Abstract
Background: Little is known about diaphragmatic function during obstructive sleep apnea syndrome. On the other hand ultrasonography has been used to image the diaphragm diagnostically but not in obstructive sleep apnea. The aim of this study was to use ultrasound technique to evaluate and quantify diaphragm function in a rat model during sleep apnea under condition of normoxia.
Methods: Experiments were conducted in ten male adult Wistar rats weighing 350 gr, which were anaesthetized with Ketamine-Xylazine intraperitoneally. Animals were breathing after being tracheostomized and connected in a circuit with an electromagnetic valve which was closing periodically every minute for 10 sec for two hours, mimicking obstructive apnoeas. Supplemental oxygen was added to keep normal arterial saturation (SaO2:97%). Diaphragm Inspiratory Amplitude (DIA) (cm), Diaphragm Inspiratory Time (Ti) (sec), breathing period (Ttot) (sec), Diaphragm Motion Time (DMT) (sec) and Diaphragm Resting Time (DRT) (sec) were measured from the M- mode sonographic images. Data analyzed and compared between quite breathing (time 0) and breathing after two hours of airway obstructions (time 0+2).
Results: All diaphragmatic measurements (DIA,Ti,Ttot, DMT and DRT) from time 0 to time 0+2 were compared using the Wilcoxon signed-rank test and showed a statistically significant reduction (p<0.05) between the two time points.
Conclusions: These findings suggest that diaphragmatic function is affected acutely during obstructive sleep apnea. It is also indicated that diaphragmatic fatigue as expressed via DIA,DMT,DRT,Ti and Ttot is present independently of hypoxeamia after two hours of airway obstructions during sleep.
- © 2011 ERS