention by neously. The sleepiness associated with include physiologic measurements of eye showing that an AHI of 5 is closely asso- OSA can lead to accidents, interfere with movement, electroencephalographic ciated with the development of disease. the activities of daily living, impair work recordings, oronasal airflow, pulse These data also suggest that sleep apnea performance, and lead to general decline oximetry, electrocardiographic activity, may progress from mild to severe dis- in satisfaction that is often perceived as chin muscle activity, and snoring. Other ease over time (Figure 2). Therefore, depression. Additional symptoms or physiologic measurements may be includ- symptomatic patients with an abnormal complaints may relate to declines in ed, depending on the diagnoses under RDI should be treated. vision, poor memory, irritability, dry consideration. Recently, a wide array of There are several adverse cardiovas- mouth, chronic fatigue, and impotence. multichannel recording devices has been cular consequences of obstructive respi- Frequently, individuals with OSA are developed for use in sites outside of the ratory events. Sympathetic increases moderately obese with a relatively nar- sleep laboratory. The recordings of the occurring with these events and the reac- row oropharynx and an increase in neck majority of these devices are not sufficient tive tachycardia often cause a transient girth. Men are two times more likely to make a diagnosis of OSA. The use of rise in blood pressure. Over time, the than women to have OSA. These indi- these devices has been reviewed and clin- increases in blood pressure become more viduals may have structural deformities ical recommendations on their use pub- persistent and develop into hypertension that contribute to the disease, such as lished.6 and other cardiovascular disorders. macroglossia, micrognathia, or an Another testing procedure, the Mul- Although recurrent hypoxia is common enlarged uvula. Occasionally, nasal tiple Sleep Latency Test (MSLT), has in OSA, is not. obstruction, nasal polyposis, structural been developed to assess for sleepiness It is a relatively rare complication more defects of the nose, or allergies may also and narcolepsy.7 The MSLT is per- commonly associated with chronic contribute to airway obstruction. Venti- formed using methods similar to those and hypoventilation. lation may also be impaired as the result for the overnight polysomnogram; how- of moderate obesity and its effect on ever, multiple short naps are taken. The

Foresman • Sleep and breathing disorders: the genesis of obstructive sleep apnea JAOA • Vol 100 • No 8 • Supplement to August 2000 • S5 naps typically are less than 20 minutes In more recent years, variations on factors involved in the administration and are assessed for the time to sleep CPAP have been attempted to improve of CPAP. onset and the occurrence of any sleep- tolerance, increase adherence, adjust to Tracheostomies have been shown to onset REM periods. In preparation for day-to-day variations in the severity of be an effective therapeutic intervention an MSLT, patients may be instructed to OSA, and provide for improved moni- for OSA. Studies performed after the discontinue taking medications or alter toring of CPAP use. More recently, introduction of nasal CPAP demon- their sleep period for several weeks. Also, machines that can automatically vary strated an improvement in mortality9 an overnight polysomnogram is per- the applied pressure have been devel- with both CPAP and tracheostomy. formed before the MSLT to rule out oped, so-called autotitrating CPAP. These Today, a tracheostomy may be an appro- other disorders and to verify the amount machines are good for initiating CPAP priate intervention for those individuals of sleep immediately preceding the but have not replaced the sleep labora- whose OSA cannot be well controlled MSLT. The performance standards and tory in the optimal determination of with CPAP or bi-level PAP, or those who indications for the MSLT have been CPAP pressures. did not tolerate PAP interventions. Sur- reviewed elsewhere.8 In general, CPAP is a less-expensive gical interventions such as uvu- modality than bi-level PAP. Bi-level PAP lopalatopharyngioplasty (UPPP), hyoid Treatment and management is more expensive because of an addi- advancement, and mandibular advance- Once the diagnosis of OSA has been tional mechanism necessary to enable ment are potential alternatives.10 The confirmed, an appropriate treatment reg- the bi-level delivery process. The more reduction in respiratory events associat- imen needs to be developed. Therapy sophisticated versions of CPAP machines ed with these interventions, either alone should first be directed at the primary are slightly to moderately more expensive or in combination, is significantly less disorder, and then, consideration should than standard machines, but significantly than that associated with CPAP; how- be given to secondary or confounding less than bi-level machines. Overall, each ever, most series show 40% to 50% of disorders. Simply treating the patient of these devices has an appropriate use, patients have reduced the number of res- with OSA without consideration of asso- and no one device represents the uni- piratory events by half. To date, no reli- ciated illnesses, behaviors, or circadian versal alternative for all situations. able test exists to determine which disturbances usually results in an inade- The choice of masks used to apply patients will benefit from UPPP or other quate treatment regimen, incomplete res- CPAP or bi-level PAP is important in surgical interventions. Also, individuals olution of symptoms, and the patient’s the appropriate care of the patient with treated with surgery have a tendency to noncompliance. OSA. The masks are of three major for- have recurrence of OSA 3 to 5 years The most common treatment modal- mats: the nasal mask, the full-face mask, after the surgery has been completed. ity for OSA is positive airway pressure and nasal prongs or pillows. Each of Laser uvulopalatopharyngioplasty (PAP). This modality applies air pres- these formats has its advantages and dis- (LAUP) has been evaluated; however, it sure to the upper airway either through advantages. The mask should be cho- appears to be an ineffective modality for the nose or through the nose and mouth sen to optimize tolerance and to mini- treating OSA. Oropharyngeal appliances by use of a full-face mask. The air pres- mize complications. are best used with individuals who have sure in the upper airway displaces the To adequately treat an individual mild OSA or in situations in which airway walls outward, providing a pneu- with OSA, adequate pressure settings patients do not have access to their CPAP matic splint to the areas of obstruction. must be used. Most centers will attempt for short periods.11 The choice of these If effectively applied, this treatment to determine an adequate pressure setting alternative modes of therapy requires modality will typically relieve the obstruc- using a titration trial. Titration studies are knowledge of the patients’ condition, tion in patients with OSA. Two major frequently performed on a night after the severity of their sleep apnea, the tol- patterns for delivering PAP are routine- the study diagnostic for OSA. Some cen- erance to previously attempted thera- ly used to treat OSA: continuous PAP ters perform the diagnostic phase and peutic interventions, and the patients’ (CPAP) and bi-level PAP. In both of the titration phase during the same study preference. No one modality works for these delivery patterns, the pressure deliv- when they have appropriate patients. all patients, and the failure of a modal- ered to the patient during exhalation This type of study is referred to as a ity such as CPAP should not preclude must be sufficient to maintain airway split-night study. Usually, this study its future use. patency and not allow complete collapse requires that a patient have a minimum Weight loss is rarely a cure for OSA, of the oropharynx. These two forms dif- of 30 respiratory events or apneas with- but it frequently reduces the severity of fer in one significant respect: the bi-level in the first 2 to 3 hours of the study, form increases its pressure during inspi- which allows sufficient time to perform ration when the tendency to collapse the the titration phase of the study. Overall airway is the greatest. This form allows goal of the properly performed titration Figure 3. Approach to patient educa- the use of lower pressures during end- study is to optimize sleep while mini- tion, highlighting topics and examples exhalation and often increases comfort. mizing the side effects and complicating of items to be included.

