Pain Flashcards
List the types of analgesia use in managing nociceptive pain in perioperative care with examples.
Opioid (1), NSAID (1), LA (1), Adjunct (0.25 each, max 1):
alpha 2 adrenoceptor agonist, MgSo4, Ketamine, Glucocorticoids (Dexamethasone, Hydrocortisone),
N20, Xenon, Beta Blocker, Cannabinoid, SNRI/SSRI, Tricyclic anti-depressant
Describe mechanism of action on NSAIDS on pain pathway.
–Pain pathway: Transduction, Transmission, Modulation, and Perception
Answer scheme: location of the pathway (0.5), receptor (0.5), action (1)
-NSAID (2): Works at transduction of pain at peripheral tissue/local injured tissue. Inhibit the enzyme cyclo-oxygenase (COX] -> preventing the production of prostaglandin (PG) -> prevent reduce threshold of pain signal transmission of 1st order neurone (pain fibre a delta and C fibres).
Describe mechanism of action on opiods on pain pathway.
–Pain pathway: Transduction, Transmission, Modulation, and Perception
Answer scheme: location of the pathway (0.5), receptor (0.5), action (1)
-opioid (2): Works at modulation of pain, agonists at opioid receptors at presynaptic and postsynaptic sites in the central nervous system (CNS) (mainly the brainstem and spinal cord) as well as in the periphery. Mimic the actions of endogenous ligands known as by binding to opioid receptors (Gi Protein) -> hyperpolarised presynaptic neurones inhibition of neurotransmitter release (acetylcholine, dopamine, norepinephrine, substance P) + postsynaptic inhibition of evoked activity->
increase the threshold of transmission of pain signal.
Describe mechanism of action on LA on pain pathway.
–Pain pathway: Transduction, Transmission, Modulation, and Perception
Answer scheme: location of the pathway (0.5), receptor (0.5), action (1)
-LA (2): Works on transmission of pain signal. Binds intracellularly to Voltage-gated Na channel on 1st and 2nd order neurone -> prevent propagation of action potential -> prevent transmission of ascending pain signal.
Describe mechanism of action on Ketamine on pain pathway.
–Pain pathway: Transduction, Transmission, Modulation, and Perception
Answer scheme: location of the pathway (0.5), receptor (0.5), action (1)
-Ketamine (2): Work at transmission, modulation, and perception of pain.
-Blockade of NMDA receptors throughout the central nervous system -> decreasing brain excitation and nociceptive signal sensitization
-blocking post-synaptic NMDA-type glutamate receptors within the dorsal horn -> reduce transmission of pain signal.
- decreases reuptake of serotonin and norepinephrine -> increasing neurotransmitter availability within the descending modisation pathway
-opioid agonist activity
-mood stabilization effect may evoke altered pain perception as well.
Describe mechanism of action on a2 Adrenoceptor agonists on pain pathway.
–Pain pathway: Transduction, Transmission, Modulation, and Perception
Answer scheme: location of the pathway (0.5), receptor (0.5), action (1)
-a2 Adrenoceptor agonists (2): Works at modulation of pain. Binding to the postsynaptic alpha2 receptors of the interneurons -> promotes the release of endogenous opioids.
Describe mechanism of action on Glucocorticoids on pain pathway.
–Pain pathway: Transduction, Transmission, Modulation, and Perception
Answer scheme: location of the pathway (0.5), receptor (0.5), action (1)
-Glucocorticoids (2): Reduce inflammatory pain/transduction of pain by blocking the intracellular conversion of phospholipids to arachidonic acid by altering gene expression -> inhibiting production of prostaglandins and leukotrienes + decrease the transcription of proinflammatory genes + increase transcription of anti-inflammatory genes. Glucocorticoids have also been shown to reduce spontaneous action potential firing in injured nerves, both centrally and peripherally
Describe mechanism of action on Gabapentinoids on pain pathway.
–Pain pathway: Transduction, Transmission, Modulation, and Perception
Answer scheme: location of the pathway (0.5), receptor (0.5), action (1)
-Gabapentineids (2): Works on transmission of pain. Act on inhibit a-2-d-1 subunit of pre-sinaptic voltage-gated calcium channels -> inhibit neuronal calcium influx -> reduction in the release of excitatory neurotransmitters (glutamate, Substance P, noradrenaline, serotonin, dopamine) from primary afferent nerve fires (1st order neurone) -> suppressing neuronal excitability after nerve or tissue injury.
Describe mechanism of action on Mgso4 on pain pathway.
–Pain pathway: Transduction, Transmission, Modulation, and Perception
Answer scheme: location of the pathway (0.5), receptor (0.5), action (1)
-MgSO4 (2): Work at transmission of pain. Block NMDA-type receptor at the synapse between the primary and secondary afferent axons in the spinal cord dorsal horn due to electrical gradient between the extracellular space and the intracellular space. Even though glutamate binds to it, the NMDA-type receptor will not usually allow passage through the channel because it is blocked by magnesium.
Describe mechanism of action on TCA/SNRI/SSRI on pain pathway.
–Pain pathway: Transduction, Transmission, Modulation, and Perception
Answer scheme: location of the pathway (0.5), receptor (0.5), action (1)
- TCA/SNRI/SSRI (2): reduce reuptake of serotonin/noradrenaline in descending inhibitory pathway, enhance the secretion of endogenous opioid
