Pain and Analgesia Flashcards
Types of pain
Physiologic
Nociceptive/Inflammatory
Neuropathic
physiologic pain - define
short duration
preprogrammed responses
no tissue damage
Nociceptive/Inflammatory pain - define
tissue damage
allodynia - pain d/t stimulus which doesn’t normally provoke pain
hyperalgesia
neuropathic pain - define
damage/dysfunction of peripheral nerves/CNS
nociception - pathway
transduction transmission modulation projection perception
transduction - define
peripheral nerves
noxious stimuli into electrical signals - action potential
varied sensitivity to mechanical, thermal, chemical stimuli
transmission - define
1st order neurons synapse in dorsal horn
myelinated Asigma fibres - 1st pain
unmyelinated C fibres - second/visceral pain
modulation - define
peripheral sensory nerve impulses amplified/supressed in the spinal cord
perception - define
unpleasant sensation in the CNS
behavioural response to pain
species variation
descending pathways - DNIC
starts in the brain
relayed via brainstem
spinal cord - release inhibitory neurotransmitters
analgesic drugs - systemic
Opioids NSAIDs Ketamine Lidocaine MLK - morphine, lidocaine (lignocaine) and ketamine α2 agonists Tramadol Gabapentin/Pregabalin
analgesic drugs - local
Local anaesthetics
Opioids
α2 agonists
partial agonist - define
same overall actions as agonist
doesn’t produce maximal effecrs
not as profound analgesia full agonists
mild-moderate pain
mixed agonist-antagonist
antagonist at u receptors - relatively poor analgesic
agonist ar k receptors - some analgesia, sedation, dysphoria
side effects of opiods - arousal
CNS depression in dogs
CNS stimulation in cats, horses + ruminants
