Opioid Induced Hyperalgesia (OIH) Modulation With Propranolol

Opioid Induced Hyperalgesia (OIH) is an entity than has been demonstrated in healthy volunteers and in animal models. Is defined as an increase in the perception to painful stimuli, increasing the opioid requirements and diminishing the pain thresholds to stimuli. The apparition of OIH is also related to the exposure to opioids during surgery, depending of the dose, the time of exposition and the type of opioid. This condition can be modulated, specially in the perioperative context. It has been seen in healthy volunteers and in animal models, than the use of propranolol can modulate this phenomena, diminishing the postoperative requirements of analgesia. It is also unknown, the dose of propranolol required to modulate adequately OIH. The objective of this work is to evaluate the efficacy of propranolol in the modulation of opioid induced hyperalgesia, with lower postoperative requirements of analgesia rescue.