Systemic toxicity

Question 0

The commonest cause of toxicity is?

Answer 0

Inadvertent intravascular administration

Question 1

Systemic toxicity is

Answer 1

the absorption of LA into the circulation causing systemic symptoms.

Question 2

LA should not be injected into inflamed or infected tissue

Answer 2

because of increased risk of being absorbed into blood

Question 3

Causes of systemic Toxicity

Answer 3

inadvertent intravascular administration
not waiting for LW to work before giving more
Not keeping count of how much has been used
LA into infected tissues

Question 4

Signs of central nervous system toxicity: Happens before CVS effects

Answer 4

Tremors
Restlessness
Numbness of the tongue
Light headedness
Dizziness
Tinnitus
Drowsiness
Convulsions
Loss of consciousness

Question 5

Signs of Cardiovascular system toxicity

Answer 5

Depression of myocardial contractility (compromises blood flow and oxygen getting to cell)
Leading to:
-decrease in BP
-cardiac arrhythmias
-cardiac arrest

Question 6

Factors affecting toxicity

Answer 6

• Age
• Body weight
• General Condition
• Site of injection
• Concentration of drug
• Use of a vasoconstrictor reduces risk of toxicity
• Poor liver function (no amide anaesthetics)

Question 7

Following regional anaesthetic procedures the maximum arterial plasma concentrations of anaesthetic develop within

Answer 7

10 to 25 mins so careful surveillance for toxic effects is necessary during the first 30 mins after injection

Question 8

3 functions of vasoconstrictors

Answer 8

1. Limit system absorption
2. Prolong the duration of the local anaesthetic
3. Decrease bleeding

Question 9

Total adrenaline does should not exceed

Answer 9

500mcg

1g in 200 000ml

Question 10

When is a vasoconstrictor not recommended?

Answer 10

Unstable angina
cardiac arrhythmias
uncontrolled hypertension
when collateral blood flow may be lacking (penis, fingers and toes) eg older patients, diabetic, vascular disease
intravenous regional anasethesia

Question 11

Amide local anaesthetic examples

Answer 11

Lidocaine
Bupivacaine
Priolocaine
Ropivacaine
Levobupivacaine

Question 12

Examples of Ester local anaesthetic (CAP)

Answer 12

Cocaine
Amethocaine
Procaine

Question 13

Amides are metabolised

Answer 13

In the liver

This is important if lots of does are given i.e continuous epidural infusion

Question 14

Ester are hydrolysed

Answer 14

in the plasma by pseudocholinesterase (like scoline). except cocaine which is largely detoxified in the liver