Bupivacaine-Lidocaine vs Bupivacaine for Ultrasound-Guided Popliteal Sciatic Nerve Block (PSSNB-BL)

Bupivacaine-Lidocaine Combination Versus Bupivacaine Alone for Ultrasound-Guided Popliteal Sciatic Nerve Block in Elective Lower Extremity Surgery: A Prospective Randomized Double-Blind Trial

This prospective, randomized, double-blind clinical trial aims to compare the efficacy of two local anesthetic regimens for ultrasound-guided popliteal sciatic nerve block in adult patients undergoing elective distal lower extremity surgery.

Eligible participants (ages 18-65, ASA physical status I-III, BMI 18-35 kg/m²) will be randomized into two equal groups of 30. Patients in Group BL will receive a combination of 10 mL 2% lidocaine and 10 mL 0.5% bupivacaine, while patients in Group B will receive 20 mL 0.5% bupivacaine alone, administered via ultrasound-guided popliteal sciatic nerve block prior to surgery.

The primary outcome is the onset time of sensory and motor blockade. Secondary outcomes include block success rate, duration of sensory and motor block, postoperative opioid consumption, pain scores assessed by the Numeric Rating Scale (NRS) at 2, 4, 8, 12, and 24 hours postoperatively, Quality of Recovery-15 (QoR-15) score, and incidence of rebound pain.

The study is conducted at Ataturk University Research Hospital, Department of Anesthesiology and Reanimation, Erzurum, Turkey.

Study Overview

• Status: Recruiting
• Conditions: Pain, Postoperative; Nerve Block; Lower Extremity; Pain, Nerve
• Intervention / Treatment: Drug: Bupivacaine-Lidocaine Combination; Drug: Bupivacaine

Detailed Description

Background and Rationale

Peripheral nerve blocks have become an increasingly preferred technique for both anesthesia and analgesia in distal lower extremity surgery, offering advantages such as reduced opioid consumption, stable intraoperative hemodynamics, lower rates of postoperative nausea and vomiting, and enhanced early mobilization. The popliteal approach to the sciatic nerve provides effective surgical anesthesia for foot, ankle, and distal leg procedures, with high patient satisfaction and a low complication profile. Ultrasound guidance further improves block success rates by enabling direct visualization of perineural anatomical structures.

The choice of local anesthetic plays a critical role in determining block onset time, duration of sensory and motor blockade, and overall analgesic duration. Lidocaine offers rapid onset and short-to-intermediate duration, while bupivacaine provides prolonged sensory and motor blockade, thereby reducing postoperative opioid requirements. The combination of these two agents theoretically enables simultaneous achievement of rapid onset and prolonged analgesia; however, the net effect of this combination on block characteristics remains inconclusive in the current literature.

Study Design

This is a prospective, randomized, double-blind, single-center, two-arm parallel-group clinical trial conducted at Ataturk University Research Hospital, Department of Anesthesiology and Reanimation, Erzurum, Turkey.

Participants

A total of 60 adult patients scheduled for elective distal lower extremity surgery will be enrolled. Inclusion criteria: age 18-65 years, ASA physical status I-III, body mass index (BMI) 18-35 kg/m², and written informed consent. Exclusion criteria include inability to provide informed consent, coagulopathy, sepsis, hepatic or renal insufficiency, known allergy to local anesthetics, prior surgery or significant scar tissue in the popliteal fossa, pregnancy, and chronic opioid use at home.

Randomization and Blinding

Eligible patients will be randomized in a 1:1 ratio using a computer-generated random number list into two groups of 30. Study solutions will be prepared by a dedicated investigator not involved in block performance or outcome assessment. Patients and the outcome assessor will be blinded to group allocation (double-blind). The anesthesiologist performing the block will be aware of the group allocation. Block procedures will be performed by an anesthesiologist with a minimum of two years of experience in ultrasound-guided regional anesthesia who is not involved in patient care.

Intervention

All patients will receive an ultrasound-guided popliteal sciatic nerve block using a total volume of 20 mL local anesthetic solution. Patients will be positioned prone or in lateral decubitus with the operative limb uppermost and the knee in slight flexion. Under aseptic conditions, a high-frequency linear ultrasound probe will be placed transversely over the popliteal fossa to visualize the popliteal artery and the tibial nerve. The probe will be advanced proximally to identify the tibial and common peroneal nerve bifurcation. A 100 mm echogenic block needle will be advanced in-plane from lateral to medial. After confirming circumferential perineural spread of 1-2 mL test injection under ultrasound guidance, the study solution will be incrementally injected with repeated aspiration checks.

