Isocapnic hypoxic ventilation. Typical changes in ventilation and gases during the 10-min isocapnic hypoxic ventilation in one subject before dexmedetomidine-induced sedation. The inspired carbon dioxide level was manually adjusted in order to keep isocapnia. Changes in end-tidal carbon dioxide (ETco₂), inspired carbon dioxide fraction (Fico₂), tidal volume, and respiratory rate are displayed as breath by breath and changes in saturation and end-tidal oxygen (ETo₂) every 10th second.