We all long for it, we all revel in it,
we all get too little of it. Sleep.
It's a much-squandered, sometimes elusive activity, to which we surrender each night. Sleep is supposed to be, by definition, restful and relaxed, but we've all, on occasion, experienced interruptions in sleep-a bad dream, a late-night trip to the bathroom, or an after-hours urge for chocolate cake. Most nights, however, we're fortunate enough to get the rest our bodies need. People who suffer from a common sleep disorder called sleep apnea, though, aren't so lucky. Night after night, sleep is interrupted when patients momentarily stop breathing.
The condition
Sleep apnea is a potentially life-threatening condition that interrupts breathing during sleep. The most common types of the condition are obstructive and central sleep apnea.
Obstructive sleep apnea, also known as the "snoring disease," is a chronic condition which causes patients to briefly stop breathing while asleep. This phenomenon occurs when the flesh and muscles of the tongue and throat relax so much that it blocks the airway, preventing any airflow. The patient is awakened by the consequent lack of oxygen in the blood and prompted to begin breathing again. This may occur with a loud snort or body jerk.
Central sleep apnea is the condition that occurs when the brain forgets to tell the muscles of the chest and diaphragm to keep breathing. Patients start and stop breathing at various intervals, instead of jerking awake in order to resume breathing.
Apnea episodes can occur as many as 100 times per hour. As a result, patients rarely feel refreshed when they wake up, even if they've had 10 hours of "sleep."
U of C Heritage researcher Dr. John Remmers explains: "The frequent interruption in sleep that is caused when patients stop breathing doesn't allow them to experience deeper sleep, or dream sleep. So, a patient may have slept for more than eight hours but actually obtained very little refreshing sleep."
Dr. Remmers has spent 14 years as a Heritage scientist studying the basic functioning of the lungs including how the brain controls breathing. He is a world authority on sleep apnea and an innovator in sleep disorder technology.
Its effects
Sleep apnea can have a dramatic effect on a patient's physical and mental health. Body organs can be affected by the lack of oxygen. Apnea episodes may put increased pressure on the heart, causing it to work harder. This can increase blood pressure and put patients at risk for stroke. Such frequent disturbances in sleep often affect patients' ability to cope with their day-to-day routine. "Most of us know that when we don't get enough sleep, we feel pretty rotten the next day. The sorts of symptoms we experience are very similar to those of patients with sleep apnea, except they have them in a more profound form. In addition to fatigue and excessive daytime sleepiness, the patient is often irritable, depressed, unable to think clearly, and may suffer from headaches," Dr. Remmers says.
The symptoms of sleep apnea can seriously affect a patient's personal and professional life. Severe sleep deprivation may contribute to reduced productivity at work, increased motor vehicle and industrial accidents and death, and increased health care costs. Patients aren't the only ones who suffer the effects of the condition. Bed partners may also lose sleep because of their mate's snoring or apnea episodes. Irritability from lack of sleep can also cause tension between the patient and family members. Sleep apnea has even contributed to divorce.
Risk factors
Snoring, gasping at night, high blood pressure, and being overweight are warning signs of sleep apnea. If you have a history of these signs, there's a good chance you have the condition.
About 7% of adult North Americans suffer from sleep apnea. In fact, 9% of men and 4% of women experience apnea episodes at least 10 times per hour. Anyone can have the condition, but it is more common among men than women. It can affect people in their mid-20s, but is most common in middle age. "Sleep apnea patients usually snore, but not everyone who snores develops sleep apnea," emphasizes Dr. Remmers.
Diagnosis
At present, patients are referred by their family doctor to a sleep lab, where they are examined by a sleep disorder specialist. If deemed necessary, a polysomnogram, a complicated test that measures 16 variables recorded during an overnight stay, is administered to help diagnose the condition. An expert technician monitors the sleeping patient. The cost of this procedure is as much as $2,000. However, new technology pioneered by Dr. Remmers and supported by the AHFMR's Technology Commercialization program, allows patients to be tested at home, eliminating these inconvenient and expensive hospital stays. Patients need only come to the hospital to pick up the small device and get instructions on its use. SnoreSAT costs about $150 to administer.
How the home monitor works
Patients hook themselves up to two probes-an oxygen probe is applied to the index finger, and a microphone is taped to the base of the neck. The patient simply turns on a bedside monitor, shuts off the lights, and retires for the night. In the morning, the machine is turned off and returned to the sleep lab for analysis by a computer. Results are then forwarded to the patient's doctor.
SnoreSAT is currently being tested in clinical trials across Canada. Dr. Remmers expects the device to be patented and become commercially available sometime in 1998. U.S.-based Healthdyne Technologies has licensed the technology, along with autoCPAP, another of Dr. Remmers' sleep apnea innovations.
At present, there is no cure for sleep apnea. Significant weight loss can greatly diminish or even eliminate the condition in overweight people. However, such weight loss is often very difficult to achieve. Another approach is laser surgery on the soft palate. While this procedure can eliminate snoring, it's usually ineffective in treating sleep apnea. Current treatment employs devices which hold the air passage open. The nasal CPAP (continuous positive airway pressure) device consists of a small bedside blower that generates low level air pressure which forces the air passage open and allows the patient to breathe normally. Dental appliances, which resemble mouth guards used by athletes, are also used to keep the airway open. The appliances, worn at night, pull the lower jaw and the tongue forward, opening the throat air passage.
CPAP has proved to be a highly effective treatment for sleep apnea. Although the device produces few side effects, it is cumbersome, and many patients have difficulty tolerating the fixed pressure it supplies. To remedy this, Dr. Remmers has refined his invention. He's developed autoCPAP, a smart device that automatically assesses the degree of airway obstruction and adjusts the pressure applied to the nose to correct breathing. AutoCPAP will be commercially available later this year. Alberta Health does not currently cover the cost of the nasal CPAP or dental device. As with SnoreSAT, autoCPAP is a cheaper alternative to the expensive hospital procedure.
Through the work of researchers such as Dr. Remmers, patients are now being offered alternatives to sometimes bleak outlooks. "The great thing about being physicians who treat people with sleep apnea is that we are often able to control the sleep apnea, allowing patients to sleep normally. Getting a good night's rest absolutely transforms patients. They become highly productive, 'normal' people."
Dr. John Remmers is a Heritage Scientist and Professor at the U of C. He also receives research support from the Medical Research Council of Canada, the Respiratory Health Network of Centres of Excellence (Inspiraplex), and the Alberta Lung Association.
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