Active clinical trials for "Hyperalgesia"

The purpose of this study is to examine whether two clinically sensible dose regimen of fentanyl (low dose vs. high dose) lead to different pain scores as measured by the nonverbal rating scale (NRS) in healthy volunteers at 4.5 to 6.5 hours after fentanyl application. Pain modalities tested will include transdermal electrical stimulation and cold pressor pain. The investigators hypothesize that the high dose fentanyl group will have an increase of approximately 20% in the NRS.

Postthoracotomy acute pain is followed by persistent postsurgical pain in 20-30% of the patients, defined as pain that lasts more than 3-6 months after surgery. Acute pain and hyperalgesia around the surgical wound are some of the risk factors associated to the development of chronic pain. Ketamine, as a NMDA antagonist mainly at spinal level, might reduce periincisional hyperalgesia and persistent postsurgical pain after thoracotomy. Therefore, the investigators hypothesized that continuous ketamine infusion at subanesthetic dose would potentiate epidural ropivacaine and fentanyl-induced analgesia after thoracotomy, reduce periincisional hyperalgesia and long-term postoperative pain. To test these hypothesis, the investigators administered a low dose of intravenous ketamine or epidural ketamine or placebo to patients who received an epidural infusion of ropivacaine and fentanyl for postthoracotomy pain.

The purpose of this study is to study the effect of intraoperative magnesium on remifentanil-induced postoperative hyperalgesia after thyroidectomy

Remifentanil is a rapid-acting opioid which has been widely used in pain treatment during surgery for the last 15 years 1. Remifentanil is rapidly eliminated (minutes) from the body after end of infusion, and this makes it easily manageable compared to other opioids. However, there are both experimental and clinical studies indicating that remifentanil, after end of infusion, triggers increased pain sensation and increased opioid consumption post-operatively. Increased post-operative opioid consumption should be avoided due to the adverse effects of these drugs (nausea/vomiting, pruritus, dizziness, fatigue and reduced respiratory rate). Thus, it's important to investigate relevant strategies to avoid the increased pain sensation (opioid-induced hyperalgesia = hypersensitivity to pain stimuli) after end of infusion of remifentanil after surgery. Several experimental and clinical trials have been conducted in this field. Ketamine has been shown to block this effect, but its adverse effect profile (i.a. hallucinations) makes it not suitable in normal clinical use. In a study of healthy volunteers, it has been demonstrated that parecoxib (a COX-2 selective NSAID) can prevent remifentanil-induced hyperalgesia. Our group has previously shown that a relatively COX-1 selective NSAID (ketorolac) can prevent hyperalgesia in an experimental pain model. This is of interest since NSAIDs are frequently administered as premedication before surgery. There are several disadvantages associated with the use of COX-2 inhibitors, e.g. the risk of myocardial infarction after long-term use (> 1 year), and potentially reduced bone healing after orthopedic surgery. However, this has not been shown with short-term use (days/week). The disadvantages associated with the use of e.g. ketorolac (a COX-1 inhibitor) are i.a. increased bleeding tendency, which is unfavourable for the surgeon, and increased risk of gastric ulcer. Therefore, it is of interest to investigate other ways of preventing opioid-induced hyperalgesia. In a recent animal study it has been shown that gradual dose reduction of remifentanil (vs. abrupt withdrawal of a relatively high remifentanil dose) can prevent the development of hyperalgesia after end of infusion. In this study we will i.a. investigate whether this is also the case in humans. In this new model, the study participants will get remifentanil infusion with two different dose reduction regimes: gradual reduction or abrupt withdrawal.

Randomized, double-blinded, three arm study in adult patients undergoing first time coronary artery bypass grafting (CABG) surgery with median sternotomy. The investigators will examine the effects of three fentanyl dosing schemes (high-dose bolus, low-dose bolus, continuous dose) on the area of hyperalgesia and allodynia at 24 and 48h as well as on persisting pain at 3, 6, and 12 months. Additionally, the investigators will measure fentanyl concentrations throughout anesthesia.

