[Postoperative on-demand analgesia with fentanyl using the CODIC infusion system. Initial clinical experiences]

Postoperative patient-controlled analgesia (PCA) was studied in 24 ASA I-III patients recovering from major gynecological surgery, who were allowed to self-administer i.v. fentanyl doses by means of the CODIC programmable infusion system. The total dose was governed by a special algorithm which made demand doses decline with time in a pseudo-exponential manner; lockout time was 4 min. Duration of the PCA period was 16.6 +/- 5.3 h (mean, SD), during which time 409 +/- 170 micrograms fentanyl was infused. The analgesic efficacy was scored retrospectively as "moderate pain all the time". Half the fentanyl dose was administered during the first 6 h of treatment, when pain relief was significantly better than during the remainder of the study. Possible explanations for these observations are discussed.