New insights into the use of dexamethasone-dexmedetomidine as perineural adjuvants in peripheral nerve and fascial blocks: an up-to-date narrative review

The discovery of the mechanism of action of local anesthetics, involving the blocking of sodium ion channels is considered a milestone in anesthesia. Potentially lethal toxic effects occur in the case of intravascular injection of local anesthetic (LA) or in case of exceeding dosages, as a result of systemic reabsorption. Attempts to prevent these life-threatening events have been made by developing novel LA and by adding adjuvants. The aim of this up-to-date review was to provide the newest insights on the two adjuvants dexamethasone and dexmedetomidine for regional anesthesia. The addition of perineural dexamethasone-dexmedetomidine combination has shown a faster onset, longer duration of action and increased intensity of neuronal blockade of regional anesthesia compared to perineural single adjunct. This is consistent with clinical studies (trials, observational studies and reports) of a marked prolongation of the local anesthetic effect. Nevertheless, further studies are needed to ascertain the full potential of this technique and all possible associated risks.