Fig. 3.
Polysomnograph (PSG) records from one representative subject of those who showed a marked reduction of apnea-hypopnea index (AHI) with isocapnic rebreathing. Repetitive obstructive apneas were indicated by the absence of flow despite respiratory effort. Most of these obstructive apneas were eliminated by isocapnic rebreathing without raising PetCO2. The 4-min periods shown for both control and isocapnic treatment conditions were representative of the breathing pattern, PetCO2, and AHI experienced during the total 90- to 95-min periods of control and treatment conditions studied in this patient. EEG, electroencephalogram; SaO2, arterial oxyhemoglobin saturation; Ab, abdominal movement; RC, rib cage movement.