Anaesthetics

1. List the injectable and inhalational anaesthetic agents used in UK veterinary practice 2. Compare and contrast the advantages and disadvantages of injectable and inhalational anaesthetic agents 3. Describe the mechanism of action, administration and main effects of the injectable anaesthetic agents 4. Describe the mechanism of action, administration and main effects of the inhalational anaesthetic agents

List inhalational anaesthetic agents

Xe

Chloroform

Ether

Halothane

Isoflurone

Sevoflurane

List injectable anaesthetic agents

Propofil

Alfaxalone

Ketamine

Thiopentone

Compare injectable vs inhalational agents

Injectables :

• simple equipment

• can be given with O2

• little risk to personell

  • harder to eliminate from body

  • hard to adjust dose

Inhalational :

• easy to remove

• easy to adjust

• delivered in O2

  • specialised equipemnt needed

  • greenhouose gasses

  • envirnmental contamination - risk

What drugs Inhibit exitatory NTs such as glutamate?

ketamine, nitrous oxide, Xe

What drugs exite the inhibition NTs sucH as GABA and glycine

Propofil, alfaxalone, thiopentone

Describe the MOA of Propfol (alfaxalon, thiopentone have same)

GABA agonist, bind to GABA receptor and make it open

What are the beneficial effects of propfol, thiopentone, alfaxalone

sedation, amnesia, unconsiousness, muscle relaxation, anti-seizure

What are the adverse effects of propofil, thiopentone, alfaxalone

vasodilation

• drops bp

respiratory depression

What are some side effects specific to propofol

preservatives may prolong recovery and cause seizures

can cause anaemia in cats with repeated use

What are some side effects specific to alfaxalone

exitatble / twitchy recoveries

What are some side effects specific to thiopentone

myocardial depression, arhythmia, resp depress, long recoveries

What is the MOA of ketamine?

antagonises NMDA receptor, prevents glutamate from causing exitation, causes dissociative anaesthetic state.

benefits of ketamine?

good anaesthetic and analgesic

side effects of ketamine

negative inotrope

symapthomimesis (increased HR, vaso cons)

hypertonicity in muscle

CN reflexes present

What is meant by MAC?

measurement, partial pressure of inhalant compared to atmospheric pressure.

minimun concentration of inhalant that

• prevents purposeful movement oin response to a noxious stimulus

• in 50% of unpremediacated patients

• at 1 atmospheric pressure

What is the MAC of isoflurane

1.3%w

What is the MAC of sevoflurane

2.3%

What factors affect MAC?

temperature

physiological state

hypoxaemia

hypercapnia

bp

age

species

mac sparing drugs

What are the side ffects of inhalants?

• bp reduction

• vasodilation

• respiration

• pungent to inhale

• greenhouse gasses