nurs 116 - lec 6

what type of mechanism is acute pain?

a warning mechanism (innate protective)

what’s the first step when you have a pt with pain?

assessment with LATER SNAPS

• quality: burning, dull…

• scale 0-10, pediatric faces tool

is it radiating?

what is another name for radiating pain? what is the cause of radiating pain?

aka referred pain

due to the body area being innervated by the same spinal nerve/plexus & interneuronal communication

3 categories of sensory receptors

special

• 5 senses

visceral

• internal organs

somatic

• skeletal musc, joints, skin surfaces

what info is carried to the CNS by what?

sensory info w afferent (AWAY FROM SOURCE)

what info is carried to the PNS by what?

motor info by efferent

two divisions (of PNS) that carry efferent info

Somatic NS and ANS

Somatic NS sends info to what effectors?

skeletal musc

ANS divisions? what effectors do they send info to?

PNS and SNS

-smooth musc

-cardiac musc

-glands

-adipose tissue

pressure sensitive cells (keep ruff pugs)

krause’s end bulb

ruffini ending

pacinian corpuscle

fine touch cells (make me rich)

meissner’s corpuscle

merkel discs

root hair plexus

what type of nerve endings detect temperature and pain?

free nerve endings

where does the afferent pathway end (cortex)?

somatosensory cortex → homunculus

what happens if an action potential doesn’t reach the threshold?

doesn’t depol

what # neuron is a nociceptor? what NS division is it found in?

1st order neuron in PNS

afferent path into spinal cord

axon → ganglion + cell body → sensory neuron → axon → spinal cord (interneuron)

efferent path out of spinal cord

spinal cord (interneurons) → motor neuron → effectors

what structures are nociceptors found in?

skin, bones, blood vessels, visceral organs

nociceptor pathway

A or C fiber (1st order) → spinal nerve → dorsal root & ganglion → posterior horn synapse (substance P NT) → 2nd order decussates → up spinal white matter column via spinothalamic tract (lateral) → thalamus (relay station) → synapse with 3rd order → somatosensory cortex → sensory homunculus

what is localization

specific body part of the sensory homunculus that brings awareness of sensation

what does decussate mean

cross over

speed of a (alpha) nerve fibers? why?

fast, myelinated

speed of c nerve fibers? why?

slow, unmyelinated

what is the sensory homunculus

maps cortex region/body part (innervation #s)

somatosensory association areas do what

link sensations to previous experiences

role of the parietal lobe?

-primary somatosensory cortex

-awareness of somatic sensation

-touch, pain, temp

what NS division is substance p in? what type of NT (exc, inh) is it?

CNS, excitatory

what type of pain is from sub P

acute pain

what type of receptors does sub p use?

mu, kappa, delta, sigma, epsilon

what type of pain is from glutamate? (come now hoe)

chromic pain, neuropathic pain, hyperalgesia

neuropathic pain aka

nerve pain

what is hyperalgesia

hypersensitivity to pain

what type of receptor does glutamate use

NMDA

how long until something is considered chronic pain

6 months

what is visceral pain

deep pain, organs

what is cutaneous pain

superificial

chronic pain travels on what fiber

c fiber

what causes chronic pain?

inflammation in the nerve area (neurogenic inflammation)

undertreated acute pain/chronic inflammation disorders

what is CRPS (complex regional pain syndrome)

type of hyperalgesia, persistent pain that is more severe than the trigger

what is bad about neuropathic pain? what causes it?

it’s hard to treat

post trauma: burns, amputations

what is phantom pain? what structures are involved?

neuropathic pain post amputation (NOT COMING FROM PERIPHERAL)

-spinal cord neurons are active without nociceptors

-interneurons still communicating

acute pain lasts how long

10 days-6 months

T or F: SNS responses active in acute pain

T. becomes exhausting

how is acute pain self-limiting?

endogenous inhibitors secreted

do you treat acute pain mildly or aggresively?

aggressive

why is chronic pain not self-limiting?

endogenous inhibitors not secreted

are SNS responses active in chronic pain?

no

what type of mechanism is chronic pain?

destructive, not beneficial to host

what other diagnoses (illness) chronic inflammation trigger?

insomnia, anxiety, anorexia, depression

what is anorexia

decreased appetite

what is CBT and why is it required?

cognitive behavior treatment to alter behavior/perception of pain

what are dermatomes

cutaneous segments serviced by the same spinal nerve

clinical application of dermatomes

assessed to determine sensory input (if pain tx is working, check extent of injury)

flexor reflex aka

withdrawal reflex

general pathway for flexor reflex

stim → sharp pain → reflex withdrawal WITHOUT cerebral control

why is the withdrawal reflex important to check?

