LE Nerve Blocks Flashcards
1
Q
equipment needed for nerve block
A
- sterile gloves
- nerve stimulator
- two syringes
- two needles to draw up LA
- local to numb the puncture site
- local for the block
- stimulating needle
- transducer cover
- antimicrobial (CHG, alcohol)
- 4x4s
2
Q
lumbar plexus
A
- arises from nerve roots L1-L4 (occasionally T12)
- innervation to lower extremities
3
Q
nerves of lumbar plexus
A
- iliinguinal nerve (L1)
- iliohypogastric nerve (L1)
- lateral femoral cutaneous nerve (L2, L3)
- femoral nerve (becomes saphenous) (L2, L3, L4)
- obturator nerve (L2, L3, L4)
4
Q
lumbosacral plexus
A
-arises from nerve roots L4-5 and S1-3 (sometimes S4)
5
Q
nerves in lumbosacral plexus
A
- sciatic nerve
- tibial nerve
- peroneal nerve
6
Q
lumbar plexus nerve blocks (4)
A
- femoral
- fascia iliaca
- adductor canal
- saphenous (thigh and ankle)
7
Q
lumbosacral plexus blocks (4)
A
- sciatic (subgluteal)
- sciatic (popliteal)
- iPACK
- Ankle blocks
8
Q
lumbar plexus innervation
A
sensory and motor innervation to thigh, anterolateral knee and SENSORY only to the medial aspect of the lower extremity below the knee (saphenous)
9
Q
femoral nerve block (FNB)
A
- targets major branch of the lumbar plexus
- anesthesia to anterior thigh, knee and medial aspect of the lower leg
- nerve is lateral to the artery and deep to the fascia lata and fascia iliaca AND superior to iliopsoas muscle
10
Q
FNB USG technique
A
- patient supine with slight external rotation of extremity
- transducer placed over inguinal crease over femoral pulse
- high-frequency linear array transducer
- short-axis image, in-plane needle insertion
- nerve is hyperechoic ovoid lateral to femoral artery and beneath fascia iliaca and lata
- 5 cm B-bevel needle
- 20 mL LA
- lateral to medial
11
Q
patellar snap
A
- quadriceps contraction that pulls patella up
- elicited when nerve stimulation is used with USG FNB
12
Q
FNB pearls
A
- doppler to verify flow in femoral vessels
- if two arteries visible, scan cephalad until a single femoral artery is identified
- LA placed below fascia lata and iliaca results in greatest efficacy
- lymph nodes in groin may appear as nerves, pre procedure scan to differentiate
13
Q
USG Fascia iliaca block
A
- similar to USG 3-in-1 lumbar plexus block
- targets = femoral nerve, obturator nerve, lateral femoral cutaneous nerve
- increased volume (40 mL) required to block all three nerves
- US imaging similar to femoral nerve block
14
Q
adductor canal block (ACB)
A
- part of ERAS for TKA
- means to identify the saphenous nerve using superficial femoral artery and vein as landmarks (to replace the FNB for TKA so there is no quadriceps weakness)
15
Q
adductor canal anatomy
A
- describes an intermuscular tunnel in the anteromedial thigh that lies posterior to the sartorius muscle
- proximal original is femoral triangle and it terminates at the adductor hiatus
- studies demonstrate that saphenous nerve and nerve to the vastus medialis pass through the canal
16
Q
ACB USG technique
A
- patient supine with slight external rotation of extremity
- transducer placed mid to distal third of thigh
- high frequency linear array transducer
- short axis image in-plane needle insertion
- LA deposited in fascial plane separating the sartorius and vastus medialis (lateral to femoral vessels)
17
Q
ACB pearls
A
- nerve branches may be located on both sides of the superficial femoral artery
- pre procedure scan detects aberrancies
- case reports demonstrate that if LA is deposited in the muscle, myotoxicity can occur
18
Q
saphenous nerve block (thigh)
A
- saphenous nerve = terminal branch of femoral nerve
- distal to adductor cannal, saphenous courses superficially in distal thigh
- provides sensory only to medial aspect of lower extremity below the knee
- used in combo with other blocks for surgical procedures involving ankle and foot
19
Q
saphenous nerve block (thigh) USG Technique
