Anesthesiology
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Opioid-induced delayed hyperalgesia and allodynia have been reported in human and animal models. The authors evaluated the influence of different opioids used during clinical anesthesia on nociceptive sensitivity and incisional pain in mice. The role of the inducible nitric oxide synthase on surgical pain and opioid-induced pronociception also was investigated. ⋯ The authors' study demonstrates that the intraoperative administration of fentanyl or remifentanil enhances the extent and duration of postoperative pain. The results suggest a role of the nitric oxide systems in the cause of acute postoperative pain and opioid-induced pronociception.
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Randomized Controlled Trial
Differential effect of ketamine and lidocaine on spontaneous and mechanical evoked pain in patients with nerve injury pain.
The mechanisms underlying neuropathic pain are incompletely understood. Targeting specific molecular mechanisms in the pain signaling system may assist in understanding key features in neuropathic pains such as allodynia. This study examined the effect of systemically administered ketamine, an N-methyl-D-aspartate receptor antagonist and lidocaine, a sodium channel blocker, on spontaneous pain, brush-evoked pain, and pinprick-evoked pain in patients with nerve injury pain. ⋯ N-methyl-D-aspartate receptor-linked systems and sodium channels are involved in generation and maintenance of pain in patients with peripheral nerve injury. It is likely that ongoing pain as well as mechanical hyperalgesia in individual patients is dependent on several separate molecular mechanisms.
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Randomized Controlled Trial
Upregulation of prostaglandin E2 and interleukins in the central nervous system and peripheral tissue during and after surgery in humans.
The central and peripheral inflammatory response to surgery may influence patient outcomes. This study examines the time course and clinical relevance of changes in prostaglandin E2 and cytokines in cerebrospinal fluid, local tissue (surgical site), and circulating blood during and after total hip replacement. ⋯ These results suggest that upregulation of prostaglandin E2 and interleukin 6 at central sites is an important component of surgery induced inflammatory response in patients and may influence clinical outcome.
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Randomized Controlled Trial
Safety and efficacy of the cyclooxygenase-2 inhibitors parecoxib and valdecoxib after noncardiac surgery.
Valdecoxib and its intravenous prodrug parecoxib are reported to increase thromboembolic risk after coronary artery bypass grafting. The authors conducted a randomized trial to examine their safety and analgesic efficacy in patients recovering from major noncardiac surgical procedures. ⋯ Parecoxib and valdecoxib are useful adjuncts to opioids for the treatment of postoperative pain in noncardiac surgical patients. Further study will be required to determine the safety profile of parecoxib and valdecoxib administered to patients with known atherosclerotic disease after noncardiac surgery.
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Opioids are the cornerstone therapy for the treatment of moderate to severe pain. Although common concerns regarding the use of opioids include the potential for detrimental side effects, physical dependence, and addiction, accumulating evidence suggests that opioids may yet cause another problem, often referred to as opioid-induced hyperalgesia. Somewhat paradoxically, opioid therapy aiming at alleviating pain may render patients more sensitive to pain and potentially may aggravate their preexisting pain. This review provides a comprehensive summary of basic and clinical research concerning opioid-induced hyperalgesia, suggests a framework for organizing pertinent information, delineates the status quo of our knowledge, identifies potential clinical implications, and discusses future research directions.