Femoral Nerve Block PDF

[Regional: Lower Extremity] **[Femoral Nerve Block]** - Indications- Anesthesia and Analgesia for: - Hip - Femur - Anterior Thigh - Knee/Patella - Analgesia for hip fractures - Goal: - LA spread around the femoral nerve - Transducer: - High...

[Regional: Lower Extremity] **[Femoral Nerve Block]** - Indications- Anesthesia and Analgesia for: - Hip - Femur - Anterior Thigh - Knee/Patella - Analgesia for hip fractures - Goal: - LA spread around the femoral nerve - Transducer: - High frequency linear array transducer - Depth: 2-4 cm - LA: - Bupivacaine 0.5% - 10-15 mL - Needle: - 22g 5 cm short bevel - Anatomy: - The femoral nerve is the largest branch of the lumbar plexus. It originates from the dorsal divisions of the ventral rami of the L2 to L4 lumbar nerves. - At the level of the fifth lumbar vertebral body, the femoral nerve exits the psoas muscle in a medial to lateral direction deep to the fascia iliaca. It continues caudally and enters the anterior compartment of the thigh underneath the inguinal ligament, anterior to the iliopsoas muscle, and lateral to the femoral artery and vein. - In the femoral triangle, it travels lateral and slightly deeper to the femoral artery and gives off multiple branches: - Deep branches innervate the anterior aspect of the hip, femur, and knee. - Muscular branches innervate the iliacus, psoas major, pectineus, rectus femoris, vastus lateralis, vastus intermedius, vastus medialis, and sartorius muscles. - Cutaneous branches innervate the skin on the anterior aspect of the thigh and knee. - The most medial part, the saphenous nerve, descends alongside the femoral artery to provide the innervation to the patella, superficial structures (skin) of the knee, and medial aspects of the leg. - The femoral nerve innervates: - Joints: Part of the hip, anterior aspect of the knee and the medial aspect of the ankle. - Bones: Anterior aspect of the femur. - Muscles: The extensors of the knee (quadriceps, sartorius, and pectineus). - Skin: Anterior and medial thigh and knee, and medial leg down to the midfoot. - Patient position: - Supine, with the LE fully extended and slightly rotated externally. - External landmarks: The femoral crease. - Position the transducer in a transverse orientation over the femoral crease. - Identify the pulsation of the anechoic femoral artery with the femoral vein medial to it. - Transducer: - - Tips: - Adjust the **pressure** and **tilt** the transducer to better visualize fascial iliaca over the nerve. - If two arteries are visualized at the initial position, **slide** the transducer more proximally until the femoral artery is identified (one artery). - **Rationale:** Performance of the block distal to the bifurcation will not result In a block of the entire nerve because some branches leave the femoral nerve more proximally. A proximal block is important only when anesthesia is desired only for the anterior knee, patella, or quadriceps muscle tendon repair. - After injection, scan slightly proximally-distally to assure the spread of local anesthetic in the fascia containing the nerve; this may not always be obvious by monitoring in the injection plane only. - Needle insertion - Insert the needle in-plane from a lateral to a medial direction to pierce the fascia iliaca lateral to the femoral nerve. - Needle inserted lateral to media - Inject 1-2 ml of local anesthetic to confirm proper needle placement and complete the block with 10-15 ml. - 20 mL local anesthetic beneath FL and FI and superior to iliopsoas muscle. - The injection is successful when: - Local anesthetic separates the two layers of the fascia and around femoral nerve (A). - Injected local anesthetic displaces the nerve away from the needle (B). - Local anesthetic spreads above, below or around the nerve between the fascia iliaca layer containing the femoral nerve. - Transducer position and sonoanatomy of the femoral nerve (FN) at the femoral crease. The FN is seen indenting the iliopsoas muscle, covered by the fascia iliaca (white arrow). The femoral artery (FA) and femoral vein (FV} are enveloped within their own vascular fascial sheath. Needle insertion in-plane and spread of local anesthetic (blue) to block the femoral nerve (FN}. FA, femoral artery; FV, femoral vein. - Tips: - Long-lasting local anesthetics(e.g. bupivacaine 0.5% or ropivacaine 0.5%) are used for anesthesia or analgesia after knee surgery. - The use of diluted mixtures of these local anesthetics (eg. 0.125.