Local Anaesthetic Toxicity Overview

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Questions and Answers

What is the time frame in which local anaesthetic toxicity can occur?

1 minute to 5 hours
30 minutes to 2 hours
15 minutes to 6 hours
10 minutes to 7 hours (correct)

What effect does sodium channel blockage have on the body?

Decreases cardiac conduction efficiency (correct)
Increases oxygen delivery to tissues
Enhances nerve signal transmission
Improves muscle responsiveness

Which property of local anesthetics allows them to cross cell membranes effectively?

Lipophilic structure (correct)
Increased water solubility
High molecular weight
Presence of $Ca^{2+}$ ions

What can increased vascularity lead to with regard to local anaesthetics?

<p>Increased risk of toxicity (D)</p> Signup and view all the answers

Which ions are crucial for muscle contraction and nerve transmission?

<p>$Na^+$ and $Ca^{2+}$ (A)</p> Signup and view all the answers

Flashcards

What is Local Anaesthetic Toxicity (LAST)?

Local anesthetic toxicity (LAST) is a serious condition that can occur when too much local anesthetic enters the bloodstream. It can happen within a few minutes to several hours after the injection. This occurs when local anesthetic blocks the transmission of pain signals to the brain.

How can dissolving rates affect LAST?

Local anesthetics like bupivacaine can differ in their dissolving rates. Some dissolve quickly, which can lead to faster absorption into the bloodstream and increase the risk of toxicity.

What role do sodium channels play in LAST?

Sodium channels are like tiny gates that allow electrical charges to flow through nerve cells. They're important for muscle contractions and nerve signals. Local anesthetics block these gates, which can lead to LAST.

How does LAST affect the heart?

Sodium is crucial for heart rhythm. It helps control the speed of electrical signals in the heart. Blocking sodium channels with local anesthetics can disrupt this rhythm, leading to dangerous heart problems.

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What is one factor that can increase LAST risk?

Increased blood flow to the area where the local anesthetic was injected can accelerate the rate at which it enters the bloodstream, increasing the risk of LAST.

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Study Notes

Local Anaesthetic Toxicity (LA)

Life-threatening adverse events can occur within 10 minutes to 7 hours after LA administration.
LA blocks pain receptors, preventing signal transmission to the brain.

Constituents

LA are composed of water-soluble salts and are lipophilic, meaning they dissolve easily in fat.
This lipophilic characteristic allows LA to readily cross cell membranes in their non-ionized form.
Increased vascularity can increase the risk of LA toxicity.

Function

Different LA have varying dissolving rates (e.g., bupivacaine), which can cause fast toxicity.
LA target sodium (Na+) channels.
Blocking Na+ channels interferes with signal transmission.
Na+ carries an electrical charge essential for muscle contractions and nerve transmission.
Sodium (Na+) is crucial for cardiac function, preventing rapid depolarization, and allowing for periods of rest between contractions.
Without Na+, arrhythmias can develop.