Anaesthetic drugs Flashcards
What action does atropine have on opioids?
Prevents opioid mediated bradycardia
What is normally done to the dose when pre medding giant breed dogs?
-reduced: they have a lower metabolic rate
How does obesity affect pre med dose?
-Should reduce it as pre med dose is based on lean bodyweight so an overweight dog would still have the liver capacity of normal weight dog.
Describe alpha 2 agonists
- Sedation + Analgesia
- Pre/post synapse effect: slows transmisssion of impulses
- Profound sedation
- Synergism between BZDs and Opioids = Reduce dose
- Give slowly- vein to brain slowed
- Small ruminants sensitive
- Atipamazole reverser (IM= smoother recovery)
- Biphasic effect on bp-intial increase then decrease
- Decreases HR
- Minimal resp effect
- Increases urine
- Transient hyperglycaemia
- Vasocontriction- reduced peripheral heat loss
Give examples of alpha 2 agonists
- Medetomidin/ dexmedetomidine: dogs/ cats
- Xylazine: horses, unselective so active at a1 too
- Detomidine/romfidine: horses
- Domosedan: oral gel used in horses)
Describe Phenothiazines
- Sedative + anxiolysis
- Duration of action incrase with larger doses
- Combo with opioid increases reliability/ quality of sedation (neuroleptanalgesia)
- Not analgesic
- Cat/ dog version. Horse one not yet licensed
- Long lasting/ irreversible!!
- Giant breeds more sensitive
- Dopamine antagonist
- NOT for breeding stallions: paralysis of penis muscle/ paraphimosis
- Alpha 1 antagonist: peripheral vasodilation, decreases BP
- Anti arrhythmic
- Decreased body temp
- CONTRAINDICATED in hypotensive/ shock/ CVS issue animals
What can ACP cause in boxers?
ACP induced orthostatic hypotension
Describe benzodiazepines
- No sedative effect in dogs/ cats
- Causes excitation (loss of inhibitory behaviour)
- Combine with opioids in dogs (reliable/ stable sedation)
- Combo with ketamine in cats
- Not in C-secs
- Minor CV effects so good for sicker patients
- Manages convulsions
- GABA receptor effects chloride ion channels
- Big therapeutic window
List common drug combinations used as pre med agents
- Alpha + opioid
- Alpha + ket
- Alpha + BZD
- Alpha + opioid + BZD
- ACP + opioid
- BZD +opioid
- BZD + Ketamine
Give appropriate drug combinations for different ASA categories (for dogs)
1: A2
2: A2+ opioid (if CV problem use ACP)
3: ACP + opioid OR if CV compromsied BZD +opioid
4: BZD + opioid
5: low dose opioid
Give appropriate drug combinations for different ASA categories (for cats)
1: dexmedotomidine (deep sedation in cats)
2: ACP+opioid (dexdom if not CV/ liver diseased)
3: ACP+Opioid
4: BZD+ket
5: low dose opioid
Describe using propofol
- Alkyl phenol (if plus then contain preservative)
- Rapid onset/ short duration
- Large Vd
- Smooth/ rapid emergence
- Good to use in liver diseased animals
- Resp depression must give slowly
- TIVA/ top ups ok
- Anticonvulsant
- NO analgesia
- Deecrease intracranial pressure
- Give to effect
- Dose is smaller in older animals
- Heinz body anaemia?
Describe using thiobarbituates (Thiopentone sodium)
- Very alkaline
- High lipid soluble
- Hard to source (no license in dogs/ cats/ horses)
- Used as top up in horses as its quicker than ketamine
- Induces rapid unconsciousness (crosses BBB quickly)
- Resp depression
- VERY short acting
- CV depression/ peripheral vasodilation
- Displaced by other drugs
- Unionised can penetrate cells
- CAN cross placenta
- Give to effect
What type of drug is alfaxan?
Steroid anaesthetic
Describe alfaxan (alfaxolone)
- Cats/ dogs/ rabbits licensed
- Neuroactive
- Activates GABA
- Potent so small doses
- Short half life, quick elimination
- Repeat boluses/ TIVA ]-Premed needed for smooth recovery
- Apnoea may be seen
- GOOD CV stability and muscle relaxation
