Figure 2.

Decline of effect site concentrations of different opioids after 24 hours of infusion. The findings are expressed as percentage of the individual maximum effect site concentration. This figure was calculated using Stanpump simulation software (by Shafer S, University of Stanford, CA, USA) for a female individual (age 80 years, height 170 cm, body weight 80 kg) and the following infusion rates: remifentanil 0.15 μg/kg per minute, sufentanil 1 μg/kg per hour, alfentanil 1.5 mg/hour, and fentanyl 0.2 mg/hour.