-0.25%), may be used to diminish, but not eliminate the quadriceps weakness. - A volume of 10-15ml is usually sufficient for an effective block. - The addition of liposomal bupivacaine for a FN block has been described. Studies show a decrease in pain scores and opioid consumption for up to 48 hours. To date, this extended-release formulation of local anesthetics has not been approved for FN block. - Tips and Algorithm - Tilt the transducer cranially-caudally to optimize the image of the nerve. - Puncture the fascia iliaca lateral to the edge of the femoral nerve. - If nerve stimulation is used (0.5 mA. 0.1 msec), the contact of the needle tip with the femoral nerve is associated with a motor response of the quadriceps muscle group. - Beware of the motor weakness of the quadriceps - risk of falls. - Circumferential spread of local anesthetic around the nerve is not necessary for this block. FL Fascia lata Fl Fascia iliaca FA Femoral artery FN Femoral nerve - Pearls - The mnemonic NAVL (nerve, artery, vein, lymph) is often used when going lateral to medial to remember the relationship of the FN to the other structures at the inguinal crease. With either technique (landmark or ultrasound guidance) the needle tip must penetrate both the fascia lata and fascia iliaca to ensure an efficacious block. Studies demonstrate that the local anesthetic volumes greater than 20 ml are not associated with improved block rates. - Risks and Complications - Although not common, inadvertent vascular puncture and nerve injury are complications associated when performing this block. Because of the associated quadriceps weakness with this block, it has been speculated that peripheral nerve blockade contributes to the rate of falls following lower extremity total joint surgery. However, contrary to these concerns, a study examining 190,000 records found that peripheral nerve block did not alter the risk of inpatient falls of 1.6% in this group. **[Adductor Canal Block]** - Indications- Anesthesia and Analgesia for: - Analgesia for knee surgery - Skin anesthesia of the medial aspect of the leg below the knee (e.g., ankle or foot surgery). - Can be combined with sciatic nerve block for surgery below the knee (e.g., foot amputation, ankle fracture). - Goal: - Depending on the level of block, LA spread around the FN in the femoral triangle or saphenous nerve in the adductor canal. - Transducer: - Linear or curved (larger patients) - Needle: - 22 gauge, 5-8 cm - LA: - 10 mL - Anatomy: - The saphenous nerve is a terminal sensory branch of the femoral nerve. It innervates the medial aspect of the leg distally to the level of the medial ankle and/or midfoot. It supplies sensory branches to the superficial structures of the knee (skin and patellar branches). - Saphenous nerve can be blocked at proximal or distal levels (above or below the knee), depending on the indication. - In the proximal thigh, the saphenous nerve travels together with the femoral vessels in the femoral triangle and into the adductor canal under the sartorius muscle. - **Saphenous nerve block at the adductor** **canal** results in anesthesia of the skin from the medial aspect of the leg and knee to the ankle joint and foot. - **You should also know:** Injection of larger volumes of local anesthetic {e.g., \> 15 ml) in the adductor canal or femoral triangle may result in a partial block of the quadriceps muscle due to spread around the femoral nerve. Larger volumes of injectate into the adductor canal may also result in spread into the popliteal fossa and popliteal plexus - a group of autonomic and genicular nerves that contribute sensory branches to the posterior capsule of the knee. - Patient position: - Supine, with the thigh abducted and externally rotated to allow access to the medial thigh. If unable, separation of the - legs may be adequate. - External landmarks: - Middle third of the thigh - Tip: - Divide the length of the thigh, from the femoral crease to the knee in 3 equal parts. The adductor canal is located somewhere about the border of the middle and distal 1/3 of the thigh. - Place the Transducer in a transverse orientation at the level of the middle third of the thigh - Identify the femoral artery deep to the sartorius muscle. - Identify the limits of the femoral triangle and adductor canal by scanning up and down until the medial border of the sartorius muscle meets the medial border of the adductor longus muscle. - From this point. continue to scan distally until the adductor longus muscle (ALM) becomes shorter in the ultrasound image, and the artery is located in the middle of the sartorius muscle (see the example below). This location is an adequate site for injection -- adductor canal. - Insert the needle in plane in a lateral to medial direction. Advance towards the femoral artery and saphenous nerve. Identify the femoral vein by applying and releasing transducer pressure. - After negative aspiration, inject 1-2 ml of local anesthetic to confirm proper injection site around the saphenous nerve. Complete the block with 10 ml local, change the needle direction to facilitate spread over the femoral artery. - Tips and algorithm - **Color doppler:** If the artery cannot be visualized: 1) Use color Doppler or Power Doppler mode and/or 2) Image the femoral artery at the femoral crease and follow the artery by scanning distally. - **Local anesthetic volume:** Do not use more than 10 ml of local anesthetic. Bigger volumes may result in motor block of the quadriceps muscle and increase the risk of local anesthetic systemic toxicity if an IV injection occurs (e.g., femoral vein). - **Do I need to visualize the nerve?** The sonographic appearance of the saphenous nerve is hyperechoic; although the nerve may not always be seen (e.g., larger patients). Regardless, injection of 10 ml of local anesthetic next to the lateral aspect of the femoral artery should be successful. The saphenous nerve often becomes better visualized after the injection. - **In-plane or out-of-plane?** Both in-plane, or out-of-plane needle insertion techniques can be used (out-of-plane may be easier in larger patients). - Femoral triangle limits: - Roof: Formed by the sartorius muscle. - Apex: Intersection between the medial borders of the sartorius and adductor longus muscles. - Important FACT: The apex of the femoral triangle defines the proximal end of the adductor canal. - Bottom line: A femoral TRIANGLE injection can block more femoral branches to the knee. An adductor canal injection blocks primarily the saphenous nerve. - Definitions clarification: The femoral triangle ends distally as the adductor canal. Adductor canal is sometimes confusingly referred to as ·subsartorius canal·, although the sartorius muscle is the roof in both - femoral triangle and adductor canal. - What is in the canal? The bottom line is that adductor canal contains saphenous nerve and femoral artery in a triangular fascial plane made by the sartorius (superficially), the vastus medialis (anterolaterally) and the adductor longus and adductor magnus (posteromedially). - Triangle versus Canal: The femoral triangle is more proximal and contains proximal saphenous nerve, often a branch to the vastus medialis, and sometimes a branch of the obturator nerve, all of which can be involved in contributing innervation to the knee joint. The adductor canal contains distal saphenous nerve, often with medial femoral cutaneous nerve, and may convey injections into popliteal fossa. - The adductor canal block (ACB) was first described by Kirkpatrick et al. as a means 10 identify the SphN in the proximal to midthigh using the superficial femoral artery as an anatomic reference. More recent studies have demonstrated that the medial vastus nerve also provides significant innervation to the knee capsule, through intramuscular, extramuscular, and deep genicular nerves. Because it spares quadriceps strength, the ACB is commonly used as part of multimodal pain management for total knee arthroplasties. It is also indicated for any surgery involving the anteromedial knee, including anterior cruciate ligament/medial collateral ligament repairs and patella fractures. Although this block has been described being performed blindly with nerve stimulation, it is normally performed under ultrasound guidance. - Ultrasound Guidance - The patient is placed in the supine position with slight external rotation of the leg. A high-frequency linear array transducer (\>7 MHz) is placed in transverse orientation on the medial aspect of the middle and distal third of the thigh. The superficial femoral artery is identified inferior to the sartorius muscle; color Doppler can assist in locating the artery if it is not readily identifiable. After the patient is appropriately prepped and draped. a skin wheal is placed al the lateral edge of the transducer. A 22-gauge, 9-cm B-bevel needle is inserted lateral to medial and advanced to the edge of the artery into the fascia! plane separating the sartorius and adductor longus muscles. Once the needle tip is located anterolateral to the artery, 1 to 2 ml of local anesthetic is injected following negative aspiration. Separation of the fascial