How to assess patient pain for using PCA (patient controlled analgesia)? How does PCA support management of pain post operation and how beneficial is it? What are the links between theory and practice? Key issues in using PCA?

Patient controlled analgesia

-How to assess patient pain for using PCA (patient controlled analgesia)?
-How does PCA support management of pain post operation and how beneficial is it?
-What are the links between theory and practice? Key issues in using PCA?