The flashcards below were created by user
Anonymous
on FreezingBlue Flashcards.
-
List some of the targets of the general anaesthetics
- GABA receptor
- NMDA receptor
- Two-pore domain K+ channels
- Glycine recptors
- Na+ channels
-
Are these receptors normally inhibitory/excitatory? a) GABA b) NMDA
- a) inhibitory
- b) excitatory
-
What is the overall mechanism of the general anaesthetics?
They decrease neurotransmission in the CNS which leads to loss of consciousness
-
Define anaesthesia
Anaesthesia = loss of feeling
-
What is the difference between general anaesthetic and local anaesthetic?
General anaesthetic = loss of feeling in the whole bodyLocal anaesthetic = loss of feeling to the part of the body where the anaesthetic is applied
-
Define general anaesthesia
General anaesthesia is a state of reversible unconsciousness with reduced sensitivity and response to stimuli
-
What is the mechanism of action of local anaesthetics? (revision of module 7)
They block sodium channels which reduces AP firing in nerves
-
List some reasons why we anaesthetise animals
- To perform painful surgical or diagnostic procedures
- To minimise patient suffering
- To reduce risk to the vet and other individuals
- To facilitate the procedure by immobilising the patient
-
Anaesthesia is usually given as a combination of different drugs, what are these?
Premedicant drugs, induction drugs and maintenance drugs
-
What type of drug will make a better general anaesthetic: water soluble or lipid soluble?
Lipid soluble drugs - the more lipid soluble the drug the faster it crosses the cell membrane and the faster it reaches the CNS to have its action
-
What type of anaesthesia is typically used for induction/maintenance? Intravenous or inhalational?
- Induction - intravenous
- Maintenance - inhalational
-
What are the advantages and disadvantages of using IV anaesthetics for induction?
- Advantages - rapid smooth induction, rapid protection of the airway, no environmental pollution
- Disadvantages - IV access required
-
What does TIVA stand for?
Total intravenous anaesthesia - anaesthesia maintained by intermittent boluses or continuous infusion of an IV agent
-
List some reasons for using TIVA
- Easy to administer
- Pharmacokinetics are known/predictable
- Inhalational anaesthetics may be unsuitable in some individuals
- Avoids risk to people administering drugs i.e. no environmental pollution
-
What are the advantages/disadvantages of using inhalational anaesthetics for maintenance?
- Advantages - delivery/elimination depends on ventilation, rapid adjustment of anaesthetic depth
- Disadvantages - equipment required (endotracheal tube, carrier gas, vaporiser, breathing system, etc), environmental pollution
-
What are the advantages/disadvantages of using inhalational anaesthetics for induction?
- Advantages - IV access can be secured after induction
- Disadvantages - environmental pollution, takes longer and delay in securing airway may be a problem in some cases
-
What is the blood:gas partition coefficient?
The b:g partition coefficient compares whether the drug would rather be dissolved in the blood or alveolar air
-
What would a low b:g/high b:g partition coefficient give with regards to induction?
- Low - gives a rapid induction and recovery
- High - gives a slow induction and recovery
-
Would a high or low oil:gas coefficient give a drug a high potency?
A high o:g coefficient
-
What brain regions do the general anaesthetics inhibit?
The reticular formation and hippocampus
-
What is the minimum alveolar concentration?
The MAC describes the minimum alveolar concentration at which 50% of patients will not respond to a particular stimulus
-
The MAC compares the ... of different inhalational anaesthetics?
potency
-
The higher/lower the MAC the more potent the agent?
lower
-
Give examples of halogenated inhalational agents
Halothane, isoflurane, desflurane, and sevoflurane
-
What is the most widely used inhalation agent?
Isoflurane
-
Why may isoflurane not be ideal for induction?
It has a pungent odour, meaning animals are likely to hold their breath
-
What are some of the advantages of isoflurane?
Minimal metabolism, cardiac output better maintained, less arrythmogenic
-
What animal is sevoflurane licensed in?
Dogs
-
True or false: sevoflurane has a pungent odour?
False: it has a pleasant odour and minimal airway irritation so suitable for induction
-
Why can nitrous oxide not be used as an anaesthetic agent on its own?
As the MAC is >100% which means you cannot get full anaesthesia with N2O on its own
-
List some IV anaesthetic agents
Propofol, Alfaxalone, Ketamine, Barbituates eg thiopentone, pentobarbitone, imidazole derivatives eg etomidate
-
Is propofol a liquid or oil at room temperature?
Oil (emulsion)
-
What receptor does propofol act on?
Propofol enhances GABA transmission
-
Is propofol high/low plasma protein bound?
High plasma protein bound
-
Does propofol have a high/low volume of distribution?
High
-
What type of metabolism does propofol undergo?
Phase II metabolism in the liver prior to excretion in the urine
-
Is propofol suitable for TIVA?
Yes
-
Under what condition may the pharmacological effects of propofol be prolonged?
Hypoproteinaemia
-
What species may show prolonged propofol effects?
Cats
-
How is alfaxolone presented?
It is insoluble in water so is presented in a cyclodextrin vehicle
-
What receptor type does alfaxalone act on?
It enhances the inhibitory effect of GABA
-
Does alfaxalone have a high/low therapeutic index?
High
-
Is alfaxalone suitable for TIVA?
Yes
-
What receptor does ketamine act on?
It inhibits NMDA receptors (interrupts the association between the limbic and cortical regions)
-
True or false: ketamine causes sensory loss as well as analgesia?
True
-
What effect does ketamine have on muscles?
It causes enhanced muscle tone
-
Describe what an animal anaesthetised with ketamine will present like
- Eyes open +/- slow nystagmus
- Active reflexes eg laryngeal and pharyngeal reflexes
- Less profound CVS and respiratory depression
|
|