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Download Lower limb anatomy and blocks - Preparing for Anaesthesia Exams
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Lower limb anatomy and blocks Lumbo-‐sacral plexus • Lumbar plexus – Ant rami L1-‐4, – Frq include branches from T12 and occ from L5 • Sacral plexus – S 1,2,&3 Sacral nerves – Plus branches from the ant rami of L4,5 Dorsal division Upper and lower divisions Lat cut n. of thigh Ventral division L1 L2 L3 Iliohypogastric nerve Genitofemoral nerve Ilioinguinal nerve L4 Femoral nerve Branch to lumbosacral trunk Obturator nerve L4 L5 Sup gluteal nerve S1 Inf gluteal nerve S2 Sciatic nerve Post cut n. of thigh S3 S4 Pudendal nerve Motor responses • Ant Femoral – Sartorius • Post Femoral – Quads ( Dancing of Patella) • Common Peroneal n sNmulaNon – Dorsiflexion – Eversion of the foot • Tibial nerve sNmulaNon – Plantar flexion – Inversion of the foot DERMATOMES MYOTOMES OSTEOTOMES PELVIS L2 L3 ILIACUS HIP JOINT RECTUS FEMORIS Femoral nerve L4 Lat circumflex femoral artery PECTINEUS SARTORIUS LATERALIS VASTUS INTERMEDIUS MED FEMORAL CUT NERVE INTERMEDIATE FEMORAL CUT NERVE MEDIALIS KNEE JOINT FEMORAL ARTERY DEEP FASCIA BELOW KNEE INFRAPATELLAR BRANCH SAPHENOUS NERVE Femoral Nerve above the Inguinal Ligament Femoral Nerve below the Inguinal Ligament Femoral vessels Iliac Vessels Sartorius Fascia Lata Femoral Nerve Facia Iliaca Fatty tissue between the two fascia often mistaken for the nerve Fascia Lata Fatty tissue between the two fascia often mistaken for the nerve Femoral Artery Femoral Nerve Facia Iliaca Fascia Iliaca Block ASIS Two “Pops” 1. FL 2. FI Fascia Lata Femoral Artery Femoral Nerve Facia Iliaca Femoral Nerve Block Femoral nerve block Femoral sheath Fascia lata Femoral Nerve Pectineus Iliopsoas Iliacus Fascia Femoral Artery and Vein Landmark • Femoral nerve lies outside the femoral sheath under the fascia iliaca • Femoral nerve divides into ant and post branch just below the inguinal ligament • Marking out the inguinal ligament and seeking the femoral nerve just under it is beUer than blocking the nerve at groin crease Motor response • Medial twitch in the adductor region indicates sNmulaNon of the ant branch, Sartorial twitch • To achieve the quads response ( dancing of the patella, advance the needle slightly medial and post ( deep) • In awake paNents start with 1.0mA (100μsec, 2Hz) and slowly decrease Nll the response disappear at around 0.4mA. Lat cut nerve of the thigh Cranial Caudal Medial Lateral Internal oblique muscle Iliacus Fascia External oblique Aponeurosis ASIS Iliacus Muscle Single “Pop” through FL Inguinal ligament Fascia Lata Lateral Cutaneous Nerve of thigh • The nerve is easily blocked with FI block • The nerve can also be easily blocked just below the ASIS, 1cm medial and 1cm cudad • Once the needle punctures the skin, feel for a single “pop” and inject 5-‐7mls and the deposit another 3-‐5mls just under the skin to catch the cutaneous branches. SciaNc Nerve Popliteal fossa Common peroneal Tibial nerve Peroneal comm. Branch Superficial peroneal Med & lat plantar nerves Sural nerve Deep peroneal SciaNc nerve Medial Cranial Caudal Lateral Approaches to SciaNc Nerve in the Gluteal Region Classic Post Approach (Labat’s) GT IT PSIS Sacral Hiatus Patient position: Patient in lateral position, side to be blocked being nondependent, with knee and hip flexed (Sim's position) Landmarks • Line between the posterior superior iliac spine and the greater trochanter. • Perpendicular line is drawn at its midpoint. • IntersecNon with a line between the greater trochanter and the sacral hiatus OR • 5 cm on a perpendicular line drawn at the midpoint of the line between the posterior superior iliac spine and the greater trochanter. Procedure • • • • 50-‐80mm sNmulaNng needle. Perpendicular to the skin. Start with Current of 1.5mA at 2Hz The first contracNon is elicited when the needle passes