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