IntroductionPain is a subjective and objective indicator of a patient's comfort level. Maintaining a tolerable level of pain is essential to patients' recovery and overall outcome. As nurses, we must assess a patient's pain level and respond appropriately. Many tools and theories have been developed and are used in different health care settings to help nurses and other disciplines better understand a patient experiencing pain. This article will give a complete analysis of the concept: Pain. Pain In the intensive care unit (ICU), many patients are mechanically ventilated and although they are mildly to moderately sedated with medications, pain control often remains a problem. Generally speaking, patients with higher positive end-expiratory pressure (PEEP) experience increased pain under the ventilator compared to those using lower PEEP settings and many of these patients have pain levels that are not properly managed due to vague indicators or lack of nursing care. awareness. Pain is unique to each individual and is therefore a complex concept to define, assess and understand. Assessing the pain level of a patient who is unable to speak and likely under sedation can be a difficult task for nurses and therefore many tools have been developed to facilitate this assessment. Controlling the patient's pain is vital for a speedy recovery and it must be remembered that just because a patient cannot verbalize pain does not equate to its absence. In many healthcare settings, pain is today considered a fifth vital sign due to its enormous prevalence, however Zalon states that poor pain relief is well documented and has been noted in the nursing literature for over 20 years (Zalon, 1995). Florence Nightingale also recognized pain and its importance...... middle of paper ......). However, the definition of pain encompasses and helps describe these other terms. Pain • An individualistic feeling of hurt, discomfort, or suffering towards the individual. Oxford University Press, Oxford, New York. Jensen, MP and Turk, DC (2014). Contributions of psychology to the understanding and treatment of people with chronic pain. American Psychologist, 69(2), 105-118. doi:10.1037/a0035641Lalloo, C., Kumbhare, D., Stinson, J., & Henry, J. (2014). Pain-QuILT: clinical feasibility of a web-based visual pain assessment tool in adults with chronic pain. Journal of Internet Medical Research, 16(5), e127. doi:10.2196/jmir.3292Matsuzaki, K. & Upton, D. (2013). Wound treatment and pain management: a stressful time. International Journal of Wounds, 10(6), 638-644. doi:10.1111/j.1742-481X.2012.01038.x