Perioperative opioid-induced hyperalgesia (OIH) can be defined as the "increased perception of pain after opioid-based anesthesia and surgery" since hyperalgesia is defined as "increased pain from a stimulus that normally provokes pain." OIH has been identified mainly after remifentanil-based anesthesia in surgical patients given the high dose and rapid withdrawal used. The mechanisms of OIH have been postulated mainly by the cellular-level adaptation in internalization of the receptors and downregulation of intracellular coupling, upregulation of spinal dynorphins, and activation of N-methyl-D-aspartate receptors have been postulated as well. The clinical aspects of OIH with various causes, especially remifentanil, have been investigated. Pros and cons related to remifentanil-induced hyperalgesia have been suggested. The dose and duration of remifentanil used in surgery and anesthesia can be the appropriate factors for OIH, including the way of setting for the control groups of those studies, and the methods for evaluating the pain. Opioids remain one of the most powerful pain killers for acute pain management. Opioids are sometimes necessary for perioperative analgesia, but OIH can be an unavoidable risk. Ongoing interest in OIH and the development of anesthesia optimized for its prevention will increase the quality of perioperative life.
- Drug tolerance