Update on pain assessment in sick neonates and infants.

This article describes developments in pain assessment in critically ill neonates and infants during the last 5 to 6 years. Pain assessment instruments show a redundancy of items and a lack of profound psychometric background. Although most research focuses primarily on acute pain, in clinical practice there is also the challenge of assessing prolonged and/or persisting pain. The effectiveness of pain assessment is still a matter of debate and has recently been challenged as a primary end point in analgesia-related trials. Integration of observation of behavior with reliable and specific neurobiology-based parameters remains a challenge.