A LONG AXIS APPROACH TO THE FEMORAL ARTERY BLOCK (FAB), FOR MANAGING TOURNIQUET PAIN AND HYPERTENSION IN BELOW-THE-KNEE FRACTURES SURGERY.

National and Kapodistrian University of Athens

Status: Begins enrollment this month

Conditions: Tourniquet Hypertension

Treatments: Other: Normal saline injection (control); Procedure: Femoral artery block - short-axis; Procedure: Femoral artery block - long-axis

Study type: Interventional

Funder types: Other

Identifiers

NCT07548567

802/30-12-2025

Details and patient eligibility

About

This is a prospective, randomized, double-blind controlled trial evaluating an ultrasound-guided femoral artery block (FAB) using a long-axis in-plane approach compared with a short-axis approach and a control group.

The study will include adult patients (ASA I-III) undergoing below-the-knee fracture surgery with tourniquet application. All patients will receive standardized anesthesia including sciatic nerve block and total intravenous anesthesia.

Participants will be randomized into three groups: short-axis FAB, long-axis FAB, or control (saline injection). The primary aim is to assess the effectiveness of the long-axis FAB in reducing tourniquet-induced hypertension. Secondary outcomes include hemodynamic stability, analgesic requirements, pain scores, block characteristics, and procedural performance metrics.

Full description

Tourniquet application during lower limb orthopedic surgery is associated with significant hemodynamic responses, including pain and tourniquet-induced hypertension (TH), which may increase perioperative cardiovascular risk. Femoral artery block (FAB) is a novel ultrasound-guided regional anesthesia technique targeting the perivascular sympathetic plexus surrounding the femoral artery to attenuate these responses.

Previous studies have described FAB using a short-axis in-plane ultrasound approach. This study proposes a novel long-axis in-plane ultrasound technique, hypothesizing that longitudinal visualization of the femoral artery may improve anatomical alignment with perivascular sympathetic structures, resulting in more effective sympathetic blockade, improved safety, and enhanced clinical efficacy.

This is a prospective, randomized, double-blind controlled trial including adult patients (ASA I-III) scheduled for below-the-knee fracture surgery requiring tourniquet application for at least 45 minutes. After informed consent and baseline assessment, patients will be randomized into three groups: (1) short-axis FAB with ropivacaine, (2) long-axis FAB with ropivacaine, and (3) control group receiving normal saline injection.

All patients will receive standardized anesthetic management including sciatic nerve block at the popliteal level and total intravenous anesthesia using propofol and remifentanil via Target-Controlled Infusion (TCI) under BIS monitoring. Hemodynamic variables (blood pressure and heart rate) will be recorded at predefined intraoperative and postoperative time points. Tourniquet-induced hypertension will be defined as a >30% increase in systolic blood pressure from baseline.

Secondary outcomes include intraoperative opioid and vasopressor requirements, incidence of femoral and saphenous nerve spread, procedural performance metrics (imaging and needling time), postoperative pain scores (VAS), and opioid consumption in the recovery unit.

Data will be analyzed using repeated-measures and comparative statistical models to evaluate differences between groups over time and between interventions.

Enrollment: 84 estimated patients

Sex: All

Ages: 18+ years old

Volunteers: No Healthy Volunteers

Inclusion criteria

• Age >18 years Physical status ASA I-III Fluent in Greek or English Scheduled surgery: below-knee fractures Tourniquet duration ≥45 minutes

Exclusion criteria

• Refusal to participate Local inflammation at block site Known allergy to study drugs Morbid obesity (BMI >40) Communication inability Systemic neurological disease affecting peripheral nerves Chronic pain therapy Diabetic neuropathy Uncontrolled hypertension

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Double Blind

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84 participants in 3 patient groups, including a placebo group

Short-axis femoral artery block

Experimental group

Description:

Ultrasound-guided femoral artery block using short-axis in-plane technique with 10 mL ropivacaine 0.5%.

Treatment:

Procedure: Femoral artery block - short-axis

Long-axis femoral artery block

Experimental group

Description:

Ultrasound-guided femoral artery block using long-axis in-plane technique with 10 mL ropivacaine 0.5%.

Treatment:

Procedure: Femoral artery block - long-axis

Saline control injection

Placebo Comparator group

Description:

Ultrasound-guided femoral artery injection using in-plane technique with 10 mL 0.9% normal saline.

Treatment:

Other: Normal saline injection (control)