S6 • JAOA • Vol 100 • No 8 • Supplement to August 2000 Foresman • Sleep and breathing disorders: the genesis of obstructive sleep apnea Explain the details of the disease Symptoms of OSA Obstructive sleep apnea (OSA) briefly and with regard to the patient’s Disorders associated with OSA learning ability Complications of OSA

Discuss options cautiously, and do Continuous positive airway pres- not oversell the options. sure (CPAP) Oropharyngeal devices Treatment options Avoid making specific recommenda- tions with regard to one type of treat- Surgery, such as ment or another, which may interfere — uvulopalatopharyngioplasty with the physician’s plan. — laser uvulopalatopharyngioplasty — maxillofacial Weight loss Positional retraining

Cleaning issues Humidification mechanisms need to Alternate options for complicated be drained daily. Heated humidifi- cases Humidity options cation may help those with frequent Cleaning agents complications of CPAP. Need may be seasonal

Explain anticipated benefits of the Elimination of apneas and intervention and a reasonable time- hypopneas Goals of CPAP titration line in which to expect them. The Improvement in oxygenation most common reason for failure of Elimination of snoring therapy is nonadherence. Reduction of use of arousals

Complications can often be avoided Nasal dryness or sinus problems or treated. Skin irritation from mask Complications of CPAP Describe the common problems. Air leaks Emphasize that regular and Exacerbation of asthma (rare) frequent care and use are the basic measures for avoiding the compli- cations.

Instruct patients to rinse the equip- Type of cleaning agent to use Care and cleaning of CPAP ment daily and to clean at least Frequency of cleaning equipment weekly. Frequency of equipment Discuss proper care. inspection/replacement

Detail outline of the care plan and Home care involvement Follow-up the duration of home care in the Physician involvement plan. Ancillary issues

Equipment problems Explain the role of each caregiver in Travel needs Caregiver roles the delivery of the patient’s care. Billing issues Explain who should or will handle Complications problems or questions that arise. Changes in equipment Most important message is to Return of symptoms contact SOMEONE. If it is not the person most able to address the issue, that person can direct patient to the appropriate caregiver.

