|Courtesy of Itamar Medical
For millions of people living with undiagnosed sleep apnea, home sleep monitoring may be the best option for assessing this serious yet treatable disorder. State-of-the-art mobile apnea assessment tools provide a less stressful and very cost-efficient alternative to traditional sleep evaluation centers.
Home sleep monitoring also gives primary care physicians a way to help patients with this common, sometimes life-threatening condition. That's important, given that a fairly large number of patients in any typical primary care practice have undiagnosed and untreated apnea.
In order to properly assess apnea, it is important to understand exactly what it is. "Apnea" is a Greek word meaning "without breath." This refers to the lapses in breathing that occur in patients with the condition. Cessation of breath for sleeping adults is defined as going 10 seconds or more without a breath.
In children—and be aware that this disorder can occur at any age—apnea is defined as a breathless interval lasting for the equivalent of two and a half missed breaths.
The National Institutes of Health has determined that more than 12 million Americans have been diagnosed with sleep apnea. An equally staggering number are thought to be undiagnosed but living with the condition.
The most common type of apnea is termed "obstructive" sleep apnea, and occurs when the airway is blocked by tissue collapsing at the back of the throat. When we are awake, muscle tone keeps our airways open to allow for normal breathing. In an individual with apnea, decreased muscle tone as the body relaxes into sleep combines with the effect of gravity, resulting in airway narrowing.
This is when snoring ensues. There are theories that snoring results in repetitive airway trauma leading to inflammation and edema, which further decrease airway size. Submucosal fat may also contribute to compression when electrical activity of pharyngeal muscles decreases during sleep.
The airway narrowing results in reduced blood oxygenation. The brain detects this, and subsequently triggers a sudden arousal, opening the airway to get a breath past the obstruction.
This cycle of relaxation leading to obstruction, reduced oxygenation and subsequent arousal may occur hundreds of times a night resulting in non-restful or poor quality sleep. People with sleep apnea often complain of fatigue; they're never getting enough deep sleep.
Sleep Lost, Weight Gained
Chronic fatigue and sleep deprivation results in overproduction and under-expression of hormones called ghrelin and leptin. Leptin is secreted by adipose cells and triggers the brain to reduce appetite. Ghrelin is secreted by the stomach and other organs and stimulates appetite.
Apnea-associated imbalance in these hormones results in increased appetite and greater calorie consumption. Coupled with decreased physical activity due to fatigue, this promotes weight gain and worsening sleep apnea, a vicious cycle that can be very difficult for patients to break without help.
Sleep apnea also results in insulin resistance. Patients with apnea show impaired insulin secretion, decreased insulin effectiveness in stimulating glucose uptake by skeletal muscles, and reduced ability to restrain hepatic glucose production.
The good news is that treating sleep apnea with Continuous Positive Airway Pressure (CPAP) has been shown to decrease levels of both ghrelin and leptin, and it has great benefit in normalizing metabolism and helping patients manage their weight.
The Apnea Profile
Most apnea patients share common characteristics: they are overweight or obese, male, over age 40, smokers, and have a family history of the disorder. But be aware that apnea also occurs in many individuals not fitting that profile, including children.
The first recognizable symptom of sleep apnea is snoring, which is a factor in the low quality of sleep (for the patient and his/her bed-mate) and chronic exhaustion. But snoring is one of the least threatening aspects of the condition.
More worrisome is the high blood pressure and the markedly increased risk of cardiovascular events, attributed to the repeated cessation of oxygen flow during sleep. Ultimately, in severe cases, the low blood oxygen could trigger a cardiac event resulting in sudden death.
Medicare Awakens to the Problem
Until recently, diagnosis and treatment of sleep apnea were the province of sleep specialists, and it obliged patients to spend nights in sleep evaluation labs. While there is still a role for specialized sleep centers, particularly in severe and difficult cases, home monitoring technology now enables primary care doctors to diagnose a far greater number of these individuals in a manner that is more convenient for the patient and usually less expensive.
In March 2008, Medicare approved reimbursement for sleep apnea home evaluation. Previously, Medicare would only pay for apnea treatment—and only in the elderly for that matter—but not the diagnostic testing. Medicare's newfound willingness to cover home monitoring reflects a growing scientific and clinical awareness of the dire health consequences of apnea. Other commercial insurance companies are starting to follow Medicare's lead.
Several companies now market excellent equipment for reliable home assessment of apnea, including Cleveland Medical Devices' "SleepScout" (www.clevemed.com), Instant Diagnostic Services' home sleep testing systems (www.instantdiagnostic.com), Respironics "RUSleeping" event monitors (www.respironics.com) and ResMed's "Apnea-Link" (www.resmed.com).
In my practice, I have been working with a device called the "Watch-PAT," made by Itamar-Medical an Israeli company with a US office in Framingham, MA (www.itamar-medical.com, 888-748-2627). The system utilizes two probes that fit painlessly over a patient's fingers. The probes plug into a small wrist-mounted device, similar to a wristwatch, that monitors and records blood oxygen levels as well as peripheral arterial tone (PAT) while the patient sleeps.
The Watch-PAT gathers a wealth of data without having to hook patients up to uncomfortable chest or face sensors. Sudden changes in the PAT signal identify apnea events with a high degree of specificity and sensitivity. The Watch-PAT also measures oxygen saturation, heart rate, sleep and wake states, and REM and non-REM sleep.
