Twice as likely to die
The study of 112 Minnesota residents who died suddenly from cardiac causes found people with obstructive sleep apnoea were twice as likely to die during that time than those without the condition.

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That's a striking departure from the pattern of sudden death in the general population, which most often strikes in the hours right after awakening, said lead researcher Dr Virend Somers, a professor of medicine and cardiology at the Mayo Clinic, in Rochester, Minnesota.

"We have always been curious about why cardiovascular deaths can occur in the early hours of the morning, when people are peacefully sleeping," Somers said. The study, published in the March 24 issue of the New England Journal of Medicine, suggests that for people with sleep apnoea, sleep can be far from a time of quiet rest.

Heart function disturbed
Sleep apnoea consists of frequent stoppages of breathing lasting about 10 seconds - not enough to shake someone awake permanently, but enough to deprive a person of rest and cause drowsiness and lethargy throughout the following day.

More than 17 percent of South African are affected by sleep apnoea. Some cases are caused by problems with the brain centre that controls sleep, but most are due to collapse and obstruction of the air passages.

Sleep apnoea disturbs heart function in several ways, Somers said.

"If you hold your breath as long as you can, your blood oxygen levels drops to 90 percent of normal," he said. "In sleep apnoea, it drops to 60 percent of normal."

"And it is not just the fact that the body is subjected to low levels of oxygen during the night," Somers added. "Sleep apnoea tightens blood vessels and significantly raises blood pressure. With low levels of oxygen and high levels of carbon dioxide, several kinds of abnormal heart rhythms can develop during sleep apnoea."

No new treatment options
Unfortunately, the study does not provide any new way to manage the problem, Somers said.

"There is no clear message that is patient-oriented," he said. "It is one more brick in the wall about why we should be more aggressive in finding sleep apnoea and treating it."

One simple treatment is to tell people to sleep on their side, not on their back. Another effective method is to attack the obesity that is a major cause of sleep apnoea, Somers said, since weight reduction can often provide significant relief. If ordinary dieting and exercise fail, some patients may want to consider bariatric surgery, which shrinks the stomach and reduces the body's ability to take in calories, he said.

Surgery to reduce obstruction of the respiratory tract usually is not effective, Somers noted: "Surgical treatment often results in a recurrence of apnoea six months to a year later."

Some people are helped by CPAP - continuous positive airway pressure, in which air is forced into the body through a mask, he said, and "in really severe cases we can go to temporary measures such as tracheotomy," in which surgeons implant a breathing tube.

Many unaware of it
The study "is part of a growing body of evidence that this disease called sleep apnoea is deadly," said Dr Steven Feinsilver, a member of the board of directors of the American Sleep Apnea Association.

While the snorts and snoring caused by sleep apnoea are unmistakable to anyone in the same room, people who sleep alone often don't realise they have the condition, Feinsilver added.

"Most people with sleep apnoea know only that they are sleepy during the day," he said. Treatment is necessary "not only because it improves sleep, but also because treatment helps people live longer," he said. "It is a major risk factor for heart disease and stroke, and we are just beginning to learn how dangerous it is." – (HealthDayNews)
 

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