High-dose remifentanil infused intraoperative ironically results in postoperative hyperalgesia. Ultra-low dose nalxone is demonstrated to prevent these opioid-induced hyperalgesia in animal model. In this clinical trial in patients undergoing general anesthesia with remifentanil, we evaluate the effects of ultra-low-dose naloxone on remifentanil-induced hyperalgesia

Pain is defined as an unpleasant sensory and emotional conscious experience, associated with actual or potential tissue damage. Nociception is the sympathetic response to noxious stimuli during unconsciousness. The appearance of different forms of chronic pain results from sensitization of both peripheral and central neural circuits of pain, which involves inflammatory mechanisms both at a systemic level and specifically in the peripheric and central nervous system, as observed through elevation of specific neuroinflammatory mediators, such as MCP-1, IL-1, IL-1b, and IL-10. Clinically, this sensitization expresses as hyperalgesia and allodynia, which increase postoperative pain and morbidity, but also induce permanent modifications in the nociceptive system. These effects may be ameliorated by adequately adjusting intraoperative analgesia through use of nociception/analgesia balance monitors, of which Nociception Level Index (NOL) shows convenient characteristics and promising results from previous studies. Objectives: The goal of our study is to assess the utility of NOL index monitoring against standard care for Fentanyl-based analgesia by measuring postoperative pain, sensorial thresholds and inflammatory markers related to nociception. Hypothesis: The use of NOL index to guide the intraoperative analgesia will produce less postoperative pain, hyperalgesia, allodynia, and neuroinflammation.

The purpose of this study is to determine whether a transversus abdominis plane (TAP) block with Clonidine added to the injectate (Clo-TAP) performed approximately 2hrs after the cesarean section (CS) will decrease the amount of postoperative hyperalgesia and ultimately reduce post-CS chronic pain.

Phantom limb pain (PLP) and scar hyperalgesia (SH) are frequent problems after amputation; in particular most persons who undergo limb amputation will experience phantom pain. The neuropathic nature of PLP suggests the involvement of both peripheral and central neurological mechanisms, including neuroplastic changes in the central nervous system. PLP as other central nervous system-related pain syndromes remains a challenge for treatment. Scar hyperalgesia involves peripheral mechanisms and results frim the production of substances liberated by damaged skin cells. These inflammatory substances lower the pain threshold by altering the chemical environment of skin nerve endings. Scan hyperalgesia is associated with secondary mechanical hyperalgesia in the skin area around the scar. The lidocaine patch 5% is a topical analgesic acting by blocking sodium channels of peripheral nerve endings and by inhibiting ectopic discharges in sensitized and hyperactive cutaneous nociceptors. The patch is noninvasive, with minimal systemic absorption resulting in a reduced risk of drug-drug interaction. In addition, a central analgesic effect of lidocaine has been suggested. The lidocaine patch 5% is currently licensed for the treatment of symptomatic postherpetic neuralgia. It also has been successfully used in patients with other neuropathic pain states, such as entrapment neuropathies, painful idiopathic distal sensory polyneuropathies and postoperative/post traumatic neuropathic chronic cutaneous pain. The lidocaine patch has not been studied for the management and prevention of phantom limb pain. The aim of the present research is to investigate if a lidocaine patch 5% is effective for reducing PLP and primary/secondary scar hyperalgesia. The hypothesis is that persistent peripheral nociceptive input from the stump after surgery may drive maladaptive cortical reorganization leading to chronic central pain and thus promote chronic phantom limb pain. Treating scar hyperalgesia on the stump with topical lidocaine may reduce the activity of peripheral nociceptive afferents and thus decrease the likelihood of developing persistent phantom limb pain. This study is designed as a randomized controlled multicentric double blind trial, in which the effectiveness of applying a 5% lidocaine patch for 6 weeks will be compared with a sham.

The aim of this study was to determine if the addition of ketamine reduces remifentanil-induced hyperalgesia, improves its analgesic effect, inhibits IL(interleukin)-6 and IL-8 (inflammatory cytokines), and stimulates IL-10 (an anti-inflammatory cytokine).