New Method Could Pull the Mask Off Apnea Treatment

BALTIMORE, July 16 -- Delivering warm, humidified air through a nasal cannula can significantly reduce the symptoms of mild obstructive sleep apnea, researchers here say.
The treatment could eventually replace continuous positive airway pressure (CPAP) to control apnea, according to Hartmut Schneider, M.D., Ph.D., of Johns Hopkins Asthma and Allergy Center, and colleagues.
In the new method -- which uses a standard nasal cannula - "the nose is the mask," Dr. Schneider said.
"Treatment with nasal insufflation," as the method is called, could be more acceptable to patients than CPAP, which has an extremely low adherence rate, the researchers noted in the second July issue of the American Journal of Respiratory and Critical Care Medicine.
"We developed a simplified method for increasing pharyngeal pressure by delivering warm and humidified air at a continuous high flow rate through the open nasal cannula," they said.
To test the method, they performed a proof-of-concept study that included 11 patients with mild to severe apnea-hypopnea disorders. Apnea was defined as complete cessation of airflow for more than 10 seconds, while hypopnea was defined as a greater than 30% reduction of airflow.
The nasal cannula delivered humidified air - warmed to about 30 degrees C by a wire in the tube -- at a rate of up to 20 liters per minute, the researchers said.
In baseline testing the volunteers went to sleep with air flowing at five liters per minute. Once they reached a stable level of sleep, air flow was adjusted to zero, 10, or 20 L/min for five minute intervals in a random order.
Following the baseline tests, they were randomized to nights on and off at 20 L/min, the researchers said.
They found that the treatment:
Reduced the mean apnea-hypopnea index from 28 to 10 events per hour, which was significant at P<0.01.
Reduced the respiratory arousal index from 18 to eight events per hour (again significant at P<0.01).
Reduced the apnea-hypopnea index to fewer than 10 events per hour in eight of 11 volunteers, and to fewer than five events per hour in four participants.
"Although we expected marked improvements in the apnea-plus-hypopnea index primarily in patients with hypopneas rather than obstructive apneas, (the treatment) lowered the index in all subjects," the researchers reported.
While the finding is promising, they said, it still requires further clinical testing. Dr. Schneider said a larger clinical trial is currently under way in Germany and another is planned for the U.S.
He estimated that between a third and a half of apnea patients could benefit from the new method.
The "challenge in technology" was to find a way to provide air pressure in the nose and throat while improving comfort, Dr. Schneider said. Warming and humidifying the air proved to be the key.
"It's quite comfortable to wear the cannula," he said.
The study was partly supported by Seleon GmbH. Dr. Schneider receives consulting fees from Seleon and is entitled to royalty payments on the future sales of products described in the study. Co-author Alan R. Schwartz, M.D., of Johns Hopkins, also has financial links with Seleon. Primary source: American Journal of Respiratory and Critical Care MedicineSource reference: McGinley BM et al. "A Nasal Cannula Can Be Used to Treat Obstructive Sleep Apnea." Am J Respir Crit Care Med 2007; 176:194-200.