La kétamine dans la douleur aiguë : de la pharmacologie à la clinique

Abstract

Ketamine is a well-known general anesthetic in use for a long time. The role of NMDA receptor in the processing of nociceptive input has led to renewed clinical interest in N-methyl-D-aspartate (NMDA) receptor antagonists such as ketamine. Animal studies on ketamine and opioid tolerance have shown promising results. Recent data in animal experiments as in clinical trials have clearly reported that pain modulation is related to an equilibrium between antinociceptive and pronociceptive systems. Therefore, the apparent pain level could not only be a consequence of a nociceptive input increase but could also result from a pain sensitization process. We evaluate the clinical literature and discuss the efficacy of low-dose ketamine in the management of acute pain when administered alone or in conjunction with other analgesic agents as morphine. Low-dose of ketamine is a peroperative intravenous bolus (0.1 to 0.5 mg/kg) followed by a constant infusion rate (1 to 2 mcg/kg per min) for 24 to 72 hours. Those ketamine doses improved postoperative pain management by reducing hyperalgesia due to both surgical trauma and high peroperative opioid doses. This antihyperalgesic action of ketamine also limited the postoperative morphine tolerance leading to a decrease in analgesic consumption and an increase in the analgesia quality. Adverse effects were not increased with small dose ketamine. The evidence suggests that low-dose ketamine is a safe and useful in postoperative pain management when used as an adjunct to local anesthetics, opioids, or other analgesic agents.