To Örebro University

An abdominal hysterectomy (AH) is associated with moderate to severe postoperative pain. In this thesis, a new technique for postoperative pain managment has been studied in 200 patients: local anesthetic (LA) was administered intraperitoneally (IP) after elective AH.

In study I, the efficacy of an IP continuous infusion of LA given postoperatively via a catheter was compared with a placebo. The conclusion was that the postoperative pain relief was significantly improved when LA was used. The plasma concentration of LA was far below toxic concentrations.

In study II, when three different doses of LA were given at a constant infusion rate, the conclusion was that satisfactory analgesia could be achieved with low doses of LA and that no advantages were seen when higher doses of LA were administered. The highest dose of infused LA did not result in toxic plasma concentration.

Study III compared a continuous IP infusion and a patient-controlled bo-lus IP injection of LA. A significant opioid-sparing effect combined with lower required amount of LA was found when the patient-controlled LA was administered compared to the continuous infusion. This was associated with a faster return of gastrointestinal function and home readiness.

Study IV tested the hypothesis that the analgesic effect of LA given intermittently IP was superior compared to the same dose administered continuously by intravenous (IV) infusion. A significant opioid-sparing effect was found when an intermittent IP injection of lidocaine was administered. The venous blood concentration of LA was significantly lower in the IP intermittent group versus the IV group. The lower supplemental morphine consumption, coupled with the lower plasma lidocaine concentration, may confirm a local peripheral rather than a systemic effect of LA administered IP.

In conclusion, when the LA was injected continuously IP, a significant opioid- sparing effect was found, which did not increase by increasing the LA dose. The opioid-sparing effect was greater when the intermittent IP injection of LA was compared to a continuous infusion. When LA was administered IP, the mechanism of pain relief seemed to be a local rather than a central effect.