Anaesthetics

Question 1

what are the 2 routes for general anaesthetic ?

Answer 1

Volatile or Inhalation

IV

Question 2

define conscious sedation

Answer 2

use of small amount of anaesthetic or benzodiazapines to produce sleepy like state - maintain verbal contact but feel comfortable

Question 3

what is anaesthesia a combination of ?

Answer 3

Analgesia , Hypnosis, Depression of spinal reflexes muscle relaxation

Question 4

what are stages of Guedel’s signs ?

Answer 4

Stage 1- Analgesia and consciousness
stage 2 - Unconscious, breathing erratic . Maybe delirium = excitement phase
Stage 3- Surgical Anaesthesia, 4 levels going down until breathing weak
Stage 4- Respiratory Paralysis and death

Question 5

what is the order that brain functions go in Volatile anaesthetics?

Answer 5

Memory , Consciousness , Movement and CV response

Question 6

what is potency ?

Answer 6

Docile concentration range at which you see a response

Question 7

how is volatile anaesthetic potency described ?

Answer 7

Minimum Alveolar Concentration

MAC

Question 8

What is MAC?

Answer 8

The Alveolar conc at which 50% of subjects fail to move to surgical stimulus

Question 9

why is MAC used ?

Answer 9

at equilibrium conc of Alveolar = Conc of spinal cord

Question 10

What is MAC-BAR used for ?

Answer 10

potency at which autonomic responses go

Question 11

what factors affect induction and recovery ?

Answer 11

Partition Coefficient - Solubility :
Blood: Gas partition (in blood) lower the quicker

Oil: Gas (In fat)
higher the longer as it accumulates so longer induction

Question 12

What can increase MAC?

Answer 12

Low age 
Hyperthermia 
Pregnancy 
alcholism 
Central stimulus

Question 13

What can decrease MAC?

Answer 13

Elderly
hypothermia
other anasethetics
Opioids

Question 14

what is the effect of MAC by adding NO? What does this lead to ?

Answer 14

decrease in MAC

Allows less side effect profile as lower the MAC the better

Question 15

what does the Meyer-Overton graph tell us ?

Answer 15

the higher the lipid solubility the higher the potentcy

Question 16

what other factor is involved in Potency of Anaesthetics?

Answer 16

GABA receptor interaction

Question 17

what are effects of GABA?

Answer 17

anxiolysis
sedation
Anaestheisa

Question 18

How do GABA receptors work ?

Answer 18

LGIC - Cl- conductance . out to in to hyperpolarise neurones

Question 19

How do Anaesthetics work ?

Answer 19

Potentiate Cl- conductance in the GABA receptor

Question 20

How do Xe, N2O and Ketamine work ?

Answer 20

block NMDA receptor to stop glutamate receptor

Question 21

what is a feature of Reticular formation ?

Answer 21

lots of GABA receptors

Question 22

what does the thalamus do in consciousness ?

Answer 22

Transmits and modifies sensory information

Question 23

What other brain circuitry does Anaesthesia target ?

Answer 23

Hippocampus - Memory
Brainstem - Resp and CVS
Spinal cord - Dorsal horn for analgesia

Question 24

what are the main IV anaesthetics and what is their onset of action ?

Answer 24

Propofol - rapid
Barbiturates - Rapid
Ketamine - Slower

Question 25

what is TIVA?

Answer 25

All 3 IV aneasthetics combined - uses defined PK algorithm to infuse at certain rate with bolus to start

Question 26

how do we measure potency of IV anaesthetics ?

Answer 26

Plasma conc to achieve a specific end point

Question 27

What is done after induction of IV anaesthetics ?

Answer 27

Switch to volatile

Question 28

What are uses of local anaesthetics?

Answer 28

``` dentistry Obs regional surgery post op Chronic pain ```

Question 29

What chemical properties determines time of onset of local anaesthetics ?

Answer 29

Lower pKa = faster onset

Question 30

what determines potentcy of local Anaesthetics ?

Answer 30

Lipid solubility

Question 31

What can affect duration of local anaesthetics ?

Answer 31

Protein binding Ester based = ultra Short acting Amide linked = long acting

Question 32

how does Bupivacaine work ? what can increase block?

Answer 32

Block VG SCs the higher the rate of activity = higher the block block small myelinated afferent nerves = prefencer in nociceptive

Question 33

what is given with locals ? why?

Answer 33

adrenaline to vasoconstrictor | opioids given as well

Question 34

what is difference between Bupivacaine, Lidocaine, Ropivacaine?

Answer 34

see table and interpret

Question 35

where do you give locals?

Answer 35

Upper = interscalene, supraclavicular, infraclavicular, axillary. • Lower extremity (e.g.,) ; femoral, sciatic, popliteal, saphenous.

Question 36

what are General anaesthetic side effects ?

Answer 36

N+V with opioids hypotension Post - op cog dysfunction = delirium chest infection