Low S(+) ketamine doses: a review.

BACKGROUND AND OBJECTIVES Low doses of ketamine or isomers are promising possibilities for anesthesia and postoperative analgesia. This study aimed at reviewing major properties of low ketamine doses, which may justify their use in anesthesia and postoperative analgesia. CONTENTS Literature suggests that ketamine induces preemptive and preventive postoperative pain relief, decreasing opioid consumption and improving patients' satisfaction. Opioid-induced tolerance and hyperalgesia may be minimized with low ketamine doses. Ketamine decreases inhalational anesthetic consumption and may protect ischemic nervous cells. Promising effects, such as neuroprotection and improvement of long-term outcomes, require further studies. CONCLUSIONS Most studies with low S(+) ketamine doses have shown preventive effects, decreasing central nervous system sensitization, opioid-induced tolerance and hyperalgesia, anesthetic and analgesic consumption, and the incidence of postoperative adverse effects.