Lower Extremity Blocks

Question 1

Advantages to lower extremity regional anesthesia?

Answer 1

Avoid general anesthesia, hemodynamic stability, may allow patient to participate during the surgery, earlier discharge, post operative analgesia, can leave airway patent to communicate with them, cardiac or pulmonary disease (COPD), avoids use of opiates, N/V, post op sedation, preemptive analgesia

Question 2

Contraindications to regional anesthesia

Answer 2

Patient refusal, inability for patient cooperation, coagulopathy (depends on their INR, risk vs. benefit) spinals are absolute for coagulopathy

Question 3

Risks of peripheral nerve blocks

Answer 3

LA toxicity (calculate their ideal body weight), allergic response (esters break down to PABS), transient nerve damage, uncomfortable patient positioning, incomplete blocks

Question 4

Neuropharmacology of LA

Answer 4

Two classes: Esters and Amides
Esters: metabolized by plasma cholinesterase’s, greater potential for allergic reactions, PABA, Chloroprocaine
Amides: Lidocaine, metabolized by hepatic processes

Question 5

Neuropharmacology of LA: Toxicity

Answer 5

Systemic absorption can result in CNS and cardiac toxicity

Depends on site of injection, total dose, use of eli

Question 6

What is the rate of absorption from max to minimum

Answer 6

Intercostals, caudal, epidural, brachial plexus, sciatic, lumbar plexus, femoral “I can eat big plates of spaghetti like fettuccini.

Question 7

S/S of CNS toxicity

Answer 7

Tongue numbness, lightheadedness, dizziness, tinnitus, disorientation, visual disturbances, seizures leading to CNS depression, respiratory depression, respiratory arrest, CV instability. Metallic taste in mouth, want to do blocks while they are awake,

1. CNS toxicity
2. Respiratory depression
3. Cardiac toxicity

Question 8

How do you prevent toxicity?

Answer 8

Vigilant monitoring, limit dose accordingly, aspirate before you inject!, inject small volumes (5ml at a time)

Question 9

General principles

Answer 9

addition of epinephrine prolongs duration of action, use of low concentrations of local anesthetic permit injection of large volumes, used as an alternative or in conduction with general anesthesia. Lower concentration= higher volumes

Question 10

How do you decide between regional or general anesthesia?

Answer 10

Patient preference, coexisting medical conditions, surgical considerations (positioning, use of tourniquets), surgeon preference, skill of anesthesia provider, do they have cardiac or COPD? Does surgeon need vasodilation for vascular cases? need continued pain management?

Question 11

What equipment is needed?

Answer 11

Peripheral nerve stimulator or ultrasound, disposable kits, insulated needles, syringes, prep solution, local anesthetic, sterile gloves, monitoring
- insulated needle

Question 12

What are the techniques to located the nerve?

Answer 12

Ultrasound (new gold standard), paresthesias, nerve stimulator technique, you need to know anatomic relationship of nerves to muscles, bones or arteries

Question 13

Sciatic nerve block indications:

Answer 13

Surgeries for foot and lower extremity, on the posterior aspect of your leg distal to the knee.

Question 14

Describe the sciatic nerve

Answer 14

Large nerve, ventral branches of the lumbar plexus, L4-S3
Anatomy: gluteus maximus muscle, gluteus medius, greater trochanter, ischial tuberosity, posterior femoral cutaneous, sciatic nerve.

Question 15

Landmarks for a sciatic nerve block?

Answer 15

Draw a line from the greater trochanter to posterior superior iliac spine, then a line from the greater trochanter to the sacral hiatus. 5 cm down from first line

Question 16

With the nerve stimulator, now do you know you’re in the right spot for sciatic nerve block?

Answer 16

Dorsiflexion or eversion of the foot indications common peroneal branch, plantar flexion is tibial branch.
Should just see twitching of toes

Question 17

What is the volume for a sciatic nerve block?

Answer 17

20-30 ml

Question 18

What are complications of sciatic nerve block?

Answer 18

Block failure (rare b/c its so large), hematoma

Question 19

Describe the femoral nerve

Answer 19

Largest branch of the lumbar plexus, emerges through the psoas and descends into the groove between psoas and illiacus, passes UNDER inguinal ligament. Breaks into many branches that supply the muscles of ANTERIOR thigh, knee and hip. Sensory and motor nerve.

Question 20

What does a femoral nerve block result in?

Answer 20

Sensory effects include anesthesia to anterior portion of the thigh, knee and small area of medial foot.
Motor effects results in inability to abduct the leg or extend the lower leg. *Excellent adjunct for postoperative pain relief

Question 21

Landmarks for the femoral nerve block?

Answer 21

Inguinal ligament and the femoral artery, insert needle LATERAL to femoral artery

Question 22

How much do you inject for femoral nerve block?

Answer 22

25-35 ml

Question 23

Complications of femoral nerve block?

Answer 23

Intravascular injection, hematoma, direct nerve injury (pt should not complain of sharp pain)

Question 24

What are the indications of femoral blocks?

Answer 24

Surgeries of the anterior thigh and knee

Question 25

Popliteal block indications and landmarks

Answer 25

Foot and ankle surgery
Landmarks: popliteal fossa crease, biceps femoris tendon, semitendinosus, semimembranosus muscles.
7cm above popliteal crease, inject between muscles.

Question 26

How do you know you’re in the right spot for a popliteal block with the nerve stimulator?

Answer 26

see a twitch of their foot or toes, inject 30 mls

Question 27

What are ankle blocks indicated for?

Answer 27

Below the ankle procedures, 5-7 ml per nerve. No nerve stimulator, no epinephrine, block posterior tibial first as it is the largest

Question 28

What are the nerves you are blocking with the ankle blocks?

Answer 28

Deep perineal, Posterior tibial, Saphenous (from femoral), Superficial Peroneal, Sural