Polysomnography and Portable Monitoring BY AHMAD YOUNES PROFESSOR OF THORACIC MEDICINE Mansoura faculty of medicine POLYSOMNOGRAPHY • POLYSOMNOGRAPHY is the standard test for 1-Diagnosis of suspected sleep-related breathing disorders 2- Positive airway pressure titration 3- Document the efficacy of prior surgical treatment and determine the efficacy of oral appliance treatment. 4- Evaluation of parasomnias (under certain conditions). 5- Narcolepsy (when combined with a multiple sleep latency test) Portable Monitoring •Attended cardiorespiratory pulmonary studies (airflow + two effort channels, oximetry, and heart rate) are an acceptable alternative to PSG for diagnosis of obstructive sleep apnea (OSA) in patients with high pretest probability of OSA or for determining the adequacy of prior surgery for OSA or effectiveness of current OA treatment. •Unattended PM monitoring is also acceptable for assessing the efficacy of non-PAP treatment of OSA. •The Centers for Medicare and Medicaid Services (CMS) now recognize a diagnosis of OSA by unattended PM as acceptable for reimbursement of CPAP treatment POLYSOMNOGRAPHY • PSG is the standard diagnostic study for evaluation of a suspected SRBD. • A diagnostic study may be repeated if the initial study was negative for sleep apnea and there is a high clinical index of suspicion for this disorder. • PSG should be performed preoperatively for planned surgery to treat snoring or suspected OSA. • A PSG is indicated after surgery for OSA (after surgical healing) to document effectiveness. POLYSOMNOGRAPHY • For patients with prior effective surgical treatment (documented by PSG), the PSG may be repeated at a later time if symptoms of sleep apnea return. • For a patient using an OA as treatment for OSA, the PSG may also be repeated while the patient wears the OA if the patient’s symptoms return. • If a patient on CPAP loses more than 10% of body weight, a diagnostic PSG is indicated to determine whether CPAP is still needed. 5 Mechanism of CSA POLYSOMNOGRAPHY • Number of circumstances in which SRBDs are very common (patients with systolic or diastolic heart failure, recent or past stroke or transient ischemic attack (TIA), coronary artery disease, and tachyarrhythmias or bradyarrhythmias) PSG is NOT routinely indicated in those circumstances unless a clinical evaluation reveals a reasonable suspicion for SRBD. • Most clinicians would also place resistant hypertension or pulmonary hypertension of unknown etiology in this category as well. • The clinician should recognize that many patients with significant OSA do not complain of daytime sleepiness. • A history of snoring and gasping would suggest a PSG is indicated. • It should also be noted that some patients with OSA complain of insomnia. • The practice parameters do list neuromuscular diseases as a group of disorders in which PSG is indicated for evaluation of SDB. POLYSOMNOGRAPHY • Routine evaluation of chronic lung disease is not an indication for PSG unless coexistent OSA is suspected. • Nocturnal oximetry is a useful tool for determining whether nocturnal oxygen desaturation is occurring in a patient with COPD. • A saw-tooth pattern is suggestive of sleep apnea. • A PSG for PAP titration is the standard procedure to select a level of pressure for treatment. • The titration can be performed on a separate night after a diagnostic PSG or during the second part of the night during a split (partial night) study. POLYSOMNOGRAPHY • A split sleep study is recommended when (1) the diagnostic portion shows an AHI > 40 /hr with at least 2 hours of monitoring, (2) there is an AHI of 20 to 40 with special clinical circumstances such as severe desaturation or arrhythmia thought due to OSA (3) at least 3 hours remain for the PSG titration. If the PSG titration does not last at least 3 hours or is not adequate, a repeat PSG titration is indicated. • If the patient is being treated on CPAP and is NOT doing well, a repeat PSG study on CPAP is indicated. However, before this expensive procedure ,it is essential to document adequate objective adherence and to optimize treatment and the mask interface. • PSG is also indicated if a patient on CPAP gains more than 10% of body weight to determine whether the pressure is adequate. However, a repeat PSG titration may not be clinically indicated. Hypercapnic CSA • Impaired Central Drive ("Won’t Breathe"): 1-Tumors or trauma-induced lesions to brainstem 2-congenital central hypoventilation syndrome (Ondine curse) 3-opioid-induced CSA 4- OHS Impaired Respiratory Motor Control ("Can’t Breathe") 1-myasthenia gravis 2-amyotrophic lateral sclerosis 3-post-polio syndrome 4-myopathies 5-Chest wall syndromes such as