Regional Anesthesia > LAST PPT > Flashcards

LAST PPT Flashcards

(58 cards)

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1
Q

What are max doses based on?

A

Max doses are summative; based on percentages.

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2
Q

What are the two types of onset for LAST?

A

LAST can appear immediate with intravascular injection or be delayed from systemic absorption.

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3
Q

How often does LAST occur?

A

LAST happens about once every 1,000 blocks.

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4
Q

Which medications decrease the threshold for cardiovascular changes in LAST?

A

Beta blockers, calcium channel blockers, and digoxin decrease the threshold for cardiovascular changes.

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5
Q

What is the negative effect associated with LAST?

A

LAST has a negative inotropic effect.

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6
Q

What is a best practice for needle tip visualization?

A

Proper needle tip visualization for blocks.

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7
Q

What should you do before administering a bolus?

A

Aspirate catheter/needle prior to administering bolus.

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8
Q

What is the recommended volume for boluses?

A

Break boluses up into less than 5 mLs at a time.

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9
Q

What should you do between boluses?

A

Aspirate between boluses.

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10
Q

What should you monitor during the procedure?

A

Monitor your ECG and other vital signs.

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11
Q

What is important to do with your patient?

A

Talk and listen to your patient.

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12
Q

What symptoms precede cardiovascular symptoms in early detection?

A

Neuro symptoms precede cardiovascular symptoms.

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13
Q

What are the mild neuro toxicity symptoms?

A

Lightheadedness/dizziness, drowsiness, metallic taste, auditory changes (ringing in your ears or echoing).

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14
Q

What are the mild cardiovascular toxicity symptoms?

A

Hypertension and tachycardia.

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15
Q

What symptoms precede cardiovascular symptoms in late detection?

A

Neuro symptoms precede cardiovascular symptoms.

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16
Q

What are the severe neuro toxicity symptoms?

A

Shivering, muscle twitching, seizures, loss of consciousness.

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17
Q

What are the severe cardiovascular toxicity symptoms?

A

Hypotension from arterial vasodilation, decrease inotropy (decrease Ca2+ release from sarcoplasmic reticulum), rhythm changes (ventricular arrythmias), bradycardia (blocking fast Na+ channels), cardiovascular collapse and arrest.

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18
Q

What is the immediate action regarding local injection?

A

Stop injecting local.

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19
Q

What support should be provided as needed?

A

Airway, Breathing, Circulation support.

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20
Q

What should you be prepared to do next?

A

Move on to the next step, do not ‘wait and see.’

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21
Q

What should you do if you need assistance?

A

Call for help.

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22
Q

What equipment should be brought in?

A

Bring in the crash cart/LAST cart/airway cart.

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23
Q

What medication should be called for?

A

Call for versed.

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24
Q

What is the lipid sink effect?

Study These Flashcards
A

The lipid sink effect is the hypothesis that lipid emulsions attract lipophilic local anesthetic molecules from the bloodstream, reducing their concentration in blood.

This helps prevent adverse effects on organs such as the heart and brain.