A
- patient supine with slight external rotation of extremity
- transducer placed at distal thigh
- high-frequency linear array transducer
- short-axis image, in-plan needle insertion
- LA deposited in fascial plane separating adductor longus and vastus medialis below subQ tissue
- 5-10 mL of LA
20
Q
lumbosacral plexus innervation
A
sensory and motor innervation to the posterior thigh, knee and lower extremity below the knee with exception to sensory innervation provided by the saphenous nerve
21
Q
sciatic block (subgluteal)
A
- sciatic nerve deep to the gluteus maximus between ischial tuberosity and greater trochanter
- block results in sensory and motor blockade of entire lower extremity below the knee except for that provided by saphenous nerve
- posterior thigh innervated by femorocuteanous nerve and may be missed by this approach
22
Q
sciatic block (subgluteal) technique
A
- patient prone or lateral
- low frequency curvilinear array transducer placed just distal to gluteal crease
- short axis image, in-plane
- LA deposited in fascial plane separating adductor longus and vastus medialis below the subQ tissue
- inject 20 mL LA
23
Q
popliteal nerve block
A
- targets sciatic nerve slightly above the knee
- sciatic branches into peroneal and tibial
- in popliteal fossa, they are bordered superiorly and medially by the semitendinosus and semimembranosus muscles AND superiorly and laterally by the biceps femoris muscle
24
Q
popliteal nerve block USG technique
A
- patient supine with operative leg elevated
- high frequency linear array transducer
- transducer placed in popliteal crease
- short-axis image
- tibial nerve superior to popliteal artery and vein, scan proximal to locate bifurcation with the peroneal nerve
- circumfrential spread around each nerve
25
popliteal block pearls
- scan proximal to distal to appreciate anatomy
- transducer may have to be angled toward foot to better image the nerves
- circumfrential spread around each nerve ensures dense block
26
iPACK block
- infiltration between popliteal artery and posterior capsule of the knee to block the terminal branches innervating the joint, sparing distal innervation of tibial and peroneal branches
- alternative to sciatic and selective tibial nerve block for pain control in TKA
27
iPACK indications
- posterior knee pain control for TKA
- preserves or minimally reduces foot drop
- facilitates post-op ambulation and rehabilitation
28
iPACK technique
- patient in lateral decubitus
- transducer placed in transverse plane above popliteal crease
- identify space betwen popliteal artery and vein AND intercondylar notch
- needle inserted lateral to medial
- 15-20 mL of LA injected while slowly withdrawing the needle
29
USG ankle blocks
- routinely indicated for surgical anesthesia and post op analgesia involving foot
- US shown to result in grater block efficacy even with lower volumes of LA
30
five nerves that innervate foot
- tibial
- deep peroneal
- superficial peroneal
- saphenous
- sural
31
tibial innervation
bottom of foot
- lateral plantar n - lateral aspect of foot, pinky toe and part of next toe
- medial plantar n - medial aspect of foot and rest of toes
- medial calcaneal n - calcaneas (heel)
32
deep peroneal innervation
in between first two toes
33
superficial peroneal innervation
top of foot except for pinky toe and most lateral aspect of top of foot
34
saphenous nerve innervation
medial aspect of leg and ankle (sensory only)
35
sural nerve innervation
lateral aspect of ankle and foot
36
USG posterior tibial nerve block
PTN always runs near the posterior tibial artery
37
USG deep peroneal nerve block
runs near the dorsalis pedis artery
38
USG sural nerve block
sural nerve runs near the lateral saphenous vein
39
USG saphenous nerve block
runs near the saphenous vein
40
USG superficial peroneal nerve block
bordered by (from lateral to medial)... EDL, fibula, and PBM
