Pain is common in critically ill patients, while efforts focus on immediate life-threatening concerns, relief of pain is often neglected. Pain experienced by patients in intensive care units has frequently been untreated because of fears of depressing spontaneous ventilation, inducing narcotic dependence, inducing cardiovascular instability, or masking under surgical pathology. Education in pain management may be the single most important tool for improving patient comfort. Pain perception occurs when a noxious stimulus activates peripheral and central nervous pathways that transmit, convey and modulate injury-related information.