Obstructive Sleep Apnea
Obstructive sleep apnea (OSA) is defined as the cessation of airflow despite continuously respiratory effort. It occurs when the tongue and soft palate collapse onto the back of the throat, blocking the upper airway and causing air flow into the lungs to be interrupted. The temporary stoppage of air flow leads to gradual reduction in oxygen level and subsequent arousals. When in the partially awakening state, the airway contracts and opens, causing the obstruction in the airway to clear and for airflow to start again, resulting in a resumption of sleep. The severity of sleep apnea is defined by the frequency of interrupted airflow events during the night, the reduction in oxygen levels and the degree of sleep fragmentation caused those events.
Sleep apnea is associated with considerable effects on quality of life and patients’ general health. In addition to excessive daytime sleepiness, studies show that sleep apnea patients are much more likely to suffer from heart attack, congestive heart failure, hypertension, strokes, as well as having a higher incidence of work and driving related accidents.
In addition to lifestyle changes, including good sleep hygiene, exercise and weight loss, there are three primary ways to treat sleep apnea. The most common method is nocturnal continuous positive airway pressure (CPAP) therapy. CPAP is applied through a tube which connects a bed-side device to a mask that covers the patient’s nose. The air pressure that is generated by the CPAP device splints the back of the throat and holds the airway open during sleep.
Other treatment modalities include the use of an oral appliance, a non-invasive therapy, which provides similar benefits to those available through CPAP, or, one of a number of surgeries to the soft palate, uvula and tongue to eliminate the excess tissue that collapses during sleep. Some patients may require more complex surgeries to reposition the anatomic structure of the mouth and facial bones in a manner that enlarges the airways.
Oral Appliance Therapy
Oral appliance therapy involves the fitting and use of a specially designed and custom fitted intra-oral device worn during sleep. Oral appliances are designed to enlarge the pharyngeal airway during sleep by repositioning and stabilizing the lower jaw and/or the tongue and by increasing the muscle tone of the tongue. The many FDA-approved oral appliances to choose from can generally be classified into one of the following categories:
- Tongue retaining appliances.
- Mandibular repositioning appliances.
Oral appliances are fitted and supported by dentists trained in this mode of therapy. The Academy of Dental Sleep Medicine has suggested the following criteria for use of oral appliance in the management of obstructive sleep apnea:1
- Patients with primary snoring or mild OSA who do not respond to, or are not appropriate candidates for treatment with behavioral measures such as weight loss or sleep-position change;
- Patients with moderate to severe OSA who are intolerant of or refuse treatment with nasal CPAP;
- Patients who refuse treatment, or are not candidates for tonsillectomy and adenoidectomy, cranofacial operations or tracheostomy.
Advantages of Oral Appliance Therapy
Oral appliance therapy has several advantages:
- Treatment with oral appliances is non-invasive, adjustable and reversible;
- Many patients failing or refusing CPAP therapy find oral appliances to be comfortable and easy to wear after a couple of weeks of acclimation to wearing the appliance;
- Oral appliances can be easily carried when traveling, allowing uninterrupted therapy.
Once a patient diagnosed with OSA is fitted with an oral appliance, on-going care, including short and long-term follow-up, is an essential element in the continuing management of the patient. Follow-up office visits with the dental specialist who initiated the therapy should be scheduled at least every six months during the first year, and at least annually thereafter, in order to monitor patient adherence, evaluate device deterioration or maladjustment, evaluate the health of the oral structures and integrity of occlusion, and assess the patient for signs and symptoms of worsening OSA. The American Academy of Sleep Medicine, in its recently updated Practice Parameters for the Treatment of Snoring and OSA with Oral Appliances,2 has recommended that an objective sleep study should be conducted for patients receiving an oral appliance after final adjustments of fit have been performed in order to assess the efficacy of the treatment.
