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Regional 1 > LA 1 And 2 > Flashcards

LA 1 And 2 Flashcards

1
Q

Duration of anesthesia of PNB is dependent on

A

Type of block (uptake)

Drug used

Concentration

Adjuncts

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2
Q

Onset of PNB

Can take up to _____ to determine if block failed

A

10 minute onset
- 15 for Ropivacaine and Bupivacaine

Up to 30 minutes to determine if failed

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3
Q

Most single shot blocks _____ duration when combined with adjunct

A

16-24 hours

Decadron or epinephrine

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4
Q

Which is longer?

Analgesic time or surgical anesthetic time

A

Analgesic time much longer

Motor block will wear off but analgesia will continue

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5
Q

3 reasons for rescue blocks

Done when primary block

A
  • failed or has nerve sparing properties
  • ineffective in providing analgesia or doesn’t cover appropriate dermatome
  • duration of LA has been exceeded
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6
Q

If primary block has failed or has nerve sparing properties

A

Supplemental distal blocks

Redo primary block targeting location of missed nerves

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7
Q

Primary block is ineffective in providing analgesia or doesn’t cover appropriate dermatome

A

Surgeon operated on unanticipated area

Pain originates outside block coverage

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8
Q

When duration of LA has been exceeded

A

Usually at 16-24 hour mark when pain is still moderate-severe in nature

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9
Q

Rescue blocks are done by

A

Single shot

Single shot with catheter placement

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10
Q

Uptake of LA based on Regional Anesthetic Technique

Highest blood concentration to lowest

A 
IV
Tracheal
Intercostal
Caudal
Paracervical
Epidural
Brachial
Sciatic
Subcutaneous

(In Time I Can Please Everyone But Sally and Susan)

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11
Q

Pathophysiology of LAST

A

LA affect SNS and PNS

Profound arterial vasodilation and smooth muscle relaxation

Slows rate of depolarization, blocking fast Na channels

Very high doses dampen SA pm cells = bradycardia and sinus arrest

Dose dependent inotropic depression from negative modulation of Ca release from SR

Hypercapnia, acidosis, hypoxia increase negative inotropic and chronotropic effects of LA

BB, Ca channel blockers, and dig decrease threshold for cardiac toxicity

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12
Q

3 classes of drugs that decrease the threshold for cardiac toxicity

A

Beta blockers

Calcium channel blockers

Digoxin

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13
Q

LA with Lower safety margin and resuscitation if more difficult in event of LAST

A

Bupivacaine

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14
Q

LA that accounts for significant portion of LAST events

A

Lidocaine

Ropivacaine

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15
Q

4 things that are more predictive of high plasma levels of LA than body weight or BMI

A

Block site

Total LA dose

Test dosing

Pt comorbidities

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16
Q

7 events in LA toxicity

First to last

A

Drowsiness

Parentheses in mouth and tongue

Tinnitus, auditory hallucination

Muscular spasm

Seizure

Coma

Respiratory arrest

Cardiac arrest

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17
Q

Systemic intoxication by LA

Cardiocirculatory increasing degree of intoxication

A

HTN, tachycardia

Bradycardia, extrasystoles, hypotension

Asystole

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18
Q

Cerebral systemic intoxication s/s by degree of intoxication

A

Psychically “abnormal”

Confusion, dizziness, tinnitus, metallic taste

Seizure

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19
Q

Bupivacaine, levobupivacaine, ropivacaine

Which requires lower dose for toxic effects of LA

A

Bupivacaine

Levobupivacaine

Ropivacaine

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20
Q

Systemic presentations of LAST

CNS only

CV only

CNS and CV

A

CNS only 43%

CV only 24%

CNS and CV 33%

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21
Q

Spectrum of CV presentations with LAST

A

Dysrhythmia 34%

Conduction delay 27%

Cardiac arrest 23%

Bradycardia/hypotension 16%

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22
Q

Spectrum of CNS presentations of LAST

A

Seizure 47%

Loss of consciousness 36%

Prodromes 11%

Agitation 6%

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23
Q

The changing slop of trend lines suggest that contemporary LAST presentations are becoming

A

More delayed as compared with previous years

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24
Q

Due to the variability in presentation of LAST pt should be monitored for at least

A

30 minutes after injection

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25
Q

Immediate (<60sec) presentation of LAST suggests

A

IV injection of LA with direct access to brain

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26
Q

Presentation of LAST delayed 1-5 minutes suggests

A

Intermittent IV injection, lower extremity injection, or delayed tissue absorption

27
Q

4 basic steps of treatment of LAST

A

Get help

Initial focus

  • airway mgmt - HYPERVENTILATE
  • seizure suppression
  • Alert nearest facility with CPB