Group BL (n=30): 10 mL 2% lidocaine + 10 mL 0.5% bupivacaine (administered sequentially in separate syringes)

Group B (n=30): 20 mL 0.5% bupivacaine (administered in two 10 mL syringes) In cases involving the medial malleolus or medial leg surface, an additional adductor canal block will be performed using 10 mL of the respective study solution.

Intraoperative Management Conscious sedation will be maintained intraoperatively with intravenous dexmedetomidine (loading dose: 0.5-1 µg/kg over 10 minutes; maintenance: 0.2-0.7 µg/kg/hour). Continuous monitoring of heart rate, non-invasive blood pressure, oxygen saturation, and electrocardiography will be performed throughout the procedure.

Postoperative Analgesia Protocol All patients will receive intravenous paracetamol 1000 mg 30 minutes before the end of surgery, repeated every 8 hours postoperatively. Intravenous dexketoprofen 50 mg will be administered intraoperatively and repeated every 12 hours. Rescue analgesia with intravenous tramadol 100 mg will be administered for NRS ≥ 4, with a maximum of 3 doses per day and a minimum interval of 4-6 hours between doses.

Outcome Measures Primary Outcome: Sensory and motor block onset time, defined as the elapsed time from completion of injection to first achievement of success criteria.

Secondary Outcomes:

Block success rate (defined as total sensorimotor score ≥12/14 and sensory score ≥7/8)

Duration of motor and sensory blockade

Postoperative opioid consumption

Numeric Rating Scale (NRS 0-10) pain scores at 2, 4, 8, 12, and 24 hours postoperatively

Quality of Recovery-15 (QoR-15) score

Incidence of rebound pain (NRS ≥7 within 24 hours after block resolution)

Neurological assessment at postoperative day 7 (paresthesia, numbness, motor deficit) Block Assessment Sensory block will be assessed using the pinprick test across four nerve territories (tibial, deep peroneal, superficial peroneal, sural nerves), each scored 0-2 (0=normal sensation, 1=analgesia, 2=anesthesia; maximum score 8). Motor block will be evaluated across three nerve territories (tibial, deep peroneal, superficial peroneal nerves), each scored 0-2 (0=normal, 1=paresis, 2=paralysis; maximum score 6). Total maximum sensorimotor score is 14. Blocks not achieving success criteria within 60 minutes will be considered failed.

Statistical Analysis Continuous variables will be assessed for normality using the Shapiro-Wilk test. Normally distributed variables will be compared using the independent samples t-test; non-normally distributed variables using the Mann-Whitney U test. Categorical variables will be analyzed using Fisher's exact chi-square test. A p-value <0.05 will be considered statistically significant. Statistical analyses will be performed using SPSS (IBM, Armonk, NY) or R (v4.2, Vienna, Austria).

• Study Type: Interventional
• Enrollment (Estimated): 60
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: AHMET MURAT YAYIK, MD, PhD; Phone Number: +95544259287; Email: ahmetmuratyayik@gmail.com
• Study Contact Backup: Name: ASLIHAN BOROGLU, MD; Phone Number: +905354378706; Email: aslbrgl_92@outlook.com

Study Locations

• Turkey (Türkiye)
  • Erzurum, Turkey (Türkiye)
    • Recruiting
    • Ataturk University
    • Contact: Ahmet Murat Yayik, MD; Phone Number: 00905544259287; Email: ahmetmuratyayik@gmail.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Age between 18 and 65 years
• American Society of Anesthesiologists (ASA) physical status classification I, II, or III
• Scheduled for elective distal lower extremity surgery (below-knee)
• Body mass index (BMI) between 18 and 35 kg/m²
• Provision of written informed consent

Exclusion Criteria:

• Refusal to participate in the study
• Morbid obesity (BMI ≥35 kg/m²)
• Known allergy or hypersensitivity to any local anesthetic agent
• Severe cardiac, hepatic, or renal disease
• Pre-existing neurological deficits or peripheral neuropathy
• Use of anticoagulant therapy
• History of prior surgery or significant scar tissue in the popliteal fossa
• Pregnancy
• Chronic opioid use at home

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Group BL (Bupivacaine-Lidocaine); Ultrasound-guided popliteal sciatic nerve block with 10 mL 2% lidocaine + 10 mL 0.5% bupivacaine administered sequentially in separate syringes (total volume: 20 mL).	Drug: Bupivacaine-Lidocaine Combination; Ultrasound-guided popliteal sciatic nerve block with 10 mL 2% lidocaine and 10 mL 0.5% bupivacaine administered sequentially in separate syringes (total volume: 20 mL).; Other Names: Lidocaine 2% + Bupivacaine 0.5%
Active Comparator: Group B (Bupivacaine Alone); Ultrasound-guided popliteal sciatic nerve block with 20 mL 0.5% bupivacaine administered in two 10 mL syringes (total volume: 20 mL).	Drug: Bupivacaine; Ultrasound-guided popliteal sciatic nerve block with 20 mL 0.5% bupivacaine administered in two separate 10 mL syringes (total volume: 20 mL).; Other Names: Bupivacaine 0.5%