Use of Portable Systems to Manage OSA
The primary means of confirming sleep apnea, following a review of medical history, symptoms and a physical exam, is to conduct a sleep study. Polysomnography (PSG), generally conducted in a hospital or in a standalone sleep laboratory facility, is considered as the most comprehensive sleep study, indicated for the diagnosis of nocturnal breathing disorders, neurological disorders such as narcolepsy and restless leg syndrome and parasomnia. In recent years, a large number of published reports have corroborated the use of new devices in providing an accurate and clinically effective diagnosis of OSA, as an alternative to PSG for many of the suspected patients.3,4,5 Most such devices record a fewer number of physiological parameters compared to PSG, as they focus mostly on diagnosing nocturnal breathing disorders rather than neurological disorders. The reduced number of monitored channels and the corresponding simpler patient interface enable such devices to be used at patients’ homes, a venue offering not only greater convenience, but in many instances, an evaluation of the patient’s natural sleep patterns in a setting devoid of artifacts caused by the foreign environment in which PSG is conducted.
As the number of patients presented with symptoms of sleep apnea continues to increase, a growing number of healthcare providers have incorporated portable systems as an optional alternative to PSG studies. An appropriate application of portable devices by qualified clinicians may often result in an enhanced level of service and reduced cost for patients and payers. The use of portable devices may shorten the time from it takes to initiate treatments to at-risk patients and address special patients’ needs. Portable devices can also play a unique role during the continuing care and follow-up phase of patients with sleep apnea, since at-home studies may offer faster and more representative information, in comparison to in-hospital PSG, when assessing the efficacy of a new therapy, or after making changes in ongoing treatment parameters.
The role of portable devices (also referred to as ‘ambulatory’ or ‘Level 3´) in ruling-out or confirming sleep apnea, or in the continuing management of the disease, is being continuously evaluated by professional societies, health plans and other healthcare policy groups, such as Minneapolis-based Institute for Clinical Systems Improvement (ICSI), which has recently suggested the following guidelines:6
“In patients with a high pretest probability of OSA, unattended portable recording for the assessment of obstructive sleep apnea is an acceptable alternative to standard polysomnogram in the following situations
1. Patients with severe clinical symptoms that are indicative of a diagnosis of obstructive sleep apnea and when limitation of treatment is urgent and standard polysomnography is not readily available;
2. For patients unable to be studied in the sleep laboratory, and
3. For follow-up studies when diagnosis has been established by standard polysomnography and therapy has been initiated.”
“Employment of portable monitoring as a second-best option is not likely to result in harm to patients with a high pretest probability of OSA, and may result in less risk than leaving the condition undiagnosed.”
The Watch-PAT (manufactured by Itamar Medical Ltd.) is an advanced diagnostic system for OSA. Initially approved by the FDA in 2001 as a portable system intended for the diagnosis and assessment of OSA, the Watch-PAT is one of the most user-friendly systems currently available, extracting the physiological information required to determine the presence and severity of OSA using a small wrist-mounted device connected to two sensors attached to the patient’s fingers. The Watch-PAT minimal and highly compact patient-device interface is dramatically contrasted with other portable systems which collect data during the night through a larger number of sensors, including some attached to the patient’s face and chest and connected by long wires to the device itself. Such sensors, in addition to contributing to patient anxiety and discomfort during sleep, are also at a higher risk of falling off during the night, compromising the quality of the data.
The Watch-PAT unique patient’s interface enables the reliable use of the system in patients’ homes, eliminating many of the variables and inaccuracies presented in studies conducted outside the natural and regular sleeping environment. Instructing the patient on operating the single-button Watch-PAT and mounting the two external sensors is generally accomplished in less than ten minutes. Once the study is completed, the information collected during the night is downloaded automatically into a standard office PC (pre-loaded with the data analysis software). This data is than analyzed (‘scored’) and within a few minutes a report is generated on the screen and a hard copy is printed. The automatic data analysis offers consistency, repeatability and accuracy unmatched by the variability of manual scoring. While in most instances only the final report is required to assess severity of sleep apnea or to evaluate the efficacy of a therapy, the entire raw data collected during the study is still available for review, further analysis or documentation.
Although the raw data is acquired from a small number of sensors embedded or attached to the Watch-PAT, the amount of clinical information provided at the completion of the study is significant. The Watch-PAT reports include all information required to accurately assess and quantify the severity of the sleep apnea, including values of all common indices, such as AHI, RDI, ODI and heart rate. In addition, the Watch-PAT also identifies and records sleep, wake and REM states, providing measures of respiratory and apnea indices based on actual sleep time, rather than ‘bed time’. The Watch-PAT is actually the only system that provides this important information without attaching EEG sensors to the patient’s skull. This sleep data enables a clinician managing any of the optional therapies to evaluate the quality of sleep pre and post intervention, and make necessary adjustments, when necessary. Sleep architecture and fragmentation can be assessed and quantified, including confirmation that the patient has entered and received sufficient amount of REM sleep.
