痛みと緩和のジャーナル

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Perineural versus Intravenous Dexamethasone for Prolongation of Multiple Nerve Blocks for Pain Relief after Total Knee Arthroplasty

Anatoli Stav, Leonid Reytman, Michael-Yohay Stav, Aksana Machluf, Roger Sevi and Mohammed Tallas

Background: Multiple nerve blocks (MNB) provide excellent time-limited perioperative analgesia following total knee arthroplasty. Both perineural and systemic use of dexamethasone (DXM) as an adjuvant to local anesthetic prolong the duration of single-shot MNB. We hypothesized that preoperative perineural injection of DXM prolongs analgesia after MNB more than the same dose of intravenous (IV) DXM injection due to direct action on the nerves and not only by a systemic action mechanism.

Methods: This is a prospective, randomized, controlled and observer-blinded study. One hundred and nine patients were randomly assigned to one of three groups: Group (Gr) 1-perineural DXM+MNB, Gr 2-systemic IV DXM +MNB, Gr 3-control group, MNB without DXM. Postoperative variables including intensity of pain at rest and during motion, grade of sensory and motor block, opioid consumption, comfort time (the first analgesic request) were the primary end-points of investigation.

Results: Ninety patients completed the study protocol. Very low parameters of intensity of pain at rest and during motion, high grade of sensory and motor block were observed up to 12 hours after MNB performance in all three groups. Patients who received MNB with DXM perineurally or systemically, experienced superior pain relief and had reduced opioid consumption 24 hours post-block compared to the control group without differences between the two "dexamethasone" groups. There were no differences between groups at 36 and 48 hours post-block. Patients in the control group suffered from pain at rest and started treatment by any analgesics significantly earlier than patients from the two “dexamethasone” groups. No difference of comfort time was observed between Gr 1 and Gr 2. In the period between 24 and up to 36 hours the block’s effect (i.e. the effect of local anesthetic with adjuvant dexamethasone) gradually weakened and somewhere at 48 hours post-block, it passed almost completely.

Conclusions: Intravenous 8 mg dexamethasone is equivalent to perineural dexamethasone in prolonging the pain relief duration of an ultrasound guided single-shot multiple nerve block with bupivacaine and adrenaline following total knee arthroplasty.