plane between the muscles and artery will further define the SphN. After confirming proper placement, 10 to 20 mL of local anesthetic is injected in 5-ml increments, confirming negative aspiration of blood prior to each injection. - Pearls - To accomplish a sensory nerve block of the SphN, the transducer is slid distally until the artery is noted to pass through the adductor hiatus, at the most distal area where the nerve still lies beneath the sartorius muscle - Visualization of the nerve is not necessary for this block; in certain individuals the saphenous or branches may lie anteromedial to the artery. If this is recognized during a preprocedural scan local anesthetic is deposited on both sides of the artery. - Risks and Complications - Proximal injections and large volumes of local anesthetic (20-30 ml) are associated with increased risk of quadriceps weakness. **[Popliteal Sciatic Nerve Block]** - Indications: - Foot and ankle surgery - Below-knee amputation - Achilles tendon surgery - Goal: - LA spread surrounding the sciatic nerve within the Vloka's sheath - Transducer: - High Frequency Linear Array - LA: - Bupivacaine 0.5% - 10-20 mL circumferential spread around CPN and TN - Needle: - 22-23 gauge, 5 cm short bevel - Inserted lateral to medial - Anatomy: - Proximal to the popliteal fossa, the tibial nerve (TN) and common peroneal nerve (CPN) make up the sciatic nerve. From their origin in the pelvis, they travel together enveloped in a common sheath. - Distal to the popliteal fossa, the TN and CPN diverge and continue their path below the knee with their own respective sheaths. - The common peroneal nerve further gives the superficial and deep peroneal nerves, which innervate the muscles of the lateral and anterior compartments of the leg. - The tibial nerve gives the medial and lateral plantar nerves and collateral branches that rise to the cutaneous sural nerves, muscular branches to the muscles to the calf, and articular branches to the ankle joint. - At the popliteal crease, the sciatic nerve is identified as a hyperechoic, oval or round structure with a honeycomb pattern. It is located superficial (posterior) to the popliteal artery and vein, with the biceps femoris muscle laterally, and the semimembranosus and semitendinosus muscles medially. The nerve consists of two parts: the larger - tibial nerve, and the smaller - common peroneal. - Always scan several cm's proximal to the popliteal fossa to recognize the level at which TN and CPN start separating. The best injection site is between the TN and CPN (just when they start separating) - Patient position: - Prone or lateral decubitus position is preferred. A block in the supine position can be accomplished by resting the foot on an elevated footrest. - External landmarks: - 3·5 cm above the popliteal fossa crease - Tendon of biceps femoris (laterally) - Tendons of semitendinosus and semimembranosus {medially) - Place the transducer in a transverse orientation, 3-5 cm above the popliteal fossa between the biceps femoris and semimembranosus and semitendinosus tendons. - Insert the needle in-plane or out-of-plane and advance the tip into the sciatic nerve sheath between TN and CPN. - Inject 1-2 ml of local anesthetic to confirm proper needle tip position. A correct injection will result in a separation of the TN and CPN by the local anesthetic. - After injection of 10 mL without removing the needle, scan 4-5 cm proximal to the injection site, and confirm that the local anesthetic is spreading in the sheath even proximally. - Complete the block by administering a total of 15-20 ml of local anesthetic. - Essential Facts: - Either in-plane or out of plane techniques of needle Insertion can be used. - The CP often t e pa h of the needle to reach the sciatic sheath and must be avoided. - Use of nerve stimulation (0.5mA without current changing) may be helpful in detecting needle nerve contact when a distal motor response unexpectedly occurs (foot, toes). - Because of (2L out-of-plane needle insertion Is often more convenient than in-plane. - Injection pressure monitoring to decrease the chance of intrafascicular Injection confers additional safety with popliteal block. - Ultrasound imaging should specifically focus on identifying the sciatic nerve sheath (Vloka\'s sheath) which contains both components of the sciatic nerve. - Asking the patient to dorsiflex and plantarflex the ankle makes the two sciatic nerve branches twist or move in relation to each other making it easier to identify them. - A successful injection will deposit local