[Patient-controlled analgesia in treatment of postoperative pain].
Patient-controlled analgesia (PCA) is a newer technique for pain management. Patients are allowed to self-administer small analgesic bolus doses, which have been preprogrammed by the physician, into a running intravenous infusion, intramuscularly, subcutaneously or even into the epidural space. Patients' demands are mostly controlled by computer-driven infusion pumps, but can also be delivered by simple disposable devices. Lockout times, concomitant infusions and hourly maximum doses can be set in most PCA pumps. Clinical experience with PCA demonstrates that individual variability in pain sensitivity and analgesic needs are of utmost importance. In contrast to earlier expectations, PCA opiate consumption is usually higher than with restrictive conventional dosing regimes, but without an increase of serious side effects. Such results let assume that many patients under conventional i.m. techniques must be considered to be underdosed. Patients acceptance is generally enthusiastic for self-control. It is suggested that PCA results should be used for the improvement of conventional techniques. PCA has also been found valuable for scientific pain studies, e.g. to determine predictors of postoperative pain, drug interactions and pharmacokinetic experiments. This review concentrates on intravenous PCA during the early postoperative period.