Pharmacokinetic Analysis of Bupivacaine in the Presence and Absence of Perineural Dexamethasone in Axillary Blockade

Pharmacokinetic Analysis of Bupivacaine in the Presence and Absence of Perineural Dexamethasone in Axillary Brachial Plexus Blockade for Distal Forearm and Hand Surgery

The investigators will conduct a prospective, randomized, double-blinded study using an axillary brachial plexus block in patients undergoing elective surgery of the distal forearm and hand to characterize and describe the pharmacokinetics of bupivacaine associated with perineural dexamethasone.

The pharmacokinetic analysis will be performed by measuring bupivacaine plasma levels at different time intervals after the blockade (15, 30, 45, 60, and 90 minutes), allowing comparison between 2 different groups: Bupivacaine (B) and Bupivacaine-dexamethasone (BD).

Thus, the hypothesis is that plasma levels of bupivacaine during the first 90 minutes after a blockade are lower in the presence of perineural dexamethasone, suggesting a decrease, at least initially, in systemic absorption from the injection site.

Inclusion Criteria:

• American Society of Anesthesiologists classification 1-2
• Real weight between 80 and 100 kg
• Body mass index between 20 and 30

Exclusion Criteria:

• Adults who are not capable of giving their own consent
• Medical history or physical findings of pre-existing neuropathy
• Coagulopathy (assessed by history and physical examination and, if deemed clinically necessary, by blood work up i.e. platelets ≤ 100, International Normalized Ratio ≥ 1.4 or prothrombin time ≥ 50)
• Renal failure (assessed by history and physical examination and, if deemed clinically necessary, by blood work up i.e. creatinine ≥ 100)
• Hepatic failure (assessed by history and physical examination and, if deemed clinically necessary, by blood work up i.e. transaminases ≥ 100)
• Allergy to local anesthetics (LAs)
• Pregnancy
• Previous surgery in the axillary region of the surgical side