Ventilatory response to decreasing inspired oxygen concentration in two subjects. End-tidal PCO2 is held constant. The left panel shows the linear response of ventilation plotted against oxygen saturation. On the right is the more traditional hyperbolic response, obtained from plotting ventilation against alveolar PO2.
VE: minute ventilation; SO2: oxygen saturation; PO2: partial pressure of oxygen; PCO2: partial pressure of carbon dioxide.
