Recent developments in patient-controlled analgesia.

Patient-controlled analgesia (PCA) has become the gold standard for acute pain management since it was first introduced 20 years ago, and its merits have been discussed in quite a large number of publications. This review summarizes the more recent developments, such as new application devices and strategies, including intranasal, spinal, and regional PCA; patient-controlled sedation; experience with children and elderly people; and some data from chronic pain situations. Analyzing PCA literature from 2001 onwards confirms the author's long belief that the PCA principle ("WYNIWYG": what you need is what you get) was the most important aspect of a patient-controlled strategy, more or less independent of the type of drug or machine. Discovering this principle has changed the understanding of pain and suffering.