Peripheral Nerve Blocks

Question 1

Choice of LA, 3 determinates:

Answer 1

1) desired onset
2) desired duration
3) desired motor/sensory block

Question 2

Lidocaine (plain) max dose an DOA

Answer 2

Max dose 4 mg/kg

DOA 30 min-2 hours

Question 3

Lidocaine (with epi) max dose an DOA

Answer 3

Max dose 7 mg/kg

DOA up to 3 hours

Question 4

Bupivicaine (plain) max dose an DOA

Answer 4

Max dose 2 mg/kg

DOA 2-4 hours

Question 5

Bupivicaine (with epi) max dose an DOA

Answer 5

Max dose 3 mg/kg

DOA 3-4 hours

Question 6

Ropivicaine (plain) max dose an DOA

Answer 6

Max dose 5 mg/kg

DOA 2-6 hours

Question 7

Ropivicaine (with eip) max dose an DOA

Answer 7

N/A

Question 8

Which LA would be the best choice for a long 4-6 hour procedure?

Answer 8

Ropivicaine (plain) DOA 2-6 hours

Question 9

What are the 4 block techniques?

Answer 9

1) Field block- targeting LA for terminal cutaneous nerves
2) Paresthesia- look & stab
3) Nerve stimulation- when needle close to motor nerve, muscle contracts
4) Ultrasound** (preferred)

Question 10

For nerve stimulation, what conditions are optimal for LA injection?

Answer 10

When + muscle contraction @ <0.5 mA current, but not at 0.2 mA= intraneural placement

Question 11

5 contraindications for PNB?

Answer 11

• Pt refusal
• LA allergy
• Local infection (infection risk/acidic tissue)
• Coagulopathy/anti-coagulant meds= hematoma risk
• With some brachial plexus blocks: severe pulm disease or preexisting contralateral phrenic nerve palsy or contralateral VC paralysis

Question 12

What are the (6) general possible complications for PNB?

and special c/o for continuous and femoral?

Answer 12

• infection
• nerve injury
• hematoma
• local anesthetic systemic toxicity (LAST)
• catheter retention (for continuous)
• ↑ fall risk for femoral blocks

Question 13

What are the 4 brachial plexus blocks?

Answer 13

1) Interscaline
2) Supraclavicular
3) Infraclavicular
4) Axillary

Question 14

6 terminal nerve blocks of the upper extremity?

Answer 14

1) Median nerve
2) Ulnar nerve
3) Radial nerve
4) Musculocutaneous
5) Digital
6) Intercostobrachial

Question 15

Which brachial plexus blocks have contraindications for

1. Severe pulm disease or preexisting contralateral phrenic nerve palsy
2. Contralateral VC paralysis

Answer 15

Interscaline and Supraclavicular (higher level)
1. Severe pulm disease or preexisting contralateral nerve pals- can block ipsilateral phrenic nerve => dyspnea, ↓PaO2, ↑ PaCO2

2. Contralateral VC paralysis=> respiratory distress possible if block recurrent laryngeal nerve (also causes hoarseness)

Question 16

What 2 factors are considered when choosing an US probe and what are the 2 choices ?

Answer 16

1) depth of target
2) needle angle approach relative to transducer

Linear probe= high frequency, high resolution/less penetration (best pic, good for superficial nerves)

Curvilinear probe= low frequency, low resolution/more penetration (best for deeper structures)

Question 17

What are the sections of the brachial plexus and which blocks work on them?

Answer 17

Roots (C5-T1)- Interscaline block (mostly C5-C7)
Trunks
Divisions- Supraclavicular
Cords- Infraclavicular
Branches- Axillary

Question 18

What is Horner’s Syndrome and with what blocks is it a risk?

Answer 18

Myosis, ptosis and anhydrosis from proximal tracking of LA to block sympathetic fibers of the cervicothoracic ganglion
Risk with interscaline and supraclavicular blocks