A computerized algorithm programmed into the device compiles the data and generates a summary report.
Itamar's PAT technology has been well validated in advanced research programs at the Framingham Heart Study, Mayo Clinic, Harvard School of Medicine, Boston University, New England Medical Center, Yale University, Pittsburgh University Medical Center, Mount Sinai NY, Cedars-Sinai, Johns Hopkins University, Emory University and others. These collaborations have yielded almost 50 peer-reviewed manuscripts.
Convenience, Comfort & Cost-Savings
Home sleep testing offers many advantages for both patients and physicians. Patients generally prefer sleep testing in the comfort of their own beds, rather than in an impersonal, unsettling sleep lab where they must try to sleep among total strangers while hooked up to strange and uncomfortable machinery. The probes used in sleep centers may, in fact, impede sleep. On the other hand, devices like the Watch-PAT are comfortable, non-intrusive, and well tolerated.
Because we're studying a patient in his/her own environment, the findings obtained are much more representative of what's actually happening in the patient's life. Simply put, home testing provides a more natural and reliable assessment. It also enables us to do sleep studies in accord with the patient's schedule, not that of a sleep center or its staff.
Home monitoring makes it far easier to get people to take part in sleep studies, which will in turn increase our apnea detection rate.
There are some significant cost savings, as well. An apnea diagnosis made via home monitoring is typically 50%–75% less costly than one made by a conventional sleep lab.
Home apnea assessment also enables us, as clinicians, to help patients who live far from a sleep center. Because of their ease of use, home monitoring devices make repeat testing a lot more feasible, allowing us to monitor the impact of apnea treatment.
New Revenue Streams
Home sleep testing can also benefit primary care doctors by providing us with an additional and much-needed revenue stream. The ease of use and minimal staff involvement can make it an optimal addition to our practices. Third party reimbursement varies from approximately $200–$750 for the global receipt.
In the future, physicians doing home monitoring may be required to obtain sleep board certification or affiliation with a sleep center headed by a physician boarded in sleep study interpretation and management. At this time, there are no such regulations specifying ownership of home monitoring equipment and, therefore, no regulations against billing for it.
In my practice, I utilize home testing for the diagnosis of suspected sleep apnea and for evaluating the efficacy of CPAP. It also helps me determine when I need to send more difficult cases to a certified sleep center for CPAP titration. This allows for precise determination of ventilatory support (CPAP or BiPAP in the majority of cases) and may also identify other sleep disorders such as periodic limb movement or other parasomnias not detectable by unattended home sleep testing.
I can recall many patients in my practice in whom apnea was not initially detected at a sleep center but who proved to have apnea on home monitoring. The false-negatives are likely due to the fact that these patients were not really able to sleep at the evaluation center, owing to the strange bed, monitoring equipment and the knowledge that they were being observed.
CPAP for Sleep Apnea
Although apnea has serious health implications, it does not necessarily call for surgical or pharmaceutical measures. In milder cases where there are fewer abnormal respiratory events per hour of sleep, lifestyle changes should be first line "treatment." This includes weight loss, smoking cessation, and for some patients, avoidance of certain sleep positions. Many people who sleep on their backs have apneas that can be avoided if they sleep on their sides.
Even small weight loss can relieve throat constriction, and lessen frequency of apnea. Alcohol and tranquilizers reduce pharyngeal muscle tone, so apneic patients should avoid them. Anti-inflammatory nasal sprays with low-dose steroids may be helpful if sinus congestion plays a role in airway obstruction.
For more significant sleep apnea, CPAP is usually effective. A CPAP device delivers air through a mask at greater pressure than the surrounding air, and keeps the upper airway open. Part of the art and science of treating apnea is in finding the correct pressure for each patient; it must be individualized. Once you find the correct settings (typically during a CPAP "titration" study), apnea is eliminated very quickly.
CPAP takes some getting-used to. A patient must adapt to having a foreign object around his head and placed over the nose, in the nostrils or around the nose and mouth. Most people adapt fairly quickly and end up being able to use it every time they sleep (including afternoon naps). Some CPAP systems include memory chips that store information about compliance, enabling us to determine how well a patient is utilizing the device.
At this time, Medicare requires compliance assessments on a regular basis. Yearly assessments of efficacy are also suggested in the form of repeat sleep studies either at home while using CPAP or in a sleep center.
Flemons WW, et al. Home diagnosis of sleep apnea: A systematic review of the literature: An evidence review cosponsored by the American Academy of Sleep Medicine, the American College of Chest Physicians, and the American Thoracic Society. Chest. 2003 Oct; 124(4): 1543–1579.
White DP. Monitoring peripheral arterial tone (PAT) to diagnose sleep apnea in the home. J Clin Sleep Med. 2008; 4(1): 73.
Collop NA. Portable monitoring for the diagnosis of obstructive sleep apnea. Curr Opin Pulmonary Med. 2008; 14(6): 525–529.
Lee A. Surkin, MD, completed a fellowship in cardiology at Yale University and holds a medical degree from Hahnemann University School of Medicine in Philadelphia, PA. He also has a master's degree in Nutrition from Columbia University School of Medicine and is board certified in cardiology and nuclear cardiology. Dr. Surkin has additional training in the evaluation and management of sleep disorders from the Atlanta School of Sleep Medicine and Technology. For more information, visit www.wellcor.com.