The standardization changes in sleep scoring outlined in the new American Academy of Sleep Medicine (AASM) Manual for the Scoring of Sleep and Associated Events: Rules, Terminology, and Technical Specifications are attracting attention from the field of sleep medicine. With many facilities now looking to transition to the new rules for AASM-accredited centers and laboratories, sleep medicine is experiencing a critical step in its evolutionary process.
The new manual is the result of more than 2 years of evidence review by AASM task forces assigned to each topical area. More than 60 contributors participated. “Revision was necessary to address new data and events,” says Conrad Iber, MD, editor of the manual and past-president of the AASM. “The variability of different interpretation data from one lab to another was acknowledged, and this standardizing brings us all together in one common method, and also brings in children.” Iber is an associate professor of medicine at the University of Minnesota, and director of the pulmonary and critical care department, Hennepin County Medical Center, Minneapolis.
The new standardized methodology for scoring of sleep and related events in adults and children spans technical specifications, recording methods, and data interpretation across the array of measured parameters. The mid-April AASM release of new scoring rules for sleep studies coincided with its announcement that AASM-accredited sleep centers and laboratories must comply with the new requirements by January 2008. Subsequently, a modified deadline of July 1, 2008, was announced after the AASM consulted with representatives of the polysomnograph equipment industry and reconsidered the timeline with attention to certain practical considerations, according to a May 31, 2007, letter from then AASM President Michael Silber, MD.
ReadSleep Review’s online news for more updates on AASM policies and procedures.
Five members of the industry panel invited by the AASM to participate in the development of the new scoring manual task force are listed in the publication,1 including two representatives from Respironics, and one each from AstroMed, Compumedics, and SleepMed Inc.
TRAINING AND TRANSITION
The new rules encompass the use of all recommended respiratory sensors and all electroencephalogram (EEG), electrooculogram (EOG), and electromyography (EMG) derivations. The rules also state that new polysomnographic equipment purchased on or after July 1, 2008, must fulfill the technical and digital specifications
published in the manual. AASM leaders say they are aware that there will be a need for future changes as the process further evolves.
Sleep health professionals from a wide range of facilities have obtained the manual from the AASM and have begun the transition to compliance with the new rules. Some are looking for further understanding of the manual through training courses at regional sleep conferences. Several sessions on the topic were available at the SLEEP 2007 annual meeting in June. The AASM also is offering a course titled “Interpreting Sleep Studies: Using the New AASM Scoring Manual” on December 1-2, 2007, in Austin, Tex.
Historically, change in any growing medical field appears to engender debate, and the presentation of the new scoring rules for sleep is not immune from such arguments. “Just ask 50 people the definition of a hypopnea, and you’ll get 50 different versions of the elusive hypopnea,” says longtime sleep technologist and sleep technology course instructor Edwin Cintron, RPSGT, from Tampa, Fla.
At the SLEEP 2007 annual meeting various arguments and opinions were expressed about the new scoring manual. “There were very interesting public meetings at APSS, and the input was extremely diverse. Some people said to scrap the manual and the rules and redo the whole thing because they felt there was not enough validity. Others said, change nothing. This shows that some people would be unhappy no matter what was done,” Iber says.
Long respected and regarded as a monumental step for the field of sleep, the 1968 “scoring bible” by Allan Rechtschaffen and Anthony Kales (R&K)2 was apparently not without its own controversy. According to a published account, “The rules by Rechtschaffen and Kales present numerous problems; they sometimes even contradict physiological facts. This is due on the one hand to the manual being limited to central leads only, and on the other hand to rules which are partly too narrow, partly too broad and partly too complex,”3 the paper states. The authors were in favor of switching from central to frontal lead placement for clearer recognition of certain waveforms. Interestingly enough, the new scoring manual revisits a similar procedure listed in the paper, and recommends alternative electrode placement to the frontal lobe.
More than 1,500 articles published between 1968 and September 2004, reviewed in seven manuscripts that comprise the March edition of the Journal of Clinical Sleep Medicine (JCSM), were intended to fortify the new scoring manual.4
An excerpt from the JCSM edition said the manual is based on “1. High levels of evidence from the review papers or, when evidence is insufficient, 2. The results of a standardized consensus process. The seven topical areas of the review papers: digital analysis and reporting parameters, visual scoring, arousal, cardiac events, movements, respiratory events, and pediatric scoring, reflect the charge of the scoring manual task forces to develop reference material to support the development of a more comprehensive scoring manual.”
