Crural and costal diaphragm activity diverge during REM sleep

<bold>Introduction:</bold> During sleep, respiratory control and mechanics change: upper airway resistance, ventilatory response to CO2 and O2, diminished activity of chest wall and abdominal muscles. However, influence of sleep stage on costal (COS) and crural (CRU) diaphragm is not known. Methods Data N=10 canines, from a database completed in 2009, was analyzed breath by breath. Signals recorded mean 9 days after implantation of sonomicrometers and EMG electrodes into COS and CRU. Ventilation and length, shortening, and EMG were examined, during wakefulness (AWAKE), non REM (NREM) and REM sleep. Results Through AWAKE, NREM and REM, tidal volume was preserved, while Minute Ventilation, and frequency decreased significantly during NREM and REM (p< 0.01). Inspiratory flow (VT/Ti) was sleep stage dependent, decreasing AWAKE to NREM, then decreasing more with REM (p< 0.01). Concurrently, baseline length and EMG activity were not different, but COS and CRU action diverged significantly during sleep stages. COS length change per breath (shortening) increased as peak EMG activity increased, in NREM and REM – a stepwise increase in contractility. In contrast, CRU shortening showed little increase as EMG activity increased, then decreased significantly in REM compared to NREM (p< 0.01). <fig><object-id>erj;64/suppl_68/PA4461/F1</object-id><object-id>F1</object-id><object-id>F1</object-id><graphic></graphic></fig> Conclusion. As breathing pattern changes during sleep stage, there is divergence of diaphragm segmental action with notable decrease in crural diaphragm shortening during REM sleep.