Femoral Nerve Block: Indications and Technique

A femoral nerve block is a basic nerve block technique that is easy to master, carries a low risk of complications, and has a significant clinical applicability for surgical anesthesia and post-operative pain management.

• Indications: Anterior thigh and knee surgery
• Landmarks: Femoral (inguinal) crease, femoral artery pulse
• Nerve Stimulation: Twitch of the patella (quadriceps) at 0.2-0.5 mA current
• Local anesthetic: 20 mL
• Complexity level: Basic

This block is well suited for surgery such on the anterior thigh, knee, quadriceps tendon repair, and postoperative pain management after femur and knee surgery. When combined with a block of the sciatic nerve, anesthesia of almost the entire lower extremity from the mid-thigh level can be achieved. The success rate of this block for surgery is very high, nearing 95%.

Surface Landmarks The following surface anatomy landmarks are used to determine the insertion point for the needle: Femoral crease Femoral artery
Anatomic Landmarks Landmarks for the femoral nerve block are easily recognizable in all patients and include: Femoral crease Femoral artery pulse
Needle insertion site is labeled immediately lateral to the pulse of the femoral artery. All landmarks should be outlined with a marking pen. TIPS: Note that this technique differs from common descriptions of the femoral nerve block, where the needle is inserted at the level of the inguinal ligament. Instead, in this technique the needle is inserted at the level of the femoral crease, a naturally occurring, oblique skin fold positioned a few centimeters below the inguinal ligament. The femoral crease can be accentuated in obese patients by asking an assistant to retract the lower abdomen laterally. The retraction of the abdomen should be maintained throughout the procedure to facilitate palpation of the femoral artery and block performance.

After a thorough cleaning with an antiseptic solution, local anesthetic is infiltrated subcutaneously at the estimated site of needle insertion. The injection for the skin anesthesia should be shallow and in a line extending laterally to allow for more lateral needle reinsertion when necessary.

The anesthesiologist is standing on the side of the patient with the pal-pating hand on the femoral artery. The needle is introduced immediately at the lateral border of the artery and advanced in the saggital and slightly cephalad plane.

TIP: The nerve stimulator is initially set to deliver 1.0 mA (2 Hz, 100 µsec). With proper needle position, advancement of the needle should not result in any local twitches; the first response is usually that of the femoral nerve.

from NYSORA.com