Patient-Controlled Analalgesia I: Historical Perspective and Newer Devices

Abstract

In designing patient-controlled analgesia (PCA) equipment, biomedical engineers have utilized negative feedback control technology. When feedback control is applied to the control of pain, the patient self-administers analgesic medication to decrease the error signal (i.e., the difference between the pain experienced and the acceptable (tolerable) level of pain) to zero (1,2). PCA techniques attempt to close the feedback loop without the necessity of nursing staff intervention, thereby, improving the effectiveness of the pain control system.