Lecture 14 - Anaesthetics

Question 1

What is the mechanism of anaesthetic related to?

Answer 1

Disruption of lipid membrane of cells

Question 2

What is the potentiation of GABA A receptor?

Answer 2

Inhibitory receptor for the inhibitory amino acid transmitter GABA amino butyric acid

Question 3

What are examples of certain anaesthetics?

Answer 3

Isoflurane

Propofol

Question 4

What is GABA A receptor?

Answer 4

Chloride Ion channel

Question 5

What examples of potentiation?

Answer 5

GABA A

Glycine

Question 6

What are examples of inhibition?

Answer 6

NAChR
5HT3
NMDA

Question 7

What is NMDA?

Answer 7

Receptor for excitatory amino acid neurotransmitters

Acted upon by Glutamate

Question 8

What is the result of receptor mediated mechanism?

Answer 8

Dampening down/quester effect on the cell

Question 9

What is the effect of nervous system?

Answer 9

Enhancement of tonic inhibition

Question 10

What is anaesthesia?

Answer 10

Constellations of effects which incorporate but not limited to Analgesia

Question 11

What happens when depth of Analgesia increases?

Answer 11

Pass through stages of unconsciousness and loss of reflexes

Question 12

What are various parts of the brain affected by?

Answer 12

Anaesthetic compounds

Question 13

What do many anaesthetics lead to?

Answer 13

Some form of Amnesia

Interference with the hippocampal function

Question 14

What is the hippocampal function closely tied up with?

Answer 14

Processes of short-term memory

Question 15

What is the stage I of anaesthesia?

Answer 15

Analgesia

Question 16

What is the effects produced by stage 1 of anaesthesia?

Answer 16

Analgesia without amnesia or loss of touch sensation

Consciousness retained

Question 17

What is stage II of anaesthesia?

Answer 17

Excitation

Question 18

What are the effects produced of stage II of anaesthesia?

Answer 18

Excitation and delirium with struggling
Respiration rapid and irregular
Frequent eye movements with increased pupil diameter
Amnesia

Question 19

What is stage III of anaesthesia?

Answer 19

Surgical anaesthesia

Question 20

What are the effects produced of stage III of anaesthesia?

Answer 20

Loss of consciousness
Plane I: decrease in eye movements and some pupillary constriction
Plane II: loss of corneal reflexes
Plane III and IV: increasing loss of pharyngeal reflex
Progressive decrease in thoracic breathing and general muscle tone

Question 21

What is IV of anaesthesia

Answer 21

Medullary depression

Question 22

What are the effects produced of stage IV of anaesthesia?

Answer 22

Loss of spontaneous respiration and progressive depression of cardiovascular reflexes

Question 23

What is intravenous anaesthetics used for?

Answer 23

Induction

Rapidly induce anaesthesia than inhalational/gaseous anaesthetics

Question 24

What is Thiopental?

Answer 24

Capable of quickly inducing anaesthesia
It’s use is widespread
It is a barbiturate
Largely replaced by Propofol

Question 25

What is ketamine?

Answer 25

Dissociative anaesthesia Patient retains some degree of consciousness but dissociated from their environment Causes perceptual disturbance

Question 26

What compound can maintain anaesthesia?

Answer 26

Propofol | With slow infusion

Question 27

What compound is used during endoscopy procedure?

Answer 27

Midazolam

Question 28

What are some examples of drugs of intravenous anaesthetics?

Answer 28

``` Propofol Thiopental Etomidate Ketamine Midazolam ```

Question 29

What is the speed of induction and recovery of Propofol?

Answer 29

Fast onset | Very fast recovery

Question 30

What is the main unwanted effect of Propofol?

Answer 30

Cardiovascular and respiratory depression

Question 31

Propofol

Answer 31

Rapidly metabolised Continuous infusion Causes pain at injection site

Question 32

What is the speed of induction and recovery of Thiopental?

Answer 32

Fast Accumulation occurs Slow recovery ‘Hangover’

Question 33

What is the main unwanted effects of Thiopental?

Answer 33

Cardiovascular and respiratory depression

Question 34

Thiopental

Answer 34

Largely replaced by Propofol Causes pain at injection site Risk of precipitating porphyria I’m susceptible patients

Question 35

What is the speed of induction and recovery of Etomidate?

Answer 35

Fast onset | Fairly fast recovery

Question 36

What is the main unwanted effects of Etomidate?

Answer 36

Excitatory effects during induction and recovery | Adrenocortical suppression

Question 37

Etomidate

Answer 37

Less cardiovascular and respiratory depression than with Thiopental Causes pain at injection site

Question 38

What is the speed of induction and recovery of ketamine?

Answer 38

Slow onset | After effects common during recovery

Question 39

What is the main unwanted effects of ketamine?

Answer 39

Psychotomimetic effects following recovery Postoperative nausea, vomiting and salivation Raised intracranial pressure

Question 40

Ketamine

Answer 40

Produces good Analgesia and amnesia

Question 41

What is the speed of induction and recovery of Midazolam?

Answer 41

Slower than other agents

Question 42

Midazolam

Answer 42

Little respiratory or cardiovascular depression

Question 43

Inhalational anaesthetics

Answer 43

Ranges from nitrous oxide to Ether

Question 44

What is the most commonly used compound for inhalational anaesthetics?

Answer 44

Isoflurane

Question 45

How is certain concentration of inhalational anaesthetics within bloodstream achieved?

Answer 45

Low blood: gas coefficient (relatively low solubility in blood)

Question 46

What does the oil:gas coefficient dictate?

Answer 46

How easily an anaesthetic once in body passes to blood into fat and other tissues

Question 47

What are the factors affecting the rate of induction and recovery?

Answer 47

Solubility in blood | Solubility in fat

Question 48

Why is induction/recovery quicker with low blood solubility?

Answer 48

Equilibrium is reached quicker

Question 49

What does oil:gas coefficient determine?

Answer 49

Potency

Question 50

What happens when there is a small partition coefficient?

Answer 50

Small proportion of anaesthetic passing into fat/lean tissue

Question 51

What are the properties of the ideal anaesthetics?

Answer 51

``` Inherently stable Non-flammable Non-explosive Potent Low blood solubility (rapid induction) Rapid emergence from anaesthesia Rapid adjustment of depth of anaesthesia Non-irritant to the airways Non-toxic Lack of sensitisation of the heart to catecholamines Analgesic Easily reversible Minimal interaction with other drugs Inexpensive ```

Question 52

What do local anaesthetic do?

Answer 52

Stop the local propagation of action potentials along the neuron

Question 53

What are local anaesthetics?

Answer 53

They are all weak bases

Question 54

Why is it crucial to have some unionised form of local anaesthetics?

Answer 54

No penetration through axonal membrane

Question 55

How do anaesthetics become ionised?

Answer 55

Significant inflammation that will lower the local PH

Question 56

What happens at normal physiological PH?

Answer 56

Anaesthetics can cross axonal membrane

Question 57

What does the ionised form block?

Answer 57

Sodium channel

Question 58

What happens if the sodium channel gate remain closed?

Answer 58

The local anaesthesia can’t get in

Question 59

What is the use-dependent pathway?

Answer 59

Local anaesthetics is reversing axonal membrane and getting inside and existing in equilibrium with ionised form which can block the sodium channel

Question 60

What is inhibited when a local anaesthetic is administered?

Answer 60

All fibres