When evidence published in peer-reviewed journals was not available to the AASM scoring manual task force, recommendations were based on consensus agreement using the RAND/UCLA Appropriateness Method,5 which combines the best available scientific evidence with the collective judgment of experts to yield a statement regarding the appropriateness of performing a procedure at the level of patient-specific symptoms, medical history, and test results. The method was developed in the mid 1980s as part of the RAND Corporation/University of California Los Angeles Health Services Utilization Study. The rationale behind the method is that randomized clinical trials—the “gold standard” for evidence-based medicine—either are generally not available or cannot provide evidence at a level of detail sufficient to apply to the wide range of patients seen in everyday clinical practice. Although vigorous scientific evidence about many procedures is lacking, physicians must nonetheless make decisions every day about when to use them.
THE CHANGES: NEW TECHNICAL REQUIREMENTS
Of the technical requisites instituted by the AASM, Natalie Morin, president and CEO of Sleep Strategies Inc, Ottawa, says that the changes will “ensure that collected data, no matter which software program is used, will meet gold standard quality recordings.” She outlines a few areas where the AASM has established requirements:
- Minimal and desirable sampling rates,
- Low- and high-frequency filter settings,
- Minimal screen and video card resolution; and
- Method of measuring actual individual impedance against a reference and minimal electrode impedances.
Some other requirements state:
- Separate 50/60 Hz filter control for each channel.
- Recorded video data must be synchronized with the PSG data and have an accuracy of at least one video frame per second.
TECHNICAL SPECIFICATIONS REGARDING ELECTRODE APPLICATION
- New EEG montages including frontal derivations, combined with the existing central and occipital derivations, are recommended.
- The frontal derivations were recommended for clearer identification and maximal occurrence of K-complexes and slow wave activity.
- EOG placement has been slightly revised as well as an alternative recommendation given.
- The electrode placement for EMG is now clearly defined, which was not in the previous R&K manual; three electrodes, including one mental and two submental electrodes, are recommended.
- For the electrocardiograph, lead II placement is recommended.
SCORING OF SLEEP STAGES
- The terminology has slightly changed with wake now being referred to as stage W, and stages N1, N2, and N3 referring to the “old” NREM stages 1, 2, and 3; REM should now be labeled stage R.
- Stage N3 represents slow wave sleep and replaces the R&K nomenclature of stage 3 and stage 4 sleep.
- Each stage now includes more detailed definitions and rules as well as procedural notes (figures are included in the manual to give some examples of the rules).
- The previous “3 minute rule” has now been abolished; therefore, the biggest impact will be noticed in the scoring of N2. N2 sleep can be scored as soon as one or more K-complexes unassociated with arousal or one or more trains of sleep spindle occur in the first half of the epoch or the last half of the previous epoch.
- Major body movements are now either scored as stage W (if more than 15 seconds of alpha is present for any part of the epoch or if an epoch of stage W precedes or follows the movement) or scored as the same stage as the following epoch.
- Specifications are given regarding definitions of sinus tachycardia, bradycardia, asystole, wide and narrow complex tachycardia, and atrial fibrillation.
- The use of both the oronasal thermal sensor and nasal air pressure transducer for airflow detection and esophageal manometry or calibrated or uncalibrated inductance plethysmography for detection of respiratory effort are the current recommendations.
- Clear recommended and alternative apnea, hypopnea, and Cheyne-Stokes definitions as well as a definition for the optional RERA events are established for both the adult and pediatric population.
- Maximum duration of a limb movement is 10 seconds.
- Minimum amplitude is an 8 μV increase in EMG voltage above resting EMG.
- Scoring criteria for bruxism, REM behavior disorder (RBD), and PSG feature of rhythmic disorder were also included.
Theresa Shumard is a longtime sleep technician, advocate for sleep, and medical columnist, and the founder of REMgazer Sleep Communications. She is the host of the “Let’s Talk Sleep with Theresa Shumard” radio program. She is a member of the Sleep Review Editorial Advisory Board and can be reached at firstname.lastname@example.org.
- Iber C, Ancoli-Israel S, Chesson AL, Quan SF. The AASM Manual for the Scoring of Sleep and Associated Events: Rules, Terminology, and Technical Specifications. Westchester, Ill: American Academy of Sleep Medicine; 2007.
- Rechtschaffen A, Kales A, eds. A Manual of Standardized Terminology, Techniques, and Scoring System for Sleep Stages of Human Subjects. US Department of Health, Education, and Welfare Public Health Service—NIH/NIND; 1968.
- Kubicki S, Herrmann WM, Höller L, Scheuler W. Comments on the rules by Rechtschaffen and Kales about the visual scoring of sleep EEG recordings [in German]. EEG EMG Z Elektroenzephalogr Elektromyogr Verwandte Geb. 1982;13(2):51-60.
- Journal of Clinical Sleep Medicine. 2007;3(2):107.
- Fitch F, Bernstein SJ, Aguilar MS, et al. The RAND/UCLA Appropriateness Method User’s Manual. Santa Monica, Calif: RAND Corporation; 2001.