through the gluteus maximus muscle; then a deeper muscular contracNon occurs when the needle passes through the piriformis muscle. Procedure • A Nbial or peroneal neurosNmulaNon is elicited 1 cm deeper. • A dorsiflexion and eversion of the foot (peroneal nerve) means that the needle is sNmulaNng the lateral part of the sciaNc nerve. • A Tibial response is preferred for a successful block. Procedure • A Nbial n. sNmulaNon will be elicited by moving the needle medially. • Bone contact = lateral part of the greater sciaNc notch of the hip bone. The needle must be redirected medially, caudally, or both. • Reduce the current slowly to 0.4mA, if the sNmulaNon occurs at less than this current, withdraw the needle. Sub-‐gluteal approach GT IT PSIS Sacral Hiatus Landmarks • PosiNon: Similar to classic appraoch • Line between the greater trochanter and ischial tuberosity. • 5 to 6 cm caudally on a perpendicular line drawn from its midpoint. Procedure • Needle is introduced perpendicular to the skin • Nerve is located at a depth of 4 to 6 cm • Tibial nerve or common peroneal nerve is sNmulated. Tibial response preferable BUT not necessary • A catheter can be inserted for a conNnuous sciaNc block. Lithotomy PosiNon (Raj) Landmark • PaNent in supine posiNon, an assistant holds the leg to be blocked with the knee and hip flexed • Landmark is the midpoint of a line between the greater trochanter and ischial tuberosity Procedure • Needle is introduced perpendicular to the skin • Nerve is located at a depth of 5 to 7 cm • SNmulaNon of the Nbial or common peroneal nerve (hamstrings may be direct muscle sNmulaNon) • The nerve lies more medially, the tendency is normally to be more lateral Popliteal Fossa Popliteal Artery and vein Tibial Sciatic Common Peroneal Sural Semimembranous Biceps Femoris Common Peroneal n Tibial n Sural communicating branch Medial and lateral heads of Gastronemius Sural n SciaNc Nerve at the apex of PF Sciatic The two components Common Peroneal LA Tibial Biceps femoris ST 7-11 cms X PosiNon and Landmarks • Flexion at the hip and Knee in supine posiNon or Prone posiNon • Popliteal fossa crease • Tendons of the biceps femoris muscle (laterally and of the semitendinosus muscle (medially) • Line along each of the two tendons. Procedure • The needle inserNon point is marked at 7cm above the popliteal fossa crease at the midpoint between the tendons • Tendons of semitendinosus and semimembranosus muscles are palpated using a two-‐finger technique Procedure • The tendons are easily felt in supine posiNon with flexion at the hip and knee joints • In the prone posiNon, landmarks can be accentuated by asking the paNent to flex the leg in the knee joint • This maneuver Nghtens the hamstring muscles and allows an easy and accurate palpaNon of the tendons Motor responses • Tibial response, plantar flexion is preferred • When local sNmulaNon of the biceps muscle is felt under the fingers of the palpaNng hand, the needle should be redirected medially • Local twitches of the semitendinosus muscle indicates a too medial needle inserNon. The needle should be withdrawn to the skin level and reinserted laterally Lateral Approach to PF 11 cm Lateral approach Lateral approach Femur Vastus lateralis Lateral Medial 1 30O 2 Biceps Femoris Landmarks • PosiNon, supine with a pillow under the knee joint • The needle inserNon site is marked around 11cms from the lateral femoral condyle in the groove between the vastus lateralis and biceps femoris (BF) muscle • The groove can be easily felt with the thumb when the BF is pinched with the lek hand Procedure • 80-‐100mm Needle is preferred • inserted in a horizontal plane between the vastus lateralis and biceps femoris muscles and advanced to contact the femur • The contact with the femur is important because it provides informaNon on the depth of the nerve (typically 1-‐2 cm beyond the skin-‐femur distance) Procedure • Once the bone is