Principles final - lower blocks

Question 1

Advantages of Lower Extremity Blocks

Answer 1

Reduced recovery room admissions
Decreased PONV
Decreased urinary retention
Improved postoperative analgesia

Question 2

What are the three nerves of the lumbar plexus?

What nerve roots is the lumbar plexus formed from?

Answer 2

Formed from the first, second, third, and fourth lumbar nerve roots (ventral rami)

Lateral Femoral Cutaneous Nerve
Formed from 2nd and 3rd lumbar nerves
First to leave the compartment
Provides sensory innervation to the lateral aspect of the thigh

Obturator Nerve
Arises from the 2nd, 3rd, and 4th lumbar nerves as an extension of the lumbar plexus
Covered by the external iliac artery and vein
Primarily a motor nerve to the adductor muscles of upper leg
Has some mixed sensory fibers to the hip, the medial aspect of the femur, and the skin and soft tissue the medial aspect of the thigh proximal to the knee

Femoral Nerve
Largest nerve in the lumbar plexus
Formed from the 2nd, 3rd, and 4th lumbar nerve roots
Two branches:
Anterior branch
Innervation to the anterior surface of the thigh and the sartorius muscle
Posterior branch
Innervation to the quadriceps muscle, knee joint and its medial ligament
The origin of the saphenous vein

Question 3

Where is the plexus formed?

Answer 3

Plexus is formed behind the psoas major muscle and in front of the quadratus lumborum muscle

Question 4

What are the three nerves of the lumbar plexus

Answer 4

Lateral Femoral Cutaneous Nerve, Obturator Nerve, Femoral Nerve

Question 5

Femoral Nerve

Answer 5

Position
At femoral crease
Nerve lateral to femoral artery and vein
From lateral–medial
NAVEL
Nerve, Artery, Vein, Empty space, Ligament

FEMORAL NERVE towards hip, FEMORAL artery more medial, FEMORAL vein most medial at groin.

***Something about navel to navel??
OUT TO IN…like outer leg to inner or belly button or something

Question 6

Indications for femoral nerve block

Answer 6

Anterior aspect of thigh
Superficial surgery on medial aspect of leg and below knee
Knee arthroscopy

Question 7

Contraindications to femoral nerve block

Answer 7

Previous ilioinguinal surgery

Femoral vascular graft, kidney transplant

Large inguinal lymph nodes or tumor

Patient refusal

Local infection

Coagulopathy

Neuropathy?

Question 8

Femoral Nerve Block Nerve Stimulator Technique

Answer 8

Prep and drape groin using aseptic technique

Injection site: 1 cm lateral to the femoral artery (NAVEL) and 1 cm inferior to the inguinal ligament

Infiltrate 2-3 mL of 1% Lidocaine in the injection site

A 22-gauge, 4-cm insulated beveled needle advanced perpendicularly into the skin just lateral of the femoral artery

With a stimulation frequency of 2 Hz, the intensity level is set at 1 mA until quadriceps twitch or patellar “snap” is elicited

Intensity level is reduced to 0.5 mA (maintaining the stimulation of the nerve)

20 – 30 mL of local anesthetic is injected in 3-5 mL increments with intermittent syringe aspiration

Question 9

Ultrasound-Guided Femoral Nerve Block

Answer 9

Patient placed supine with groin exposed

Ultrasound probe is placed axially between the inguinal crease and the inguinal ligament

Anchoring landmarks for visualization are the femoral artery, femoral vein, and femoral nerve

Femoral nerve will appear triangular, hyperechoic, and lateral to the femoral artery

22-gauge, 2-inch needle inserted from lateral to medial

Once fascia iliaca is pierced and the needle tip is visualized close to the femoral nerve, 20 mL of local anesthetic is injected

Question 10

Continuous Femoral Nerve Block

Answer 10

Improves postoperative rehabilitation and analgesia

Reduces incidence of PONV

Insertion is similar to a single injection femoral block, except for the more 45-60 degree cephalad insertion angle
This assists in threading the catheter

