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Basic Science II > Peripheral Nerve Blocks > Flashcards

Peripheral Nerve Blocks Flashcards

1
Q

hypoechoic background with hyperechoic lines. Compressible

A

Fat

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2
Q

Bright hyperechoic lines

A

Fascia

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3
Q

hypoechoic background with hyperechoic lines. Non-Compressible. Surrounded by hyperechoic lines

A

Muscle

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4
Q

Very bright hyperechoic line with anechoic region beneath.

A

Bone

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5
Q

Hyperechoic and hypoechoic. Honeycomb appearance. Above clavicle more hypoechoic and below clavicle more hyperechoic

A

Nerves

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6
Q

Postganlionic sympathetic and afferent sensory. Only unmyelinated nerve fiber. Autonomic, pain and sensation

A

C Fibers

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7
Q

Preganglionic sympathetic. Autonomic

A

B Fibers

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8
Q

Afferent sensory nerve. Pain and sensation

A

A(delta)

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9
Q

Afferents to muscles and joints. Proprioception

A

A(Beta)

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10
Q

Efferents to muscle spindles. Muscle Tone

A

A(gamma)

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11
Q

Efferents to motor and joints. Motor

A

A(alpha)

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12
Q

Nerve block onset

A

B >C & A(d) > A(g) > A(b) > A(a)

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13
Q

Nerve block recovery

A

A(a) > A(b) > A(g) > C & A(d) > B

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14
Q

LAST (LA Systemic Toxicity ) - Drugs not to use

A

B-Blockers, Ca Channel Blockers, or LAs

Dont give Propofol

Also, reduce ept to < 1mcg/kg

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15
Q

T or F. Heparin 5000 SQ BID and Aspirin/NSAIDs may be administered at any time with no restriction on regional.

A

True

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16
Q

In general must wait anywhere from __-__ half-lives after administration of anticoagulant before regional can be safely performed.

A

3-5 half lives

Kidney and Liver dysfunction means one should wait longer before regional can be safely performed

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17
Q

Current intensity = measured in __. You should start at ___ and dial down. When you get to < ___ it is ok to inject LA

A

mA, 1.5mA, 0.7mA

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18
Q

_____ is used foe sensory vs. motor differentiation and is especially useful in neuropathic patients

A

Pulse duration = duration of current.

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19
Q

Typical pulse duration is about ___microseconds - which will get motor without sensory involvement

A

100msec

may have to increase for neuropathic pts

20
Q

___ = pulses per second.

A

Stimulation frequency (Hz) - 2 Hz is typically adequate

21
Q

_____ = pulse duration at which threshold current amplitude is twice that of rheobase

A

Chronaxie

Important for nerve differentiation

22
Q

_____ = lowest current amplitude with long or infinite pulse duration applied to depolarize (stimulate) a nerve.

A

Rheobase

23
Q

Equation for current you need in order to stimulate a nerve

I = ______

A

I =Ir(1 + C/t)

I = Current
Ir = Rheobase
C = Chronaxie
t = pulse duration
24
Q

Block is done at the C5-C7 root/trunk level.
C8-T1 (ulnar nerve) spared.

Block acceptable for shoulder and top half of humerus)

Deltoid/Biceps twitch acceptable

Side effects (ipsilateral horner syndrome, SOB, and hoarseness)

Complications (epidural/subarachnoid spread, paralysis, respiratory failure)

A

Interscalene Block

25
Q

Block is deeper than the other blocks of the brachial plexus. Thus technically more difficult to visualize with ultrasound

Acts at level of cords

The best block when performing and upper extremity catheter.

Sensory innervations from mid-humerus down.
Pneumothorax a major concern

A

Infraclavicular Block

26
Q

Musculocutaneous nerve, ulnar nerve, median nerve, and radial nerve blocked
Technically more challenging because individual nerves have to be anesthetized
No risk of pneumothorax
Very difficult to place a catheter

A

Axillary Block

27
Q

Spinal of the arm

Acts at the level of the divisions

Covers from the mid-humerus down.
Does not cover shoulder because the axillary nerve and dorsal scapular nerve are spared

Pneumothorax a real concern especially with the land-mark technique

A

Supraclavicular block

28
Q

Median, Ulnar, and Radial nerves blocked
Easily done with nerve stimulation, landmarks, or ultrasound.
Great supplemental block if one of the brachial plexus blocks is incomplete

A

Wrist and Elbow blocks

29
Q

Innervation to anterior thigh and medial aspect of lower leg.
Quadriceps contraction ideal (as opposed to sartorial twitch)
Anterior and Posterior division
Significant quadriceps weakness
Ideal for knee replacements and ACL reconstructions
Fascia iliaca block only blocks femoral, lateral femoral cutaneous, and obturator 50% of the time.

A

Femoral Nerve Block

30
Q

In rare situations when there is considerable medial knee pain
Obturator nerve divides into anterior and posterior divisions which traverse through the adductor muscles.

A

Obturator Nerve Block

31
Q

“Femoral nerve block from the back”
Reliably blocks femoral, lateral femoral cutaneous, and obturator nerves
Advanced block ( Complications include epidural and subarachnoid spread and retroperitoneal hematoma)

A

Lumbar Plexus Block (Psoas Compartment Block)

32
Q

Difficult to see under u/s guidance
Sensory nerve to lateral aspect of thigh
Location is 2 cm medial and 2 cm inferior to anterior superior iliac spine

A

Lateral Femoral Cutaneous Nerve Block

33
Q

The only unmylenated fibers we have

A

C Fibers

34
Q

Visceral Pain

A

A-delta

35
Q

Somatic Pain

A

C fibers

36
Q

Smallest fibers

A

C fibers

37
Q

___ fibers are stimulated at shorter pulse durations

A

motor (50-100 micro sec chronaxie)

38
Q

___ fibers are stimulated at longer chronaxie

A

pain - A(d) - 170 micros sec and C fibers - 400 micro sec

39
Q

Largest and most sensitive nerve in the body (anesthetized with the lowest concentration of local anesthetic and anesthetized for longest duration)

Easily injured (torturous course and low blood flow)

Posterior cutaneous nerve of the thigh can only be blocked with parasacral approach

A

Sciatic Nerve Block

40
Q

Several different places nerve can be blocks (above knee, below knee and ankle)
Quadriceps sparing (purely sensory nerve)
Excellent for foot and ankle surgery

A

Saphenous Nerve Block

41
Q

5 nerves blocked

  • Saphenous (fem)
  • Deep peroneal (sci)
  • Superficial peroneal (sci)
  • Posterior tibial (sci)
  • Sural (sci)
A

Ankle Block

42
Q

Excellent block for breast and thoracic surgery

u/s, landmark, or loss of resistance appropriate technique.

Pneumothorax, epidural or intrathecal spread real concerns

A

Paravertebral Nerve Block

43
Q

If you are doing an interscalene block and your pt starts to hiccup, what should you do?

A

You hit the phrenic nerve - should aim more posteriorly and laterally

44
Q

If you are doing an interscalene block and rather than getting a deltoid and bicep twitch, you get a shoulder raise, what does that mean?

A

stimulating accessory nerve - too posterior and need to aim more anteriorly

45
Q

Excellent coverage T10 and below (subcostal tap if higher segmental coverage needed)

Umbilical surgeries will need a rectus sheath block

A

TAP Block

Basic Science II (6 decks)

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