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Sensory and Motor Block Onset Time	Time elapsed from completion of local anesthetic injection to first achievement of block success criteria, defined as a total sensorimotor score ≥12/14 and sensory score ≥7/8. Blocks not meeting success criteria within 60 minutes will be considered failed.	From completion of injection up to 60 minutes

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Block Success Rate	Proportion of patients achieving a total sensorimotor score ≥12/14 with a sensory score ≥7/8 within 60 minutes of injection.	Within 60 minutes after injection
Duration of Sensory Block	Time from block success to first return of sensation in the blocked dermatomes, assessed by pinprick test.	Up to 72 hours after block application
Duration of Motor Block	Time from block success to recovery of voluntary movement in the blocked extremity, assessed by motor scoring of tibial, deep peroneal, and superficial peroneal nerve territories.	Up to 72 hours after block application
Postoperative Opioid Consumption	Total amount of rescue tramadol (mg) administered intravenously during the first 24 hours postoperatively for NRS pain score ≥4.	First 24 hours postoperatively
Postoperative Pain Score	Pain intensity assessed using the Numeric Rating Scale (NRS, 0-10; 0=no pain, 10=worst imaginable pain) at 2, 4, 8, 12, and 24 hours postoperatively.	At 2, 4, 8, 12, and 24 hours postoperatively
Incidence of Rebound Pain	Proportion of patients experiencing rebound pain, defined as NRS ≥7 within 24 hours after resolution of the sensory block.	Within 24 hours after sensory block resolution, up to 72 hours postoperatively
Neurological Assessment at Postoperative Day 7	Presence of any neurological sequelae including paresthesia, numbness, or motor deficit in the blocked extremity, assessed by telephone interview or clinic visit at postoperative day 7.	Postoperative day 7
preoperative and 24 hours postoperatively	Patient-reported quality of recovery assessed using the validated QoR-15 questionnaire (total score 0-150; higher scores indicate better recovery).	At 24 hours postoperatively

Collaborators and Investigators

• Sponsor: Ataturk University
• Investigators: Principal Investigator: AHMET MURAT YAYIK, MD, PhD, Ataturk University Faculty of Medicine, Department of Anesthesiology and Reanimation; Principal Investigator: ASLIHAN BOROGLU, MD, Ataturk University Faculty of Medicine, Department of Anesthesiology and Reanimation

Publications and helpful links

General Publications

• Wieder B, Arbisfeld J. Overriding Safety Controls. Am J Nurs. 2023 Nov 1;123(11):9. doi: 10.1097/01.NAJ.0000995280.93037.b9. No abstract available.
• Gallipoli A, MacLean G, Walia JS, Sehgal A. Congenital Chylothorax and Hydrops Fetalis: A Novel Neonatal Presentation of RASA1 Mutation. Pediatrics. 2021 Mar;147(3):e2020011601. doi: 10.1542/peds.2020-011601.
• Occhipinti G, Ruberti AA, Alcocer J, Gimenez-Mila M, Vidal B, Regueiro A. Sex differences in patients undergoing aortic valve replacement: a tale of 2 hearts. Rev Esp Cardiol (Engl Ed). 2025 Oct;78(10):916-918. doi: 10.1016/j.rec.2025.01.014. Epub 2025 Feb 6. No abstract available. English, Spanish.

Study record dates

Study Major Dates

• Study Start (Actual): December 1, 2025
• Primary Completion (Estimated): December 1, 2026
• Study Completion (Estimated): March 1, 2027

Study Registration Dates

• First Submitted: April 15, 2026
• First Submitted That Met QC Criteria: April 20, 2026
• First Posted (Actual): April 24, 2026

Study Record Updates

• Last Update Posted (Actual): May 12, 2026
• Last Update Submitted That Met QC Criteria: May 8, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Local anesthetic; Lidocaine; Bupivacaine; Postoperative analgesia; Regional anesthesia; QoR-15; Lower extremity surgery; Ultrasound-guided nerve block; Popliteal sciatic nerve block; Block onset time
• Additional Relevant MeSH Terms: Pain; Neurologic Manifestations; Nervous System Diseases; Postoperative Complications; Pathologic Processes; Neuromuscular Diseases; Peripheral Nervous System Diseases; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Pain, Postoperative; Neuralgia; Organic Chemicals; Anilides; Amides; Aniline Compounds; Amines; Acetanilides; Bupivacaine; Lidocaine
• Other Study ID Numbers: B.30.2.ATA.0.01.00/927

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No