Peripheral Blocks 3 Lower Extremity Blocks

1. Peripheral Blocks 3Lower Extremity Blocks Vincent Conte, MD Associate Clinical Professor FIU College of Nursing Nurse Anesthesia Program

2. Lower Extremity Blocks • Blocks to be covered today are: • Femoral Block • Sciatic Block • Ankle Block • LE Digital Block • LE Bier Block (IV Regional Anesthesia)

3. Equipment • Usually to perform a Femoral or Sciatic nerve block, you will need specialized equipment • This equipment includes specially insulated needles and a Nerve Finder Control Box • They are hooked up to each other to generate a pulse current so that when you are near a nerve, you will see the area innervated by the nerve react • This helps you localize the nerve much more efficiently and makes the percentage of you getting a good block climb tremendously • It is no longer a completely “BLIND” technique

6. LE Blocks • In performing LE Blocks, some familiarity with the LE anatomy is important • The Lumbar and Lumbosacral plexi are the major nerves to the LE’s • The Lumbar plexus is derived from the VENTRAL rami of L1-L4 with some occasional contribution from T12

8. Lumbar Plexus • Primarily from L2-4, the Lumbar Plexus forms three major nerves that innervate the lower extremity: • Lateral Femoral Cutaneous Nerve • Femoral Nerve • Obturator Nerve • These nerves supply motor and sensory innervation to the ANTERIOR portion of the LE and the CUTANEOUS sensory portion of the MEDIAL lower leg

11. Lumbosacral Plexus • The LS plexus is created by the nerve roots of L4-L5 and S1-S3 and primarily forms the SCIATIC nerve • The SCIATIC nerve supplies innervation, both motor and sensory, to the POSTERIOR aspect of the entire Lower Extremity and the foot • The Sciatic nerve is the LARGEST nerve in the body, usually measuring about 2.5 cm wide (about as wide as your thumb)

14. LE Innervation • Four major nerves innervate the LE: • The Femoral Nerve (L2-L4) • The Obturator Nerve (L2-L4) • The Lateral Femoral Nerve (L1-L3) • The Sciatic Nerve(s) (L4-S3) • The first three nerves arise from the Lumbar Plexus • The Sciatic breaks up into the Common Peroneal and Tibial nerves in the lower leg

17. LE Blocks • Spinal and Epidural anesthesia are most commonly employed for regional anesthesia of the LE • The Peripheral nerve blocks in the LE by themselves are usually not sufficient to provide adequate surgical anesthesia • Done in combination though, they can provide enough sensory blockade for surgery

18. LE Blocks • Since multiple blocks have to be done to provide surgical anesthesia, the LE blocks are usually rarely used as the primary form of anesthetic for LE surgery • Their most common use is in the treatment of Post op Pain • For actual surgery, the Ankle block is the easiest and most commonly used Lower Extremity Block • It can be used for any type of foot or ankle surgery

19. Femoral Nerve Block • The Femoral Nerve block can be used to provide anesthesia for the anterior thigh, knee and a small part of the medial foot • It is typically used in conjunction with other LE blocks (mostly the Sciatic) • It’s most effective use is for treatment of post-op pain from Knee surgery

20. Femoral Nerve Block • The anatomy needed to perform the Femoral block are: • Anterior Superior Iliac Spine • The Superior-Lateral corner of the Pubic Tubercle • The Femoral Artery

21. Femoral Block • The technique for the block begins by drawing a line between the Anterior Superior Iliac Spine and the Superior-Lateral corner of the Pubic Tubercle (Symphysis Pubis) • You palpate along the mid point of this line until the Femoral pulse is located

23. Femoral Block • You then pick your insertion point which is 2cm lateral to the Femoral pulse and 2cm distal from your line that you just drew • With a 2”, 22-gauge stimulating needle, you make your insertion and advance, using your nerve finder, until you obtain quadriceps twitches

25. Femoral Block • At that point you aspirate through the needle, and if negative, you inject 2-3cc of local and watch for a fade in twitch from the stimulator • If you see a fade, carefully aspirate, and begin to inject your local, stopping every 5cc to re-aspirate, until a total of 20-30cc of LA is injected • You can use Lido 2% w/EPI but most commonly Bupivicaine 0.5% plain is used to get the maximum duration possible out of the block

