Clinical uses of low-dose ketamine in patients undergoing surgery.

Ketamine acts mainly as a N-methyl-D-aspartate receptor (NMDAr) antagonist. Originally developed as a general anesthetic, it is now seldom employed as such in richer countries due to the relatively high risk of psychotomimetic adverse effects. Recently, low-dose regimens in the range of 0.25-0.5 mg/kg as an initial bolus followed by 50-500 kappag/kg/h have been proposed as an adjuvant for postoperative analgesia and for the reduction of exogenous opioid-induced hyperalgesia. In this review, we examine the evidence for clinical usefulness of perioperative ketamine infusion and its role in the context of general and/or regional anesthesia.