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N931 Advanced Principles of Anesthesia I > LE Nerve Blocks > Flashcards

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
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2
Q

lumbar plexus

A
  • arises from nerve roots L1-L4 (occasionally T12)

- innervation to lower extremities

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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)
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4
Q

lumbosacral plexus

A

-arises from nerve roots L4-5 and S1-3 (sometimes S4)

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5
Q

nerves in lumbosacral plexus

A
  • sciatic nerve
  • tibial nerve
  • peroneal nerve
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6
Q

lumbar plexus nerve blocks (4)

A
  • femoral
  • fascia iliaca
  • adductor canal
  • saphenous (thigh and ankle)
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7
Q

lumbosacral plexus blocks (4)

A
  • sciatic (subgluteal)
  • sciatic (popliteal)
  • iPACK
  • Ankle blocks
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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)

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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
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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
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11
Q

patellar snap

A
  • quadriceps contraction that pulls patella up

- elicited when nerve stimulation is used with USG FNB

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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
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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
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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)
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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
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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)
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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
Q

popliteal block pearls

A
  • 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
Q

iPACK block

A
  • 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
Q

iPACK indications

A
  • posterior knee pain control for TKA
  • preserves or minimally reduces foot drop
  • facilitates post-op ambulation and rehabilitation
28
Q

iPACK technique

A
  • 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
Q

USG ankle blocks

A
  • 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
Q

five nerves that innervate foot

A
  • tibial
  • deep peroneal
  • superficial peroneal
  • saphenous
  • sural
31
Q

tibial innervation

A

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
Q

deep peroneal innervation

A

in between first two toes

33
Q

superficial peroneal innervation

A

top of foot except for pinky toe and most lateral aspect of top of foot

34
Q

saphenous nerve innervation

A

medial aspect of leg and ankle (sensory only)

35
Q

sural nerve innervation

A

lateral aspect of ankle and foot

36
Q

USG posterior tibial nerve block

A

PTN always runs near the posterior tibial artery

37
Q

USG deep peroneal nerve block

A

runs near the dorsalis pedis artery

38
Q

USG sural nerve block

A

sural nerve runs near the lateral saphenous vein

39
Q

USG saphenous nerve block

A

runs near the saphenous vein

40
Q

USG superficial peroneal nerve block

A

bordered by (from lateral to medial)… EDL, fibula, and PBM

N931 Advanced Principles of Anesthesia I (19 decks)

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