25
How do lipid emulsions enhance local anesthetic metabolism?
Lipid emulsions may enhance the metabolism of local anesthetics in the liver, breaking down the anesthetic agent more rapidly and reducing overall toxicity. ## Footnote This process is critical for minimizing the side effects associated with local anesthetics.
26
What role do lipid emulsions play in membrane stabilization?
Lipid emulsions help stabilize cell membranes, including those in the heart and central nervous system, and prevent calcium ion influx. ## Footnote This stabilization can mitigate cardiac and neurological complications caused by local anesthetics.
27
What is the potential effect of lipid emulsions on toxic metabolites?
Lipid emulsions may bind to and sequester toxic metabolites produced during the breakdown of local anesthetics, preventing harmful effects on the body. ## Footnote This binding action can significantly reduce toxicity levels in patients.
28
What is the initial bolus dose for lipid infusion?
1.5 mL/kg
29
What is the initial infusion rate for lipid infusion?
0.25 mL/kg/min
30
What should you do if a patient experiences hypotension during lipid infusion?
Double the infusion rate to 0.5 mL/kg/min
31
What is the second bolus dose for CV instability during lipid infusion?
1.5 mL/kg
32
What is the initial approach to treating LAST?
HIGH LEVEL OF SUSPICION!
33
What symptoms precede cardiovascular symptoms in LAST?
Neuro symptoms precede cardiovascular symptoms.
34
What are the neuro changes associated with mild toxicity in LAST?
Lightheadedness/dizziness, drowsiness, metallic taste, auditory changes.
35
What are the cardiovascular changes associated with mild toxicity in LAST?
Hypertension and tachycardia.
36
What are the neuro changes associated with severe toxicity in LAST?
Shivering, muscle twitching, seizures, loss of consciousness.
37
What are the cardiovascular changes associated with severe toxicity in LAST?
Hypotension from arterial vasodilation, decrease inotropy, rhythm changes, bradycardia, cardiovascular collapse and arrest.
38
What causes hypotension in severe toxicity of LAST?
Hypotension from arterial vasodilation.
39
What is the effect of decreased inotropy in severe toxicity of LAST?
Decrease Ca2+ release from sarcoplasmic reticulum.
40
What rhythm changes can occur in severe toxicity of LAST?
Ventricular arrhythmias.
41
What causes bradycardia in severe toxicity of LAST?
Blocking fast Na+ channels.
42
What is the recommended dose of epinephrine?
Administer epinephrine at doses ≤1 μg/kg. ## Footnote Higher doses can cause pulmonary vasoconstriction, leading to ventilation-perfusion mismatch and decreased oxygenation.
43
Why should higher doses of epinephrine be avoided?
To avoid impaired pulmonary gas exchange and prevent increased afterload. ## Footnote Excessive epinephrine elevates systemic vascular resistance, adding stress to the heart.
44
What is the first choice drug for ventricular fibrillation or pulseless ventricular tachycardia?
Amiodarone. ## Footnote Indicated for cases unresponsive to CPR, defibrillation, or vasopressor therapy.
45
Why is amiodarone preferred over lidocaine?
Amiodarone is effective on refractory arrhythmias, has minimal cardiac depression, and no local anesthetic properties. ## Footnote Lidocaine can exacerbate neurotoxicity and cardiotoxicity in LAST.
46
What are the risks of using lidocaine in LAST?
Lidocaine is a local anesthetic that may worsen cardiac conduction disturbances. ## Footnote Its use can exacerbate neurotoxicity and cardiotoxicity.
47
Why do weak bases matter in anesthesia?
Most drugs used in anesthesia are weak bases (local anesthetics, opioids, benzodiazepines, ketamine). ## Footnote The ionized vs. nonionized fraction determines onset of action, potency at receptor sites, and placental transfer.
48
What happens to weak bases in basic environments?
Weak bases become more nonionized in basic environments (higher pH). ## Footnote Base + Base = Nonionized.
49
What is pKa?
pKa is the pH where a drug is 50% ionized and 50% nonionized.
50
What is the significance of the nonionized fraction?
The nonionized fraction is lipid soluble and can cross membranes (nerve sheath, BBB, placenta).
51
What is the significance of the ionized fraction?
The ionized fraction is water soluble and does not cross membranes but binds receptors once inside the nerve axoplasm.
52
What is the pKa and ionization of Bupivacaine at physiologic pH?
Bupivacaine has a pKa of 8.1. At physiologic pH (7.4), it is approximately 17% nonionized and 83% ionized. ## Footnote pKa – pH = 8.1 – 7.4 = 0.7 → favors ionized form.
53
What is the clinical implication of Bupivacaine's ionization?
Bupivacaine has a slower onset compared to agents with lower pKa due to fewer lipid-soluble molecules available to cross the nerve membrane.
54
How does Lidocaine compare to Bupivacaine?
At pH 7.4, Lidocaine (pKa 7.9) is approximately 24% nonionized and 76% ionized, leading to a faster onset compared to Bupivacaine. ## Footnote Bupivacaine is approximately 17% nonionized and 83% ionized.
55
What happens at physiologic pH (7.4) for Bupivacaine and Lidocaine?
At physiologic pH, both Bupivacaine and Lidocaine are more ionized than nonionized.
56
What occurs when tissue pH is increased to 8.0?
At pH 8.0, Lidocaine becomes greater than 50% nonionized, while Bupivacaine remains more than 50% ionized.
57
What is the concept of placental transfer and ion trapping?
Nonionized local anesthetic crosses the placenta; fetal blood is more acidic, leading to more drug becoming ionized in the fetus, which cannot cross back. ## Footnote This is a concern if a large amount of local anesthetic is injected around a highly vascular area.
58
What should be monitored during an episode of LAST?
During LAST, it is important to create a gradient that pulls the drug from maternal circulation first and then from fetal circulation.
Regional Anesthesia
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