Impact of Acetazolamide and CPAP on Cortical Activity in Obstructive Sleep Apnea Patients

Study Objectives: 1) To investigate the impact of acetazolamide, a drug commonly prescribed for altitude sickness, on cortical oscillations in patients with obstructive sleep apnea syndrome (OSAS). 2) To examine alterations in the sleep EEG after short- term discontinuation of continuous positive airway pressure (CPAP) therapy. Design: Data from two double- blind, placebo- controlled randomized cross- over design studies were analyzed. Setting: Polysomnographic recordings in sleep laboratory at 490 m and at moderate altitudes in the Swiss Alps: 1630 or 1860 m and 2590 m. Patients: Study 1: 39 OSAS patients. Study 2: 41 OSAS patients. Interventions: Study 1: OSAS patients withdrawn from treatment with CPAP. Study 2: OSAS patients treated with autoCPAP. Treatment with acetazolamide (500-750 mg) or placebo at moderate altitudes. Measurements and Results: An evening dose of 500 mg acetazolamide reduced slow-wave activity (SWA; approximately 10%) and increased spindle activity (approximately 10%) during non-REM sleep. In addition, alpha activity during wake after lights out was increased. An evening dose of 250 mg did not affect these cortical oscillations. Discontinuation of CPAP therapy revealed a reduction in SWA (5-10%) and increase in beta activity (approximately 25%). \Conclusions: The higher evening dose of 500 mg acetazolamide showed the `` spectral fingerprint'' of Benzodiazepines, while 250 mg acetazolamide had no impact on cortical oscillations. However, both doses had beneficial effects on oxygen saturation and sleep quality.