Figure 9. Procedures of the measurement regime.

Procedure 1 measures the changes in slopes (ΔS) and thresholds (ΔT) of the ventilatory responses to CO₂ for a given change from hyperoxia to hypoxia (ΔO₂). Procedure 2 measures the time course of the decline in ventilation between 5 and 20 min after the start of isocapnic hypoxia at a specified CO₂ and O₂ in terms of the percentage HVD and the time constant of the fitted exponential decline. Procedure 3 measures the ventilatory response (ΔV_f and ΔCO₂) after 20 min of poikilocapnic hypoxia at a specified O₂.