Figure 6-22 The ventilatory responses to acute isocapnic hypoxia (to approximately 44 mm Hg) in one subject during control (i.e., awake) and at 0.1 and 0.2 minimum alveolar concentrations (MACs) of isoflurane. Solid bars indicate period A (2-minute period before induction of hypoxia) and period B (minutes 3 and 4 of hypoxia). V̇_E , minute ventilation. (Adapted from van den Elsen MJLJ, Dahan A, DeGoede J, et al: Influences of subanesthetic isoflurane on ventilatory control in humans. Anesthesiology 83:478, 1995.)