Mgmt of cardiac arrhythmia

  • BLS and ACLS
  • avoid vasopressin, BB, Ca channel blockers, LA
  • reduce epi dose to <1mcg/kg

Lipid emulsion therapy

28
Q

Drugs to avoid in management of cardiac arrhythmias with LAST

A

Vasopressin

Calcium channel blockers

Beta blockers

LA (lidocaine)

29
Q

Lipid emulsion therapy dosage

A

20% therapy

Bolus 1.5mg/kg (lean body mass) over 1 minute

Infusion 0.25ml/kg/min (at least 30min)
- double rate if BP remains low

Repeat bolus up to 2 times of CV collapse

Max 10-12 ml/kg over first 30 minutes

30
Q

Seizure control in LAST

A

Benzodiazepines

Small doses of propofol (avoid if CV collapse)

Small doses of succ or NMB to minimize acidosis and hypoxemia

31
Q

Epinephrine dosage during cardiac arrest due to LAST

A

<1mcg/kg

32
Q

If ventricular arrhythmias develop

Treatment of choice

A

Amiodarone

Avoid lidocaine and procainamide

33
Q

Pt with significant CV event should be monitored for

A

At least 4-6 hours

34
Q

If event is limited to CNS symptoms that resolve quickly they should be monitored for

A

At least 2 hours

35
Q

Steps to prevent IV injection

A

Slow injection

Multiple needle redirections and small injection 2-3ml

Aspirate for blood every 5 ml

Awake and monitored pt

US

Epi 2.5-5mcg/ml vascular marker

Vigilant monitoring

36
Q

Dose of LA is product of

A

Volume X concentration

37
Q

IV injection of epi s/s

A

> 10bpm increase in HR

> 15mmHg increase in BP

38
Q

S/S IV injection of epi are masked in

A

Beta blocked pt

Active labor

Advanced age

General/neuraxial anesthesia

39
Q

To decrease risk of LAST associated with truncal blocks

A

Use lower concentration

Dose on lean body weight

Adjunctive epi

Observe at least 30-45 minutes

40
Q

Myotoxicity of LA

A

IM injection of LA causes muscle damage and necrosis

41
Q

Myotoxicity of LA causes

A

Increase intracellular Ca

42
Q

Myotoxicity of LA

Which causes most damage

A

Bupivacaine

43
Q

Why use adjuncts of LA

A

Increase block duration

Post op analgesia

44
Q

Which blocks is epi for duration excluded

A

Sciatic

Digit blocks

45
Q

Adjuncts to LA examples

A

Epi

A2 agonist (precedex, clonidine)

Decadron

(Tramadol, buprenex, mag investigational)

46
Q

First liposomal, bupivacaine encapsulated drug

A

Exparel

47
Q

Exparel is a _____% solution

A

1.3%

48
Q

Max dose of Exparel

A

266 mg

49
Q

Dilution of exparel

A

Diluted to 0.89 mg/ml with NS or LS

Use within 4 hours

50
Q

FDA approved use of exparel

A

TAP blocks

51
Q

If exparel has been used. Don’t give bupivacaine for

A

96 hours

Increased risk of toxicity

52
Q

Obstacles in regional block anesthesia

A

Surgeon resistance

2 man procedure, stress staff resources

Risk of persistent parethesia, nerve injury, paralysis

Neurotoxicity from LA

IV injection

53
Q

Key to IV injection

A

Prevention

Early recoginition

54
Q

Dose of Decadron

IV

PNB

A

10mg IV after GETA induction

2mg per block

55
Q

LA works by

A

Blocking NA gated voltage channels

56
Q

Form of LA that is active

A

Protonated

Ionized

Lipid insoluble

57
Q

To speed the onset of LA you can add HCO3

MOA

A

More unprotonated from to cross the lipid bilayer

1MeQ of NAHCO3 for every 10 ml of LA

58
Q

First to disappear with LA blockade

A

B sympathetic fibers

Then Fast pain (Type A delta fibers)

59
Q

Most resistant fiber to LA

A

Slow pain (Type C fiber)

60
Q

Order of common LA from vasodilatory properties to vasoconstricitive properties

A

Tetracaine

Lidocaine

Bupivacaine

Mepivacaine

Ropivacaine

61
Q

LA onset/duration from fastest to slowest

A

Lido

Mepivacaine

Ropivacaine

Bupivacaine

Levobupivacaine

Exparel

62
Q

LA are only pharmacologically active in

A

Free, unbound state

63
Q

Rationale behind hyperventilating patient when suspect LAST

A

Pushes pH more alkaloid so more LA bound to protein so less free for CV and CNS toxicity

Regional 1 (8 decks)

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