Motor-Sparing Femoral Nerve Block Dose

University of Chile

Status and phase: Terminated; Phase 4

Conditions: Knee Injuries; Osteoarthritis, Knee

Treatments: Drug: Lower Bupivacaine Concentration; Drug: Same Bupivacaine Concentration

Study type: Interventional

Funder types: Other

Identifiers

NCT02909257

OAIC 823/16

Details and patient eligibility

About

Femoral nerve blocks are commonly used to provide pain control for total knee replacement, anterior cruciate ligament (ACL) reconstruction. Commonly employed local anesthetic concentrations result in motor block of the quadriceps and constitute an inherent risk factor for patient fall.

The aim of this study is to determine the minimum effective concentration of bupivacaine in 90 % of patients (MEC90) required for a motor-sparing, successful sensory block of the femoral nerve.

Full description

With the approval of Ethics Committee of the University of Chile Clinical Hospital, approximately 60 patients undergoing ACL repair or TKR will be recruited. All blocks will be conducted preoperatively in an induction room.Dose assignation will be done using an up-and-down sequential method, where the dose of each subsequent patient depends on the response of the previous patient, called the Biased Coin Design.

The assignment of each subsequent concentration will be based on the response of the previous patient.As soon as we recruit 45 patients with random dose assignment, we will terminate the enrollment procedure.

The injectate will be prepared and administered by a research assistant using syringes connected to the block needle. The operator and the patient will be blinded to the concentration injected.

Enrollment: 31 patients

Sex: All

Ages: 18 to 75 years old

Volunteers: No Healthy Volunteers

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 inguinal region
• Chronic pain syndromes requiring opioid intake at home

Trial design

Primary purpose: Supportive Care

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Double Blind

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31 participants in 2 patient groups

same dose

Experimental group

Description:

patient is exposed to the same previously successful dose

Treatment:

Drug: Same Bupivacaine Concentration

lower dose

Experimental group

Description:

patient is exposed to a lower concentration dose

Treatment:

Drug: Lower Bupivacaine Concentration