Management of chronic pain Flashcards
What is pain?
An unpleasant sensory and emotional experience, associated with actual tissue damage, or described in terms of such damage
What is acute pain?
Usually obvious tissue damage, protective function, increased nervous system activity, pain resolves upon healing
What is chronic pain?
Pain beyond expected period of healing, pain no longer serves a useful purpose, changes in pain signalling and detection, degrades health and function
What are some behavioural and physiological features suggestive of pain?
Behavioural - grimacing, rigid body posture, limping, frowning or crying
Physiological - increased BP and HR
What is nociceptive pain?
An appropriate physiologic response to painful stimuli via an intact nervous system
What is neuropathic pain?
An inappropriate response caused by a dysfunction in the nervous system
How does neuropathic pain commonly present?
Description - burning, shooting, tingling, sensitivity
Examination - allodynia, hyperalgesia
What are some common causes of neuropathic pain?
Shingles, post-herpetic neuralgia, surgery, trauma, diabetic neuropathy, amputation
Why is it important to treat pain early and effectively?
Chronic pain is associated with morphological changes in the CNS, once present, the changes are often persistent and don’t totally resolve even with treatment
List the pharmacological approaches to pain management in order of WHO guidelines
Non-opioid analgesics e.g. paracetamol, NSAIDs
Opioid analgesics e.g. tramadol, codeine, morphine, oxycodone
Anti-depressants e.g. amitriptyline
Anti-convulsants e.g. gabapentin, pregabalin
Topical analgesics e.g. capsaicin
Local anaesthesia
How effective are NSAIDs in managing pain?
Mainly act on nociceptive pain
Inhibit cyclooxygenase 1 and decrease synthesis of prostaglandins
E.g. aspirin and ibuprofen
Side effects include renal toxicity and GI bleeds
How effective is paracetamol in managing pain?
No anti-inflammatory action but does have analgesic and antipyretic effects
Inhibits central prostaglandin synthesis
Side effects include risk of toxic liver damage
How effective are opioids in managing pain?
Mainly effective in nociceptive pain, less effective in chronic states and only partially effective in neuropathic pain
They activate the endogenous analgesic system
E.g. tramadol and codeine (weak) morphine and oxycodone (strong)
Side effects include N+V, constipation, dizziness, dry skin and somnolence
How effective are TCAs in managing pain?
Effective in neuropathic pain, complex regional pain syndrome and tension headache
They inhibit neuronal reuptake of NA and serotonin
E.g. amitriptyline and imipramine
Side effects include constipation, dry mouth, somnolence, insomnia and increased appetite
How effective are SSRIs and SNRIs in managing pain?
Effective in neuropathic pain.
SNRId are better analgesics than SSRIs
They provide analgesia by intensifying descending inhibition
E.g. duloxetine and venlafaxine
Side effects include N+V, constipation, somnolence, dry mouth, increased sweating and loss of appetite
