Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Anaesthesia > Premedicant drugs > Flashcards

Premedicant drugs Flashcards

1
Q

Premedicant Role

A

Sedation and analgesia

Calm patient

Smooth Induction

Drug Sparing (reducing dose of induction and maintenance agent required)

May help reduce adverse effects of anaesthetic/surgical procedure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Premed considerations

A

Correct dose tailored to animal

Quiet environment

Enough time for drug to take effect

Route of administration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Phenothiazines

A

Provide tranquillisation, with sedation at higher doses

They do not provide any analgesia

Often used synergistically with opiods

Dopamine receptor antagonists - located in CNS

e.g acetylpromazine (ACP)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Acetylpromazine

A

ACP

Phenothiazine

Commonly used pre-medicant usually in combo with opiods

Injectable and tablet formulations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Acetylpromazine Advantages

A

Tranquillise/sedation - increasing dose may lead to
longer duration of sedation rather then deepening

Long duration of action – up to 6hrs

Smooth recovery

Relatively safe for CVS – ‘protective’ effect against
arrhythmias (at standard doses)

Relatively safe for resp system – at standard doses

Anti- emetic (binds same receptors as metoclopramide)

Smooth muscle relaxation – gut, urethra

Mild anti-histamine effect

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Acetylpromazine sensitive/resistant breeds

A

Sensitive
Boxers, Giant breeds

More resistant
Cats, toy breeds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Acetylpromazine side effects

A

Causes vasodilation and will lead to a HYPOTENSION –
care with dehydrated/hypovolaemic patients

May cause HYPOTHERMIA - vasodilation and effects
on hypothalamus

Decreased seizure threshold

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Acetylpromazine Disadvantages

A

Slow to peak effect 30mins after i/m inj

Long duration of action up to 6 hrs depending on
dose given

No analgesia

Unpredictable effects

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Acetylpromazine - Use with care in

A

Hypo-volaemic or dehydrated patients

Large breeds = small doses

epileptics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are alpha-2s?

A

Drugs that bind alpha 2 receptors in the brain and
spinal cord

Block the transmission of nociceptive impulses

Provide sedation and analgesia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Name two alpha-2 agonists

A

Medetomidine e.g.. Domitor

Dexmedetomidine e.g.. Dexdomitor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are alpha 2’s used for?

A

Sedation - +/- with opioid, reasonably predictable
sedation

Premedication - if used as pre-med then can achieve
profound drug sparing effect i.e. lower doses of other
agents required

Anaesthesia – in combo with ketamine, esp cats

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Analgesia with Alpha 2 Agonist

A

They can be used as part of a multi-modal analgesic
approach

If you reverse them then the analgesic effect is lost
too.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Alpha 2 Agonist Advantages

A

Duration and level of sedation dose dependent

Profound drug sparing effect

Provides muscle relaxation

Provides analgesia

Complete reversal possible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Alpha 2 Agonist Disadvantages

A

Profound effects on CVS

Causes vasoconstriction -&raquo_space; pale mm.s

Slows heart rate , may&raquo_space;> reduced CO

Respiratory depression, may cause apnoeic pauses

Reduces liver blood flow

May cause vomiting

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Alpha 2 agonist - patients you should avoid/ use with extreme caution in

A

Patients with cardiovascular disease

Patients with liver disease

Patients where vomiting would be risky

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Alpha 2 agonist - suitable patients

A

Fit & healthy animals

18
Q

Alpha 2 Reversal

A

Complete reversal of effects is possible

Drug; atipamezole eg. Antisedan

Reversal of sedation also = removal of analgesia

19
Q

Opioids

A

They are ANALGESICS

Act by combing with specific receptors in the brain
and spinal cord

Opioid receptors may also develop at sites of
inflammation

They decrease the transmission of noxious stimuli i.e.
pain across these receptors

20
Q

Full opioid agonists

A

Methadone, Morphine, Pethidine, Fentanyl

‘stronger’ produce a maximal effect – bind all
receptors

Can be topped up to increase analgesic effect

For moderate to severe pain

21
Q

Partial opioid agonist

A

e.g. buprenorphine

Cant induce a maximal response, not topped up

Used for mild to moderate pain, premedicant in
combo with phenothiazine or alpha2s

22
Q

Opioid antagonist

A

Work against the analgesic effects of the agonists

I.e. can be used as an antidote

e.g. naloxone

23
Q

How do opioids affect the patient?

