[Intravenous patient-controlled analgesia (PCA) in the treatment of postoperative pain: rationale and clinical application].

The clinical use of the patient-controlled analgesia (PCA) represents a further improvement in the treatment of post-operative pain. In this way in success due to inadequate protocols, unpredictability of the drug absorption and variability of the response to one drug or to the same pain patterns between patients can be avoided. This technique allows the patient himself to control the pain without depending upon nurses or physicians for the administration of analgesic drugs. Although the PCA is in use since several years, there are still some unresolved problems which are considered in this paper.