anesthetic within the Vloka\'s sheath. - Once the injection is made into the Vloka sheath, sliding the transducer 5 cm proximal to the injection site should allow visualization of the local anesthetic proximal to the injection level as it spreads within the sheath. This assures the correct injection plane. - Ultrasound Guidance: - The ultrasound-guided sciatic block in the popliteal fossa can be performed in the supine, Lateral, or prone position. Here we discuss the supine approach. A high-frequency (10-12 MHz) linear array transducer is placed in transverse orientation at the popliteal crease where the artery and vein are initially identified. The TN is typically visualized at this level superficial to the popliteal vessels. Lateral to the nerve lies the biceps femoris muscle. medial to the nerve lie the semimembranosus and semitendinosus muscles. Once the TN is identified, the transducer is slowly slid cephalad to the point where the TN is joined by the CPN. The lateral thigh is prepped in the appropriate manner, and a 22-gauge, 9-cm B-bevel block needle is inserted lateral to medial using an in-plane approach and advanced until the needle tip is between the bifurcation of the two nerves. Following negative aspiration, 5 mL of local anesthetic is injected to confirm needle tip placement between the two nerves. The needle is then advanced further to the medial border of the TN. Following negative aspiration, 10 mL of local anesthetic is injected to create a circumferential spread around the TN. The needle is then withdrawn until it is positioned at the lateral edge of the peroneal nerve. Following negative aspiration, 10 ml of local anesthetic is deposited observing for circumferential spread around the nerve. Nerve stimulation can be used in conjunction with ultrasound to confirm appropriate muscular movement. - Pearls: - The sciatic nerve divides into the TN and CPN at varying locations along the popliteal fossa, making it important to scan the region proximally and distally to determine the area that offers the greatest chance of success. - The practitioner should also note the point at which the sciatic nerve begins to divide as it is the desired location for local anesthetic placement. - II is important to note that when one performs the block with the patient in the supine position. the ultrasound image is inserted, and the transducer should be reversed to produce the proper orientation. - Risks and Complications: - Although uncommon. inadvertent vascular injection from an unrecognized puncture can result in a LAST event. Hematoma. and nerve injury are also possible. **[Hip (PENG) Block]** - Indications: - Analgesia after hip fractures or arthroplasty (especially through anterior approach) - Provides analgesia without loss of motor function - Goal: - Local anesthetic spread in the plane between the iliopsoas muscle and pubic ramus, and anterior capsule of the hip cranially to the acetabular rim. This injection anesthetizes most of the nociceptive fibers to the hip joint capsule which emanate from the lumbar plexus. In addition, this injection may prevent or decrease the postoperative spasm of the iliacus muscle, which is a common cause of postoperative pain after anterior hip arthroplasty. - Transducer: - Low frequency curvilinear array transducer - LA: - 20 ml local anesthetic above IPE - Bupivacaine 0.5% or ropivacaine 0.5-0.75% are the best choices to provide prolonged analgesia after a hip surgery. Similarly, as with other fasciaI plane infiltrations, adding liposome bupivacaine to bupivacaine may extend the analgesia duration. - Needle: - Needle inserted lateral to medial - Anatomy: - Pain after total hip replacement comes primarily from the anterior hip capsule which is innervated by the terminal nerves of the lumbar plexus: - **Femoral nerve:** The articular branches from the femoral nerve descend over the surface of the iliopsoas notch which is located between the anterior inferior iliac spine (AIIS) and the iliopubic eminence. These nerve endings reach the plane between the iliopsoas muscle and the iliofemoral ligament (iliopsoas plane) and innervate the anterior and lateral aspects of the hip capsule. - **Obturator nerve:** The articular branches exit the pelvis through the obturator foramen between the external obturator and pectineus muscles to innervate the anterior and medial aspects of the hip capsule. - **Accessory obturator nerve:** Formed by the ventral divisions of L2 to LS, it contributes to the innervation of the hip in 10%-30% of the patients. It travels