CHRONIC CO2 DRIVE IN PATIENTS WITH OBSTRUCTIVE SLEEP-APNEA AND EFFECTOF CPAP

Obstructive sleep apnea (OSA) can be associated with depressed hyperca pnic ventilatory response (HCVR) (White D.P., N.J. Douglas, C.K. Picke tt, C.W. Willich and J.V. Well, Am. Rev. Respir. Dis. 128:984-986, 198 3), which might be responsible for aggravating the sleep-related breat hing disorder (SRBD). The present study evaluated whether in patients with various types of sleep apnea a significant decrease in the HCVR c ould be found (COMPARATIVE STUDY). In a second part of the study chron ic CPAP therapy (Continuous Positive Airway Pressure) was evaluated in relation to control of breathing (CPAP STUDY). In the comparative stu dy a significant increase of the slope in the normocapnic OSA and over lap group could be seen. A depressed HCVR could only be observed in ch ronic hypercapnic OSA. In the CPAP-study it was shown that changes in the AHI after CPAP do not parallel the HCVR. We conclude that in eucap nic OSA patients CPAP therapy does not change CO2 drive. We believe th at increased chemical CO2 drive can contribute to its pathogenesis.