No clinical evidence of acute opioid tolerance after remifentanil-based anaesthesia

We have prospectively assessed whether remifentanil-based anaesthesiais associated with clinically relevant acute opioid tolerance,expressed as greater postoperative pain scores or morphine consumption.Sixty patients undergoing elective gynaecological, non-laparoscopic,surgery were randomly assigned to receive remifentanil (groupR, n=30) or sevoflurane (group S, n=30) based anaesthesia. Postoperativeanalgesia was provided with morphine through a patient-controlledinfusion device. Mean (SD) remifentanil infusion rate in groupR was 0.23 (0.10) µg kg^–1 min^–1 and mean inspiredfraction of sevoflurane in group S was 1.75 (0.70)%. Mean (SD)cumulative morphine consumption during the first 24 postoperativehours was similar between groups: 28.0 (14.2) mg (group R) vs28.6 (12.4) mg (group S). Pain scores, were also similar betweengroups during this period. These data do not support the developmentof acute opioid tolerance after remifentanil-based anaesthesiain this type of surgery. Br J Anaesth 2001; 87: 866–9