Computer-modulated patient-controlled analgesia. Preliminary evaluation of a prototype.

Abstract

To provide patients with better postoperative pain relief, the authors developed a prototype computer-controlled infusion pump capable of establishing a steady drug plasma concentration based on patient needs. A two-compartment pharmacokinetic model was used to compute the required infusion scheme. Using known pharmacokinetic parameters, the model and the pump's accuracy were studied in four dogs. In the first part of the study, the morphine pharmacokinetic profile of each dog was analyzed and used to develop the parameters of a model tailored to that particular dog. In the second part, this tailored model was implemented to test whether the infusion device was able to achieve the desired concentration profile. The computer-controlled infusion device was able to achieve all the desired plasma concentrations. These data suggest that it is possible to refine postoperative pain management with adaptive computer algorithms implemented to establish stable plasma analgesic concentrations and to automatically wean the analgesic over time.