Jeff Kuznia is the Vice President of Marketing for Compumedics USA, Inc. with more than twenty five years of experience in the neuro, sleep and cardiopulmonary diagnostics market. Previously, he held positions at Compumedics, Ltd as International Product Manager and Business Development Manager. He has been involved with sleep medicine since 1984 when he was instrumental in establishing the Sleep Disorder Center at Abbott-Northwestern Hospital, Minneapolis, MN. Jeff’s years of involvement with leading clinicians and researchers in the area of sleep medicine have kept him at the leading edge of the technology and business of sleep medicine.
When interpreting the output of a Type I/II PSG study, the use of norms for the parameters is only one factor. In many cases, reaching a conclusion that a patient’s study is consistent with one or more sleep disorders relies on recognizing patterns and interrelated factors: Do the obstructive events only occur while in the supine position? Are the arousals related to limb movement or respiratory events? Is there a high level of alpha frequency electroencephalography (EEG)?
Proper interpretation also requires the integration of clinical information on the patient: Are they on medications that affect EEG patterns? Do they have comorbid cardiac disease or COPD? Did the patient have a sleep experience that was “normal” for them or did the sleep lab environment make it better or worse?
The first step is to recognize normal sleep patterns. There are several textbooks on sleep medicine and articles in the published literature that cover the parameters for sleep architecture and events such as arousals, limb movements, respiratory events, and cardiac events that occur in the sleep phase of a healthy adult who doesn’t meet any criteria for a sleep disorder.
Articles related to normal sleep parameters:
Hirshkowitz M, Moore CA, Hamilton CR 3rd, Rando KC, Karacan I. Polysomnography of adults and elderly: sleep architecture, respiration, and leg movement. J Clin Neurophysiol. 1992;9:56-62.
Kahn A, Dan B, Groswasser J, Franco P, Sottiaux M. Normal sleep architecture in infants and children. J Clin Neurophysiol. 1996;13:184-197.
Ohayon MM, Carskadon MA, Guilleminault C, Vitiello MV. Meta-analysis of quantitative sleep parameters from childhood to old age in healthy individuals: developing normative sleep values across the human lifespan. Sleep. 2004;27:1255-1273.
Pavlova MK, Duffy JF, Shea SA. Polysomnographic respiratory abnormalities in asymptomatic individuals. Sleep. 2008;31:241–248.
Uliel S, Tauman R, Greenfeld M, Sivan Y. Normal polysomnographic respiratory values in children and adolescents. CHEST. 2004;125:872-878.
An online presentation of this paper is available from the Stanford Sleep Epidemiology Research Center Sleep-Eval Research website: http://www.sleepeval.com/Normal_Sleep_Introduction.htm
TCM of pCO2 (TcpCO2) has long been used to evaluate hypoventilation in pediatric and adult populations in the sleep lab. Improvements in TCM technology in the last 10 years have made it more reliable. The accuracy and correlation of TcpCO2 compared to Paco2 (sampled from arterial blood) is affected by several factors, primarily vascular bed blood flow in the area where the sensor is placed. It was thought at one time that skin thickness may have an effect on the reading, but several studies in recent years have demonstrated this isn’t so.
The location of the sensor probe is important as TcpCO2 readings are affected by local vasoconstriction (a drop in the TcpCO2 value may indeed be a sign of sympathetic vasoconstriction in response to apneic events). Locating the sensor on the earlobe, the forehead, or the upper chest may be best to minimize the effects of local blood flow limitations.
Obesity related hypoventilation syndrome is usually evaluated using TCM, and several studies have been published in obese subject populations, one with average body mass index (BMI) values in excess of 50.1 There is no documented or recommended cutoff for the use of TCM in obese patients.
Rather than direct you to a specific PSG system, let me provide some criteria that you might incorporate when evaluating a replacement for your current system. The American Academy of Sleep Medicine (AASM) Scoring Manual Version 2.02 applies the same recommendations for diagnostic sleep systems for both adult and pediatric testing.
That being said, pediatric sleep testing often has an additional set of technical needs. Pediatric sleep centers evaluate disorders not commonly encountered in adult sleep centers, such as gastric reflux and airway obstruction from tonsillitis. Many labs use extensive external device signals (not built into the PSG amplifier system itself) such as pH monitors, TcCO2, TcO2, EtCO2, and specialized Spo2 monitors. All of these external device signals need to interface with the PSG system, which must have robust support for these calibrated channels. If evaluating patients for epilepsy, narcolepsy, or other neurological disorders, the system should support a full complement of EEG channels.
Software should support the marking and reporting of pH events, TcpCO2, TcpO2, EtCO2, and specialized Spo2 monitors. The AASM Scoring Manual states that sleep staging for infants age 2 months or greater should use standard NREM–REM sleep staging. If you routinely see infants less than 2 months of age, you may want to use Quiet and Active sleep for staging.
