Sleep and breathing disorders the genesis of obstructive sleep apnea

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					                                                                                                   major findings is that OSA contributes an
                                                                                                   independent risk for the development of
                                              Sleep and breathing                                  cardiovascular disease after accounting
                                                                                                   for other known risk factors. Conse-
                                              disorders: the genesis                               quently, the identification of these dis-
                                              of obstructive sleep apnea                           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-

                                                                                                   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 sleep apnea (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. Obstructive sleep apnea 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

S   leep encompasses approximately a
    third of our lives; however, the phys-
iologic processes active during sleep or
                                                    gest that 10% to 15% of the general
                                                    population have frequent daytime sleepi-
                                                    ness, while some select groups may
                                                                                                   brainstem. Were it not for a secondary
                                                                                                   mechanism, these signals would initiate
                                                                                                   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:                       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

      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
  *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

                                                   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 apneas/hypopneas                      Often                 Rare                    Absent                   Frequent

      Response to metabolic
      stimuli                                       Variable              Mild decrease           Mild decrease            Moderate decrease

      Chest wall movement                           Phasic                Phasic                  Phasic                   Occasionally

                                                                    Table 3
                                                     Characteristics of Respiratory Events

   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
      respiration                  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 pharynx
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-

                                                      Habitual snoring                                     apnea–hypopnea syndrome
imum reduction of 30% to 50% is nec-
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, pulmonary hypertension 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
hypoxemia 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)
                                                       Avoid making specific recommenda-                       Oropharyngeal devices
  Treatment options
                                                       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-
  Humidity options                                                                                              cases
                                                        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-

                                                        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
  Caregiver roles                                                                                               Travel needs
                                                       the delivery of the patient’s care.
                                                                                                                Billing issues
                                                       Explain who should or will handle
                                                       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
                                                                                               1. Young T, Palta M, Dempsey J, Skatrud J, Weber S,
needed for effective control of respiratory   is likely to increase with advancing age.        Badr S. The occurrence of sleep-disordered breathing
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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,
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rather than an increased CPAP may be          ty of knowledge, it is likely that effective     1085.
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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
                                                                                               6. Practice parameters for the use of portable record-
treated with CPAP.                            In summary, the key points of this arti-         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
                                                                                               sleepiness. Sleep 1986;9:519-524.
quately treated OSA have an increased             Patients with cardiovascular disor-
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-
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