Anaesthetics

Question 1

What are the types of anaesthetics?

Answer 1

General and local

Question 2

What are the subdivisions of general anaesthesia?

Answer 2

Onhalation or volatile

IV

Question 3

WHat is the other less common category of anaesthesia?

Answer 3

Conscious sedation- small amounts of anaesthetic or benzodiazepine to produce a sleepy state

Question 4

WHart are the stages of anaesthesia in surgery?

Answer 4

Predication
Induction
Intraoperative analgesia
Muscle paralysis- intubation
Maintencance
Reversal of muscle paralysis and recovery which includes [pstoperative analgesia
Provision for PNV

Question 5

What are some examples of IV general anaesthetics?

Answer 5

Popofol
Barbiturates
Etomidate
Ketamine

Question 6

What are some examples of volatile general anaesthetics?

Answer 6

N2O
Chloroform
Cycloporpane
Diethyl-ether
Fluroxene
Xenon

Question 7

WHat are the stages in Guedel’s sign?

Answer 7

Stage 1- analgesia and consciousness
Stage 2- unconscious, breathing erratic with delirium–> excitement phase
Stage 3- Surgical anaesthesia with 4 subdivisions
Stage 4- respiratory paralysis and death

Question 8

WHat is weird about the stages of Guedel’s sign?

Answer 8

Stage 2, instead of further relaxing, leads to an excitement phase with stecatic breathing

Question 9

For volatile general anaesthetics, what is used to describe potency?

Answer 9

MAC- Minimum alveolar concentration

Question 10

What is the definition of MAC?

Answer 10

[Alveolar] at 1 atm at which 50% of subjects fail to move to a surgical stimulus (premeditated breathing O2/air)

Question 11

What factors affect induction and recovery?

Answer 11

Partition coefficients

Question 12

What are partition coefficients also known as?

Answer 12

Solubility

Question 13

What are the subdivisions of partial coefficients?

Answer 13

Blood: Gas partition (in the blood)
- low value fast induction and recovery e.g. deslurane
Oil:Gas partition (in fat)
Determines potency and slow accumulation due to partition into fat

Question 14

What affects MAC

Answer 14

Age (High in infants, lower in elderly)
Hyperthermia (increased); Hypothermia (decreased)
Pregnancy (Increased)
Alcoholism (Increased)
Central stimulants (Increased)
Other anaesthetics and sedatives (decreased)
Opioids (decreased)- have a MAC sparing efefct

Question 15

What is the result of the combination of MAC and NO?

Answer 15

MAC sparing, so to get same surgical plane and alagesia, need to use a lot less analgesia if NO is used as well

Question 16

Describe the relationship between potency and GABA interaction?

Answer 16

Anaesthetic agents partition into fat and interact with GABA receptors

Question 17

Why are GABA receptors critical targets for anaesthetics?

Answer 17

It is a major inhibitory transmitter in the CNS that allows Cl- condictance

Question 18

WHat are the results of potentiating GABA activity?

Answer 18

ANxiolysis
Sedation
Anaesthesia

Question 19

What are exceptions to the use of GABA receptors as a target? What receptors do they target instead?

Answer 19

Xe
N2O
Ketamine
They use NMDA receptors

Question 20

What balance do anaesthetics modulate?

Answer 20

In the CNS, the balance between excitation (Glutamate) and inhibition (GABA)

Question 21

WHat are the brain circuitry targets in general anaesthetics?

Answer 21

Reticular formation is depressed (conscious control)
Thalamus (sensory)
Hippocampus is depressed (Memory)
Brainstem depressed (resp and some CVS)
Dorsal horn in spinal cord ( analgesia) and moror neuronal activity (MAC)

Question 22

WHat are the target sites for IV anaesthetics?

Answer 22

Same as inhalation- so GABA receptors and NMDA by the exceptions

Question 23

How do we describe IV anaesthetic potency?

Answer 23

TIVA (Total IV Anaesthesia) is sued to define pk based on algorithm to infuse as a rate to maintain the set point

Question 24

What are IV anaesthetics used in conjunction with and when does the switch occur?

Answer 24

Bolus iV to end pt and then switch to volatile

Question 25

What are examples of uses of local and regional anaesthesia?

Answer 25

``` Dentistry Obstretrics Regional surgery Post io Chronic pain management ```

Question 26

What are some examples of local anaesthetics?

Answer 26

Lidocaine Bupivacaine Ropivacaine Procaine

Question 27

Describe the structure of a basically local anesthetic

Answer 27

Aromatic ring - Link- Amine

Question 28

What are the 2 types of links in the structure of local anaesthetics

Answer 28

Ester link | Amide Link

Question 29

Which of the 2 types of links leafs to showered duration of action?

Answer 29

Ester link because plasma is full of esterases

Question 30

What is the relationship of lipid solubility with potency?

Answer 30

Higher solubility leads to higher potency

Question 31

Describe the mechanism of action of local anaesthetics

Answer 31

Bind to voltage gated Na channels and blocks the Na influx therefore AP is blocked They block small myelinated afferent nerves preferentially and hence lead to nociceptive and symptoms block

Question 32

What does use dependant block mean?

Answer 32

The more active the channel, the greater the local anaesthetic effect

Question 33

Where are upper extremity regional anaesthetics administered?

Answer 33

Interscalene, supraclavicular, infraclavicular, axillary

Question 34

Where are lower extremity regional anaesthetics administered?

Answer 34

Femoral, sciatic, popliteal and sphenous

Question 35

What are the main anaesthetic side effects of general anaesthetics?

Answer 35

``` PONV (opioids) CVS- hypotension POCD (cognitive dysfunction) Chest infection BEWARE ALLERGIES ```