Minimum Effective Volume of Lidocaine-Bupivacaine for Subgluteal Block

Minimum Effective Volume of Lidocaine-Bupivacaine for Ultrasound-Guided Subgluteal Sciatic Nerve Block

The aim of this study is to determine the minimum effective volume of LA in 90 % of patients (MEV90) required for US-guided subgluteal sciatic nerve block.

The aim of this study is to determine the minimum effective volume of LA in 90 % of patients (MEV90) required for US-guided subgluteal sciatic nerve block.

Success rate is defined as a minimal composite score of 6 points (out of 8 points) at 30 minutes.

Inclusion Criteria:

• age between 18 and 75 years
• American Society of Anesthesiologists classification 1-3
• body mass index between 20 and 35

Exclusion Criteria:

• adults who are unable to give their own consent
• pre-existing neuropathy (assessed by history and physical examination)
• 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 partial 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 LA
• pregnancy
• prior surgery in the subgluteal region
• chronic pain syndromes requiring opioid intake at home