Impact of Intravenous, Perioperative-Administrated Lidocaine on Postoperative Serum Levels of Endogenous Opioids in Children.

Abstract

Endogenous opioids are neuropeptides involved in pain-relieving processes. In the periphery, they are synthesised and stored in cells of the immune system. In the current study, we describe the influence of perioperative, intravenous (i.v.) lidocaine infusion in children on postoperative, serum endogenous opioid concentrations in children. Forty-four children undergoing major spinal surgery were enrolled in the cohort study. They were divided into two groups: group A (n = 21) generally anesthetised with fentanyl, propofol, rocuronium, a mixture of oxygen/air/sevoflurane and with analgetics and co-analgetics: morphine, acetaminophen, metamizole, gabapentin, dexamethason and group B (n = 23) where, in addition to the above-described general anesthesia, patients were given i.v. lidocaine as a co-analgesic. We also recruited 20 healthy age- and gender-matched children (group C). We measured endogenous opioid levels in serum using immunoenzymatic methods. We evaluated postoperative pain intensity using a numerical or visual pain scale and demand for morphine. The levels of measured endogenous opioids were similar in the control and in the studied groups before surgery. We noted that group B patients had lower pain intensity when compared to group A subjects. In group B, the elevated serum concentrations of β-endorphin, enkephalin and dynorphin in the postoperative period were reported. We also observed that the levels of endogenous opioids negatively correlated with morphine requirements and positively correlated with lidocaine concentration. Multidrug pain management including lidocaine seems to be more efficient than models without lidocaine. The endogenous opioid system should be considered as a novel target for pain relief therapy in children.