Background Periodic breathing (PB) during sleep and exercise in heart failure (HF) is related to respiratory acid-base status, CO2 chemosensitivity, and temporal dynamics of CO2 and O2 sensing. We studied inhaled CO2 and acetazolamide to alter these factors and reduce PB. Methods and Results We measured expired and arterial gases and PB amplitude and duration in 20 HF patients during exercise before and after acetazolamide given acutely (500 mg intravenously) and prolonged (24 hours, 2 g orally), and we performed overnight polysomnography. We studied CO2 inhalation (1%-2%) during constant workload exercise. PB disappeared in 19/20 and 2/7 patients during 2% and 1% CO2. No changes in cardiorespiratory parameters were observed after acute acetazolamide. With prolonged acetazolamide at rest: ventilation +2.04 ± 4.0 L/min (P =.001), tidal volume +0.11 ± 1.13 L (P =.003), respiratory rate +1.24 ± 4.63 breaths/min (NS), end-tidal PO2 +4.62 ± 2.43 mm Hg (P =.001), and end-tidal PCO2 -2.59 ± 9.7 mm Hg (P 2 -61 ± 109 mL/min (P =.04) and VCO2 101 ± 151 mL/min (P 2 and acetazolamide reduce exercise PB with additional benefits of acetazolamide on sleep PB.
- cardiopulmonary exercise test
- Oscillatory ventilation
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine