PNB Complications Flashcards

1
Q

Higher incidence of neurologic injuries involve which blocks

A

Brachial plexus blocks

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2
Q

_______________ while doing a block is associated with high incidence of post op neurologic injury

A

Elicitation of paresthesia

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3
Q

What is more common with PNB

A

Transient neurologic dysfunction

Typically resolves with time

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4
Q

Most symptoms of PNB injury resolve when

A

Within 2-4 weeks

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5
Q

Surgeries associated with most complications r/t PNB

A

Rotator Cuff Repair

Carpal Tunnel Release

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6
Q

Patient characteristics associated with PNB injury

A

Preexisting neurologic disease**

DM **

Smoker

BMI extreme

Male

Elderly

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7
Q

Perioperative characteristics associated with PNB injury

A

Pain with injection***

Prolonged tourniquet time***

Positioning ***

Parenthesis with needle placement

Sedated during block

Hypothermia

Prolonged hospitalization

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8
Q

Barriers to PNI recognition

A

Sedation

Post op pain/analgesia

Regional anesthesia (failure to report, failure to peruse)

Patient periop naivety/uncertainty

Dressings,drains, casting ***

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9
Q

Types of neurologic injury

Mild

Recovery 2-3 weeks

A

Neuropraxia

Most common

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10
Q

Cause of neuropraxia

S/S

A

Hit nerve with needle- mild inflammation

No deficit in sensory or motor

Tingling or paresthesias

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11
Q

Types of neurologic injury

Severe

Regeneration 1mm/day

Recovery 6-12months

A

Axonotmesis

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12
Q

Causes of axonotmesis

A

Injury to nerve directly but not transected

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13
Q

Types of neurologic injury

Degeneration

Neuroma formation

Permanent and irreversible

A

Neurotmesis

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14
Q

Causes of neurotmesis

S/S

A

Complete disruption in axoplasmic flow

Sensory or motor in either direction disrupted

Aka Wallerian degeneration

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15
Q

Sunderland classification of nerve injury and prognosis

1
2
3
4
5
A

1- neuropraxia good

2- axonotmesis. Fair

3,4,5- neurotmesis poor

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16
Q

4 causes of neural injury

A

Mechanical

Ischemic

Chemical

Co-existing neurologic disease and comorbidities (obese, smoker, elderly)

17
Q

4 types of mechanical nerve injury

A

Needle contact

Intrafasicular injection

Compression

Stretch

18
Q

Needle angle to reduce intraneural injury

A

Tangential and long axis approach

19
Q

Does intraneural injection always cause neurologic dysfunction

20
Q

Chemical nerve injury MOA

A
  • all LA are neurotoxic
  • duration of nerve exposure to LA increases risk
  • pre-existing neural blood flow increases risk if low
  • adjuvants may have neurotoxic potential
21
Q

MOA for LA being causative agents for neurotoxic injury

A

Increase in cystolic Ca

Depletes ATP, mitochondrial injury, membrane dysfunction, cell death

22
Q

Which nerves more susceptible to neurotoxicity injury

A

Small diameter

Transmitting pain and temperature

23
Q

LA

Vasodilator to vasoconstrictor

A

Lidocaine(dilate)

Bupivacaine

Mepivacaine

Ropivacaine (constrict)

24
Q

All LA except______ have shown to reduce neural blood flow

A

Tetracaine

25
Lidocaine 2% reduces neural blood flow by ______ when epi added
20-80%
26
Doses of bupivacaine >0.5% have mild _______ action
Vasodilator
27
Should always use __________ drugs for PNB
Preservative free drugs
28
3 non LA drugs that have been shown to be neurotoxic at high doses
Ketamine Midazolam Dexamethasone (dose dependent)
29
_____________ has been shown to be neuroprotective and may prolong block duration
Dexmedetomidine
30
Which route of dexamethasone administration prolongs block more IV or PNB additive
Added to PNB
31
Buprenorphine addition findings
Prolong by 8 hours SIGNIFICANTLY INCREASES RISK OF PONV
32
When doing PNB on diabetic pt you should
Reduce concentration and volume of LA in PNB Eliminate adjuncts (especially epi)
33
Pt undergoing chemo changes in PNB
Limit concentration, volume, and adjuncts
34
Tips for performing PNB
Eval for pre-existing neurologic disease/disorder pre-op Use lowest concentration and volume possible