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Anesthesia Pharmacology > Lecture 18 (Exam 4 Local Anesthetics Part III) > Flashcards

Lecture 18 (Exam 4 Local Anesthetics Part III) Flashcards

1
Q

What is the percentage of lidocaine allergic reactions?

A

Very Rare, Less than 1%

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2
Q

What is lidocaine allergic reaction attributed to?

A

Excess plasma levels of lidocaine.

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3
Q

Which class of local anesthetic is more prone to an allergic reaction?

A

Esters d/t to the PABA metabolite

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4
Q

This preservative in both ester and amide LA can cause an allergic reaction.

A

Methylparaben

Similar structure to PABA

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5
Q

Is there cross-sensitivity between esters and amides?

A

No

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6
Q

True LA reactions will exert what symptoms?

A
  • Rash
  • Urticaria
  • Laryngeal edema w/ or w/o hypotension
  • Bronchospasm
  • Anaphylaxis attributed to IgE
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7
Q

What does LAST stand for?

What is LAST d/t?

A

Local Anesthetic Systemic Toxicity

LAST is d/t excess plasma concentration of the drug.

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8
Q

What can cause LAST?

A
  • Entrance of LA to systemic circulation from inactive tissue redistribution and clearance metabolism.
  • Accidental direct IV injection
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9
Q

The magnitude of systemic absorption depends on what factors?

A
  • Dose
  • Vascularity of site
  • Epi use
  • Physiochemical properties
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10
Q

What are the CNS effects of LAST?

A
  • Drowsiness
  • Facial twitch
  • Seizures (Hyperkalemia w/ LA will promote this)
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11
Q

Plasma venous concentration of lidocaine needs to be monitored when the cumulative epidural dose of lidocaine is greater than ______ mgs.

A

900 mgs

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12
Q

Lidocaine at ________ mcg/mL will promote circumoral numbness but no CV effects.

However, high plasma concentrations of LA will block what?

A

5 -10 mcg/mL

Block cardiac sodium channels

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13
Q

What happens if the cardiac sodium channels are blocked?

A

Slow conduction of cardiac impulses → prolonged PR interval and QRS widening

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14
Q

What are the effects of accidental IV administration of Bupivacaine?

A
  • Precipitous hypotension
  • AV Block
  • Cardiac Dysrhythmias
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15
Q

What predisposing factors to LA Systemic Toxicity of CV System Effects?

A
  • Pregnancy (↓plasmaesterases, ↓ plasma proteins)
  • Arterial hypoxemia, acidosis, hypercarbia
  • β-blockers, Digoxin, CCB (↓ myocardial impulse propagation)
  • Epi and Neo (↑ Bupivacaine-induced catecholamine production)
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16
Q

What are the top three anesthetics to have LAST CV System Effects?

A
  1. Bupivacaine
  2. Ropivacaine
  3. Lidocaine
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17
Q

What two factors predispose our OB population to LA toxicity?

A. ↓ Plasma Esterase
B. ↓ Plasma Proteins
C. ↑ Plasma Esterase
D. ↑ Plasma Proteins

A

A, B

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18
Q

What are the 3 goals for the treatment of LA Systemic Toxicity?

A
  1. Prompt airway management
  2. Circulatory support
  3. Removal of LA from receptor sites
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19
Q

What are airway management for LAST?

A
  • 100% O2 in a non-rebreather mask to inhibit hypoxemia and metabolic acidosis.
  • Hyperventilation
  • Barbiturates/Benzos (prevent LA-induced seizures)
  • Epi as an additive (if following ACLS algorithm)
20
Q

What are treatments for LA-induced seizures?

A
  • Supplemental O2
  • Benzo (midazolam, diazepam)
  • Propofol: if hemodynamically stable
  • Succinylcholine or NMBD
  • Intralipid: lipid emulsion
21
Q

In preparation for anesthetic blocks (epidurals/spinal), what is the standard of care to always have nearby?

A

Intralipid/ Lipid Emulsions

22
Q

What is the MOA of Intralipids?

A

Creates lipid compartment, provides for fat for myocardial metabolism, and encapsulates LA

23
Q

Intralipid
Bolus Dose:
Infusion Dose:
1st 30 minutes:

A

Intralipid
Bolus Dose: 1.5 mL/kg of 20% lipid emulsion
Infusion Dose: 0.25/mL/kg/min for at least 10 mins
1st 30 minutes: 3.8 mL/kg (1.2-8 mL/kg)

24
Q

What are the modified epinephrine doses if cardiac arrest occurs secondary to LAST?