kyphoscoliosis PSG Indications: Nonrespiratory Disorders • A PSG preceding an MSLT is indicated for evaluation of suspected narcolepsy or to help differentiate narcolepsy from idiopathic hypersomnia. • PSG is indicated for evaluation of suspected periodic limb movement disorder but NOT the restless legs syndrome (RLS; a clinical diagnosis). • A PSG is indicated to evaluate (1) nocturnal behavior possibly due to seizures, (2)atypical parasomnia behavior (frequent episodes each night ,stereotypic behavior, or behavior unusual for age), (3) nocturnal behavior/parasomnia that has resulted in injury to the patient or others (4) presumed parasomnia or nocturnal seizure disorder that does not respond to conventional treatment, or (5) if there are legal/forensic implications of nocturnal behavior. PSG NOT Indicated CSA • PSG is not indicated for evaluation of insomnia (unless OSA is suspected) or unless insomnia does not respond to usual treatment. • PSG is not indicated for diagnosis of depression or insomnia with depression. • The practice parameters for use of PSG in evaluation of insomnia state “PSG is indicated when initial diagnosis is uncertain, treatment fails (behavioral or pharmacologic), or precipitous arousals occur with violent or injurious behavior (Guideline). • Although the PSG finding of a short REM latency is common in depression, this finding is not sufficiently sensitive or specific to warrant a PSG in evaluating patients with suspected depression. • A PSG is NOT indicated for (1) typical uncomplicated and noninjurious parasomnias when the diagnosis is clearly delineated or (2) patients with known seizure disorders who have no nocturnal complaints. Approach to the Sleepy Patient on PAP Treatment • If a patient with OSA continues to have daytime sleepiness on adequate PAP treatment (documented adequate adherence and adequate control of respiratory events), there are two options., an alerting agent such as modafinil may be added. If there is a suspicion of narcolepsy in addition to OSA, a nocturnal PSG on PAP treatment (documenting adequate treatment) followed by an MSLT on PAP can be performed • If unambiguous cataplexy is present, the patient likely has narcolepsy and the MSLT is simply confirmatory. • It is essential that adequate PAP treatment for OSA be confirmed before expensive testing. This includes documentation of adequate objective adherence. • Many PAP devices also have the ability to record residual AHI. • A high residual AHI would be an indication for an adjustment in pressure (empirical increase) or a PSG PAP titration. • The PAP device estimate of residual AHI is not always accurate, but a high value has a reasonable positive predictive value that the residual AHI is indeed elevated. • A surprising number of patients (up to 15%) on chronic PAP treatment are not adequately treated (AHI >10/hr). Approach to Reading the PSG • Before the PSG is read, a review of the clinical history with special attention to symptoms of sleep apnea, narcolepsy, RLS, and medications is very useful. • The presence of underlying lung disease may help explain a low awake arterial oxygen saturation (SaO2) or low baseline sleeping SaO2. • A clinical history of pacemaker insertion or known atrial fibrillation is also very helpful in providing a useful interpretation of ECG findings. • If a PAP titration is planned for a patient currently using CPAP, the current treatment pressure level should be noted. • All digital PSG systems have a view that shows graphical summary information of the entire night. It is often useful to look at the big picture before going through the data in smaller time windows. • The biocalibrations are often helpful in noting the appearance of eyesopen wake in a given patient and whether the patient produces an alpha rhythm with eye closure . Summary view shows three periods of significant arterial oxygen desaturations (A, B, and C) during rapid eye movement (REM) sleep. In addition, the summary view shows that no supine REM sleep was recorded. SpO2 = pulse oximetry. PORTABLE MONITORING (HOME SLEEP TESTING, OUT OF CENTER SLEEP TESTING) • The tests are not always performed in the home ;hence, the terms HST or PM are not ideal but are used in much of the literature on this subject. • In the past, PM has been used to diagnose OSA in settings in which access to PSG is limited or delayed. • The original classification used “level I, II, III, and IV” to refer to different classes of monitoring but currently the terminology is “type 1, 2, 3, and 4.” • The Centers for Medicare and Medicaid Services (CMS) has a different classification for monitoring The CMS terminology defines the respiratory disturbance index (RDI) as the total number of apneas and hypopneas per hour of monitoring time. Therefore, the index determined by PM (no EEG) would be an RDI using the CMS definition. CMS also refers to PM as HST. Accuracy of PMs • There are a number of reasons why the AHI from PSG and PM might differ. Even if the same type of sensors are used and the same number of events are identified, the two devices would still give different AHI values as monitoring time (PM) would exceed total sleep time (PSG). • It is also possible that the oximeters used in different systems could differ in their ability to detect desaturations. • Comparing PM and PSG AHI values during simultaneous recording reduces the effects of night-to-night variability. • The AHI values could differ simply due to night-to-night variability in the AHI. In general for milder OSA, the amounts of REM and supine sleep are the major determinants of the AHI. These patients have elevated AHI mainly in the supine position or during REM sleep. In milder OSA patients, night-to-night differences in the proportions of REM and supine sleep are a significant source of night-to-night variability. Accuracy of PMs • Differences in the AHI during simultaneous monitoring were likely due to the effect of using monitoring time versus TST to compute the AHI. • During PM monitoring at home, less supine sleep also contributed to differences in the AHI. • To compensate for night-to-night variability, many PM devices now have the ability to monitor multiple nights. • One study suggested that night-to-night variability in the home might be less than in the sleep center. Clinical Use of PM • • • • • • • Indications for Attended PM is rarely used in the attended setting. In 1994 and 1997 practice parameters,attended type 2 or 3 PMs were stated to be acceptable alternatives when treatment of OSA is urgent and PSG is delayed, the patient is unable to be studied in the sleep center (safety or immobility), or the diagnosis of OSA is already established and the purpose is to evaluate the response to treatment. The 2003 practice parameters for the use of portable monitoring added that certain PMs may be used in the attended setting to rule in or to rule out OSA. The 2005 practice parameters for PSG stated that attended cardiorespiratory studies (type 3 PM) are an acceptable alternative to PSG for diagnosis of OSA in patients with a high probability of OSA as long as a negative PM study was followed by PSG. Attended cardiorespiratory studies were also said to be acceptable for preoperative evaluation for planned surgery for snoring or OSA. After surgery, attended cardiorespiratory studies were acceptable to document surgical effectiveness in patients with moderate to severe OSA. A specific statement concerning the use of attended cardiorespiratory studies in patients being considered for an OA treatment of snoring or suspected sleep apnea was not made in any of the practice parameters. In the attended setting, cardiorespiratory studies are acceptable to document the effectiveness of an OA (after adequate adjustment) or in OSA patients treated with surgery or an OA when symptoms return. Indications for Unattended PM • PM is most often used in the unattended setting. • The recent AASM PMGs state that unattended PM “may” be indicated for diagnosis of OSA in patients with a high pretest probability or for documenting the efficacy of non-PAP treatments for OSA—IF guidelines for patient selection and procedures for PM performance and interpretation are followed. • In brief, PM must be combined with a comprehensive sleep evaluation by a qualified physician, patients must have a high probability of moderate to severe OSA, there must be an absence of medical co-morbid conditions that degrade the accuracy of PM (severe lung disease, neuromuscular disease, and congestive heart failure). Patients with comorbid sleep disorders (e.g., narcolepsy) requiring PSG should also be excluded. A minimum of airflow, respiratory effort, and oxygen saturation must be measured (type 3 PM). If a PM study is negative or technically inadequate, a PSG should be ordered to avoid a false-negative PM result. Patient Selection for PM • Ideally, each patient should be seen by a sleep physician before PM testing. • If this is not possible, an evaluation can be performed with questionnaires before or at the time of testing. • Review of the medical record to exclude patients with co-morbidities that degrade PM accuracy is also important. these include patients with severe pulmonary disease, neuromuscular disease, or congestive heart failure (CHF). • The rationale is that such patients may exhibit hypoventilation without discrete respiratory events or