Digital video recording for pediatric studies is often more demanding with a need for zoom capability with sharp images and clear audio. The best cameras tend to process and digitize the image in the camera itself and transmit the data via an IP interface.
In most hospitals, the ability to interface the sleep lab patient data and sleep study reports to the facility electronic medical record is a necessity. Having a data management system that supports bidirectional HL7 data transfer between the lab and the facility EMR should be part of your criteria.
I am familiar with some of the work from Dr. Richards related to sleep and aging. Your question is of course related to a research application and to acceptability in peer-reviewed publication, rather than a routine clinical focus. Your question is broad enough to cover several topics regarding PSG scoring, sleep staging, and various event detection and identification processes. Currently there are two approaches to staging sleep studies that have been used routinely. For many years that standard for staging sleep was the Rechtschaffen and Kales manual (R&K) on staging sleep published in 1968. The vast majority of published studies have used this method. With many advances in technology and in understanding the sleep-wake continuum, the AASM convened a task force to review and propose new PSG scoring guidelines. The Task Force published the new AASM Manual for the Scoring of Sleep and Associated Events in 2007 (available through the AASM website www.aasmnet.org). They recommended changes in the channels to record for sleep staging and in the rules for deciding the sleep stage of an epoch (30 seconds) of recorded data.
Identifying and scoring events associated with a PSG, including respiratory events, limb movements, arousals, and cardiac events have also had several different sets of standards published are various times over the years. With the development of better sensor technologies, the AASM Task Force made recommendations that monitoring for respiratory events include inductive respiratory bands, nasal pressure sensors, and thermal airflow sensors, as well as adequate pulse-oximeter devices. Alternative rules for scoring one type of respiratory event, hypopnea, have been accepted primarily because published results from the Sleep Heart Health Study demonstrated that a 4% desaturation with hypopneas (with a 30% or greater reduction in effort or airflow) were associated with increased incidence of hypertension, cardiovascular disease and reduced quality of life. Medicare subsequently implemented this rule in its guidelines for AHI calculated to qualify for CPAP therapy. The alternative allowed by the AASM requires a 50% or greater reduction in effort or airflow with either a 3% or greater oxygen desaturation or a terminating arousal.
The background articles from the Task Force may be found in the Journal of Clinical Sleep Medicine (Journal of Clinical Sleep Medicine, Vol. 3, No. 2, 2007).
What will CMS accept? They will accept either the R&K or the new AASM criteria for sleep staging. For respiratory events, CMS does define a hypopnea as respiratory event lasting a minimum of 10 seconds with at least a 30% reduction in movement or airflow accompanied by a drop in oxygen saturation of 4 percentage points or more. As with all research, document the criteria you use to score events to allow for comparison with other studies.
The short answer is yes, the neurologist may perform sleep studies in his/her office as an extension of their practice. But adding these services requires due diligence in compliance with regulatory requirements to ensure services are covered and reimbursable.
When a physician considers adding sleep diagnostic testing as an extension of their office practice there are several business related questions that will determine the requirements for the facility. The most critical decision is whether services will be provided to patients covered by Medicare or Medicaid. If yes, this adds some very specific requirements. Current CMS requirements can vary depending on the region of the country where you operate.
In California, the Local Coverage Determination (LCD) is set by the Medicare Contractor, Palmetto GBA; their current LCD on Polysomnography and Sleep Studies can be accessed here: http://www.cms.gov/medicare-coverage-database/details/lcd-details.aspx?LCDId=27589&ContrId=171&ver=32&ContrVer=1&CntrctrSelected=171*1&Cntrctr=171&name=Palmetto+GBA+(01101%2c+MAC+-+Part+A)&s=6&bc=AggAAAIAAAAA &
If the facility intends to apply for accreditation through the American Academy for Sleep Medicine (AASM), there are additional specific requirements that need to be met, including the size of patient bedrooms--the standards have become more flexible and there no longer is a required minimum square footage. The current AASM standards for sleep labs can be downloaded from http://www.aasmnet.org/accred_centerstandards.aspx
Several third-party insurance payers may also have requirements for accreditation or board certification of the physician; so a review of their coverage policies is important when deciding to add these services.
Home sleep testing (HST) is an established and growing component of the evaluation of sleep disorders, specifically obstructive sleep apnea. Medicare has approved the use of HST for the qualification of patients with suspected OSA for treatment. Other third-party payers have been changing their guidance directives to not only approve the use of HST, but in some cases to require HST as the initial diagnostic evaluation. So home studies are here to stay and will become a significant part of the diagnostic processes in evaluating people suspected of having sleep disorders.
Though there is ample evidence to document that HST is an appropriate and effective diagnostic tool in patients whose symptoms are consistent with and suggestive of obstructive sleep apnea, there is recognition that patients with any of several complicating factors should be tested in the sleep lab.
That being said, it is the expectation that all sleep labs should add home sleep testing services to their operations.
The guidelines for providing home sleep services allow primary care physicians as well as many specialists to perform this testing. It is a requirement for Medicare and some other insurers that the study results are interpreted and reported by a physician who is board certified in Sleep Medicine.