deep to the psoas muscle and over the superior pubic ramus, to supply the inferomedial aspect of the hip capsule. - The **cutaneous innervation of the anterolateral thigh** is conferred by the lateral femoral cutaneous nerve (LFCN), which travels underneath the inguinal ligament, medially to the anterior superior iliac spine (ASIS) and courses distally, superficial to the sartorius muscle. - The **posterior aspect of the hip joint** is innervated by the sciatic nerve and branches of the sacral plexus (superior and inferior gluteal nerves, and an articular branch from the quadratus femoris nerve). - Patient position: - Supine with the leg fully extended and slightly rotated externally. - External landmarks: - Femoral crease, and anterior inferior iliac spine. - Transducer Positioning: - Place the transducer over the femoral crease in a transverse oblique orientation to image the head of the femur. - Slide the transducer cranially until the anterior inferior iliac spine (AIIS), and iliopubic eminence are visualized (pelvic rim). - Slide, tilt. and apply pressure to the transducer to improve the view of the hyperechoic surface of the iliopsoas notch, and hyperechoic psoas tendon, between the AIIS and iliopubic eminence. Not : apply only subtle tilting maneuvers. - Identify also: The hypoechoic iliopsoas muscle, and femoral artery /nerve superficial to the iliopsoas muscle. - Needle Insertion: - Insert the needle in-plane from lateral to medial through the iliopsoas muscle toward the plane between the psoas tendon and bone. Note: The needle path should be steep to avoid injury to the femoral nerve/artery. - After negative aspiration, inject 10· 15 ml of local anesthetic while observing for an adequate spread along the fasciaI plane. - Tips: - The needle position is adjusted when the spread occurs within lliacus muscle Instead of - underneath it. - If high resistance is perceived while injecting the needle is slightly withdrawn as it could be obstructed by the periosteum or tendon. - Routinely identify the femoral artery and nerve superficial to the lliopsoas muscle to avoid their injury. - Use color Doppler to identify the femoral vessels when not clearly visualized. - Always start with the identification of the femoral artery and nerve to avoid their injury. - Insert the needle in a steep angle to avoid puncture of the femoral nerves and vessels. - Note: - The hip block confers analgesia after hip fractures and anterior hip replacement surgery. Although analgesia with the Hip Block does not impair ambulation, it is Inferior to analgesia with a suprainguinal fascia ilaca. Therefore in patients who are not candidates for fast-tracking ( ASA\> II, revision surgery, fractured hip), suprainguinal fascia iliacaI is favored over hip block. - The pericapsular nerve group (PENG) block is a single-injection technique recently described for analgesia following hip fracture and arthroplasty. This block targets the articular branches of the FN, as well as the accessor obturator and obturator nerves, while sparing the FN and its associated quadriceps innervation. Several small case studies have demonstrated significant pain relief without quadriceps weakness. However, currently there are no cadaveric studies demonstrating dye spread of local anesthetic or randomized controlled trails establishing efficacy, safety, or advantages over other procedures. - Ultrasound Guidance: - The patient is placed supine, and a low-frequency (2-5 MHz) curvilinear array transducer is placed in a transverse orientation parallel to the inguinal ligament at the level of the ASIS. The transducer is then slid caudally until the anterior inferior iliac spine and pubic ramus are visible. At this level, the FN, artery, and vein are identified. The iliopubic eminence, created by the junction of the ilium and pubis, is also identified. After the patient is prepped and draped appropriately, a skin wheal is raised at the lateral edge of the transducer. A 22-gauge, 9-cm 8-bevel block is inserted in-plane, lateral to medial between the muscle with prominent tendon and the pubic ram us, medial to the anterior inferior iliac spine. Following negative aspiration, up to 20 ml of local anesthetic is injected in 5-ml increments. - Pearls: - Because the PENG is an analgesic block, it does not require large volumes of high-concentration local anesthetics. - Risks and Complications: - Because the ureter in the pelvis is within close proximity of the ON, advancing the needle too far medially places it and other vital structures at risk for injury.