Fig. 3. The effect of raising the transition PCO2. Raising the transition PCO2 reduces oscillations in the post-hyperventilation period. The ventilatory response for a transition PCO2 of 36.75 mm Hg is highly oscillatory, while that for a transition PCO2 of 38.5 mm Hg is comparatively damped, with only several small amplitude oscillations. Alertness factor is -2 liters/minute.