Use of Premedicants & Sedative drugs Flashcards
What is the difference between sedation and premedication?
Sedation: the use of drugs to allay anxiety and cause some drowsiness or immobility; used to allow minor procedures to be carried out without a general anaesthetic
Premedication: the administration of drugs prior to general anaesthesia
Sufficient sedation requires relatively…
high individual doses
What medications make up a pre-med?
Combo of sedative + analgesic +/- anticholinergics +/- antihistamines, antinausea, gastroprotectants
What is specific when it comes to the level of flatness in premedication?
You do not want the same level of flatness in premed that you get in sedation EXCEPT in dangerous animals
What are the 5 aims of premedication?
- To make the patient easier to handle/ safer/ calmer
- provide analgesia
- decrease the dose of induction agent
- to reduce the dose of maintenance agents
- make the recovery smoother if possible
Sedation is NOT
premedication
GA can be achieved with smaller dosages thus there is…
less need for drugs
Which is more safer? GA or sedation?
GA
What are some reasons for using anaesthetic pre-med?
- To calm & control nervous P’s
- to provide pre-emptive analgesia
- To facilitate smooth induction of anaesthesia & reduce the dose of the induction agent
- To reduce the amount of anaesthetic required to maintain anaesthesia
- To provide smooth recovery from anaesthesia
- to reduce side effects of anaesthetics
- to prevent other anaesthetic or procedural complications
What are the 4 main classes of sedatives?
Phenothiazines
Alpha-2 agonists
Benzodiazepines
Butyrophenones
Which sedative drugs have a wide therapeutic index?
Benzodiazepines
What sedatives have minimal cardiovascular system side effects?
Benzodiazepines
What sedatives have minimal respiratory side effects?
Acepromazine & Butyrophenones
What sedatives are considered reliable?
Alpha 2 agonists
What sedatives have analgesic properties?
alpha 2 agonists
What sedatives have multiple routes of administration?
Benzodiazepines
Alpha 2 agonists
Acepromazine
What sedatives are not painful or irritants?
Benzodiazepines
What sedatives have antagonists available?
Benzodiazepines
Alpha 2 agonists
What sedatives are considered hazardous to humans?
Benzodiazepines
Alpha 2 agonists
What is a caution to remember of alpha-2 agonists?
it can provide what LOOKS like super deep sedation, but these animals can still be completely aware & aroused easily, therefore they can STILL BE DANGEROUS
Why do you not use an alpha 2 with an opioid?
can be dangerous in a dangerous patient
what level of medication is required to provide analgesia from an alpha-2?
high dosages
Some benzos can cause pain on IM injection. How do you know?
Check the bottle/makeup
What occurs in regards to alpha-2 antagonism and analgesia?
When high doses of alpha-2s are used for analgesic effects and then an antagonist is used, it reverses the analgesic effect so you need to ensure other analgesics are on board prior to reversing an alpha 2
what makes alpha-2s harmful to humans
Can lead to severe hypertension
what makes benzos harmful to humans?
can be abused
What is required to achieve the 5 goals of premed?
combo of 2-3 drugs, with 1 always being a sedative
Acepromazine is licensed in what animals?
horses
dogs/cats
What are the main uses of acepromazine in dogs/cats?
sedation & premed of healthy animals
travel sickness
What are the main uses of acepromazine in horses?
sedation & premed of healthy animals
cardioprotection in a premed
post-op myopathy
What is important to remember of acepromazine in horses?
It is contraindicated in very sick patients & colics
What are some cautions of acepromazine?
- Vasodilation (avoid in hypotensive, hypovolaemic, shocky patients)
- avoid in liver dz, hypoalbuminaemia
What dogs require special attention when using acepromazine? Why?
- Giant breeds, boxers, brachycephalics require reduced doses
- Collies (MDR1 mutation) undergo excessive sedation because it increases the BBB permeability so reduce doses or do not use
- avoid in epileptics
What is important to remember when using Acepromazine in stallions?
It can cause priapism & penile prolapse so it should be avoided in breeding stallions
When should you use allometric scaling of drugs?
At all times so use lower doses based on surface area: vol ratio
What are the main uses of alpha-2 agonists in dogs/cats/rabbits?
- Sedation & premed of health (& sick) or vicious animals
- Intra-op CRI to reduce inhalation agent & provide vasoconstriction & analgesia
- Post-op CRI for sedation
What are the main uses of alpha-2 agonists in horses & farm animals?
- only reliable sedation & premed agents
- standing sedation in equines
- intra-op CRI to reduce inhalation agents
- Triple drip to maintain anaesthesia (Eq)
What are the main cautions with alpha-2 agonists?
- reduction in cardiac output
- not for small kittens/puppies < 3 mos old
- avoid in very sick animals
- analgesia requires higher plasma levels than sedation
- alpha-2 agonist-induced bradycardia does not need to be treated unless it leads to hypotension (if so, use anticholinergics)
What is Vatinoxan? What is it used for? In what species?
- Premix w/ medetomidine for DOGS ONLY (DO NOT USE IN CATS)
- Peripheral alpha-2 agonist that does not cross BBB
- only licensed for sedation, NOT premed in EU/ not noted in USA
- may be safer sedation in geriatric and sick dogs
What species are benzodiazepines licensed in?
Dogs/cats
horses
what are the main uses of benzodiazepines in dogs/cats?
- sedation & premed of very young, very old & sick P’s
- co-induction agent w/ propofol, ketamine or alfaxalone
- treatment of seizures
What cautions are there when using benzodiazepines in dogs/cats ?
- not great in young, healthy patients
- can cause paradoxic excitation in healthy animals
What are the main uses of benzodiazepines in horses (with a passport)?
- co-induction agent w/ ketamine to improve muscle relaxation & conditions for endotracheal intubation
- effective sedation of foals
What is the main butyrophenone? What animal is it used in? What is it used for?
Azaperone
Used in pigs/zoo med
For sedation & premed
What is atipamezole? What is it used for?
- Alpha-2 antagonist
- To reverse medetomidine & dexmeditomidine sedation
- Left on board after GA for analgesia effects
When does alpha-2 agonist bradycardia require treatment? How do you treat it?
- if it leads to hypotension
- treat w/ anticholinergics
What is flumazenil?
- reversal of benzodiazepines
What are the main anticholinergic agents?
Atropine, glycopyrrolate
what are the main uses of anticholinergics?
- to treat bradycardia & associated hypotension caused by opioids & other anaesthetics OR vagal stimulation during a procedure
Bradycardia caused by hypothermia does not respond to
anticholinergics
there is a high risk of cardiac arrhythmias if anticholinergics are given with
an alpha-2 without hypotension
What other uses are there for anticholinergics?
- pupil dilation
- to treat some types of heart block
- to reduce saliva production
- during CPR
What cautions are present with anticholinergics?
- pre-existing tachycardia
- glaucoma
- paralytic stasis of the gut causing colic in horses/equines
- do not pre-emptively give w/ alpha-2 agonists
What four questions are essential to ask before choosing sedation over GA for a procedure?
- Will the sedated patient be safe?
- Does the patient (or procedure) require analgesia?
- How long will the effects last?
- Is sedation to be followed by general anaesthesia?
