Lumbar Plexus block & Femoral nerve Block

Presented by Marwa A. Khairy Assistant Lecturer of Anesthesia & intensive care Faculty of Medicine-Ain Shams University Lumbar Plexus block &Femoral nerve Block

MCQs • All about lumbar plexus anatomy are true except: • Formed mainly by anterior rami of L1-L4 • Receive contribution from S1-S2 • Embedded in the psoas ms • Supplies the posterior aspect of the thigh.

MCQs • The lumbar plexus Block landmark: • At the PSIS • At the Midline • At point 4 cm lateral to intersection between midline & intercrestal line • At L2-L4 vertebrae

MCQs • Lumbar plexus Block • Advanced technique • High volumes are needed • Hemodynamic instability is a potential problem • Not used in anticoagulated patients

MCQs • The femoral nerve • Formed by the anterior divisions of the anterior rami of L2–L4. • Supply the adductors of the thigh • Supply the medial aspect of the lower leg via the saphenous nerve. • it is positioned immediately lateral and slightly deeper than the femoral artery

MCQs • The femoral nerve block • The first sign of onset of blockade is the loss of sensation of the skin over the medial aspect of the leg below the knee (saphenous nerve). • Typical onset time for this block is 10-15 minutes • Visible twitch of the quadriceps muscle) at 0.2-0.5 MA current is the optimal response. • Carry high risk of postoperative falls.

Lumbar Plexus Block • Introduction • Anatomy • Distribution of anesthesia • Patient positioning • Equipment • Nerve stimulator guided technique • US guided technique • Complications

Introduction • The lumbar plexus block is an advanced nerve block technique. • The block has significant clinical applicability and because of this, it is used commonly in our practice. • However, this block has a relatively higher potential for complications and should be practiced only after appropriate training

Indications • Anterior, medial, and lateral procedures of the thigh including harvest of skin grafts, malignant hyperthermia (MH)-biopsy procedure. • Knee replacement, • Total hip replacement ,hip fractures. • Anterior and posterior cruciate ligament reconstruction.

Anatomy of Lumbar Plexus The lumbar plexus is formed by the anterior rami of the first four lumbar nerves; it frequently includes a branch from T12 and occasionally from L5. The plexus lies between the psoas major and quadratuslumborum muscles in the so-called psoas compartment.

Distribution of Anesthesia The femoral nerve supplies motor fibers to the quadriceps muscle (knee extension), skin of the anteromedial thigh, and the medial aspect of the leg below the knee and foot. The obturator nerve sends motor branches to the adductors of the hip and a highly variable cutaneous area on the medial thigh or knee joint. The lateral femoral cutaneous and genitofemoral nerves are purely cutaneous nerves

Patient Positioning The patient is in the lateral decubitus position with a slight forward tilt. The foot on the side to be blocked should be positioned over the dependent leg so that twitches of the patella can be seen easily.

Equipment A standard regional anesthesia tray is prepared with the following equipment: Sterile towels and 4"x4" gauze packs 20-mL syringes with local anesthetic Sterile gloves, marking pen, and surface electrode One 1½" 25-gauge needle for skin infiltration A 10-cm long, short bevel, insulated stimulating needle Peripheral nerve stimulator

Landmarks Landmarks for the lumbar plexus block include: Iliac crest Midline (spinous processes) Needle insertion 4-cm lateral to the intersection of landmarks 1 and 2

Technique Local anesthetic skin infiltration After a cleaning with an antiseptic solution.

Technique The needle is inserted at a perpendicular angle to the skin. The nerve stimulator should be initially set to deliver 1.5 mA current.

Technique As the needle is advanced, local twitches of the paravertebral muscles are obtained first at a depth of a few cms.

Technique The needle is then advanced further until twitches of the quadriceps muscle are obtained (usually at the depth of 6-8 cm). After the twitches are obtained, the current should be lowered to obtain stimulation between 0.5 mA and 1.0 mA. At this point, 25-35 mL of local anesthetic is slowly injected with frequent aspiration to rule out inadvertent intravascular placement of the needle. .

Choice of Local Anesthetic • Requires a relatively large volume of local anesthetic • The choice of the type and concentration of local anesthetic should be based on whether the block is planned for surgical anesthesia or pain management. • Due to the highly vascular nature of the area there is high potential for inadvertent intravascular injection, rapid absorption from the deep muscle beds, and epidural spread

Choice of Local Anesthetic

Block Dynamics and Perioperative Management • Adequate sedation and analgesia are necessary to ensure a still and tranquil patient. • Typically, we use midazolam 4-6 mg after the patient is positioned and alfentanil 500-1000 µg just before needle insertion. • A typical onset time for this block is 15-25 minutes, depending on the type, concentration, and volume of local anesthetic and the level at which the needle is placed.

Block Dynamics and Perioperative Management • The first sign of the onset of blockade is usually the loss of sensation in the saphenous nerve territory (medial skin below the knee).

Complications • Infection • Hematoma (should not be performed in anticoagulated pts) • Nerve injury • Vascular puncture • Local Anesthetic Toxicity • Hemodynamic consequence (Spread of the local anesthetic to the epidural space may result in significant hypotension and occurs in as many as 15% of the patients)

US Guided Ultrasound Landmarks: The transverse processes of the third and fourth lumbar vertebrae and the psoas muscle. Transducer Type: Linear or curved array, 3 to 7 MHz Transducer Position: Sagittal plane, 4 to 5 cm lateral to the posterior spinous process of the fourth lumbar vertebra

US Guided Longitudinal sonogram of the lumbar paravertebral region showing an optimal scan for lumbar plexus block the ‘trident sign’.

Femoral Nerve Block • Introduction • Anatomy • Distribution of anesthesia • Patient positioning • Equipment • Nerve stimulator guided technique • US guided technique • Complications

A Common Scenario….. • An 83-yr-old woman (70 kg ) is admitted to the emergency room after a fall in her nursing home. She has fractured the neck of her femur, but otherwise there is no trauma. In addition, she has many medical problems, including coronary artery disease, hypertension, and chronic obstructive lung disease. • On examination, she was cooperative and orientated for time and place. HR 100 atrial fibrillation, blood pressure (BP) 170/100. The electrocardiogram (ECG) shows old MI change with left-axis deviation. Room oxygen saturation is 91%. Her chest is clear, except for crepitations at the bases and increased respiratory wheeze.

A Common Scenario….. • Because she is orientated for time and place, she requests a spinal anesthetic, as she is worried about going to sleep. You are happy to oblige and explain that she must either sit up or lie on her side for you to do the spinal. She absolutely refuses and claims this will be very painful.

A Common Scenario….. • You attempt to sit her up, but she complains of severe pain. You give her midazolam 0.5 mg and fentanyl 50 mg, slowly. A little later she claims to feel better. However, her oxygen saturation has now fallen to 87% on room air. You give her supplemental oxygen and her saturation improves to 93%. You attempt to sit her up again, but she complains bitterly. You could use a small dose of ketamine so that you can place the spine in a lateral position, but you are concerned about a potentially unacceptable increase in BP with ketamine and the need to use atropine with its side effects.

A Common Scenario….. • What else could you do to make her pain free. so that you can perform the spinal block? • You can perform a femoral nerve block

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

Indications • Anterior thigh surgery • ACL repair • Knee arthroscopy (+ intra-articular local) • Femur surgery • Knee arthroplasty (pain management only)

Anatomy The femoral nerve, formed by the dorsal divisions of the anterior rami of L2–L4, is the largest terminal branch of the lumbar plexus.

Anatomy The femoral nerve passes underneath the inguinal ligament into the thigh. As the femoral nerve passes underneath the inguinal ligament, it is positioned immediately lateral and slightly deeper than the femoral artery

Anatomy At the femoral crease, the nerve it is covered by the fascia iliacaand separated from the femoral artery and vein by a portion of the psoas muscle and the ligamentumileopectineum. This physical separation of the femoral nerve from the vascular fascia explains the lack of the spread of a "blind paravascular" injection of local anesthetics toward the femoral nerve.

Anatomy • After emerging from the ligament, the femoral nerve divides into an anterior and posterior branch. At this level it is located lateral and posterior to the femoral artery anterior branch Motor Sartorius and pectineus ms Sensory skin of the anterior and medial thigh posterior branch Motor quadriceps muscles Sensory medial aspect of the lower leg via the saphenous nerve

Distribution of Anesthesia A femoral block results in anesthesia of the entire anterior thigh and most of the femur and knee joint. The block also confers anesthesia of the skin on the medial aspect of the leg below the knee joint (saphenous nerve - a superficial terminal extension of the femoral nerve).

Patient position The patient is in the supine position with both legs extended. In obese patients, a pillow placed underneath patient's hips may facilitate palpation of the femoral artery and block performance.

Equipment Sterile towels and 4"x4" gauze packs 20 mL syringes with local anesthetic Sterile gloves, marking pen, and surface electrode One 1½" 25-gauge needle for skin infiltration A 5-cm long, short bevel, insulated stimulating needle Surface electrode Peripheral nerve stimulator

Landmarks Landmarks for the femoral nerve block are easily recognizable in all patients and include: Femoral crease Femoral artery pulse

Landmarks Needle insertion site is labeled immediately lateral to the pulse of the femoral artery. All landmarks should be outlined with a marking pen

Technique After a thorough cleaning with an antiseptic solution, local anesthetic is infiltrated subcutaneously at the estimated site of needle insertion.

Technique The anesthesiologist is standing on the side of the patient with the pal-pating hand on the femoral artery. The nerve stimulator is initially set to deliver 1.0 mA (2 Hz, 100 µsec). The needle is introduced immediately at the lateral border of the artery and advanced in the saggital and slightly cephalad plane

Technique The femoral nerve innervates a number of muscle groups. A visible or palpable twitch of the quadriceps muscle (patella twitch) at 0.2-0.5 mA current is the optimal response.

Choice of local Anesthetic • A femoral block can be accomplished with as little as 10 mL of local anesthetic. However, we often use larger volumes of local anesthetic (e.g., 20-25 mL), because the local anesthetic often disperses underneath fascia iliaca laterally and results also in block of the lateral femoral cutaneous nerve of thigh.

Choice of local Anesthetic • The choice of the type and concentration of local anesthetic should be based on whether the block is planned for surgical anesthesia or pain management. • Long-acting local anesthetic should be avoided in ambulatory patients undergoing relatively minor procedures as ambulation is affected by prolonged motor block of the quadriceps muscle.

Choice of local Anesthetic

Lumbar Plexus block & Femoral nerve Block