Premed and sedation drugs Flashcards Preview

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Flashcards in Premed and sedation drugs Deck (18)
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1

Describe the ideal anaesthesia

Achieves the triad

Smooth induction and recovery

Minimal effect on body systems

2

How do we achieve the ideal anaesthesia?

Use a combination of drugs

Reduces the dose required of each individual drug

Therefore likelihood of side effects is reduced

Synergistic effect (1 + 1 > 2)

Anaesthetic protocol

3

What are the anaesthetic protocol stages?

Pre-medication (pre-med)

Induction

Maintenance

(Sedation)

4

What are the aims of pre-medication?

Calm the patient

Reduce the total dose of anaesthetic drugs needed

Relieve pain

To allow a smooth recovery

Reduce autonomic side effects

To reduce other side effects of anaesthesia

5

Give examples of pre-meds used

Phenothiazines

Opioids

Benzodiazepines

α-2 agonists

Anti-muscarinics (anti-cholinergics)

Butyrophenones

(Non-steroidal anti-inflammatories(NSAIDs))

(Ketamine)

6

Describe Phenothiazines

Acepromazine

Generally used in combination with an opioid

Effects: Aggression & seizures

Problems: Bracycephalics and boxers

7

Describe opiods

Bind to specific receptors in CNS to block pain signals
Pure agonist / partial agonist / pure antagonist
Partial agonists tend to bind most strongly to receptor sites
Compete for the same sites if given together (theoretically)

8

Describe Benzodiazepines

Diazepam and midazolam

9

Describe a-2 agonists

Effects:
Profound sedation

Reduces total anaesthetic dose (by 50% or more)

Muscle relaxation

Gives visceral analgesia

Examples:
Medetomidine, xylazine, dexmedetomidine

10

What are some potential problems with a-2 agonists?

Problems:
Profound cardiovascular effects
Vomiting
Diuresis
Hyperglycaemia
Abortion
Unreliable on its own for sedation

11

When may a-2 agonists be used?

alone or with opioids for pre-meds
at higher doses for sedation (e.g. cleaning ears) and if used with an opioid provide enough analgesia for minor wound repair.
The effects are variable, may wake unexpectedly, noise sensitive. Beware !


In combination with an opioid and ketamine for general anaesthesia.
May be given iv or im. The sc route is less reliable. Can also be absorbed across mms so take care when handling!
Medetomidine and dexmedetomidine can be reversed with Atipamezole

12

Describe Anti-muscarinics

Effects:
Block parasympathetic system
Prevent bradycardia
Reduce respiratory secretions
Reduce salivation
Example:
Atropine
Glycopyrrolate

13

What are some potential problems with Anti-muscarinics?

May cause tachycardia
Pupillary dilation
Cause dry mouth

Boxers and other brachycephalic breeds?
Enucleation involving traction on the eyeball?
Laryngeal surgery?

14

Describe Butyrophenones

Only one in veterinary use is Fluanisone
in Hypnorm, licensed for rabbits, in combination with the opioid Fentanyl
“neuroleptanalgesia”
tranquilliser (neuroleptic) combined with a potent analgesic (opioid) to give heavy sedation or anaesthesia.

15

Describe NSAID's

Analgesic
Often considered part of a pre-med
Sometimes contentious issue between vets…
Disadvantage
Reduces renal blood flow
Examples
Carprofen (Rimadyl)
Ketoprofen (Ketofen)
Meloxicam (Metacam)

16

Compare sedation to pre-med

Often the same drugs used
Doses may be higher for sedation
The term sedation tends to be used when not progressed to full anaesthesia

17

How do you calculate a dog if given in ml/kg?

volume to be given (ml) = dose (ml/kg) x weight (kg)

18

How do you calculate a dog if given in mg/kg?

volume to be given (ml) = dose (mg/kg) x weight (kg)
/ strength of solution (mg/ml)