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Anesthesia Pharm (A) > LA Complications & Rescue (4) > Flashcards

LA Complications & Rescue (4) Flashcards

1
Q

What are common local anesthetics complications?

A
  • Allergic reaction
  • Local Anesthetic Systemic Toxicity (LAST)
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2
Q

How common are allergic reactions from local anesthetics?

A

Rare <1%
(mild IgE anaphylaxis)

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3
Q

Which LA would be more prone to causing an allergic reaction?

A

Esters (d/t PABA preservative)

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4
Q

Which preservative is found in both esters and amides?

A

Methylparaben→ similar structure to PABA, can use preservative free

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5
Q

How do allergic reactions to LA present?

A
  • Rash
  • Urticaria
  • Laryngeal edema with or without hypotension and bronchospasm
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6
Q

What steps needs to happen if a pt experiences and allergic reaction from a local anesthetic?

A
  • Stop administration
  • Supportive care (airway, O2, fluids)
  • Epi, Antihistamines, Corticosteroids
  • Allergic testing: skin test with preservative free LA
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7
Q

Based off the article in the lecture, which LA most commonly cause allergic reactions?

A

Lidocaine

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8
Q

What 2 things are predictive factors for LA allergy confirmed by skin tests?

A
  • Cutaneous manifestations
  • History of LA exposure (twice or more)
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9
Q

What can cause local anesthetic systemic toxicity (LAST)?

A

Excess plasma concentration of drug
- Entrance into systemic circulation from inactive tissue
- Accidental direct IV injection
- Co-morbidities, meds, location and technique, dose

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10
Q

What does the magnitude of systemic absorption of LA depend on?

A
  • Dose
  • Vascularity of site
  • Epinephrine use
  • Physicochemical properties
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11
Q

Which route of LA admin results in the highest vs lowest blood concentrations?

A
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12
Q

The use of _______________ decreases systemic absorption of LA by 1/3.

A

epinephrine

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13
Q

What are the CNS effects of local anesthetic systemic toxicity of lidocaine?

A
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14
Q

How does hyperkalemia impact effects of local anesthetics?

A

Hyperkalemia promotes seizures with LAs→ predisposed lower AP threshold

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15
Q

Which LA has the biggest negative effect on CV system?

A

Bupivacaine (Big issue with CV toxicity)

Bupivacaine>Ropivacaine> Lidocaine

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16
Q

What are predisposing risk factors for LAST CV effects?

A
  • Pregnancy: lower plasma esterases
  • Hepatic and renal disease
  • Arterial hypoxemia, acidosis, or hypercarbia (in animals)
  • Beta blockers, Digitalis preparations, Ca+ Channel Blockers
  • Epinephrine & Phenylephrine Use
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17
Q
A

A and B

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18
Q

How does a decrease in plasma proteins with pregnancy predispose to LA toxicity?

A

Lower A1 glycoprotein for LA to bind to = more free drug

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19
Q

How does Lidocaine at 5mcg/mL with circumoral numbness effect CV system?

A
  • High plasma concentration block cardiac sodium channels
  • Conduction delays with cardiac impulses (negative inotropy, prolonged PR interval, QRS widening)
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20
Q

Why do we not give lidocaine during cardioversion?

A

Prolonged conduction impulse delay

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21
Q

What are the side effects of accidental Bupivacaine given IV?

A
  • Hypotension
  • AV block
  • Cardiac dysrhythmias: SVTs, ST/T wave changes, PVCs, wide QRS, VTach, possible arrest
22
Q

What are the treatments for systemic LA toxicity?

A
  • Stop LA immediately
  • Call for help
  • 100% O2 (prevent hypoxemia and metabolic acidosis)
  • Hyperventilation
  • Sedation: barbs or propofol if stable
  • Epi as an additive
23
Q

How are seizures from LAST treated?

A
  • Supplemental O2
  • Benzos (versed or valium)
  • Propofol if hemodynamically stable
  • Muscle relaxant (Succs or NMDA)
  • Intralipid: lipid emulsion
24
Q

What is the MOA of lipid emulsion for systemic LA toxicity?

