Nocturnal continuous positive airway pressure decreases daytime sympathetic traffic in obstructive sleep apnea

Background-Patients with obstructive sleep apnea (OSA) have high levels of muscle sympathetic nerve activity (MSNA). We tested the hypothesis that lon g-term continuous positive airway pressure (CPAP) treatment will decrease M SNA in OSA patients. Methods and Results-We measured blood pressure, heart rate, and MSNA in II normotensive, otherwise healthy patients with OSA who were treated with CPA P, The measurements were obtained at baseline and after 1 month, 6 months, and 1 year of CPAP treatment. These measurements were compared with these r ecorded in 9 otherwise healthy OSA patients who were not treated with CPAP for 1 year. Tn both untreated and treated patients, blood pressure and hear t rate did not change over time. MSNA was similar during repeated measureme nts in the untreated group. By contrast, MSNA decreased significantly over time in patients treated with CPAP. This decrease was evident after both 6 months and 1 year of CPAP treatment (P = 0.02 for both). Conclusions-CPAP treatment decreases muscle sympathetic traffic in patients with OSA. This effect of CPAP is evident only after an extended duration o f therapy.