Perioperative Opioid-induced Hyperalgesia and Its Prevention With Ketamine and Methadone

Perioperative Opioid-induced Hyperalgesia and Its Prevention With Ketamine and Methadone

Background: In perioperative period inhibition of N-Methyl-D-Aspartate receptor prevents opioid-induced hyperalgesia and reduce postoperative opioid requirement after abdominal surgery. Methadone is both a µ-opioid receptor agonist like Morphine and a N-Methyl-D-Aspartate antagonist. Study Aim. To evaluate the efficacy of intraoperative Ketamine and postoperative Methadone analgesia in preventing opioid-induced hyperalgesia after abdominal surgery.

not desired

Inclusion Criteria:

• patients undergoing open colo-rectal surgery

Exclusion Criteria:

• ASA status more than II, history of chronic pain, ischemic heart disease or chronic pulmonary disease, allergy to any drugs used in the protocol. Body Max Index more than 35.