A

Provides analgesia and euphoria, sedation

Little effect on respiration at correct dose (caution
with fentanyl iv)

Little effect on CVS – but can cause bradycardia

Drug sparing effect

Pain relief provided may improve ventilation in cases
of thoracic wall injury

24
Q

Opioid disadvantages

A

High doses lead to profound respiratory depression

Contraindicated in animals with increased ICP

Vomiting may occur due to morphine

Constipation

Antitussive effect

Urinary retention if given spinally

25
Q

Antimuscarninics

A

THEIR USE IS NOT ROUTINE AND GENERALLY
RESTRICTED TO PARTICULAR CASES

They antagonise the parasympathetic nervous system

Prevent bradycardia

Decrease salivation

26
Q

Antimuscarninic drugs

A

ATROPINE

GLYCOPYRROLATE

27
Q

Antimuscarninic Advantages

A

Reduces salivation and bronchial secretion

Counteracts bradycardia where there is vagal
stimulation likely eg. ocular or laryngeal surgery

Counteracts bradycardia in patients with high vagal
tone eg. brachycephalics

Helps prevent ‘vagal events’ during reversal of muscle relaxants

28
Q

Antimuscarninic Disdvantages

A

Cause increased HR and metabolic rate

May cause arrhythmias

Thickens bronchial secretions

Gastrointestinal ileus (counteract PNS)

Pupil dilation&raquo_space; visual disturbance

29
Q

When are Antimuscarninics used?

A

Eye surgery

Laryngeal surgery

Brachycephalics

When reversing muscle relaxants

30
Q

NMBA’s

A

Muscle relaxants = neuromuscular blocking agents

31
Q

What do muscle relaxants do?

A

Interrupt transmission of impulses from motor nerve to muscle synapse

Act at nicotinic receptors to block release of acetylcholine

 May be ;
 DEPOLARISING
 NON-DEPOLARISING

32
Q

Depolarising muscle relaxant

A

E.g. Succinylcholine, Suxamethonium

Cause initial surge at NMJ followed by refractory
period where muscle does not respond

Uncommon in veterinary medicine

(rapid onset and short acting, intubation in humans)

33
Q

Non-depolarising muscle relaxant

A

E.g. Vecuronium – lasts 20 mins
Atracurium – lasts 45 mins

They block the receptors at the muscle end plates (
there is no initial surge)

Used in vet practice ( but ?frequency)

Can be reversed

34
Q

Muscle relaxant facts

A

They are given by slow i/v and work within a few
minutes

They last 10-45 mins and may be topped up if longer
duration of relaxation required

They DO NOT AFFECT CONSCIOUSNESS as they
do not cross the blood brain barrier

They paralyse only skeletal muscle

THIS MEANS THE PATIENT IS UNABLE TO MOVE
OR RESPOND TO INADEQUATE ANAESTHESIA.

If you use them you must provide
adequate general anaesthesia and
be able to provide IPPV

35
Q

Muscle relaxant order of function loss

A

Facial/neck muscles >
tail/limb/abdo muscles>
intercostal/diaphragmatic muscles

36
Q

Circuits for IPPV

A

 Bain
 Ayres T-piece
 Circle (ADE )

Less suitable
 Lack
 Magill

37
Q

Muscle relaxant disadvantages

A

Hypothermia due to decreased muscle tone

Difficult to assess anaesthetic depth

Some drugs in this group may cause hypotension

Increased effects if used with aminoglycosides eg.
streptomycin, gentamycin

Increased susceptibility if used alongside halothane,
isoflurane, corticosteroids, some diuretics and
epinephrine

38
Q

Why would we use muscle relaxant

A
  1. Facilitate controlled IPPV – eg. for patients
    undergoing thoracic surgery
  2. During intraocular surgery ( avoids changes in
    eye position)
  3. Where good muscle relaxation is required to
    facilitate the surgery eg. ortho ops, laparotomies
  4. As part of balanced anaesthesia technique for
    high risk patients
39
Q

Reversal of NMBA’s

A

Non-depolarising NMBAs can be reversed

This may make recovery period safer

Drugs used – neostigmine or edrophonium

40
Q

NMBA reversal side effects

A

Reversal may lead to bradycardia & excess
salivation

therefore reversal agents are often given with
atropine or glycopyrrolate (anticholinergic drugs) to
counteract this

Anaesthesia (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions