PURPOSE: Diverse physiological sensors have been utilized to quantify airflow limitation and respiratory effort in patients with suspected sleep related breathing disorders (SRBD). Due to both a lack of research and established guidelines, the diaphragmatic EMG (DEMG) is not recommended as a mandatory measurement of respiratory effort in general patient population. The current gold standard for defining central apnea requires an absence of both airflow and respiratory effort. We hypothesized that DEMG is as effective as the respiratory impedance plethysmography (RIP) belts for detecting both central apneas and other SRBD.
METHODS: We conducted a review of ten randomly selected polysomnographies (PSG) performed at the UMN sleep center. DEMG was utilized during all these studies. A total of 50 epochs of 60 seconds duration (5 epochs per PSG) with central apnea events were identified per the aforementioned standard. The respiratory effort in all these events was measured in pixels using the Image J software. The signal tracings of the DEMG, thoracic belt and abdominal belt were used from three breaths preceding the central apnea event and during the event to obtain these measurements. A comparison was made between the three signals in their ability to measure a decrease in the respiratory effort by comparing the percent decrease in the pixel strength. Finally the percent decrease in the DEMG was compared with both thoracic and abdominal effort individually.
RESULTS: DEMG showed a 93% decrease in the respiratory effort during the central apnea event. The decrease for the thoracic belt was 91% and the abdominal belt was 90%. There was no statistically significant difference between the three tracings.
CONCLUSION: DEMG measurements of respiratory effort can reliably identify central apnea events. Further studies are recommended to establish its effectiveness in diagnosis of other SRBD, including possible differentiation of REM hypopneas into obstructive vs. central.
CLINICAL IMPLICATIONS: DEMG measurements may offer an additional tool for clinicians in the differentiation of REM hypopneas.
DISCLOSURE: Snigdha Pusalavidyasagar, No Financial Disclosure Information; No Product/Research Disclosure Information