Facial expression and pain in the critically ill non-communicative patient: state of science review.

The aim of this review is to analyse the evidence related to the relationship between facial expression and pain assessment tools in the critically ill non-communicative patients. Pain assessment is a significant challenge in critically ill adults, especially those who are unable to communicate their pain level. During critical illness, many factors alter verbal communication with patients including tracheal intubation, reduced level of consciousness and administration of sedation and analgesia. The first step in providing adequate pain relief is using a systematic, consistent assessment and documentation of pain. However, no single tool is universally accepted for use in these patients. A common component of behavioural pain tools is evaluation of facial behaviours. Although use of facial expression is an important behavioural measure of pain intensity, there are inconsistencies in defining descriptors of facial behaviour. Therefore, it is important to understand facial expression in non-communicative critically ill patients experiencing pain to assist in the development of concise descriptors to enhance pain evaluation and management. This paper will provide a comprehensive review of the current state of science in the study of facial expression and its application in pain assessment tools.