PAIN and its management Flashcards
describe acute pain
there is usually obvious damage
protective function
increased NS activity
pain resolves on healing
describe chronic pain?
when there is pain beyond expected period of healing
when pain no longer has a useful purpose
degrades function and health
name 2 types of pain
nociceptive
neuropathic
what is nociceptive pain?
an appropriate response to painful stimuli
what is neuropathic pain?
an inappropriate response caused by a dysfunction in NS
pain from something that normally isnt painful?
allodynia
more pain than expected from something?
hyperalgesia
name some causes of neuropathic pain?
shingles surgery trauma diabetic neuropathy amputation
bad effects of NSAIDS
GI bleed
renal toxicity
CVS side effects
what is bad about paracetamol
toxic to liver
bad side effects of opiods?
nausea and vomiting constipation dizzy itch dry skin
bad effects of tricyclic antideprressants?
constipation
insomnia
increased appetite
change in HR
bad effects of SSRIs?
nausea and vomiting constipation dry mouth increased sweat decreased appetite
bad effects of anti convulsants e.g gabepentin
sedation dizzy atxia peripheral oedeama nausea weight gain
how does nociceptive pain begin?
by the activation of nociceptors- these are first order afferent neurones which are activated by intense or damaging stimuli. the cell bodies are located in the dorsal root ganglion
name the types of nociceptors?
C fibres- slow pain
Aδ fibres- fast pain
what type of nociceptor is not myleinated?
C fibre
what are the subtypes of Aδ fibre?
Type 1- high threshold mechanoreceptors- need strong mechanical stimuli for activation or temp >53- mediate first pain to mechanical stimuli
Type 2- respond to heat (43-47)- mediate first pain to heat
what are the subclasses of C fibres?
C-MH= respond to mechanical stimuli and heat, sensitive to capsain and prolonged stimuli C-M= respond to mechanical stimuli C-H= respond to noxious heat stimuli C-MiHi= normally not sensitive to either. acquires sensitivity by inflammatory mediators
where are primary afferent cell bodies located?
dorsal root ganglion
where do the axons of primary afferents terminate?
in dorsal horn of spinal cord in various laminae of REDEX
what is visceral pain from?
nociceptors on organs
what is referred pain?
when the brain interprets the pain from the viscera from an area of skin that is distant to the original organ
what are the 2 nociceptive tracts?
spinothalamic tract- fast pathway
spinoreticular path- largely transmits C fibre pain (slow pathway)
what does this describe?
the nerve impulse evoked by injury are influenced in the spinal cord by other nerve cells that act like gates, either preventing the impulses from getting through, or by helping them
gate control theory
things that might open the gates?
of C/A fibres are active bad injury not enough meds anxiety /stress/ fear introvert
opiate -what is it?
substances extracted from opium
opiod- what is it?
any agent that acts upon opiod receptors
what are the 3 opiod receptors?
mu- responsilbe for most analgesic activity
delta
kuppa
is morphine an agonist and when is it used?
agonist
used in acute and chronic pain
when is diamorphine used?
can be used post op in the UK
also an agonist
what is Fentanyl used for?
maintenance of anaesthesia
(also an agonist)
when is codeine used?
it is a weaker opiode so used for mild-moderate pain
taken orally
what analgesic should be avoided in epilepsy?
tramadol
