Although the usefulness of EMGdi is similar to esophageal pressure in terms of distinguishing central from obstructive sleep apnea, EMGdi can offer additional information on neural respiratory drive and is little affected by airflow and the changes in lung volume, told Dr. Yuan-Ming Luo from Guangzhou Medical College, Guangzhou, People’s Republic of China.

Dr. Luo and team conducted a study to assess the reliability of EMGdi for distinguishing central from obstructive sleep respiratory events and compared it with both esophageal pressure measurements and uncalibrated respiratory inductance plethysmography (RIP) which is the standard assessment used in many sleep laboratories.

The authors reported that there were no changes in EMGdi or esophageal pressure during central sleep apnea events, whereas EMGdi signals and esophageal pressure consistently detected obstructive sleep apnea events.

They also explained that both EMGdi and esophageal pressure measurements were significantly more accurate than conventional RIP in identifying central sleep apnea. EMGdi or esophageal pressure criteria found that about 30% of apneic events classified as central by uncalibrated RIP were not central.

Moreover, if uncalibrated RIP alone had been used to measure respiratory effort, 1 of 19 patients would have received a wrong diagnosis of central sleep apnea.

According to researchers esophageal pressure and EMGdi were not statistically different for the identification of obstructive events.

Don’t take conventional polysomnography as gold standard to diagnose central sleep apnea, Dr. Luo said. Any central sleep apnea should be further confirmed by esophageal pressure or EMGdi, especially in patients whose diagnosis is in doubt.

This technique may also be a powerful tool to assess the effect of any new device and treatment method on central sleep apnea, Dr. Luo added.