Lecture 5 - Anaesthetics

Question 1

Define anaesthesia

Answer 1

Lack of feeling, perception and sensation

Question 2

What the non drug methods of anaesthesia?

Answer 2

Cold
concussion
carotid compression
nerve compression
hypnosis
blood letting

Question 3

What are the drug methods of anaesthesia?

Answer 3

Canabis
alcohol
cocaine
opium
hyoscine (Mandrake)

Question 4

What are the methods of administration of anaesthesia?

Answer 4

Inhalation
IV
Intradermal

Question 5

Explain the stages of anaesthesia

Answer 5

Stage 1 - Analgesia
Stage 2 - Excitement
Stage 3 - Anaesthesia
Stage 4 - Medullary paralysis

Question 6

Describe stage 1 of anaesthesia

Answer 6

conscious, drowsy
can still produce tears

Question 7

Describe stage 2 of anaesthesia

Answer 7

Loss of consciousness but delirium
irregular cardio-respiration, apnoea, spasticity, gagging
progressively lose more reflexes

Question 8

Describe stage 3 of anaesthesia

Answer 8

Regular respiration, loss of reflex and muscle tone
used for painful situations

Question 9

Describe stage 4 of anaesthesia

Answer 9

Depression of cardio-respiration and death

Question 10

Name some common inhalation anaesthetics

Answer 10

Desflurane
Halothane
Isoflurane
Enflurane
Sevoflurane
Nitrous oxide

Question 11

Name some common IV anaesthetics

Answer 11

Propofol
Fospropofol
Barbiturates
Benzodiazepines
Opioids
Ketaine
Etomidate

Question 12

Name the mechanisms of action of anaesthetics

Answer 12

Affect different types of ion channels
Enhance activity of inhibitory ion channels
Reduce neuronal excitability through effects on K+ channels
Block excitatory ligand-gated ion channels

Question 13

Name the common local anaesthetics

Answer 13

Topical
infiltration
nerve block
spinal
epidural

• DO NOT LOSE CONSCIOUSNESS

Question 14

Name the common topical anaesthetics

Answer 14

Benzocaine
Lidocaine
Applied directly to the skin or mucous membrane
Commonly given to numb area before an injection
Used to relieve pain or prevent pain from minor burns, irritation, itching

Question 15

Name the common infiltration anaesthetics

Answer 15

Procaine, chloroprocaine, lidocaine, bupivacaine
Produce loss of sensation restricted to a located area in the Boyd
Injected directly into the area of terminal nerve endings
Used for minor surgical and dental procedures

Question 16

Define nerve block and give examples of anaesthesia

Answer 16

Lidocaine, prilocaine, bupivacaine
Injection of local anaesthetic to numb the nerves supplying a particular part of the body such as the hand, arm or leg

Question 17

Define spinal anaesthetics

Answer 17

Single injection with a thin needle that puts the local anaesthetic close to the nerves
Used to numb the lower part of the body
Rapid onset only lasts a few hours
Lidocaine, tetracainene, and bupivacaine

Question 18

Define epidural

Answer 18

Injection into the space outside the sac
fine plastic tube threaded through a needle and the tube is left in the epidural space
slow onset, long duration of action
Lidocaine, bupivacaine, articaine

Question 19

What are the side effects of a epidural?

Answer 19

Heart rhythm problems or seizures, hepatoma in the epidural space, headache

Question 20

What are the side effects of spinal anaesthesia?

Answer 20

Low BP, headache and back pain

Question 21

Describe the MOA of local anaesthetics

Answer 21

1) Block the voltage gated Na+ channels
2) no entry of Na+ ions into the cell
3) no depolarisation
4) no generation of action potential
5) no generation and conduction of impulse to CNS

Question 22

Give examples of approaches in surgical anaesthesia

Answer 22

Pre-op (sedation, anxiolysis, amnesia)
- midazolam and other benzodiazepines
Rapid unconsciousness
- i.v. of rapid short acting agent e.g. thiopental
Maintain unconsciousness
- inhalation agents e.g. nitrous oxide, halothane
Supplement analgesia
- i.v. agents e.g. fentanyl
Paralysis
neuromuscular block e.g. suxamethonium