Anaesthetics

Question 1

How does local anesthaesia work

Answer 1

Blocks afferent activity in CNS and PNS

Question 2

2 catagories of local anaesthetics

Answer 2

Amide group and ester group

Question 3

Names of local anaesthetics in the ester group

Answer 3

Bupavicaine, lidocaine, mepivacaine, Etidocaine, prilocaine

Question 4

Local anaesthetics in the ester group

Answer 4

Cocaine, procaine, chloroprocaine, tetracaine

Question 5

Which form of local anaesthetic is better action and which form has better onset

Answer 5

Charged form has better action - cannot exit closed na+ channel

Uncharged form better onset

Question 6

Pharmacokinetics of local anaesthetics

Answer 6

Onset is not dependant on absorption and distribution but offset and systemic toxicity is dependant on absorption and distribution.

Question 7

How are local anaesthetics metabolised

Answer 7

Ester type local anaesthetic is broken down by butrylcholine esterase found in the blood
Amide type local anaesthetic is broken down by CYP p450 in the liver

Question 8

Mechanism of action of local anaesthetic

Answer 8

• Bind to intracellular end of Na+ channel
• reduce depolarisation
• increase time taken for repolarisation

Question 9

Choice of local anaesthesia

Answer 9

Duration of action

• procaine short acting
• lidocaine medium acting
• bupavacaine long acting

Question 10

Anaesthesia effect can be prolonged using?

Onset time can be reduced using ?

Answer 10

Prolong anaesthesia duration

1. Higher dose
2. Add vasoconstrictor

Reduce onset time

1. Add sodium bicarbonate to keep LA neutral
2. Choose local anaesthetic with rapid penetration of the skin

Question 11

Toxicity of local anaesthetic is

Answer 11

Sleepiness, metallic taste, nystagmus, coma, seizure

Question 12

Factors affecting absorbtion and distribution of inhalational anaesthetic are

Answer 12

Solubility in blood
Rate and depth of pulmonary ventilation
Pulmonary blood flow
Arteriovenous concentration gradient
Anaesthetic concentration in inhaled air

Question 13

Metabolism and excretion of general anaesthetic is dependant on

Answer 13

1. Solubility in blood
2. Duration of exposure
3. Hepatic metabolism
4. Pulmonary blood flow and ventilation

Question 14

How do General anaesthetic work

Answer 14

Modify ion flow at GABA channel proteins

Question 15

Actions of general anaesthetic on an organ system

Answer 15

Reduced pulmonary ventilation
Reduced hypercapnic response
Increased cerebral blood flow
Increased apnoeic threshold 
Depression of myocardial function
Reduced mean arterial pressure
Reduced blood flow to liver and kidney

Question 16

Types of intravenous general anaesthesia

Answer 16

Barbiturates, Benzodiazepine, Propofol, Ketamine

Question 17

Barbiturate

Answer 17

• Intravenous general anaesthesia
• Example is thiopental
• Crosses BBB rapidly so used for induction of anaesthesia
• Unlike rest of General anaesthetic barbiturates reduces cerebral blood flow

Question 18

Benzodiazepines

Answer 18

Intravenous general anaesthesia
Slower acting than barbiturates
Requires higher doses to reach sama activity but has a longer off set time
Flumazenil = drug to reduce off set time
Examples of benzodiazepines = Diazepam, Lorezapam, Midozolam

Question 19

Propofol

Answer 19

Intravenous general anaesthesia
As rapid onset as barbiturates but even more rapid offset
Used to induce anaesthesia
Rapidly metabolised in liver and excreted in kidney

Question 20

Ketamine

Answer 20

• metabolised by liver and excreted by kidney

- only intravenous anaesthetic to have both anaesthetic and analgesic effects

Question 21

What is balanced anaesthesia

Answer 21

Balanced anaesthesia is giving a patient both intravenous anaesthesia and inhalational anaesthesia

Question 22

What is monitored anaesthetic care

Answer 22

Monitored anaesthetic care is giving a patient local anaesthesia and intravenous anaesthesia

Patient needs to be monitored continually