Pain & Sensory Regulation

pain

unpleasant sensation, a feeling of discomfort resulting from stimulation of pain receptors in the body when tissue damage occurs or is about to occur; a defense mechanism; warning of a problem; subjective; caused by infection, ischemia (decreased blood supply to tissue/organ), tissue necrosis, stretching of tissue/inflammation, chemicals, burns

nociception

process of receiving messages from noxious stimuli

transduction

stimuli (pressure, trauma, heat, chemicals) damages the tissue which activates nerve endings; stimuli -> nerve impulse

transmission

relaying the message from the stimuli to the brain

unmyelinated C fibers are ____ causing dull, burning, aching pain

slow

myelinated A-delta fibers are _____ causing sharp sensation at time of injury

fast

perception

complex integration of several processes resulting in interpretation of pain; brain says "that hurts"

modulation

modify neurotransmission activity to decrease the intensity; endogenous opioids released to inhibit pain sensation; gate control theory

gate control theory

"gates" are built into the normal pain pathway that can modify the pain's impulse's movement to the brain

all "gates" are open

pain signal passes all the way up

a "gate" is closed

pain signal reduced or modified; applying ice -> more aware of cold feeling

What type of nociceptor is stimulated by extremes of temperature?

Thermal nociceptors

What type of nociceptor is stimulated by acids or compounds produced within the body?

Chemical nociceptors

What type of nociceptor is stimulated by pressure?

Mechanical/physical nociceptors

stage 1 & 2 of pain pathway

nociceptors

What type of fibers are myelinated A delta fibers?

Fast afferent fibers

What stimuli do myelinated A delta fibers respond to?

Thermal and physical stimuli

Where are myelinated A delta fibers found?

Skin and mucous membranes

What type of fibers are unmyelinated C fibers?

Slow afferent fibers

What stimuli do unmyelinated C fibers respond to?

Thermal, physical, and chemical stimuli

Where are unmyelinated C fibers found?

Muscle, tendons, myocardium, GI tract, and skin

stage 3 pain pathway

afferent fibers

stage 4 pain pathway

synapse

What is the role of reflex response in the synapse?

It generates a motor impulse (efferent fibers) back to the muscles for involuntary action.

What happens to muscles during a reflex response?

Muscle contraction occurs away from the stimulus.

stage 5 pain pathway

cross over the spinal cord

stage 6 pain pathway

ascending tract to the brain

stage 7 pain pathway

reticular activating system (RAS) - influences brain's awareness of incoming pain stimuli *main drugs work here to depress the pain experience

stage 8-10

somatic sensory areas of the brain

• perception & location of pain

• response to pain

• stress, emotional, physical

acute pain

short-term, time-limited, with resolution of noxious stimuli

chronic pain

persistent pain, beyond 6 months

somatic pain

acute or chronic, activated in skin or deep tissue

neuropathic pain

peripheral nerve damage

visceral pain

GI tract, viscera & deep somatic structures

pain sign and symptoms are _____________________

subjective experience for everyone

associated symptoms with pain

nausea, vomiting, fainting, dizziness, anxiety, fear, restlessness vs guarding

referred pain

pain perceived at a site distant from the source

what is guarding

holding stomach/don't want to be touched

patient-reported pain goal

acceptable pain level for patient

pain assessment OPQRSTU

onset, provocation/palliation, quality, region/radiation, severity, timing, understanding

onset

when it started

Provocation/Palliation

what makes it feel better or worse

quality

stabbing, burning, aching. throbbing, ask for words to describe pain

region/radiation

where is it, does it travel

severity

0-10 intensity score

timing

when does it occur, same time eahc month (period)

understanding

what do you think is going on

clinical manifestations pain assessment

wincing, grimacing, guarding, nausea, vomiting, sleep disturbance, decreased appetite, socially withdrawn vs hypervigilant

pain management is objective

relieve discomfort, improve function, enhance recovery

pain management is not

one size fits all

pain management is multimodal (multiple strategies)

increase efficacy, reduce side effects of Rx therapy, minimize need for opioids

nonpharmological measures

ice, heat, rest, compression, splint, massage, acupuncture, distraction

therapeutic class of acetaminophen (APAP)

analgesic (pain), antipyretic (fever)

pharmacologic class of acetaminophen

centrally acting analgesic, antipyretic

indication for acetaminophen

mild to moderate pain, fever; severe pain if combined with an opioid

MOA for pain (acetaminophen)

unclear; activation of descending serotonergic inhibitory pathway in the CNS?; blocking prostaglandin synthesis in the CNS?

