Lost sleep finds reprieve in standards

2008-04-01

We've all had mornings when we've felt worn down, dragged out, and tired beyond what we'd expect from the number of hours we've slept. For most people, it's nothing to worry about. But for millions of Canadians, it's a sign of the condition known as sleep apnea.

The Canadian Lung Association reports that about one in five Canadian adults, and thousands of children, suffer from sleep apnea. While sleeping, an individual afflicted with sleep apnea will repeatedly stop breathing for short periods.

Obstructive sleep apnea, which occurs when the back throat-muscles relax so completely that they block the person's airway, is considered the most common form of the condition.

Not only is there medical treatment available to people with obstructive sleep apnea, but the latest revisions to an international standard on the condition will now make those afflicted more likely to use it.

The Continuous Positive Air Pressure (CPAP) treatment—most widely prescribed to treat this form of sleep apnea since 1985—involves using a machine that blows air through a mask worn on the patient’s face while sleeping. The continuous pressure created by air props open the back of the patient's throat, and prevents stoppages in breathing.

However while CPAP therapy is effective, many people who have tried it, have stopped before completing treatment. One reason some patients cite for quitting is that they find the blower part of the system to be too noisy to allow them to sleep well, during treatment.

The 2007 revisions to the International Organization for Standardization (ISO)'s standard for sleep apnea breathing therapy (ISO 17510-1-2) address the problem of noisy machines, says Dr. Karen Brown, an anaesthesiologist at McGill University, and vice-chair of the Canadian committee that helped revise the standard.

"It should encourage people to use CPAP therapy more," she adds.

The previous edition of the sleep apnea standard is recognized as a National Standard of Canada, meaning that the national version (CAN/CSA-C22.2) meets specific criteria established by the Standards Council of Canada including language availability and consideration for its effects on trade. The Canadian Standards Association (CSA) is currently working on revisions to this document.

The latest version of the international standard also address various safety concerns with the CPAP machines. Dr. Brown explains that the international standard requires the air tube connecting the mask to the blower to be more resistant to kinks so as to address a situation where the patient where to roll onto the tube while asleep. Also, she says the standard includes testing requirements that could prevent patients from suffocating should the machine lose power during the night.

A possible power outage could present "a big issue," according to Dr. Brown. Since the blower usually keeps forcing oxygen into the mask, a patient’s exhaled carbon dioxide is simply blown away. But if the power was to go out, and the patient didn't wake-up when the machine shut-off, the patient could potentially suffocate from re-breathing the build-up of exhaled carbon dioxide in the mask. The re-breathing test, included in the revised standard, helps manufacturers determine whether the mask attachment allows the patient to breathe fresh air even when the machine isn't working.

"This is Canada: we're going to have power outages," Dr. Brown said. "These changes should help people feel safer when using CPAP."

Anything that makes it more likely that people will continue CPAP treatment is good news. The Canadian Lung Association says people abandoning CPAP is the main reason therapy stops working.

People with sleep apnea tend to be chronically overtired because they wake up briefly when they gasp for air at the end of each sleep pause. Dr. John Fleetham, a respirologist at the Vancouver General Hospital in British Columbia, says this poor quality of sleep can seriously affect a person's daily functioning.

"Daytime sleepiness has major impact in terms of work performance," he says. "And it's a major cause of motor vehicle accidents: if you have sleep apnea, you're seven times more likely to have a motor vehicle accident."

Sleep apnea has also been linked to serious illness, such as heart disease and stroke. Dr. Fleetham says this is due to the extra strain on the heart, and higher blood pressure caused by the momentarily reduced supply of oxygen.

"It's felt to be as important as hypertension and diabetes in terms of contributing to heart attack and strokes," Dr. Fleetham says.

He considers CPAP treatment to be the most important one developed in respirology in the last 25 years.

"This treatment is incredibly important to people with sleep apnea," says Dr. Fleetham. "It's very common condition—the estimates globally are about a million people being started on this treatment a year."

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