Fig. 5. Simulations using 1,000 bootstrap replicates on a log-linear scale. Data are presented as median ± 95% predication intervals for analgesia ( continuous line ) and respiration ( dashed line ) relative to baseline (= 1). A value of 0.4 indicates 60% depression of respiration; a value of 2 indicates doubling of current for pain threshold. ( A ) A single 90-s infusion of 0.2 mg/kg morphine at t = 0. ( B ) Morphine 90-s infusion at t = 0, followed by a continuous infusion of 1 mg · 70 kg−1· h−1. ( C ) Four 90-s infusions of 0.1 mg/kg morphine at 6-h intervals.