Anaesthetics - Pain and Pain relief Flashcards
(27 cards)
what is nociceptive pain?
Obvious tissue injury or illness, Also called physiological or inflammatory pain, Protective function. Sharp ± dull. Well localised
What is neuropathic pain?
Nervous system damage or abnormality. Tissue injury may not be obvious. Does not have a protective function. Burning, shooting ± numbness, pins and needles. Not well localised. Abonrmal processing of thhe pain signal
give examples of neuropathic pain
Nerve trauma, diabetic pain (damage), Fibromyalgia, chronic tension headache (dysfunction)
what are pathalogical mechanisms of nneuropathic pain?
increased receptor numbers, abnormal sensation of nerves, chemical changes in the dorsal horn, loss of onrmal inhibitory modulation
along what types of fibres does pns signals travel along?
Ab and C
what tract does pain travel along?
Spinothalamic
where in the brain does pain perception occur?
cortex
how is pain modulated?
gate theory of pain modulation. As well as a descending pathwy form the brain to the dorsal horn
name simple analgesics
paracetamol (acetaminophen), Non-Steroidal Anti-inflammatory drugs, Diclofenac, ibuprofen
name opioids
Mild - Codeine, Dihydrocodeine. Strong - Morphine, Oxycodone, Fentanyl
other analgesics
tramadol, nefopam, amitriptyline, gabapentin, Ketamine,
Peripeheral tx…
rest, ice, compression, NSAID’s
Spinal cord tx…
opioids, ketamine.
Brain tx…
paracetamol, opioids, amittiptyline,clonidine
ADX and DISADX of Paracetamol
cheap, safe, can be givenn orally, rectally or by iv, good for mild pain. May cause Liver damage.
ADX and DISADX of NSAID’s
Advantages - Cheap, generally safe, Good for nociceptive pain, Best given regularly with paracetamol (Synergism)
Disadvantages - Gastrointestinal and renal side effects plus cause bronchospasm in sensitive asthmatics
ADX and DISADX of Codeine
Advantages - Cheap, safe, Good for mild-moderate acute nociceptive pain, Best given regularly with paracetamol
Disadvantages - Constipation, Not good for chronic pain
ADX and DISADX of Tramadol
Weak opioid effect plus inhibitor of serotonin and noradrenaline reuptake (modulation)
Advantages - Less respiratory depression, Can be used with opioids and simple analgesics, Not a controlled drug
Disadvantages - Nausea and vomiting
ADX and DISADX of Morphine
Advantages - Cheap, generally safe, Can be given orally, IV, IM, SC, Effective if given regularly, Good for: Mod-severe acute nociceptive pain (e.g. post-op pain), Chronic cancer pain
Disadvantages - Constipation, Respiratory depression in high dose, Misunderstandings about addiction, Controlled drug, Oral dose is 2-3 times IV / IM / SC dose
ADX and DISADX of Amitriptyline
Tricyclic antidepressant (TCA) - Increases descending inhibitory signals Advantages - Cheap, safe in low dose, Good for neuropathic pain, Also treats depression, poor sleep Disadvantages - Anti-cholinergic side effects (e.g. glaucoma, urinary retention)
ADX and DISADX of Anti-convulsants
Examples - Carbamazepine (Tegretol), Sodium valproate (Epilim), Gabapentin (Neurontin)
Also called membrane stabilisers, Reduce abnormal firing of nerves, Good for neuropathic pain
WHO pain ladder for Nociceptive pain…
Mild - Paracetamol (± NSAIDs)
Moderate - Paracetamol (± NSAIDs) + codeine/ alternative
Severe - Paracetamol (± NSAIDs) + morphine
for neuropathic pain which drugs are usually used?
Amitriptylline, Gabapentin, Duloxetine
nociceptive and neuropathic pain tx overview…
noci - use WHO pain ladder, neuro - use alternative analgesia, not responsive to WHO pain ladder drugs.