The Watch-PAT is being used on a regular basis in a diverse range of medical establishments, including academic and community hospitals, stand-alone sleep labs, physician offices, as well as dentists specializing in oral appliance therapy. The large body of clinical experience accumulated in recent years is reflected in the extensive list of publications, reporting on multiple validation and outcome studies.7
sleep apnea have incorporated the Watch-PAT into their respective protocols, taking advantage of its versatility, accuracy and simple patient’s interface. Following recommended practice guidelines, such specialists use the Watch-PAT to identify optimal settings of the device, demonstrate and document treatment efficacy, or rule-out sleep apnea before fitting an appliance to patients seeking relief for primary snoring.
The primary goals of oral appliance therapies include lowered AHI, reduced daytime fatigue and significantly attenuated snoring. Once an appliance is fitted, it is recommended that an assessment is made to demonstrate and document treatment efficacy. In practices using the Watch-PAT, patients can now be evaluated objectively, measuring their breathing disturbances and sleep quality with and without the appliance in place. Until incorporating the Watch-PAT, dentists fitting oral appliances had to rely on patients’ own reports on how well the treatment works, or send patients for a PSG study in one of the local sleep labs to objectively evaluate treatment efficacy. In some situations, patients were equipped with pulse oximetry for an in-home recording. While PSG provided the required information, it was in most instances associated with significant time delays, inconveniency to the patients and an additional significant cost outlays to patients or their health plans. Oximetry studies, while conducted at the privacy and convenience of patients’ homes, simply do not provide sufficient clinical information to appropriately determine treatment efficacy. Most other portable devices used by dentists for this purpose lack data on actual sleep patterns and quite often, are too cumbersome for most patients to handle independently.
Some practices use the Watch-PAT to only evaluate the actual and absolute level of apneas once the appliance has been properly titrated, as determined by patient’s own report on improvement in his or her sleep and daytime fatigue. Other practices record data using the Watch-PAT, first without the appliance and than again, with the oral appliance in place. Having two Watch-PAT studies, one serving as the base line and the other as a post-intervention record, each with numerical and graphical summaries of breathing patterns, apnea indices, oxygen desaturation levels, sleep time and amount of REM sleep, allow for an easy, simple and accurate assessment of the effectiveness of the treatment. Most dentists review the reports with their patients, and when requested, provide copies to their primary care physician and/or the diagnosing sleep lab to assist in additional follow-up, as needed.
Typically, the studies with the Watch-PAT are conducted a number of weeks after initiation of therapy in order to assess the ‘steady state’ performance. In certain cases, especially those associated with patients presented with extremely high AHI, if studies point to insufficient therapeutic results in spite of an elaborate and methodical titration process, such patients are referred back to the sleep lab for a retry of CPAP therapy, potentially in conjunction with an oral appliance. In certain situations patients may also be advised to seek an opinion about one of the surgical options.
A number of specialists have modified their protocol to better accommodate local practices or to better integrate their efforts with the local sleep labs. In one of the active practices contacted for this report, patients are instructed to adjust their device until they realize significant reduction in their pre-treatment symptoms, including less daytime fatigue, improved alertness and reduced snoring. A sleep study using the Watch-PAT is than being conducted to confirm low AHI, acceptable sleep architecture and sufficient REM. Once this is done, patients are referred back to the sleep lab that has performed the original diagnosis, where they undergo a full-night PSG coupled with an in-lab oral appliance titration. Recent analysis conducted by the practice confirmed that the current protocol does achieve the optimal setting for most patients, although in certain cases, the final PSG/titration study suggests further adjustment of the appliance.