Once patellar twitch is observed at 1 mA, the current is reduced go 0.5 mA and twitch response is reestablished

After negative aspiration for blood, 15-20 mL bolus of local anesthetic is slowly injected

Continuous infusion of local anesthetic is immediately initiated (8 – 10 mL/hr)
Femoral catheter should be removed within 48 hours

Question 11

Sciatic Nerve Block

Answer 11

Indications:
Lower extremity surgery

Anatomy of the Sciatic Nerve:
Formed by 4th Lumbar through 3rd Sacral roots

Is a continuation of the upper division of the sacral plexus

Largest nerve trunk in the body

Divides into tibial and common peroneal nerves

May require saphenous block

Contraindications:
Patient Refusal
Local infection
Coagulopathy
Neuropathy?

Question 12

Sciatic Nerve Block Technique (Classic Technique)

Answer 12

Monitors placed
Line is drawn from the posterior superior iliac spine to the greater trochanter of the femur

A second line is drawn from the sacral hiatus to the greater trochanter

A third line is perpendicular to and bisecting the first line

Intersection of second and third lines is point of entry
PNS used to identify location – confirmed by plantar flexion motor response

10 mL local anesthetic injected

Question 13

The three landmarks of the Popliteal Fossa Approach to Sciatic Nerve Block

Answer 13

popliteal crease

the medial border of the femoris biceps

tendon of the semitendinous muscle medially

Question 14

This nerve is frequently missed when an ankle block is performed

Answer 14

Deep Peroneal Nerve

Question 15

Ankle Blocks

Answer 15

Anatomy Of the Ankle
Ankle Block is performed by anesthetizing the five nerves at the level of the ankle:

Tibial Nerve
Arises from 4th and 5th lumbar and 1st, 2nd and 3rd sacral roots
Larger of the two branches of the sciatic nerve
Provides sensory innervation of the foot

Sural Nerve
Sensory innervation to the posterior portion of the sole of the foot, portion of the heel, and a portion of the Achilles tendon immediately above the ankle

Superficial Peroneal Nerve
Arises from the roots 4th and 5th lumbar roots and 1st and 2nd sacral roots
Becomes superficial in the middle two-thirds of the lower leg and remains subcutaneous into the dorsum of the foot

Deep Peroneal Nerve
Arises from same nerve roots as the superficial peroneal nerve
Provides innervation to the short extensors of the toes and provides sensory innervation to the skin n the lateral side of the hallux
*This nerve is frequently missed when an ankle block is performed

Saphenous Nerve
Terminal branch of the femoral nerve and travels subcutaneously from the lateral side of the knee joint
Provides sensory innervation to the medial side of the malleolus and the skin of the medial aspect of lower leg
*With an adequate saphenous block, a patient can tolerate a tourniquet above the ankle

Question 16

when should a continuous femoral block catheter be removed?

Answer 16

removed within 48 hours

Question 17

How do you insert for a continuous femoral nerve block?

Answer 17

similar to a single injection femoral block, except for the more 45-60 degree cephalad insertion angle - assists in threading the catheter

Question 18

What is the largest nerve trunk in the body?

Answer 18

sciatic nerve, duh!

Question 19

How do you confirm the location for a sciatic nerve block?

Answer 19

PNS used to identify location – confirmed by plantar flexion motor response

Question 20

Which block is used to block distal leg and foot
Ankle surgery, Achilles tendon repair, tibia or fibula surgery

Answer 20

Popliteal Fossa Approach to Sciatic Nerve Block

Question 21

Treu/False: With an adequate saphenous block, a patient can tolerate a tourniquet above the ankle

Answer 21

True

Question 22

Which nerve of the foot provides sensory innervation to the foot and is the larger of the two branches of the sciatic nerve?

Answer 22

tibial nerve