Cheyne-Stokes breathing (common in severe systolic CHF). • However, one can argue that if PM devices use the same sensors that are used for PSG (the recommendation), then PM and PSG should have similar ability to detect central apnea, Cheyne-Stokes breathing, or hypoventilation (manifested by a low SaO2 without discrete events). • The counter argument is that such patients will likely need a PSG PAP titration. In this case, a split-sleep study may be more cost effective than PM followed by a PSG titration. PM also would miss arrhythmias because pulse rate obtained from the oximeter rather than an ECG tracing is usually recorded. Recommended PM Methodology • • • • • • • • • • The PMGs recommend monitoring at a minimum airflow ,respiratory effort, and SaO2 . The recommended sensors for PM are the same as those recommended for PSG in the AASM scoring manual. Note that CMS uses the metric RDI rather than AHI for PM [(apneas + hypopneas)/monitoring time]. RDI usually means AHI + RERA index. Adequately trained personnel should either place the monitoring equipment on the patient or train them on the application of the sensors. This is essential to avoid a high percentage of technically inadequate studies. The PM data must be viewed in the raw form, and if automated scoring is used, it must be edited for accuracy. A physician must look at the raw data as well as the data summary before making an interpretation. It was recommended that PSG be interpreted by a sleep physician or a physician associated with an accredited sleep center. For quality assurance, standard operating procedures for the PM process must exist. To verify adequate scoring, interrater reliability on scoring of PM studies should be performed on a routine basis and documented. If PM is inadequate technically or if the study results are negative in a patient with a high pretest probability of having OSA, an attended PSG should be performed. Recommended PM Methodology • Numerous devices are available for PM. Devices having more sensors provide more information but are more difficult for patients to place. • It is always a trade off between information and complexity of sensor application. • Respiratory effort is monitored by chest and abdominal respiratory inductance plethysmography (RIP) bands. • An oximetry channel and derived heart rate are also recorded as well as body position., actigraphy to enable elimination of periods of wake/artifact from the final index time (the monitoring time used for AHI calculation) is available in some devices. PM devices. A, Embletta (Embla). B, WatchPAT 100 (Itamar). C, Stardust II (Philips-Respironics). D, ARES (Advanced Brain Monitoring). A 60-second tracing shows an obstructive hypopnea recorded with a type 3 PM device (PDX by Philips-Respironics). An oronasal thermal device (NO flow) and nasal pressure (N Press), chest and abdominal respiratory inductance plethysmography (RIP) bands, snoring, oximetry, pulse rate (from the oximeter), and body position (S = supine) are recorded. SpO2 = pulse oximetry. Tracing from a type 3 PM device (Embletta ) shows nasal pressure, oronasal thermal flow, chest and abdominal respiratory inductance plethysmography (RIP) channels, oximetry (SpO2), and pulse. The illustrated event is a central apnea of the Cheyne-Stokes type. This was an unexpected finding. The patient had no history of known congestive heart failure but did report nocturnal dyspnea. In this tracing from an Embletta, the nasal flow channel is inadequate (likely nasal cannula dislodged or occluded) but the derived XFlow (derivative of thorax and abdomen RIP bands) provides a reasonable estimate of flow. SpO2 = pulse oximetry. Peripheral Arterial Tonometry • • • • • • • Unique PM devices that detect respiratory events by recording changes in sympathetic tone (rather than airflow) using peripheral arterial tonometry (PAT) are also available. Devices using this technology (Watch PAT 100, 200, Itamar Medical) are worn on the wrist. The devices have two probes—a PAT probe and an oximetry probe— worn on separate digits. The PAT signal is a measure of the blood volume in the digit. Increases in sympathetic tone stimulate alpha receptors on the digital blood vessels, causing constriction. A reduction in blood flow to the digits decreases the finger tip volume and the PAT signal. Because surges in sympathetic tone follow respiratory event termination, the combination of a decrease in PAT signal, a fall in pulse oximetry (SpO2) followed by an increase, and an increase in heart rate allows determination of respiratory events. Watch PAT 100 Watch PAT 100 • The device has a built-in actigraphy to help with estimation of an appropriate index time (used to compute an event index). • Recently, the combination of actigraphy and the PAT signal has been used to determine estimates of wake, non–rapid eye movement (NREM) sleep, and REM sleep because the sympathetic tone characteristics of these sleep stages differ. • Newer models also have a body position sensor and a snore sensor. • The device has been validated with several studies. • The device cannot be used in patients on alpha blockers (e.g., terazosin) and with patients in atrial fibrillation. • Another downside is that the PAT probes are relatively expensive. • The national carrier determination for HST recognizes “3 channels of monitoring including PAT,oximetry, and actigraphy” as a valid PM method. Practical Considerations in PM • Devices with more sensors provide more information but are more difficult to apply. • The software should provide accurate autoscoring to minimize the amount of event editing required. • If the software is similar to that used for PSG, this may be an advantage to reduce training costs. • The durability of the device and cost of expendables (e.g., nasal cannula) should be considered. • PM devices can be placed in the sleep center or in the home by a technologist. Alternatively, the patient can be trained on the device and apply the device himself or herself at home. • PM devices are typically either returned to the sleep center the following day or mailed if patients live a distance from the center. • Device loss can be a major expense. • The application of the PM device by a technologist in private homes is expensive and has safety issues. Therefore, having patients come to the sleep center is recommended if possible. • The more complex the PM device, the less likely patients can apply it themselves. . Practical Considerations in PM • Adequate training is essential.. • Common problems include dislodgment of either the nasal cannula or the oximeter probe as well as pulling leads out of the PM device during body movement • It is also useful to have patients complete a brief sleep diary to record their estimate of how long they slept and if the night of sleep was fairly typical. • An occasional patient will sleep very poorly with the device attached. If minimal sleep is recorded, a false-negative study is likely. • Devices that can record more than one night provide another monitoring night opportunity and may also reduce the influence of night-to-night variability. Integration of PM into the Overall Patient Care Algorithm • Diagnosis of OSA using PM is only the first part of the process if the study is positive. • It is expected that in populations with a high probability of OSA, a high percentage of PM tests will be positive. • If PAP is chosen for treatment, there are several alternative pathways to proceed . • The standard approach would be to perform a PSG PAP titration and subsequent PAP treatment. • Patients could also use an auto-PAP (autotitrating, positive airway pressure [APAP]) device at home for 3 days or more and information obtained could be used to select a pressure for chronic CPAP treatment. • Commonly, the 90th or 95th percentile pressure is chosen for treatment with a fixed pressure (CPAP). • A third possible approach is starting CPAP at a pressure derived using prediction equations with subsequent adjustment based on oximetry, symptoms, or machine estimates of residual AHI. • Finally, simply treating the patient with an auto-PAP (autoadjusting) eliminates the need for titration. Overall Approach to Using PSG and PM • A clinical evaluation determines whether there is a high probability of OSA, if other sleep disorders are present, or whether complicating issues are present that will likely require a PSG titration. • Patients with a high probability of OSA undergo PM, and if OSA is diagnosed, they can have APAP treatment or APAP titration followed by CPAP treatment. • If the PM is negative, a PSG can be performed. • If other sleep disorders are suspected or there are complicating factors such as CHF (Cheyne-Stokes possible), narcotics, obesity hypoventilation possible (supplemental oxygen or massive obesity), a PSG with split study if indicated is performed. • Although PM can often diagnose Cheyne-Stokes breathing, a PSG titration will likely be needed. ACTIGRAPHY • Actigraphy utilizes a portable device (the actigraph) usually worn on the wrist that records movement over an extended period of time . • Sleep-wake patterns are estimated from the pattern of movement. • Software is available to estimate TST and wake time from the data. • The sleep/wake pattern of actigraph data is extremely valuable in documenting patterns of sleep and wake. • Actigraphy is still not