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18 Cards in this Set
- Front
- Back
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How does anaethesia differ from analgesia? |
Anaethesia is the depression of the CNS leading to unconsciousness and decreased perception of all senses but does not cause analgesia. Analgesia can occur while the patient is still conscious. |
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What drugs are the barbiturates and what is their MOA? |
Thiopentone Phenobarbitone Pentobarbitone Work by binding to CNS Cl- channels causing uncapped hyperpolarisation of the cell making it harder to depoloarise. |
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What is the significance of the distribution pattern of the barbiturates? |
When given IV drug will distribute to most vascular parts of the body (brain, heart, lungs, liver) to have effect. It then rapidly moves to less vascular areas to reach equilibrium in the body meaning it is a short acting general anaesthetic |
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What is the significance of fat deposition in regards to the barbiturates? |
If giving top-up doses while previous dose is still in the fat the top-up dose will be less able to enter the fat (think fat filling up) and so the CNS depressant effects will be intensified |
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What does fat distribution of barbiturates mean in terms of extremely lean or obese animals? |
Lean = reduced fat depots drug unable to redistribute to fat - thus accumulates in muscle leading to prolonged recovery. Obese = Weight being over represented by fat meaning appropriated CNS will be lower than per kg dose. |
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What is the significance of how barbiturates are metabolised in terms of its use? |
Metabolised solely by the liver. Shouldn't be used in liver failure or Caesareans . |
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Why is the acidic nature of barbiturates important? |
Has to be prepared in an alkaline preparation to increase solubility. This means if extravated (missing the vein) will cause damage to the surrounding tissue and sloughing of skin. |
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What is thiopentone used for? |
General anaesthesia |
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What is pentobarbitone used for? |
Primarily as a euthanasia solution Secondarily used as an anticonvulsant when diazepam is ineffective |
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What is phenobarbitone used for? |
Oral an injectible anticonvulsant |
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What is propofol and what is its MOA? |
GABAergic - IV general anaesthetic Increases Cl- influx leading to hyperpolarisation and CNS depression. |
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How does propofol differ to thiopentone in terms of use as a general anaesthetic? |
Pros: Not just metabolised by the liver (caesareans) Not toxic if extravated Less lipophilic so can give top-ups Cons: Greater degree of CVS and respiratory depression |
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What is alfaxalone and what is its MOA? |
GABAergic neurosteroid Increases Cl- ion influx leading to hyperpolarisation of CNS cells. |
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What are the dissociatives? |
Ketamine Tiletamine |
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What are the benefits of ketamine as a general anaesthetic (3)? |
No CVS depression - good for shock Good bioavailiability when given non-IV can be used on a variety of species Cheap |
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What are the disadvantages of ketamine as a general anaesthetic (2)? |
Many reflexes persist so these cannot be used to monitor level of anaesthesia. Less comfortable recovery from anaesthetic so must be coupled with another drug. |
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What is Zoletil? |
A combination of tiletamine and zolazepam |
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What are the benefits of injectable GAs vs inhalant? |
Requires minimal equipment Easy to induce GA Can be given more easily (wild animals) Can gain fine control through use of CRI |
