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, Page: 1 2 3 4 Related medicine news :1
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