27. Femoral Nerve Block • A Femoral nerve block is very useful in numerous procedures involving the thigh and knee, such as skin grafting, knee arthroscopy and patellar surgery • It can also be used as an adjunct to procedures distal to the knee that require anesthesia to the medial aspect of the lower leg

28. Femoral Nerve Block • An increasingly common practice in many centers is the insertion of an indwelling femoral catheter for continuous perineural infusion along with an accompanying sciatic nerve block for patients recovering from complex reconstructive knee surgery that may require aggressive post-op pain relief

29. Sciatic Nerve Block • The Sciatic Nerve originates from the Lumbosacral trunk and is composed of nerve roots L4-L5 and S1-S3 • It supplies sensory fibers to the posterior hip capsule as well as the knee • It provides motor activity to the hamstrings and to ALL the muscles distal to the knee • It also supplies the sensory innervation to 90% of the LE below the knee

31. Sciatic Nerve Block • Anatomic landmarks needed for the Sciatic block are: • The Greater Trochanter of the hip • The posterior Superior Iliac Spine • The Sacral Hiatus • You also will need at least a 4” 21-22g Insulated needle and a Nerve Finder

33. Sciatic Nerve Block Procedure • You begin by placing the patient in the Sim’s position (lateral decubitus with the operative leg up and bent at the knee and hip at a 90 degree angle) • You next draw two lines, one from the Posterior Superior Iliac spine to the Greater Trochanter and the other from the Greater Trochanter to the Sacral Hiatus

34. Sciatic Nerve Block Procedure • Lastly, you draw a third line connecting the midpoint of both line • The spot where the third line intersects the lower line between the Greater Trochanter and the Sacral Hiatus is your injection point

37. Sciatic Nerve Block Technique • For the injection, you advance a 4” 21-22g Insulated needle in the direction perpendicular to the skin • After passing through the gluteal muscle the needle is inserted further until a motor response is confirmed in the distal ankle, foot or toes • At that point, after aspiration, 2-3cc of LA is injected and if an attenuation of the twitch is witnessed, the remainder of your LA is injected in 5cc increments to a total of 20-25cc, aspirating at every 5cc

38. Sciatic Nerve Block • Again, if needed for extended post-op pain relief, a perineural catheter can be inserted and secured in place for future injections • The same agents may be used for the Sciatic block; Lidocaine 2% w/EPI or Bupivicaine 0.5%

39. Ankle Block • Most frequently used LE block • They say it is the “easiest” to learn and do but I have found in clinical practice that this is farthest from the truth • In my opinion, the Femoral block is used much more frequently and is much easier to learn to do • Remember NO EPIin your local for the ankle or digital block

40. Ankle Block • Either a complete or partial block of the foot can provide adequate anesthesia for many of the surgical procedures that are performed by Podiatrists and Orthopedic Surgeons • The nerves are easy to locate and the procedure can be accomplished with relatively little experience

41. Ankle Block • This tool can prove invaluable in the care of certain high risk patients, such as those with gangrene of the foot, those with Diabetes who have foot ulcers and patients with pressure sores of the heel and foot • If, however, any of the lesions are infected, then it may be prudent to avoid multiple injections so close to infected tissue (may seed other locations or cause hematogenous spread)

42. Ankle Block • The Ankle block is performed by blocking five nerves: • The Tibial nerve (L4-L5 nerve roots) • The Sural nerve (formed from the union of a branch of the Tibial nerve and the Common Peroneal nerve) • The Superficial Peroneal nerve (L4-L5 nerve roots) • The Deep Peroneal nerve (L4-L5 nerve roots) • The Saphenous nerve (terminal end of the Femoral Nerve)

47. Ankle Block Deep Peroneal Block

48. Deep Peroneal Nerve Block • The Deep Peroneal nerve is blocked by identifying the groove formed by the Extensor Hallicus Longus tendon and the Extensor Digitorum Longus tendon • At that point, a superficial injection is made with a 25g needle and 5-8cc of LA injected Subq

49. Deep Peroneal Nerve block • Then perpendicular to the skin, the needle is advanced until the periosteum is contacted and 5-8cc of LA is injected after aspirating • This should block the Deep Peroneal nerve