Secondary hyperalgesia to the administration of remifentanil has been documented in both animal and experimental studies in humans and its incidence has increased given its increasingly common for maintenance during different anesthetic procedures use, balanced general anesthesia, total intravenous anesthesia and sedation . Secondary hyperalgesia use of remifentanil is a related pro-nociceptive process but which differs from the acute tolerance, in which excitatory neurotransmitters of N-methyl D-aspartate (NMDA) play a central role. Therefore ketamine has been used in different doses for preventing said hyperalgesia is established without their effectiveness for prevention and treatment of this condition.
