Pain Flashcards
Physiological process of pain
transduction
transmission
perception
modulation
Nociceptors
sensory neurons that detect painful stimuli
Chemical Mediators causing pain
prostaglandins (tissue cell membrane) histamine (mast cells) bradykinin (liver protein) serotonin (platelets) substance P
Epidemiology of pain in OA
> 50% in community have chronic pain
>80% in nursing homes have chronic pain
Acute Pain
rapid onset
clearly linked to triggering injury/event
short duration
decreases with healing
Chronic Pain
pain lasting >3 months. can last years
can be d/t underlying pathology, injury, medical treatment, inflammation, neuropathic
Pain Theories
gate-control theory
neuromatrix theory
Eudynic pain
normal transduction of pain sensation d/t noxious stimuli
Types of pain
referred
cutaneous
somatic
visceral
Somatic pain
sharp pain localized to an area of injury
Visceral pain
pain that occurs w/i a body cavity (thorax, abdomen, pelvis)
may radiate to other area
caused by: swelling, stretching, hypoxia
Hypoxia
pain caused by decreased availability of oxygen to tissue cells
can occur d/t hypoperfusion or hypoxemia
Nociceptive pain
eudynic pain
normal associated with tissue injury
Neuropathic pain
caused by disease or pathology to the somatosensory system
pain sensation that originates in the PNS/CNS without afferent stimuli
Neuropathic pain exemplars
postherpetic neuralgia diabetic neuropathy phantom pain trigeminal neuralgia post-stroke pain complex regional pain syndrome
Individual Risk Factors
communication barriers
cognitive impairment or developmental barriers
Pain assessment tools
pain scale (numbers or faces)
self-assessment
behavioral pain tools
Analgesic classes
non-opioid
opioid
adjuvant analgesic
Non-Opioid analgesia
acteminophen
NSID
COX-2 selective NSAID
*mild pain. used as an adjunct w/ opioids
Opioid analgesia
hydromorphone oxycodone fentanyl morphine *moderate-severe pain
Adjuvant analgesai
anticonvulsant (gabapentin)
local anesthesia
antidepressant
First Line Treatment for Neuropathic Pain
anticonvulsants (gabapentin)
antidepressants
Somatic Senses
pain
touch
temperature
proprioception
Types of somatic neurons
general - pain, touch, temp. widespread
special somatic - muscles, joints, tendons. proprioception & kinesthesia
general viscera - viscera. fullness & discomfort
Somatosensory pathway
1st order neuron - periphery to CNS
2nd order neuron - reflex/sensory pathway. spinal cord –> thalamus
3rd order neuron - thalamus –> cerebral cortex
Types of somatosensory fibers (peripheral)
A, B, C
Sensory neurons transmitting info from limbs/trunk
first-order dorsal root ganglia
Sensory neurons transmitting info from head
trigeminal sensory neurons
A-delta fibers
myelinated. fastest rate of conduction
detect somatic stimuli (touch, heat, heat/mechanical pain)
associated with withdrawal reflex
B fibers
myelinated
detect cutaneous/subcutaneous stimuli
C fibers
non-myelinated. slowest rate of conduction
detect warm-hot mechanical/chemical pain, heat-cold pain
Hyperalgesia
hypersensitivity to pain
Pain etiology
nociceptive - stimulation of pain receptors
neuropathic - damaged or dysfunctional sensory axons
Pain threshold
minimum amount of stimuli required for pain perception
Pain tolerance
maximum amount of pain a person is willing to tolerate
Peripheral nerve fibers that detect pain
A & C
Pain Classification
duration (acute, chronic)
location (cutaneous, somatic, visceral, referred)
etiology (nociceptive, neuropathic)
frequency (intermittent, constant)
Somatic tissue
muscle
joints
tendons
periosteum
Physiological pathway of pain
1st order
2nd order. decussates and ascends to thalamus
3rd order
Factors influencing pain
psychological state cultural/spiritual other (age, sex, comorbidities) cognitive past experience
Noxious Stimuli
mechanical
thermal
chemical
Mechanical stimuli
pressure
swelling/distension
incision, cut, abrasion
Thermal stimuli
burns (contact, fire, electrical, radiation)
scalds (steam, hot liquid)
frostbite
Chemical stimuli
inflammatory or chemical mediators
acid
capsaicin
Substance P
neuropeptide released by C-fibers at the dorsal horn
may result in unlocalized pain d/t diffusion of neuropeptide
Cutaneous pain
superficial structures
can have slow or rapid onset
sharp, burning
localized region
Somatic pain
deeper somatic structures (periosteum, bone, muscle, tendon, joints)
diffuse area
radiation can occur
Visceral pain
occurs in the organs. caused by damage to visceral walls
usually diffuse, unlocalized area. can be referred elsewhere.
commonly associated with pathology & SNS symptoms
Referred pain
pain that manifests in a location different from the origin
moreso assoc with visceral > somatic pain
occurs d/t convergence of somatic/visceral afferent neurons in the spinal cord & embryologic origin of tissue
Examples of referred pain
peritoneum –> umbilicus
diaphragm –> shoulder
myocardium –> radiating up jaw or down arm
Characteristics of acute pain
<3-6 months recent onset nociceptive assoc with SNS symptoms , anxiety subsides when underlying pathology resolved protective function
Characteristics of chronic pain
> 3-6 months
no SNS activation
psychological/behavioral changes (irritability, anxiety, depression, withdrawal, decreased sleep, libido, appetite changes)
pathological condition
Types of opioid receptros
mu
kappa
Mu side effects
analgesia pupillary constriction respiratory depression decreased GI motility euphoria physical dependence
Kappa side effects
some analgesia
pupillary constriction
sedation
dysphoria
Transduction
transformation of sensation into neurochemical stimulus that travels from sensory receptor –> spinal cord
Transmission
transmission of nerve impulse from spinal cord to cortex for processing
Perception
conscious awareness/perception of painful stimuli
Modulating
release of endorphins/chemicals that help minimize or affect the sensation of pain
4 P’s of Pain Mgmt
Prevention
Psychological
Physical
Pharmaceutical
Preventive pain mgmt
mobilization
use of mobility aids
proactive referrals
use of braces/splints
Psychological pain mgmt
Guided imagery Meditation Relaxation techniques Reiki Counseling Humor
Physical pain mgmt
RICE hot/cold therapy acupuncture TENS machine massage physiotherapy positioning exercise
Pharmaceutical mgmt
Opioid analgesics
Non-opioid analgesics
Adjuvant analgesics
PQRST
provoking/palliative factors quality/quantity region/radiation severity temporal
