Pain Flashcards

1
Q

Define pain.

A

An unpleasant sensory and emotional experience associated with, or resembling that associated with, actual and potential tissue damage.

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2
Q

Define nociception.

A

The neural process of encoding noxious stimuli.

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3
Q

Define nociceptive pain.

A

Pain that arises from actual or threatened damage to non-neural tissue and is due to the activation of nociceptors.

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4
Q

Define neuropathic pain.

A

Pain caused by a lesion or disease of the somatosensory nervous system.

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5
Q

Define hyperalgesia and give an example.

A

Increased pain from a stimulus that normally provokes pain.

E.g. palpation normally vs. when bruised

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6
Q

Define allodynia and give an example.

A

Pain due to stimulus that does not normally provoke pain.

E.g. no longer being able to tolerate being stroked.

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7
Q

What is the difference between acute and chronic pain?

A

Acute pain lasts a short period of time (minutes/hours to weeks)

Chronic pain lasts longer than a few weeks

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8
Q

What is the biological function of acute pain?

A

Protective up to a point - e.g. stop an animal walking on a broken leg.

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9
Q

What is the importance of quantification of pain?

A

Allows categorisation of pain / assessment of treatment efficacy / judgement-making about quality of life.

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10
Q

What are the physiological signs associated with pain?

A

Increased HR, BP and temp.
Altered respiration
Stress hormones
EEG activity

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11
Q

What signs of pain do both cats and dogs exhibit?

A
Hunched appearance
Pain face
Lack of grooming
Inappetence
Condition-specific signs
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12
Q

What signs of pain do cats exhibit?

A
Absence of normal behaviour repertoire
Hide away at back of cage
Unwilling to relax
Fear-aggression
Resent human contact
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13
Q

What signs of pain do dogs exhibit?

A

Positive behavioural signs rather than reduced repertoire
More likely to seek attention
Submissive
May be more likely to vocalise

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14
Q

What pain signs might a rabbit exhibit?

A
Immobility
Depression
Not grooming
Eyes half-closed/shut
Bruxism
Abnormal body position
Change in temperament
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15
Q

What pain signs might a horse exhibit?

A
Low head carriage
Vocalisation
Agitation
Tail swishing
Lameness/limb lifting
Pain face
Bruxism
Muscle fasciculations
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16
Q

List the 7 signs that indicate chronic pain in all species.

A
Changes in normal behaviour
Unkempt coat
Loss of body condition/weight loss
Slowing down/sleeping more
OR more fidgety/restless
Signs associated with reluctance to move
Difficulty in accessing higher places
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17
Q

What four ways can you score acute pain?

A

Numerical rating scale
Visual analogue scale
Simple descriptive scale
Dynamic interactive visual analogue scale

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18
Q

What is the issue associated with acute pain score scales?

A

Inter-observer variation.

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19
Q

Explain the canine composite pain score.

A

Score out of 20 (dog can’t stand) or 24 (if dog can stand)

Intervention level is 5/20 or 6/24

20
Q

Explain the feline composite pain score.

A

Maximum score is 20

Intervention level is 5/20

21
Q

How do we score chronic pain and why?

A

Health-related quality of life scoring - shows pattern of pain and wider effects, brings in additional items such as appetite/sleep, includes pain over a period of time (e.g. 7 days).

22
Q

Why is assessment of health-related quality of life important?

A

Aids decision-making about analgesia and euthanasia

Improved patient wellbeing through holistic care

Improves continuity of treatment

Helps build and maintain vet-owner relationships

23
Q

Describe preventative analgesia.

A

Admin before, during and after procedure

Causes a reduction in intensity/duration of acute pain, and a reduction in chronic pain

24
Q

Describe multimodal analgesia.

A

Use of different classes of analgesic agents

Leads to more effective analgesia with lower doses of agents

25
Q

What is the key pharmacology of opioids in cats/dogs/horses?

A

Delta/kappa/mu receptor agonists

Full / partial agonists, mixed agonist-antagonists, antagonists

26
Q

What opioids are used in cats, dogs, horses and rabbits?