MOA for fever (acetaminophen)

inhibition of the hypothalamic heat-regulating center

routes for acetaminophen

oral, IV, rectal

side effects of acetaminophen

pruritus (itching), nausea, vomiting, constipation, headache

adverse effects

hepatoxicity at high doses -> liver toxicity; Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis

Nursing Considerations for Acetaminophen

max daily dose - 4000mg (3000mg for older adults or existing liver issues); safe in pregnancy and lactation

Stevens-Johnson Syndrome & Toxic Epidermal Necrolysis

violent immune response that is a severe reaction to a drug, or more rarely, an infection; acute destruction of epithelium of skin and mucous membranes;

systemic symptoms for 1-3 days with Stevens-Johnson Syndrome & Toxic Epidermal Necrolysis

fever, cough, headache, anorexia, myalgia, nausea

specific symptoms with Stevens-Johnson Syndrome & Toxic Epidermal Necrolysis

red rash -> blisters; palms, sores, trunk, then face and extremities; mucosal lesions in eyes, mouth, genitals; PAINFUL

treatment for Stevens-Johnson Syndrome & Toxic Epidermal Necrolysis

identify and STOP the offending drug; supportive care, often ICU

antidote for acetaminophen

acetylcysteine

morphine sulfate therapeutic class

analgesic (pain)

pharmacological class of morphine sulfate

pure opioid agonist

indication of morphine sulfate

moderate, severe, chronic pain

MOA of morphine sulfate

binds to opioid receptors in CNS which blocks the ascending pain pathway

routes for morphine sulfate

oral, IV, subcu, intrathecal (spinal cord), epidural, rectal

side effects of morphine sulfate

pruritus (itching), N/V/C/, dizziness, headache, urinary retention

adverse effects of morphine sulfate

respiratory depression, sedation, bradycardia, physical dependence

nursing considerations of morphine sulfate

monitor respiratory status; watch for/educate aboout constipation and urinary retention; crosses placenta, can harm fetus; inconclusive data about use in breastfeeding

antidote for morphine sulfate

Naloxone (Narcan)

gabapentin therapeutic class

analgesic (pain), anticonvulsant

gabapentin pharmacological class

gabapentinoids

indication for gabapentin

neuropathic pain, postherpetic neuralgia, fibromyalgia, seizures

MOA of gabapentin

binds to receptor sites in the brain to reduce excitatory neurotransmitters (decreases pain signals)

routes for gabapentin

oral

side effects of gabapentin

dizziness, fatigue, drowsiness, confusion, neuro status

adverse effects of gabapentin

respiratory depression, sedation, psychiatric disturbances, suicidiality

nursing considerations of gabapentin

educate about adverse effects, avoid alcohol, crosses placenta and into breastmilk

general anesthetics

widespread depression of the CNS by enhancing inhibitory neurotransmitters and reducing excitatory neurotransmitters

types of general anesthetics

amnesia, unconsciousness, analgesia, and immobility

local anesthetics

block transmission of impulses in nerve fibers to reduce or eliminate sensation; at specific site of application

types of local anesthetics

spinal analgesic, peripheral nerve blocks, subcutaneous/tissue infiltration, topical anesthesia

lidocaine therapeutic class

analgesic (pain)

lidocaine pharmacological class

local anesthetic

indication of lidocaine

relief of localized pain

MOA of lidocaine

decreases membrane permeability to sodium -> inhibits depolarization of the nerve -> blocks nerve impulse

(low sodium, work well)

routes for lidocaine

topical, otic (Ear), opthalmic (eye), systemic (local and regional)

side effects of lidocaine

application site reaction, pruritus (itching)

adverse effects of lidocaine

with systemic exposure, cardiovascular & CNS effects (bradycardia, hypotension, shock, confusion, dizziness, paresthesia, seizure)

nursing considerations of lidocaine

if anticipate systemic absorption, monitor VS & near status; crosses placenta, use with caution; safe for breastfeeding

migraine headaches

complex pain disorder; may include an aura (visual/sensory symptoms prior); may report a prodrome - vague sense that soemthing is going to happen (up to 24hrs prior)