Patient-controlled analgesia: a review.

The patient-activated analgesic system was introduced in 1968. Early trials, although uncontrolled, supported the safety and efficacy of patient-controlled analgesia (PCA) in several kinds of pain, such as that relating to surgery, cancer, trauma, and obstetric procedures. In the past decade, prospective, randomized trials have reported several advantages of PCA over conventional analgesia in the early postoperative period. Although not supported by all controlled trials, they include improved pain relief, less sedation, lower level of narcotic consumption, fewer postoperative complications, greater patient satisfaction, and improved pulmonary function. Preliminary results in the management of chronic pain indicate that PCA can lead to significant lifestyle improvements in ambulatory patients with cancer. The most significant, although infrequent, adverse effect is respiratory depression, the majority of cases occurring in patients predisposed secondary to concomitant illness or as a result of human error. The clinical use of PCA will likely see a significant increase among persons with cancer, and an increase in epidural administration. The cost benefit of PCA has yet to be assessed in inpatient and outpatient settings.