Analgesia and pain management Flashcards
Define pain
An unpleasant sensory and emotional experience associated with actual or potential tissue damage
3 types of pain
Nociceptive
Inflammatory
Neuropathic
What fibres are involved in upper pain transmission
A fibres and C fibres
What happens to C fibre during inflammation
It becomes more sensitised
What chemical mediators are released during inflammation
Potassium Hydrogen Bradykinin Histamine 5-HT NO
What is activated in peripheral mechanism
Activation of arachidonic acid pathways producing leukotrienes and prstanoids
Activation of peripheral nociception
What is neuropathic pain
Lesion somewhere in the nervous system producing neuropathic pain (eg diabetes)
What 5 mechanisms may underly peripheral neuropathic pain
- Alterations in ion channel expression
- Ectopic and spontaneous discharge
- Ephatic conduction
- Collateral sprouting at primary afferents
What is ephatic conduction
Conduction without a NT
What is central hypersensitivity
Brain becomes extra sensitive to pain
Hyperallegeisia
What happens to the inhibitory pathways in central sensitisation
They fail
GABA, opiod and monoaminergic
What is acute pain
Nociceptive
What neurones are involved in acute pain
Primary afferent neurones
How long does acute pain last more
<12 weeks
How is chronic pain characterised
- No apparent ongoing tissue damage
- Response to treatment less effective
- Significant psychological component
What are the steps of the WHO pain ladder
step 1- non opiod
step 2- weak opiod
step 3- strong opiod
Does paracetemol have any peripheral action?
No
Is paracetemol opiate sparing? What does this mean
Yes
By carrying opiates can spare some of the side effects without compromising pain killing effects too much
What is the NNT of paracetemol
4.6
Major side effect of paracetemol
Liver damage in overdose
What is diclofenac an example of
An NSAID
How does diclofenac work
Inhibits prostaglandin via COX 1 and COX 2
What are the side effects of diclofenac
GI, renal, CVS and bleeding effects
What is the NNT of diclofenac
2.3
What kind of drug is tramadol
Very weak opiod
Via which pathways does tramadol act
Monoaminergic pathways
What is the site of action of tramadol
CNS, LC, DR
What are the side effects of tramadol
Nausea and vomiting
Dizziness
Sweating
What is the NNT of tramadol
4.8
Do opiods work peripherally or centrally
Centrally
What are the 3 main receptor types are where are they found
mu, kappa, gamma
found mainly centrally but also peripherally (gut)
Do opiods agonise or antagonise the receptor
Antagonise
Side effect of morphine
Constipation
Nausea
Pruitiis
Drowsiness
What receptor does morphine antagonise
mu opiod receptor
Name 4 drug types whose primary action isn’t pain killing but are used as pain killers
Anti-neuropathic agents
Anti convulsants
Anti depressants
Topical creams
What SNRI/ SSRI is commonly used for diabetic neuropathy
Duoloxetine
Typical tricyclic to use? Higher or lower dose than antidepressant dose?
Amitriptyline
Lower
