ABSTRACT
OBJECTIVE: To evaluate the variability of neural respiratory drive in patients with obstructive sleep apnea (OSA) and the effect of continuous positive airway pressure (CPAP) upon neural respiratory drive. METHODS: We recorded diaphragm electromyogram (EMGdi) with multi-pair esophageal electrodes and its variability during wakefulness, sleep and treatment with CPAP in 13 patients with moderate to severe OSA diagnosed by an overnight full polysomnography (OSA group). Six normal subjects (control group) were also studied. RESULTS: Coefficient of variation of EMGdi (CV-EMGdi) during wakefulness (15.4% +/- 3.8%) was similar to that during sleep (17.3% +/- 5.2, P > 0.05) in the control group. The CV-EMGdi during wakefulness, sleep, sleep apnea events and treatment with CPAP in OSA group was 14.7% +/- 1.9%, 40.7% +/- 12.0%, 29.1% +/- 7.5% and 15.4% +/- 4.6% respectively, CV-EMGdi during sleep or sleep apnea events was larger than that during wakefulness (P < 0.01). However, there was no difference in the CV-EMGdi during wakefulness and during treatment with CPAP (P > 0.05). CONCLUSION: The variability of neural respiratory drive in patients with OSA is higher than that in normal subjects, and CPAP can reduce the variability of neural respiratory drive in patients with OSA.
