Intro to analgesia

Question 1

define nociception

Answer 1

Perception of a noxious stimuli

Question 2

define pain

Answer 2

Unpleasant sensory or emotional experience associated with tissue damage
Subjective experience with a strong emotional affective component

Question 3

define chronic pain

Answer 3

> 3 months of pain, despite appropriate treatment

Embedded with emotional, environmental and social factors

Question 4

3 benefits of pain

Answer 4

• Withdrawal from damaging situations
• Protection of damaged tissue while it heals
• Avoidance of similar experiences in the future

Question 5

describe the pain pathway

Answer 5

transduction: Afferent nerve endings (nociceptors) translate a noxious stimulus into a nociceptive impulse
transmission: Process of sending signals along the spinal cord to the brain
modulation: Dampening or amplification of pain signals in periaqueductal Gray area (midbrain) and descending pathways (spinal cord)
perception: The conscious awareness of the experience of pain (nociception). Product of transduction, transmission, modulation, emotion and psychology.

Question 6

describe the pain pathway in terms of the anatomy

Answer 6

site of injury to spinal cord to brainstem to cerebrum

Question 7

role of a beta fibres

Answer 7

touch

Question 8

2 roles of a delta fibres

Answer 8

pain and temperature

Question 9

3 roles of c fibres

Answer 9

pain, temp, touch

Question 10

difference bewteen the 3 types of nerve fibres

Answer 10

a beta- widest, most myelinated, fastest conduction

a delta: myelinated, medium conduction speed

c fibres- non-myelinated, narrowest

Question 11

describe the type of pain felt by the a delta and c fibres

Answer 11

a delta- sharp, well-localised pain

c fibres- dull, diffuse, burning pain

Question 12

how do we classify pain

Answer 12

• Pathophysiology
• Causes
• Duration
• Severity

Question 13

example of nociceptive pain

Answer 13

tissue damage

Question 14

example of neuropathic pain

Answer 14

damage to a central or peripheral nerve

Question 15

describe the type of pain felt for nociceptive pain

Answer 15

ache, sharp, stabbing, throbbing

Question 16

describe neuropathic pain

Answer 16

Numbness, burning, prickling, electric shock, tingling

Question 17

examples of causes of pain

Answer 17

mechanical- stretch, compression, chearing, spasm
chemical- internal e.g. inflammation, ischaemia, external e.g. acids, irritants
thermal e.g. burns

Question 18

mediators that increase pain

Answer 18

Local pain mediators: Kinins e.g. bradykinin, prostaglandins, ATP

Modulators of the pathway: substance P, CGRP, Glutamate

Question 19

mediators that decrease pain

Answer 19

modulators of the pathway- endogenous opioids e.g. beta-endorphin, GABA, serotonin, noradrenaline

Question 20

problems with assessing pain

Answer 20

Subjective/qualitative

Question 21

5 ways to approach pain relief

Answer 21

treat underlying cause
non-pharmacological measures
analgesia
adjuvant treatments 
complementary medicine

Question 22

types of analgesic drugs

Answer 22

Non-opioid (e.g. paracetamol/NSAIDs)

Weak opioids (e.g. codeine, dihydrocodeine, tramadol)

Strong opioids (e.g. morphine, diamorphine, fentanyl)

Adjuvants

Question 23

clinical uses of analgesics

Answer 23

Perioperative pain relief
Medical and surgical emergencies
Palliative care
Management of chronic conditions e.g. rheumatoid arthritis and pain syndromes e.g. lower back pain

Question 24

describe the WHO analgesic ladder

Answer 24

mild pain: non-opioids e.g. paracetamol +/- NSAID

moderate pain: weak opioids e.g. codeine

severe pain: strong opioids e.g. morphine

Question 25

3 examples of opioids

Answer 25

morphine, tramadol, codeine

Question 26

MOA opioids

Answer 26

Mu receptors. G-protein coupled receptor. CNS. Reduce sympathetic response to pain.

Question 27

therapeutic effects of opioids

Answer 27

Analgesia, euphoria, sedation, anti-tussive

Question 28

side effects of opioids

Answer 28

Drowsiness, Respiratory depression, constipation, N+V, hypotension, itching, coma, pupillary constriction
Addiction, tolerance and physical dependence

Question 29

examples of NSAIDs

Answer 29

Ibuprofen, naproxen, diclofenac, aspirin

Question 30

MOA of NSAIDs

Answer 30

Cyclooxygenase inhibition (COX1/COX2) 
inhibit production of prostaglandins in periphery and spinal cord

Question 31

therapeutic effects of NSAIDs

Answer 31

anti-inflammatory, analgesic, antipyretics, anti-thrombotic

Question 32

unwanted side effects of NSAIDs

Answer 32

Gastric ulcers and bleeding, N+V, Kidney injury, rashes, MI and stroke (?via hypertension), bronchospasm

Question 33

examples of adjuvants

Answer 33

antidepressants e.g. amitriptyline, corticosteroids, neuroleptics, local anaesthetics, muscle relaxants

Question 34

5 examples of neuropathic agents

Answer 34

tricyclic antidepressants e.g. amitriptyline
anti-epileptic drugs e.g. gabapentin, pregablin, carbamazepine
ketamine
cannabinoids
botox

Question 35

define hyperalgaesia

Answer 35

increased amount of pain associated with a mild noxious stimulus

Question 36

define allodynia

Answer 36

pain evoked by a non-noxious stimulus

Question 37

NICE guidelines for chronic pain

Answer 37

Patient-centred care
Good communication
Antidepressants can be considered
Acupuncture, psychotherapy and group exercise programmes (NICE 2020)
Does not recommend paracetamol, non-steroidal anti-inflammatory drugs, benzodiazepines, opioids, anti-epileptic drugs, local anaesthetics, ketamine and antipsychotics.