make sure the pt can protect themselves from things like choking (under/after anesthesia)

types of receptors (stimulus dependent) - mnpt

mechano, noci, pressure, temp

what is pain gate theory

pain signals can be interrupted in the substantia gelitanosa/gate (inhibitory neuron) of the spinal cord

-ex. rubbing your hand

what are endogenous opioid peptides? examples?

inhibitory NT/neuromods

endorphins, enkephalins, dynorphins

what releases endogenous opioid peptides? what pathway do they follow? where do they bind? what do they inhibit?

released from: hypothalamus, limbic system, reticular formation

pathway: descending/efferent

where do they bind: opioid receptors

inhibit: sub P

what are the CNS endogenous pain-relief secretions? what path do they follow?

serotonin & norepi

pathway: descending/efferent

what does norepi bind to?

opioid peptide receptors

what are the 3 barriers to pain relief (general)

healthcare professionals (bias)

healthcare system (insurance)

pt (denial)

routes of admin for pain relief

IV (PCA), PO (extended release), PR (per rectal), epidural (PCA), spinal, nerve block, intranasal

PCA stands for

patient controlled analgesia

analgesia tx at CNS level (+ examples)

1. non-opioid centrally acting agents

   • acetaminophen

2. opioids

   • morphine

analgesia at peripheral lvl (+example, other fx)

1. NSAIDS

   • ibuprofen

   • inflammation

what acetaminophen tx efficacy from most to least?

1. antipyretic

2. overdose

3. very weak pg inhibitor (not considered anti-inflammatory)

how do you admin tylenol?

PO, q4h

tylenol pathway?

tylenol → p-aminophenol → AM404 (activates analgesia/blocks COX) → TRPV1 & CB1 (receptors)

tylenol ADME

Absorption

• PO, good bioavailability

• cmax 30-60 min

Distributed well

• low (20%) PPB

Active metabolites

• hepatic metabolism CYP 3A4/1A2

• hepatoxic metabolite n-acetyl-benzo (NAPB) → phase 1 metabolized by glutathione

Renal elimination

• t1/2: 2-3 hrs

what is an opioid

any drug derived from opium

what does opium contain (drugs)

morphine and codeine

do narcs depress or excite the CNS?

CNS depressing substances

what is the narcotic terminology associated with

illegal use/used in clinical settings to imply drug is monitored → narc count

opioid drug schedudling

controlled dispensing and prescribing (monitored)

most are schedule 1 (sometimes 2)

what receptors are opioids agonists for?

mu, kappa, delta

high efficacy opioids (“fat hippos make me mad”)

fentynal

hydromorphone - 5x stronger than morphine

meperidine

morphine

methadone

mod efficacy opioids. main (hoot)

main:

• hydrocodone

• oxycodone

• oxytocin

• tramadol

mod efficacy opioids. combo (python’s pee toxic venom)

percocet, percodan, tramacet, vicodin

codeine combo drugs?

tylenol 1-4, codeine, caffeine

percocet combo

oxycodone + acetaminophen

percodan combo

oxycodone + ASA

vicodin combo

hydrocodone + acetaminophen

tramacet combo

tramadol + acetaminophen

opioids ADME

Absorption

• IV, PO etc

Distribution

• moderate ppb (30%)

• lipophilic → quickly distribute into tissue → accumulate in fat (esp for obese ppl - need higher dose)

Metabolism

• hepatic (first pass)

• codeine metabolized into morphine by CYP 2D6/3A4

Excretion

• renal

• bile - biliary secretion

• very small

can you give codeine to kids

NO

mu1 opioid receptor effects (hd-

• histamine, dopamine release

analgesia

euphoria

confusion

dizziness

nausea

sedation

mu2 opioid receptor effects *rhumm”

resp depression

cardiovasc effects (hypotension)

urinary retention

gi effects (slow motility)

miosis

delta opioid receptor effects (arc)

analgesia

resp depression

cardiovasc

kappa opioid receptor effects (kappa go krazy)

analgesia

psychomimetic effects (nightmares)

general side effects of opioids

CNS depression/effects

N&V (nausea/vomiting)

pruritus

constipation

urinary retention

what drug protocol do you use to treat opioid dependence?

methadone protocol

4c’s of addition (psychological)

loss of Control

use despite Consequences

Compulsion to use

Craving

pain tx (<4/10)

-non-opioids

-less invasive (PO)

-NSAIDS, tylenol

pain tx (4-6/10)

opioids

less invasive (PO)

combination drugs, morphine

pain tx (>6/10)

higher potency opioids

IV

PCA

treat MI pain (myocardial infarction) - drug + mechanism

morphine (opioid)

cause vasodilation (decreased BP & CO)

how does ASA act as a cardiac tx?

low-dose antithrombotic (no clot formation)

treat GI pain - drug + mechanism (di-mu-smore)

dicyclomine

muscarinic antagonist

GI smooth musc relaxant