Pain Basics COPY Flashcards
Pain most paitients feel in the perioperative period
Protective physiologic pain from tissue damage
Peripehral nociceptive neuron stimulated by noxious stimuli asrnd signal to CNS - brain and spinal cord for input and sensation of pain
Protective physiologic pain from tissue damage
firing of a neuron that is not indicative of of physical damage, but is a pathalogical firing
Neuropathic pain
Pain out of proportion to noxious stimuli
Hyperalgesia
Pain evoked by a non-noxious stumuli
Allodynia
pain with no apparent stimuli - it is NERVE pain
spontaneous pain
Peripheral nociceptive neuron activated by intense noxious stimimuli (tissue damage) via
- Mechanical
- thermal
- chemical
slow conduction, dull, burning, diffuse
non-mylinated C fibers
fast conduction - sharp and well localized
A-delta fibers
nociceptiv impulse depends on the balance between
excitatory and inhibatory receptors
excitatory catioon channel activated by:
- Protons
- heat
- capsaisin
- Endovanilloids
TRIP1
Blocking this TRPV1
Pain medicine too good, lost protective mechanism ad could not perceive pain
- inhibatory
- Bind to GPCR to initiate cascade (PKA)
- increase K conductance hyperpolarizing the cell
Opioids
hyperpolarizing the cell with opioids means
cells will need a stronger stimulus to fire
Locations of opioid receptors
- Peripheral tissues
- dorsal horn of spinal cord
- Brain (this is wher opioids work)
promotes depolarization and stimulates pain
Bradykinin and Prostaglandins
Area of dorsal horn that is very rich in opioid peptides and receptors
substantia geletinosa
Synapse in dorsal horn at lamina I, II, III, V
A-delta fibers
Synapse in dorsal horn at lamina I and II
C-fibers
Located in lamina II and III
Substantia gelatinosa
what is in the substantia gelatinosa
- short inhibatory neurons that receive afferent fibers from A-delta and C fibers
- descending pathways that are moculating pain signals (they are inhibatory)
Determine weather a pain signal is sent to the higher centers for processing or modulated
Internurons
sends pain signals to the thalamac which then sends pain signals to the somatosensory cortes
neospinothalamic tract
responsible for the experience of pain
neospinathalamic tract
sends pain signals to the brainstem which then signals to the thalamus, hyptothalamus and elsewhere
peleospinothalamic tract
Causes the stress response to pain
paleaospinothalamic tract
tract we want to supress with pain that causes the SNS to release a ton of cortisol
paleospinothalamic tract
Opioids releive not only the ____________ aspect of pain, it also releves the ___________ aspect thereby preventing ___________ or _____________ from the exaggerated stress response.
- somatosensory
- physiologic
- MI
- prolonged healing
descending _____________ pathways originate in the ____________/ __________ including areas such as _____________, ____________, ___________, ______________
- inhibatory
- midbrain/brainstem
- Periaquaductal gray
- amygdala
- corpus striatum
- Hypothalmus
In descending pathways neurons from the midbrain/brainstem project into the ______________which then sends its descending neurons __________ to synapse in the ____________
- nucleus raphe magnus
- down the spinal cord
- substantia gelatinosa
opioids and the brain
act pre and post synaptically to activate descending inhibatory pathways
opioids and the spinal cord
work directly on the dorsal horn of the spinal cord
opioids and the periphery
act on peripheral teminals of nociceptive neurons
why is the perception of noxious stimuli not the same as pain?
it is lacking the emotional component
Opioids can change patients __________ without necessarily changing the patients ability to __________ noxious stimuli
- tolerance of pain
- perceive
ie- they can still tell you where the wound is
Opioids are effective for both ________ and _______ pain
somatic and visceral
The main use of opioids on anestehsia
Attenuate the SNS response to noxious stimuli- Laryngoscopy
During inductons opioids are used to _____________and causes the patient to have _______________
- maintain stable hemodynamics
- less Cardiovascualr comprimise
If opioids are not given to someone with coranary artery disease durring laryngoscopy
could have an MI with a really fast heart rate
opoids and inhaled anesthetics
act as an adjunct allowing for less use of inhaled agent
cardiac anestheisia and opioids
opioids are used as a sole anesthetic
natrurally occuring drugs derrived from opium from the poppy plant
Opiate
- Morphine
- Codeine
Natural and synthetic substances that bind to opioid receptors and produce and agonist effect
- Opioid
- anything that acts like an opiate
Term for DEA regualtions
narcotics
therepeutic agents with the general opioid structure
Opioids
Opioids produce analgesia without loss of
- Touch
- Propioception
- Conciousness
Unique characteristics that set opioids apart
- no ceiling effect or max dose
- tolerance and cross tolerance
Tolerance with opiods is associated with ____________ but not necessarily __________ - this is expected
- Physical dependance
- psychological
naturally occuring opioids
- Morphine
- Codeine
semisynthetic: analogs of morphine
- heroine and dihydromorhone
- heroine and fentanyl are very structurally similar
Synthetic Opioids
- Exogenous
- Has 4 classifications
- agonist
- partial aginist
- mixed agonist/antagonist
- antagonist
Synthetic antagonist
Narcan
- can reach maximum eficacy on dose response curve
- their potency is what varries
Synthetic agonists (full)
- will have a ceiling effect
- cannot reach maximum effect on dose response curve
Synthetic partial agnosts
Synthetic opioid agonist / antagonist
- agonist at kappa receptors
- antagonist and mu receptors
if their is any potential you will need to switch to a full agonist you want to start with
a parial agonist and NOT an agonist / antagonist
OPIOIDS MECHANISM OF ACTION
Activate ___________________ and act
-
_______________to directly decrease neurotransmission by:
- increase K conductance (_______________)
- Ca++ channnel inactivation (_________________)
- inhabitionof ____________ (______________)
- Modulation of___________- signaling cascade for phospholipase C
-
_______________
- Decrease ____,__________,________and ___________
- anytime you hyperoplarize a membrane you decrease _______________
OPIOIDS MECHANISM OF ACTION
Activate stereo-specific G-protein coupled receptors and act
-
post-synaptically to directly decrease neurotransmission by:
- increase K conductance (hyperpolarization)
- Ca++ channnel inactivation (decreased NT release)
- inhabitionof adenylate cyclase (decreased cAMP)
- Modulation of phospinositide- signaling cascade for phospholipase C
-
Pre synaptically
- Decrease ACh, dopamine, norepi and Substance p release
- anytime you hyperoplarize a membrane you decrease NT release
anytime you hyperpolarize a cell you
decrease neurotransmitter release
Opioids POST-synaptic mechanism of action
- increase K conductance (hyperpolarization)
- Ca++ channel inactivation (decreases NT release)
- Modulationo of phospinositide- signaling cascade for phospholipase C
- Inhabition of adenlyate cyclase (decrese cAMP)
Opioids PRE-synaptic mechanism of action
- inhibits the release of excitatory neurotransmitters
- ACh
- Dopamine
- Norepi
- Substance P
Opioid receptors
- Mu (agnoist binding site)
- Kappa (antagonist binding site)
- Delta
When opioids bind to receptors they
activate endogenous pain modulating systems