A
Fentanyl
Methadone
Pethidine
(Morphine)
Buprenorphine
Butorphanol
27
Q

What are the side effects of opioid use?

A
Respiratory depression
Sedation (dogs)
Excitation
Bradycardia
Nausea/vomiting
Decreased GI motility
Various effects on urinary system
28
Q

What is the key pharmacology of NSAIDs?

A

Inhibit prostaglandin production either through inhibition of COX or LOX.

29
Q

What are the side effects of NSAID use?

A

GI ulceration
Renal ischaemia
Hepatopathy
CNS dullness

30
Q

What is the key pharmacology of local anaesthetics?

A

Enter nerve fibre, block Na channel, blocks nerve conduction
“Membrane stabilising effect”
Less effective in inflamed tissue due to change in pH

31
Q

What are the two types of local anaesthetics and give examples?

A

Ester (no ‘i’ before ‘caine’) - e.g. procaine

Amide (‘i’ before ‘caine’) - e.g. lidocaine/bupivacaine

32
Q

What are the side effects of local anaesthetic use?

A
CNS toxicity (occurs at lower doses than CVS)
CVS toxicity
Do not exceed total safe dose
33
Q

When/how are local anaesthetics used?

A

Provide anaesthesia in standing, conscious patient
Postop pain relief
Desensitisation for procedures
Lameness investigation in horses

34
Q

How can paracetamol be used in animal patients?

A

Dogs - when NSAIDs are contraindicated
Horses - adjunctive analgesic in painful cases (laminitis)/when NSAIDs are contraindicated

TOXIC to cats!!

35
Q

State some key facts about gabapentin.

A

May have a role in management of neuropathic type pain conditions
Sedation is major side effect
Reduce dose over 1-2 weeks (not abruptly) before stopping therapy

36
Q

State some key facts about amantadine.

A

Not an analgesic but a hyperalgesic
Excreted via the kidneys
May be helpful in chronic pain states to reverse/obtund central sensitisation
Best used as an adjunctive agent
May take 3-4 weeks to see clinical benefit of therapy

37
Q

What 2 other drugs may rise in popularity for treatment of chronic pain?

A

Pregabalin

Amitriptyline

38
Q

Define epidural.

A

Epidural = anaesthetics injected into epidural space (via a catheter)

39
Q

Define spinal.

A

Spinal = anaesthetic is injected directly into cerebrospinal fluid (via a much smaller needle)

40
Q

What affects potency of local anaesthetics (LAs) and how does this affect toxicity?

A

pKa and lipid solubility affect potency

LA toxicity increases as potency increases

41
Q

What factors affect duration of action of LAs?

A

Lipid solubility (ease of penetration and amount of drug reaching Na channel)
Strength of binding to channel
Speed of removal
Metabolism of LA

42
Q

How are the two different types of LAs metabolised?

A

Esters = hydrolysis by plasma esterases / PABA formed (can cause allergic reactions)

Amides = hydrolysis by cytochrome P450 enzymes in liver

43
Q

Define baricity and name the molecule usually added to overcome this.

A

Baricity = weight of one substance compared with weight of equal volume of another (for spinal anaesthesia it is CSF)

Glucose is added to the LA solutions to make them heavier

44
Q

Explain the addition of vasoconstrictors to LA solutions.

A

Adrenaline added to reduce speed of systemic absorption/prolong duration of action
Reduces risk of toxicity
Reduces bleed ing at injection site

45
Q

Describe the CNS toxicity of LAs.

A

Minor behavioural changes
Muscle twitching and tremors
Tonic-clonic convulsions
CNS/respiratory depression and death

46
Q

Describe the CVS toxicity of LAs.

A
Hypotension
Dysrhythmias (drug remains bound to Na channels during diastole)
47
Q

How can we prevent toxicity of LAs?

A

Do not exceed safe maximum dose
If greater volume needed dilute with NaCl 0.9%
Use appropriately sized syringes/needles
Aspirate before injection to confirm not in blood vessel