Most patients seen today by oral appliance specialists have already been diagnosed in a sleep lab and in most instances have tried and failed, or simply refused, CPAP treatment. Yet, some patients are self-referred, typically with complaints of heavy snoring. While some dentists send all such patients for a PSG in one of the local sleep labs, some will conduct a series of evaluations, including an assessment of daytime sleepiness, physical evaluation and medical history, and, if as a result of such evaluations determine that a given patient is unlikely to have sleep apnea, will order a study with the Watch-PAT to obtain a final and conclusive confirmation of primary snoring with no sleep apnea. Some of these self-presenting patients may have had a sleep study years ago, and after failing CPAP have remained untreated for long time and are now considering resumption of therapy with an oral appliance. Such patients are generally encouraged to undergo a new PSG study to evaluate their current sleep apnea. Some practices, when encountering patients that simply refuse or are otherwise unable to undergo an in-lab PSG, will conduct a home study as an alternative, as suggested by the respective guidelines. Some dentists have been trained in the diagnosis of sleep apnea and thus, review the study results themselves in order to determine suitability for treatment, while other dentists rely on a review of the data by a sleep specialist to advise them before proceeding with therapy.
In addition to offering a methodical clinical pathway and verification of treatment efficacy, the Watch-PAT contributes also to overall patients’ satisfaction. As most patients are already experienced with an in-lab PSG study performed for their primary diagnosis, they recognize the pros and cons of the Watch-PAT study. Indeed, dentists offering their patients the Watch-Pat as an alternative to an additional PSG point to a high degree of satisfaction from these patients who appreciate the convenience and privacy of the at-home study, and at times, its lower cost, especially when they are responsible for a considerable portion of the charges of the test as a result of deductibles or a significant co-pay.
The number of patients seeking treatment for sleep apnea is increasing rapidly, in tandem with the growing understanding of the debilitating effects of the disease and its implications on quality of life and other serious morbidities. CPAP is considered the first and preferred mode of therapy for sleep apnea. However, in-spite of many improvements made in such devices, significant percentage of patients requiring therapy either resist the treatment or fail to comply with it over time. Other than changes in lifestyle and significant reduction in weight, the only other non-invasive option available for these patients is use of an oral appliance therapy. Once used mostly for primary snoring, such appliances are now recommended for patients with mild and moderate, and in certain instances, even severe sleep apnea. A growing number of dentists are now providing oral appliance therapy to larger numbers of patients referred to them by sleep specialists after these patients have failed CPAP therapy, or self-referred patients, especially those seeking relief from snoring. Guidelines published by the Academy of Dental Sleep Medicine emphasize the importance of conducting follow-up studies for such patients. The Watch-PAT system provides friendly patient’s interface and ability to measure breathing parameters and oxygen desaturation levels, as well as sleep time and quality. The Watch-PAT is quickly becoming the system of choice for dentists involved in the delivery of oral appliance therapy, replacing older, less sophisticated and more cumbersome systems, or providing an alternative to repeat PSG studies on one hand, or reliance on clinically-limited measures such as pulse oximetry, on the other hand. Primary application of the Watch-PAT within an oral appliance practice is during the assessment of optimal titration of the appliance and in generating treatment efficacy records. Other applications of the Watch-PAT include identifications of failed oral appliance therapy, or using it to rule-out sleep apnea in patients complaining about snoring. Patients’ response to the Watch-PAT studies is highly favorable, and all clinicians contributing to this report have expressed high degree of satisfaction with the system.
2. “Practice Parameters for the Treatment of Snoring and OSA with Oral Appliances: An Update for 2005” American Academy of Sleep Medicine Report, 2005, Sleep, Vol. 29(2), 240–243.
3. Bar A, Pillar G, Dvir I, Sheffy J, Schnall RP, Lavie P. Evaluation of a portable device based on arterial peripheral tonometry (PAT) for unattended home sleep studies. Chest, March 2003, 123(3):695–703.
4. Pittman DS, Ayas NT, MacDonald MM, Malhotra A, Fogel RB, White D. Using a Wrist-Worm Device Based on Peripheral Arterial Tonometry to Diagnose Obstructive Sleep Apnea: In-Laboratory and Ambulatory Validation. Sleep 2004, Vol.27 (5), 923–933.
5. Penzel T, Kesper K, Pinnow I, Becker FH, Vogelmeier C. Peripheral arterial tonometry, oximetry and actigraphy for ambulatory recording of sleep apnea. Physiol. Meas. 25 (2004) 1–12.
6. ICSI, Diagnosis and Treatment of Obstructive Sleep Apnea, Third Edition, March 2005.