Lower Extremity Blocks Flashcards by Carol Dumond

What nerves are blocked in the Fascia Iliaca Block?

AKA the 3 in 1 block
-Femoral Nerve
-Lateral Femoral Cutaneous
-Obturator (unreliable coverage)

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Why is the Fascia Iliaca block called a Volume Dependent Compartment Block?

High volume of dilute LA solution needed to catch all the individual nerves

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What are the indications for the Fascia Iliaca Block?

-Anterior Thigh
-Knee Surgery
-Hip procedures
-Femur Fx

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What are the complications associated with the Fascia Iliaca Block?

Very safe block to perform, no major nerve or blood vessels near site of injection.

Complications:
-Block failure
-Hematoma
-Toxicity
-Nerve damage

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What are the two approaches to the Fascia Iliaca Block?

-Transverse
-Parasagittal

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Describe the Transverse Approach to the Fascia Iliaca Block.

-Probe is placed in Femoral Crease
-Inject LA just below fascia iliaca, covering iliacus muscle (lateral 1/3 of line between ASIS and pubic tubercle)
-Hope LA will leak towards Lateral Fem Cutaneous nerve (can be blocked individually)

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Describe the Parasagittal Approach to the Fascia Iliaca Block.

-Start in femoral crease
-Locate ASIS and move medially until “Bow Tie” appears
-Insert needle up and underneath fascia iliaca, driving LA up and underneath fascia
-Goal: Injection of LA below Fascia Iliaca, between Sartorius and Internal Obliques.

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What is innervated by the Anterior Division of the Femoral Nerve?

-Cutaneous branches: Intermediate and medial femoral cutaneous nerve (cutaneous innervation to anterior thigh)
-Muscular branches: Pectineus and Sartorius muscles

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What is innervated by the Posterior Division of the Femoral Nerve?

-Motor innervation to the Quadriceps: Rectus Femoris and Vastus muscles (lateralis, medialis, and intermedius)
-Articular Branches: sensory innervation to the knee joint.

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What are the indications for a Femoral Nerve Block?

-Anterior thigh
-Knee Surgery
-ACL, PCL Patellar tendon
-Total/partial joint
-Has fallen out of favor due to quad weakness and falls (now doing more Adductor Canal Blocks)

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What makes up the Femoral Triangle?

-Ilioinguinal Ligament
-Adductor Longus muscle
-Sartorius muscle

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What is the relevant anatomy for a Femoral Nerve Block?

-Femoral Triangle
-NAVEL or VAN

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Describe the Nerve Stimulator technique for a Femoral Nerve Block.

-Supine (obese may need retraction of pannus)
-Palpate femoral artery in femoral crease
-Insert needle lateral to artery, perpendicular to skin, slightly cephalic
-Goal: Quad twitch (Patellar snap)

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What must be pierced for the Femoral Nerve Block to work?

The Fascia Iliaca.
-Femoral Nerve runs in the groove created by iliacus and Psoas muscles, below the iliacus fascia
-Won’t soak into nerve itself if it’s above the fascia iliaca.

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How would you perform a Femoral Nerve Block? (US)

-US probe in femoral crease
-Nerve appears oval or triangular, usually hyper echoic
-Needle is inserted lateral to medial
-LA must be injected below the Fascia Iliaca
-Encircle nerve with LA

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What are the indications for a Lateral Femoral Cutaneous nerve block?

-Lateral thigh
-Hip procedures
-Tourniquet pain

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How do you locate the Lateral Femoral Cutaneous nerve?

-LFCN runs between the Tensor Fascia Lata muscle and the Sartorius muscle.
-Find ASIS, palpate ilio inguinal ligament. Orient needle in lateral to medial, slightly caudal fashion and create a fan pattern of LA to try to catch nerve.
-Injection must dissect fascial layer between muscles
-5-10 mL LA
-Sensory only nerve

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What does the Obturator nerve innervate?

Motor to Adductor muscles:
-Magnus, Longus, Brevis, Gracilis

Sensory:
-Skin: Medial thigh, knee
-Medial knee joint

What are the indications for an Obturator nerve block?

-Knee surgery
-Amputations
-Tourniquet pain
-TURBT surgery (knee jerk scenario that occurs with obturator nerve stimulation during ablation of tumor)

How do you perform an Obturator Nerve Block?

-Patient supine, with leg abducted and slightly externally rotated
-Probe 2-3 cm distal to femoral crease
-Interfacial approach: inject LA in a facial plane (between muscles): Longus-Brevis and Brevis-Magnus
-Nerve stimulator will produce adduction for both branches

What are the benefits of the Adductor Canal Block?

-Blocks sensory to the knee
-Motor sparing (vastus medialis is occasionally blocked tho)
-Decreases opioid usage and patient can still ambulate
-Can be done in combo with a popliteal block for foot/ankle procedures.

What are the indications for an Adductor Canal Block?

-Knee surgery
-Medial leg/Ankle procedures

How do you perform an Adductor Canal Block?