A

Creates a lipid compartment for the LA to be drawn out of the tissue and provides fat for myocardial metabolism

25
What is the bolus and infusion for lipid emulsion?
Bolus: 1.5 mL/kg of 20% lipid emulsion Infusion: 0.25 mL/kg/min for at least 10 min
26
What is the epinephrine dose given with LA if cardiac arrest occurs?
10-100 mcg
27
What is the next step if there is no improvement in condition after lipid emulsion for LA toxicity?
Cardiopulmonary bypass
28
What is the upper limit for lipid emulsion initial dosing?
10 mL/kg for 30 minutes
29
How does LAST resuscitation differ from standard ACLS?
AVOID: LA, beta blockers, CCBs, vaso Smaller than normal epi doses preferred
30
What are the steps for treatment of local anesthetic systemic toxicity?
- Call for help - Support ventilation - Initiate CV life support protocol - Alert nearest cardiopulmonary bypass facility - Bolus 1.5 mg/kg lipid emulsion - Infuse 0.25 mL/kg/min lipid emulsion - If hypotensive after double infusion to 0.5mL/kg/min - if cardiovascular instability repeat bolus (1.5mL/kg) up to 3mL/kg total
31
16,200mg
32
What are other systemic toxicities from local anesthetics?
- Neural Tissue Toxicity - Cauda Equina Syndrome - Anterior Spinal Artery Syndrome - Methemoglobinemia - Ventilatory Response to Hypoxia - Hepatotoxicity - Cocaine Toxicity
33
What causes neural tissue toxicity from LA?
- Direct neurotoxic effect on neurons from high concentration of LA or prolonged exposure - Can be transient or permanent neurologic injury
34
What are the 3 categories of neural tissue toxicity from LA?
- Transient Neurologic Symptoms (TNS) - Cauda Equina Syndrome - Anterior Spinal Artery Syndrome
35
What are transient neurologic symptoms of neural tissue toxicity associated with LA?
- Moderate to severe pain (lower back, buttocks, and posterior thighs) within 6-36 hours after uneventful single shot SAB
36
What is the cause of transient neurologic symptoms?
Unknown→ Lidocaine> other LAs
37
What is the treatment for transient neurologic symptoms?
Trigger point injections and NSAIDs Recovery 1-7 days
38
What causes cauda equina syndrome?
- Spinal anesthesia - High concentration of LA - Compression or ischemia of cauda equina
39
Cauda Equina Syndrome is associated with:
- Large lumbar disc herniation - Prolapse or sequestration with urinary retention
40
What causes anterior spinal artery syndrome?
- Effects of hypotension or vasoconstrictor drugs - PVD - Spinal cord compression from epidural abscess or hematoma - Thrombosis or vasospasm of bilateral anterior artery
41
What are S/S of anterior spinal artery syndrome?
Lower extremity flaccid paresis with variable sensory deficit
42
What is a potential life threatening complication with local anesthetics?
Methemoglobinemia→ decreased O2 carrying capacity
43
What causes methemoglobinemia?
Prilocaine, benzocaine > Lidocaine, nitroglycerine, phenytoin, sulfonamides
44
What is the treatment for methemoglobinemia?
Methylene blue 1 mg/kg over 5 minutes (max 7-8 mg/kg)
45
How quickly does methylene blue reverse methemoglobinemia?
Reversal from methemoglobin (Fe3+) to hemoglobin (Fe2+) within 20-60 min
46
____________ depresses the ventilatory response to arterial hypoxemia
Lidocaine *Susceptible patients: CO2 retainers*
47
What local agent can cause hepatotoxicity?
Continuous or intermittent epidural bupivacaine to treat postherpetic neuralgia *stoping infusion normalizes liver function*
48
C
49
What is the MOA of cocaine toxicity?
SNS stimulation by blocking presynaptic uptake of NE and dopamine (increased NE and dopamine postsynaptic levels)
50
What are the adverse effects from cocaine toxicity and how long can they last?
Can last up to 6 weeks: - HTN, tachycardia, coronary vasospasm, MI, ventricular dysrhythmias (vfib) - decreased uterine blood flow (fetal hypoxemia) - hyperpyrexia→ seizures
51
What is the treatment for cocaine toxicity?
- Benzos - Nitro - NO beta blockers

Anesthesia Pharm (A) (19 decks)

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