reimbursed by most insurance plans or Medicare. • Studies of actigraphy have usually compared the results with that of PSG or sleep logs. However, actigraphy does not measure sleep (EEG) or the subjective experience of sleep (sleep logs). Actigraphy. The dark black represents the amount of activity (when present = wake). The light blue represents periods of low activity identified as sleep. The light gray represents ambient light detection. Indications • Actigraphy provides a fairly accurate estimate of sleep patterns in normal, healthy adult populations and in patients suspected of certain sleep disorders. • Actigraphy is indicated to assist in the evaluation of patients with advanced sleep phase syndrome (ASPS), delayed sleep phase syndrome (DSPS), shift work disorder, in the evaluation of patients suspected of jet lag disorder and non– 24-hour sleep-wake syndrome (including that associated with blindness). • Actigraphy is also useful for documenting the response to treatment in circadian disorders. • When PSG is not available, actigraphy is indicated to estimate TST in patients with OSA. Actigraphy in OSA • If the number of events detected by PM was divided by a better estimate of TST than the monitoring time, this might improve the estimate of the AHI. • Patients with OSA by the very nature of the disorder have periodic movements at the end of respiratory events. • A special actigraphic system optimized for use in OSA patients was compared with PSG on an epoch-by-epoch basis. The overall sensitivity and specificity to identify sleep were 89% and 69%, respectively. The agreement ranged from 86% in the normal subjects to 86%, 84%, and 80% in the patients with mild, moderate, and severe OSA, respectively. • There was a tight agreement between the mean values of actigraphy and PSG in determining mean sleep efficiency, TST, and sleep latency. Whereas for most individuals, the difference between the PSG and the actigraphy was relatively small, for some, there was a substantial disagreement. • Another study did not find good agreement between actigraphic and PSG estimates of TST. • Actigraphy combined with respiratory monitoring are a better estimate of the AHI than use of time in bed. The utility of actigraphy with PM remains to be determined. However, it certainly allows elimination of large portions of the night in which wake is obvious. Patients with Hypersomnia • Practice parameters on use of PSG/MSLT to diagnose narcolepsy stated that sleep logs may be obtained for 1 week before to assess sleep-wake schedules. • Not all patients can keep accurate sleep logs. Therefore, actigraphy could be potentially useful to document sleep patterns before MSLT . • Current practice parameters for actigraphy do not list evaluation of sleep before MSLT as an indication. Actigraphy in Insomnia • The practice parameters for actigraphy did not recommend testing as a routine evaluation of patients with insomnia. • However, actigraphy was said to be “useful” in documenting sleep-wake patterns. • Therefore, documenting sleep patterns rather than the absolute amount of sleep and wake is likely the best use of the actigraph. • In insomnia patients, periods of low activity in which patients lay quietly in bed but are awake may be scored as sleep by actigraphy software. • When performing actigraphy, it is essential to require patients to complete a sleep log (lights off, lights on, out of bed, actigraph off for shower, and so on, estimated TST; and sleep latency). • This information enables a correct interpretation of actigraphic tracings. For example, total absence of movement usually indicates that the actigraph has been removed (shower, swimming), but here patient logs are essential to verify device removal. Actigraphy in Insomnia • Many modern wrist actigraph devices also provide the capability of recording the amount of ambient light. • This is useful in patients with circadian rhythm sleep disorders in whom light exposure may either exacerbate or improve the underlying disorder. • Some actigraphy devices also have event markers that the patient can press when getting in bed, trying to sleep, or after awakening in the morning. • Sleep logs and actigraphy provides complementary information. • Both actigraphy and sleep logs underestimated TST and overestimated wake time. • Actigraphy underestimated the sleep latency whereas sleep logs overestimated the sleep latency. • Actigraphy was found to be more sensitive at detecting treatment effects than sleep logs. In contrast, different results was found in a group of older adults treated for primary insomnia (expected to have more wake time). Actigraphy slightly overestimated TST and underestimated wake.