-Probe is placed mid-thigh
-Needle is inserted anterior to posterior
-Locate the Superficial Femoral Artery under the Sartorius muscle.
-15-20 mL of LA is injected to displace the Sartorius muscle.
-LA needs to be on both sides of the Superficial Fem. Artery
-Saphenous nerve is not always visible
-Can place continuous catheter above Super. Fem Artery, but absolutely needs to be below Sartorius muscle.
-Can lay catheter up/over artery and use arterial pulsations to move LA around.

What does the Sciatic nerve innervate?

The longest peripheral nerve in the body.
-Motor innervation to the hamstring muscles and the muscles of the lower leg and foot
-Sensory Innervation to the posterior thigh and the majority of the area below the knee (lower leg and foot, except Saphenous)

What are the indications for Sciatic nerve block?

-Knee surgery: Adjunct to Femoral or AC -Surgery of posterior Leg: Hamstring reattachment -Surgery of lower leg or foot

How do you perform a Sciatic Nerve block?

-Curvilinear probe may be needed -Long block needle may be required -Goal: Twitch of calf, foot, or toes

Why is Hamstring twitching not a reliable predictor of Sciatic nerve stimulation?

Hamstring innervation leaves the sheath early. -Could be getting direct muscle stimulation of hamstring muscles themselves.

What are the complications that occur with Sciatic Nerve blocks?

-Infection -Hematoma -Vascular puncture (femoral artery and vein) -LA toxicity -Nerve injury: Sciatic nerve is uniquely sensitive to mechanical and pressure injury.

How do you prevent nerve injury to the sciatic nerve?

-Nerve stimulation and slow needle advancement should be employed -Never inject on pain or pressure -Never inject with <0.2 mA -Avoid using Epi!! -Use Ropivicaine

Describe the Anterior approach to the Sciatic Nerve.

-Draw a line in between ASIS and Pubic tubercle (shows you where ilio inguinal ligament lies) -Feel femoral pulse -Draw a perpendicular line 4-5 cm from the line for insertion site -Puts you over the top of lesser trochanter of femur -Needle inserted perpendicular to skin (may need longer needle -sciatic is very deep) -Advance until twitch of calf, foot, or toes seen -Contact with bone: Frequently due to contact with lesser trochanter. Withdraw needle 1-3cm. Internally rotate leg. Re-advance needle to just past bone. -Elevate heel off of bed to help identify twitches -Sciatic nerve is prone to injury: Avoid vasoconstrictors, use careful needling, and prevent mechanical injuries of the anesthetized limb) -Risk of injury to Femoral nerve if it is anesthetized first.

Describe the Subgluteal approach to the Sciatic Nerve.

-Probe is underneath gluteal fold (a few cm distal from between Greater Trochanter and Ischium Tuberosity) -Sciatic nerve is located below gluteus maximus, between femur and ischial tuberosity. -Don't have to go through gluteus maximus (less tissue, may allow for use of linear probe). -Less variability -Search laterally/medially to find nerve.

What are the indications for a Popliteal approach to the Sciatic nerve?

-Foot or Ankle surgery -Analgesia adjunct for knee surgery -Frequently paired with Femoral or Adductor Canal

What are the landmarks for the Popliteal approach to the Sciatic nerve? (NS)

-Popliteal Fossa Crease -Lateral: Tendon of Biceps Femoris -Medial: Tendon of Semitendinous and Semimembranosus -Measure 7cm from crease -Needle insertion midpoint between tendons -Typically 3-5cm deep -Sciatic nerve can run just lateral to midpoint.

How do you perform the Popliteal Approach to the Sciatic nerve? (US)

-Probe transverse at popliteal crease -Identify artery, vein, and tibial nerve (Tibial nerve lays directly above and slightly off center to popliteal artery) -Move proximally -Watch tibial and peroneal come together -Place injection when 2 have converged together

What is the indication for an individual Tibial Nerve Block?

-Total knee: Avoids the foot drop seen when peroneal nerve is also anesthetized Care taken to only place LA near tibial nerve leaving Peroneal untouched

What is the indication for an Ankle Block?

Foot and toe surgery

What 5 nerves are blocked in an Ankle Block?

-Superficial Peroneal -Sural -Saphenous -Posterior tibial -Deep Peroneal

How do you identify the Deep Peroneal Nerve?

-Identify Extensor Hallucis Longus -Insert needle just lateral, advancing until contact with bone, withdraw 2 mm and inject 2-4 ml of LA US: runs with anterior tibial artery

How do you identify the Posterior Tibial Nerve?

Identify medial malleolus, insert posterior to and contact bone, withdraw 2mm and inject 2-4 ml of LA US: runs immediately posterior to posterior tibial artery

The superficial nerve blocks of an Ankle Block are blocked by ?

Creating a subcut wheal around the entire ankle.

How do you block the Saphenous nerve in an ankle block?

Create a Wheel from tibial ridge directed medially to Achilles US: Small nerve visualized proximal to medial malleolus. Runs with the Saphenous vein

How do you block the Superficial Peroneal nerve in an ankle block?

Create a Wheel from tibial ridge laterally to lateral malleolus US: nerve lies superficial to fascia. Probe proximal and anterior to lateral malleolus

How do you block the Sural nerve in an ankle block?

Create a Wheel from lateral malleolus to Achilles US: Proximal to lateral malleolus, runs with small saphenous vein