Foresman • Sleep and breathing disorders: the genesis of obstructive sleep apnea JAOA • Vol 100 • No 8 • Supplement to August 2000 • S7 the disease and may reduce the CPAP disease is approximately 1.2 to 1.5 and References needed for effective control of respiratory is likely to increase with advancing age. 1. Young T, Palta M, Dempsey J, Skatrud J, Weber S, Badr S. The occurrence of sleep-disordered breathing disturbances. Some patients will have To date, little is known about the effects among middle-aged adults. N Engl J Med clear worsening of their respiratory of treating OSA with regard to prevent- 1993;328:1230-1235. events when in the supine position. In ing the development or progression of 2. Quan SF, Howard BV, Iber C, Kiley JP, Nieto FJ, these instances, positional retraining cardiovascular disease. Despite this pauci- O’Connor GT, et al. The Sleep Heart Health Study: design, rationale, and methods. Sleep 1997;20:1077- rather than an increased CPAP may be ty of knowledge, it is likely that effective 1085. an effective intervention. Supplemental interventions will have a significant oxygen may be necessary to control impact. With regard to accidents, it has 3. Rechtschaffen A, Gilliland MA, Bergmann BM, Win- ter JB. Physiological correlates of prolonged sleep desaturations in some patients. been clearly shown that effective treat- deprivation in rats. Science 1983;221:182-184. The treatment of young children with ment of OSA reduces the risk of acci- 4. Redline S, Sanders M. Hypopnea, a floating metric: OSA may vary somewhat. For this rea- dents. Recent efforts by the National implications for prevalence, morbidity estimates, and son, young children and neonates should Institutes of Health and several agen- case finding. Sleep 1997;20:1209-2017. be studied only in selected centers. Also, cies, including the American Academy 5. Practice parameters for the indications for surgical interventions may be more com- of Sleep Medicine, have begun to address polysomnography and related procedures. Polysomnog- mon and more effective in children than these issues. raphy Task Force, American Sleep Disorders Associ- ation Standards of Practice Committee. Sleep in adult patients. Children of an appro- 1997;20:406-422. priate size and stature may also be well Comment treated with CPAP. In summary, the key points of this arti- 6. Practice parameters for the use of portable record- ing in the assessment of obstructive sleep apnea. Stan- cle are as follows: dards of Practice Committee of the American Sleep Patient education, health Sleep-related breathing disorders are Disorders Association. Sleep 1994;17:372-377. promotion, quality of life, common in the general population. 7. Thorpy MJ. The clinical use of the Multiple Sleep and public policy Approximately 2% to 5% of the popu- Latency Test. The Standards of Practice Committee of the American Sleep Disorders Association [pub- Once a diagnosis of OSA is made, then lation are symptomatic and meet criteria lished erratum appears in Sleep 1992;15:381]. Sleep patient education is necessary to avoid for these disorders. 1992;15:268-276. complications and optimize compliance Patients with sleep-related breathing 8. Carskadon MA, Dement WC, Mitler MM, Roth T, with physician recommendations (Fig- disorders commonly present with exces- Westbrook PR, Keenan S. Guidelines for the multiple ure 3). Patients with untreated or inade- sive daytime sleepiness. sleep latency test (MSLT): a standard measure of quately treated OSA have an increased Patients with cardiovascular disor- sleepiness. Sleep 1986;9:519-524. risk of accidents. The laws involving OSA ders have a greater likelihood of having 9. He J, Kryger MH, Zorick FJ, Conway W, Roth T. vary from state to state and may be OSA than the general population, and Mortality and apnea index in obstructive sleep apnea. Experience in 385 male patients. Chest 1988;94:9-14. dependent on the occupation of the OSA may worsen their cardiovascular afflicted patient. In some circumstances, disease. 10. Practice parameters for the treatment of obstructive sleep apnea in adults: the efficacy of surgical modifi- reports may need to be forwarded to the Diagnosis of sleep-related breathing cations of the upper airway. Report of the American appropriate administrative body such as disorders depends on some simple ques- Sleep Disorders Association. Sleep 1996;19:152-155. the Federal Aviation Authority or Depart- tioning of the patient and ordering the 11. Practice parameters for the treatment of snoring ment of Transportation. Once under ade- appropriate diagnostic studies (eg, and obstructive sleep apnea with oral appliances. Amer- quate treatment, most professional pilots polysomnography). ican Sleep Disorders Association. Sleep 1995;18:511- 513. and drivers will require yearly updates Therapy for OSA usually incorpo- in order to maintain their operational rates CPAP, which is effective in most status. Regardless of occupation, evary individuals, but may include surgery, patient should be cautioned with regard weight loss, and other modalities. to the risk of accidents, and follow-up Treatment should address behaviors should be tailored accordingly. related to sleep (eg, smoking, drinking) and the patterns of sleep (eg, shift work, Health and public policy limited sleep). Important issues with regard to public policy and OSA include the develop- ment of cardiovascular disease and the prevention of accidents. Recent data now suggest that OSA is not only a cause of hypertension, but it is also an indepen- dent risk factor for the development of cardiovascular disease. The relative risk for the development of cardiovascular

S8 • JAOA • Vol 100 • No 8 • Supplement to August 2000 Foresman • Sleep and breathing disorders: the genesis of obstructive sleep apnea