With the increased use of home sleep testing to confirm obstructive sleep apnea, treatment options will continue to evolve. Auto-titration PAP systems can certainly have a place in providing treatment. The expanded involvement of primary care physicians in the evaluations of sleep disorders should be welcome, as it will result in more patients with sleep disorders being evaluated, diagnosed and treated. There is a concern, which is shared by some that primary care physicians may pull patients away from the sleep centers. I believe that this is a great opportunity for the sleep centers, which have a concentration of expertise in managing the care of patients with sleep disorders to build relationships with the primary care physicians who are involved with home sleep testing programs. In my experience, most primary care physicians will want to refer their patients to a qualified expert for the ongoing management of their sleep disorders--creating a referral relationship with the primary care physicians is important.
First I want to thank you for your service to our country. As far as being diagnosed with a sleep disorder, the place to start is with your primary care physician and discuss your symptoms and concerns. A referral to a physician who specializes in sleep disorders may be appropriate and depending on the evaluation, a overnight sleep study may be warranted. Excessive weight is a definite risk factor for some sleep disorders, such as obstructive sleep apnea, regardless of racial heritage. If you are overweight, then weight loss could definitely reduce the risk for sleep apnea or even reduce or resolve snoring, which may be disruptive to your sleep or to a partners sleep.
The Provent nasal EPAP unit from Ventus Medical is a unique device that has been shown to be effective in many patients with mild to moderate sleep apnea. Several published studies have demonstrated effectiveness, though as with many non-CPAP treatment, the majority of papers can be accessed from the Ventus Medical website: http://www.proventtherapy.com/hcp/nasal-epap-clinical-information.php . A few patient testimonials are also available for viewing on the website.
Dr. Meir Kryger, one of the researchers who have published on the device has stated that the device works well in many patients with mild to moderate OSA, even some with severe OSA. Currently, it remains a second line of treatment, in part because of limited reimbursement. Two groups that it will not work well with are patients who sleep with their mouth wide open (since the device relies on nasal breathing to operate) and those who have nasal obstructions (deviated septum, tissue hypertrophy, allergic nasal congestion) (Source: personal communication).
Aerophagia related to CPAP treatment is not common, but it does occur. An excellent review article presenting some of the more recent scientific thought on the cause of aerophagia was written by Regina Patrick, RPSGT, in the October 2010 issue of Sleep Review.
In this article, the work of Watson and Mystkowski showed that abnormal function of the upper and lower esophageal sphincters, often associated with gastroesophageal reflux disease (GERD) may be a major cause of this condition. (Watson NF, Mystkowski SK. Aerophagia and gastroesophageal reflux disease in patients using continuous positive airway pressure: a preliminary observation. J Clin Sleep Med. 2008;4(5):434–438.)
Suggested methods for reducing the aerophagia include body position (head inclined), limiting food consumption prior to bed (reducing GERD), reducing the mean positive airway pressure may help, and some have advocated a switch to APAP systems, which sometimes produce lower mean airway pressures.
Another option to consider is to work with a dentist to produce an oral appliance to advance the mandible (lower jaw bone), which may either allow you to forego CPAP altogether or it may allow the CPAP pressure to be lowered to a point that reduces the incidence or severity of the aerophagia. Look for a dentist who has specific training in applying oral appliances in sleep apnea and is willing to work with your sleep physician in adjusting your CPAP treatment level.
Yours is a common concern when learning to implement the new scoring rules. There are two issues here that interact, sleep stage and arousal.
Let’s address the arousal definition first. The rules state that an arousal is scored if the EEG frequency shifts for a period of at least 3 seconds when preceded by at least 10 seconds of stable sleep. This could occur during any portion of the 30 second epoch, even the very first few seconds, if the last 10 seconds of the previous epoch demonstrated sleep.
As I am sure you know, scoring an epoch Wake requires that more than 50% of the 30 second epoch show alpha rhythm, eye blinks, in-phase rapid eye movements, and often elevated chin EMG. Since the rule requires more than 15 seconds of this activity to score the epoch Wake, it is entirely possible to have an epoch that is scored Wake, but also having an arousal. For example, the first 16 seconds demonstrate alpha rhythm, followed by 11 seconds of sleep, with a shift in EEG frequency the 3 seconds. In this case the arousal is scored, if the next epoch is scored Sleep (N1-3 or R).
What is not clearly stated, but can be inferred from these two rules, is that arousals that last longer than 15 seconds are indeed considered awakenings. So in your example, if the arousal event extends across two epochs, but lasts less than 15 seconds, it should be scored as an arousal. If the arousal lasts longer than 15 seconds and the next epoch is scored Wake then you definitely have an awakening.
So your ‘rule-of-thumb’ that, “If they stay awake, I score it as "awakening"… and, If it's just an arousal and they keep sleeping, I score it as an arousal,” is useful. I hope this is helpful.
Contact us about this feature or to become an expert.