contacted the needle is redirected by around 30o from the iniNal inserNon in a posterior direcNon by around 1-‐2 cms in order to sNmulate the nerve • It is important that the feet is internally rotated or kept in a neutral posiNon, the tendency is for the leg to externally rotate in supine posiNon Ankle block Superficial Peroneal nerves Great Saphenous Vein and Saphenous Nerve Medial Malleolus Dorsal Paedis Artery Deep Peroneal Nerve Lateral Malleolus Post Tibial Artery Tibial Nerve Achilles Tendon Sural Nerve Small Saphenous Vein The 5 Nerves 1 branch from femoral • Saphenous 4 from sciaNc • Superficial Peroneal • Deep Peroneal • Post Nbial • Sural Dermatomal distribuNon Saphenous Sural Superficial Peroneal Deep Peroneal Medial plantar Lateral plantar POST TIBIAL NERVE MEDIAL MALLEOLUS SURAL NERVE MEDIAL MALLEOLUS POST TIBIAL ARTERY AND NERVE ACHILLES TENDON Post Nbial • Important nerve for the sole of the foot and the calcaneum • Provides the calcaneal, medial and lateral plantar nerves • Lies behind the post Nbial artery • Easy to feel landmark • Can be blocked blindly or using a PNS • 5-‐7mls of LA Sural • Purely sensory • Supplies the lateral foot and the lateral aspects of the proximal sole of the foot • Lies between the Achilles tendon and lateral malleolus • Needle is inserted lateral to the tendon and is directed toward the malleolus as 5 to 10 mL of LA is injected subcutaneously SAPHENOUS NERVE SUPERFICIAL PERONEAL NERVE NAT DEEP PERONEAL NERVE SUPERFICIAL PERONEAL NERVE Saphenous, Superficial and deep Peroneal • All 3 can be blocked through a single needle entry site • A line is drawn across the dorsum of the foot connecNng the malleoli • Feel for the dorsalis pedis artery, insert your needle lateral to the artery and deposit 3-‐5 ml of LA to block the deep peroneal nerve Saphenous, Superficial and deep Peroneal • The deep peroneal nerve supplies the skin between the first and second toes and the short extensors of the toes • Now direct the needle laterally through the same skin puncture while injecNng 3 to 5 mL of soluNon subcutaneously, thus blocking the superficial peroneal nerve Saphenous, Superficial and deep Peroneal • This nerve supplies the dorsum of the foot, excluding the first interdigital clek • The same maneuver can now be performed in the medial direcNon, thereby anestheNsing the saphenous nerve • Saphenous nerve is the terminal branch of the femoral nerve that supplies a strip along the medial aspect of the foot Cases Anaesthesia and Blocks 82 yrs old paNent with fracture Hip DHS or IMHS PaNent posiNoning for DHS/IMHS Incision points Nerve Blocks • Femoral and Lateral Cutaneous • 3 in 1 Block • Fascia Iliaca Block 78 yrs old paNent for hemi-‐ arthroplasty Nerve Blocks • Lumbar and Sacral Plexus Block ideally • Fascia iliaca block with Large volume ( 40-‐50mls) • Femoral (large volume with distal pressure, 20mls) and proximal sciaNc (Labat approach) Blocks • Since the paNent is posiNoned in lateral; perform the Femoral Block with large volume and once paNent is posiNoned on the side proximal sciaNc nerve block can be done • Total volume used is around 40mls of 0.375% (Levo)Bupivicaine 28yr old paNent for ORIF of Tibia and Fibula Blocks • Tibia is supplied by sciaNc nerve, it is only the medial side of the skin that is supplied by femoral via Saphenous nerve • Popliteal fossa and saphenous nerve blocks are necessary for complete pain relief in these paNents • In awake paNent proximal blocks will delay the onset of tourniquet pain 55 yrs old diabeNc paNent for amputaNon of the big toe of Rt foot Just for the big toe • Saphenous • Superficial and deep peroneal • Post Nbial nerve Tourniquet pain • Awake paNents can tolerate this for around 30-‐40 mins • Nerve blocks delay this upto 45-‐60mins • No point in using Opioids, they do not work for ischemic pain • Propofol infusion is a beUer opNon, it is known to delay the ischemic injury of the muscles
