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Complex Apnea May Explain Sleepless Nights

by Neela George on  September 2, 2006 at 2:23 PM Research News   - G J E 4
Complex Apnea May Explain Sleepless Nights
Failure of continuous positive airway pressure to resolve apparent obstructive sleep apnea may result in complex sleep apnea syndrome according to researchers.
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Timothy Morgenthaler, M.D., of the Mayo Clinic, and colleagues, reported in the Sept. 1 issue of Sleep reports that complex sleep apnea syndrome may cause a patient to lose sleep from a combination of physical and neurologic causes.

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According to the researchers poor sleepers with symptoms consistent with both the obstructive and central forms of sleep apnea constitute a poorly recognized class of patients requiring novel therapies.

A consensus panel of sleep experts from the Europe, United States, Asia and Australia recently recommended classification of sleep-related breathing disorders into three clinical entities which are obstructive sleep apnea or hypoapnea syndrome marked by physical causes of airway disruption, central apnea-hypoapnea syndrome, and the Cheyne-Stokes breathing syndrome are related to abnormalities in central nervous control of respiration. However Mayo investigators have found that some patients with sleep apnea don't fit neatly into any of those categories.

Dr. Morgenthaler said, "All of us in our sleep lab have observed for years that there are patients who appear to have obstructive sleep apnea, but the CPAP doesn't make them all that much better. They still have moderate to severe sleep apnea even with our best treatment and subjectively don't feel they're doing very well.

"When they're put on a CPAP machine, they start to look like central sleep apnea syndrome patients. This phenomenon has been observed for years, but this study is the first attempt to categorize these people," he said.

Dr. Morgenthaler and colleagues conducted a retrospective review of 223 consecutive patients referred to the Mayo Clinic Sleep Disorders Center for evaluation over one month, plus an additional 20 consecutive patients who had been diagnosed with central sleep apnea.

Data on medical history, hypertension, diabetes, body mass index, polysomnography, and treatment were reviewed. They excluded all patients with a clinical history of congestive heart failure or a left ventricular ejection fraction at 40% or less, leaving at total of 219 patients for analysis.

The researchers proposed that patients have obstructive apnea if they had five or more combined episodes of obstructive apnea and hypoapneas per hour, or if the patients complained of sleepiness and had 10 or more respiratory-related arousals per hour, which is consistent with the presence of the upper airway resistance syndrome. Patients who have the central apnea index was higher than five events per hour, and at least 50% of the total apnea-hypoapnea index was central in origin and without obstructive components was said to have central sleep apnea. Failure of continuous positive airway pressure to resolve apparent obstructive sleep apnea, complex sleep apnea syndrome may result according to researchers Timothy Morgenthaler, M.D., of the Mayo Clinic, and colleagues, reported in the Sept. 1 issue of Sleep reports that complex sleep apnea syndrome may cause a patient to lose sleep from a combination of physical and neurologic causes.

According to the researchers t poor sleepers with symptoms consistent with both the obstructive and central forms of sleep apnea constitute a poorly recognized class of patients requiring novel therapies.

A consensus panel of sleep experts from the Europe, United States, Asia and Australia recently recommended classification of sleep-related breathing disorders into three clinical entities which are obstructive sleep apnea or hypoapnea syndrome marked by physical causes of airway disruption, central apnea-hypoapnea syndrome, and the Cheyne-Stokes breathing syndrome are related to abnormalities in central nervous control of respiration. However Mayo investigators have found that some patients with sleep apnea don't fit neatly into any of those categories.

Dr. Morgenthaler said, "All of us in our sleep lab have observed for years that there are patients who appear to have obstructive sleep apnea, but the CPAP doesn't make them all that much better. They still have moderate to severe sleep apnea even with our best treatment and subjectively don't feel they're doing very well.

"When they're put on a CPAP machine, they start to look like central sleep apnea syndrome patients. This phenomenon has been observed for years, but this study is the first attempt to categorize these people," he said.

Dr. Morgenthaler and colleagues conducted a retrospective review of 223 consecutive patients referred to the Mayo Clinic Sleep Disorders Center for evaluation over one month, plus an additional 20 consecutive patients who had been diagnosed with central sleep apnea.

Data on medical history, hypertension, diabetes, body mass index, polysomnography, and treatment were reviewed. They excluded all patients with a clinical history of congestive heart failure or a left ventricular ejection fraction at 40% or less, leaving at total of 219 patients for analysis.

The researchers proposed that patients have obstructive apnea if they had five or more combined episodes of obstructive apnea and hypoapneas per hour, or if the patients complained of sleepiness and had 10 or more respiratory-related arousals per hour, which is consistent with the presence of the upper airway resistance syndrome. Patients who have the central apnea index was higher than five events per hour, and at least 50% of the total apnea-hypoapnea index was central in origin and without obstructive components was said to have central sleep apnea

They diagnosed complex sleep apnea if CPAP titration eliminated events defining obstructive apnea, but patients still had a residual central apnea index of 5 per hour or more, or development of a prominent and disruptive Cheyne-Stokes respiratory pattern.

They diagnosed complex sleep apnea if CPAP titration eliminated events defining obstructive apnea, but patients still had a residual central apnea index of 5 per hour or more, or development of a prominent and disruptive Cheyne-Stokes respiratory pattern.

heir study revealed that the prevalence of obstructive apnea was 84% in the one-month sample population, compared with 15% for complex apnea, and 0.4% for central apnea. The diagnostic apnea-hypoapnea index for the complex syndrome was 32.3±26.8, compared with 20.6±23.7 for obstructive apnea, and 38.3±36.2 for central apnea (P=0.005).

The researchers reported, "Patients with complex sleep apnea syndrome are mostly similar to those with obstructive sleep apnea-hypoapnea syndrome until one applies CPAP. Like patients having obstructive sleep apnea hypoapnea syndrome, they differ from patients with central sleep apnea in that they have less sleep maintenance insomnia."

They concluded that Neither the pathophysiologic mechanisms nor optimal treatment for patients with complex sleep apnea are known.



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