Figure 11-8 Influence of morphine administration (bolus dose of 100 µg/kg given at time 0 minutes, followed by a continuous infusion of 30 µg/kg/hour) on resting inspired minute ventilation and resting pressure of end-tidal CO₂ (P_ET CO₂ ) in a single subject. A one-component exponential was fitted to the data. The estimated time constant for the V_i data is 3.0 minutes and for P_ET CO₂ data is 2.6 minutes. The time delays are between 1 and 2 minutes. (From Sarton E, Teppema L, Dahan A: Sex differences in morphine-induced ventilatory depression reside within the peripheral chemoreflex loop. Anesthesiology 90:1329–1338, 1999.)