Low-Dose Perineural Dexamethasone Prolongs Effects of Brachial Plexus Nerve Block

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Female sex, increased age, and increased local anesthetic dose were all associated with longer duration of analgesia.
Female sex, increased age, and increased local anesthetic dose were all associated with longer duration of analgesia.

Low doses of perineural dexamethasone were shown to prolong the duration of ropivacaine brachial plexus nerve block analgesia in a study published in Pain Medicine.

In this retrospective cohort study, 1027 patients undergoing brachial plexus nerve block who received low-dose (2-4 mg; n=393), very low-dose (≤2 mg; n=537), or no (n=97) perineural dexamethasone were evaluated. Exclusion criteria included use of continuous catheter techniques, local anesthetics other than ropivacaine, and block locations with <15 participants.

Low-dose or very low-dose dexamethasone was used in 90.6% of ropivacaine brachial plexus nerve blocks (median dose, 2 mg). Perineural dexamethasone was associated with an increased mean block duration of 5.9 hours for low-dose and 4.9 hours for very low-dose (P <.001 for both).

When compared with very low-dose dexamethasone, low-dose dexamethasone was associated with an increase in block duration of 1 hour (P =.026). After adjustment, no difference was noted between the 2 dose groups for block duration (P =.420).

Female sex (P =.022), increased age (P =.048), and increased local anesthetic dose (P =.01) were all associated with longer duration of analgesia.

The study authors noted that "very low and low doses of perineural dexamethasone are associated with prolonged interscalene and supraclavicular brachial plexus block duration compared with ropivacaine alone." Given the lack of difference between dose groups, they concluded that "very low doses may be considered if dexamethasone is utilized as a perineural adjunct."

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Reference

Schnepper GD, Kightlinger BI, Jiang Y, Wolf BJ, Bolin ED, Wilson SH. A retrospective study evaluating the effect of low doses of perineural dexamethasone on ropivacaine brachial plexus peripheral nerve block analgesic duration [published online September 23, 2017]. Pain Medicine. doi: 10.1093/pm/pnx205 

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