What drug is not recommended?

A

10 to 100 mcg

Vasopressin not recommended

25
Q

LAST Treatment: Failure to respond to lipid emulsion and vasopressor therapy should prompt the institution of __________.

A

Cardiopulmonary Bypass (CPB)

26
Q

Local Anesthetic Systemic Toxicity Flowchart

Memorize

27
Q

A 60-year-old, 120 lbs female has the following vital signs after the administration of Bupivacaine 0.5% 20 ml through the epidural catheter:
HR: 38 bpm
NIBP: 70/35
RR: 40
SaO2: 92%

How much of the 20% intra-lipid in mg would you bolus?

A

I. Lbs to Kg
120/2 = 60
10% of 60 = 6
60 - 6 = 54 kg

II. 1.5 mL/kg
1.5 x 54 = 81 mL

III 20% lipid emulsion = 200 mgs
81 x 200 = 16, 200 mg

28
Q

Neural tissue toxicity secondary from LA complications can be _________ or __________.

A

Transient; Permanent

29
Q

What are three categories of Neural Tissue Toxicity from LA?

A
  • Transient Neurological Symptoms (TNS)
  • Cauda Equina Syndrome
  • Anterior Spinal Artery Syndrome
30
Q

How do Transient Neurologic Symptoms manifest?

Cause:
Treatment:
Recovery:

A

Moderate to severe pain in the lower back, butt, and posterior thigh within 6 to 36 hours after an uneventful single-shot subarachnoid block.

Cause: Unknown (but blame lidocaine)
Treatment: Trigger point injections and NSAIDs
Recovery: 1 to 7 days

31
Q

Describe Cauda Equina Syndrome (CES).

A

Diffused injury at lumbosacral plexus → varying degrees of:
* Sensory anesthesia
* Bowel and bladder dysfunction
* Paraplegia

32
Q

What is Cauda Equina Syndrome associated with?

A
  • Large lumbar disc herniation
  • Prolapse or Sequestration with urinary retention
33
Q

Cause of CES?

A

Unknown, but blame lidocaine

34
Q

What is Anterior Artery Spinal Syndrome?

A

Lower extremity paresis with a variable sensory deficit.

35
Q

What are the causes of Anterior Artery Spinal Syndrome?

A
  • Thrombosis
  • Spasms
  • Hypotension
  • Vasoconstrictors
  • PVD
  • Spinal cord compression d/t epidural abscess or hematoma
36
Q

What is Methemoglobinemia?

Methemoglobinemia can be caused by what LA?

A

Potentially life-threatening complication d/t ↓ O2 carry capacity (metHb > 15%)

Can be caused by Prilocaine and Benzocaine

37
Q

What is the treatment for Methemoglobinemia?

How fast can this reversal take place?

A

Methylene Blue: 1 mg/kg over 5 mins (max 7 to 8 mg/kg)

Fe3+ (Ferric) can be reduced to Fe2+ (Ferrous) within 20 to 60 minutes.

38
Q

Lidocaine can depress the ventilatory response to arterial hypoxemia. Who are the susceptible patients?

A

CO2 retainer (COPD)

39
Q

How can LA cause Hepatotoxicity?

Treatment:

A

Continuous or intermittent epidural bupivacaine to treat postherpetic neuralgia.

Treatment: Stop infusion → normalize liver transaminase enzyme

40
Q

What is the most common first intervention when an adverse event is identified?
A. Call for help
B. Administer Antidote
C. Discontinued the causative agent
D. ABC

A

Call for help first → ABC → d/c causative agent → administer antidote

41
Q

What is the MOA of cocaine?

A

SNS stimulation blocks presynaptic uptake of NE and Dopamine, leading to ↑ postsynaptic levels.

42
Q

What are the adverse CV effects of cocaine (can last up to 6 weeks)?

A
  • HTN
  • Tachycardia
  • Coronary Vasospasm
  • MI
  • Ventricular Dysrhythmias
43
Q

What are the adverse parturient effects of cocaine?

A

↓ Uterine Blood Flow leading to fetal hypoxemia

44
Q

Cocaine can cause hyperpyrexia which can lead to _______.

45
Q

Cocaine-Associated Chest Pain Flow Chart.

Another one to memorize.

46
Q

Best treatment for cocaine toxicity coronary artery vasospasm.

A

Nitroprusside

Anesthesia Pharmacology (20 decks)

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