Femoral Peri-arterial Local Anesthetic Injection Decreases Tourniquet Associated Ischemic Hypertension

The purpose of this prospective randomized double-blind study is to determine if the novel technique of ultrasound guided peri-arterial injection of local anesthetic around the femoral artery decreases ischemic hypertension associated with prolonged lower extremity tourniquet time during total ankle arthroplasty (TAA) and foot fusion surgeries. Efficacy will be determined by analyzing incidence of intraoperative ischemic hypertension, defined as >30% increase in systolic blood pressure, associated with tourniquet inflation times greater than 90 minutes. The study will involve a total of 30 patients (15 in each group) and with a power of 80% to detect a 50% difference. The patients involved in the study will be ASA 1-3 patients who are undergoing either TAA or foot fusion surgeries. Patients will receive standard of care for their anesthesia, which at Duke Hospital includes placement of popliteal and saphenous perineural catheters and a general anesthetic with a laryngeal mask airway. Patients will be randomized to receive femoral peri-arterial injection with either 1.5% mepivacaine with 1:400,000 epinephrine or 0.9% saline which will be performed preoperatively at time of perineural catheter placement. Patients will assume standard risk associated with nerve blocks, including theoretical risk of nerve damage and local anesthetic systemic toxicity. Possible benefits include improved intraoperative hemodynamic stability, decreased intraoperative opioid and antihypertensive medications, and decreased tourniquet associated pain post-operatively.

Inclusion criteria

Patients that will be included in the study are English speaking 18-75 year old ASA 1-3 patients undergoing total ankle arthroplasty.

Exclusion criteria

• ASA 4 or 5
• Diagnosis of chronic pain
• Daily chronic opioid use (over 3 months of continuous opioid use).
• Inability to communicate pain scores or need for analgesia.
• Infection at the site of block placement
• Age under 18 years old or greater than 75 years old
• Pregnant women (as determined by standard of care day-of surgery urine bHCG)
• Intolerance/allergy to local anesthetics
• Weight <50 kg
• Suspected, or known addiction to or abuse of illicit drug(s), prescription medicine(s), or alcohol within the past 2 years.
• Uncontrolled anxiety, schizophrenia, or other psychiatric disorder that, in the opinion of the investigator, may interfere with study assessments or compliance.
• Current or historical evidence of any clinically significant disease or condition that, in the opinion of the investigator, may increase the risk of surgery or complicate the subject's postoperative course