Pain Flashcards
What are the similarities between acute and chronic non cancer pain?
relief of pain is highly desirable for both
What is the difference between acute and chronic non cancer pain?
duration based 3 months
tx goal is pain reduction for acute and functionally for chronic
List with a small explanation the steps of pain transmission
transduction - something stimulates
conduction - chemical signal is sent
transmission - into electrical moves along the neurons
perception - signal gets to the brain & we realize its pain
modulation - descending response back
Define nociceptive pain
Arises from damage to body tissue; typical pain one experiences as a result of injury, disease, or inflammation
Usually described as sharp, aching, or throbbing pain
e.g., burning your hand on a hot stovetop (tissue damage = adaptive)
define neuropathic pain
Arises from direct damage to the nervous system itself, usually peripheral nerves but can also originate in central nervous system
Usually described as burning or shooting/radiating, the skin might be numb, tingling, or extremely sensitive – even to light touch (allodynia)
e.g., post-herpetic neuralgia (i.e. shingles pain)
Define nociplastic pain
Arises from a change in the way sensory neurons function, rather than from direct damage to the nervous system; sensory neurons become more responsive (sensitization)
Usually described similar in nature to neuropathic pain
e.g., fibromyalgia (no tissue damage = maladaptive)
MOA of acetaminophen
inhibit CNS prostaglandins, peripherally block pain impulse generations
S/E of acetaminophen
liver toxicity
overdose
may increase systolic BP
rare neutropenia and thrombocytopenia
Key considerations of acetaminophen
caution in severe liver dysfunction
opioid sparing
Place in Therapy for Acetaminophen
reduction of fever
mild-moderate acute pain
pediatric moderate pain
MOA of NSAIDS
reversibly inhibit COX-1 and 2 enzymes which decrease formation of prostaglandin precursors
S/E of NSAIDS
Dyspepsia
Edema
GI Bleed
N/V
Phototoxic Reaction
CNS : Dizziness, drowsiness, headache, tinnitus, confusion (especially in the elderly & with indomethacin). CNS effects may be dose related.
Minor or serious skin rashes, pruritus
COX-2 selective – similar efficacy & renal/CV toxicity to other NSAIDS, but less GI risk
Key considerations for NSAIDS for pain
caution if GI ulcer/bleed risk, renal/cardiac dx
opioid sparing
CI - CKD
Place in Therapy for NSAIDs
Mild to moderate pain (osteoarthritis, acute & chronic low back pain)
Dysmenorrhea-induced pain
Fever (only ibuprofen and naproxen)
MOA of ASA
Irreversibly inhibits COX-1 and COX-2 enzymes via acetylation which decreases formation of prostaglandin precursors
Antipyretic, analgesic, and anti-inflammatory properties (see dosing)
Place in Therapy for ASA
mild moderate pain (short term use)
reduction of fever
S/E of ASA
Adverse Drug Effects
Dyspepsia
Edema
GI Bleed
N/V
Phototoxic Reaction
CNS : Dizziness, drowsiness, headache, tinnitus, confusion (especially in the elderly & with indomethacin). CNS effects may be dose related.
Minor or serious skin rashes, pruritus
COX-2 selective – similar efficacy & renal/CV toxicity to other NSAIDS, but less GI risk
Key considerations of ASA
CI - hypersensitivity to NSAIDs, anaphylaxis, CKD, GI ulcer
What is pain?
an unpleasant sensory and emotional experience associated with or resembling that associated with, actual or potential tissue damage
Classification of Pain based on pathophysiology
nociceptive
neuropathic
nociplastic
Classification of Pain based on intensity
mild
moderate
severe
Classification of Pain based on duration
acute
subacute
chronic
List the two types of nociceptive pain
somatic and visceral
Define as somatic pain
arises - skin, bone, joint, muscle, or connective tissue
described as sharp, hot, stinging, throbbing
localization - generally localized with surrounding with surrounding tenderness
examples - fracture, strain, laceration, burn, arthritis
Describe visceral pain
Arises from - internal organs
described as dull, cramping, colicky, gnawing, aching, squeezing, pulsing
localization - poorly localized
examples - pancreatitis, appendicitis, peptic ulcer disease, menstrual cramping
Describe the nociceptive pain pathophysiology
transduction -
conduction -
transmission -
Perception -
modulation -
Describe Transduction stage of nociceptive pain pathophysiology
stimulation by noxious stimuli in somatic and visceral structures releases chemical that activate nociceptors
Describe conduction stage of nociceptive pain pathophysiology
chemical signal converted to electrical signal, action potential conducted along A-d (fast) and C (slow) nerves to the spinal cord
Describe transmission stage of nociceptive pain
movement of impulses along spine via complex array of event including more chemical signals with glutamate and substance P
Describe perception stage of nociceptive pain
signals are received by the thalamus which acts as a relay station to structures that sense pain and make it a conscious experience
Describe modulation stage of nociceptive pain
descending pathways signals can either be made stronger with glutamate or substance P, or can be inhibited by endogenous opioids, GABA, NE, and 5HT
How is neuropathic different nociceptive pain
no noxious stimuli
results of damage or abnormal functioning of the PNS +/- CNS
What is the two main type of neuropathic
peripheral nerve injury
central nerve system injury
Describe peripheral neuropathic pain
arises from - peripheral nerves
described as - sharp shooting/radiating tingling, burning, freezing, itching
localization - generally localized with shooting/radiation up the nerve fibre
examples - Post-herpetic neuralgia, diabetic peripheral neuropathy, chemotherapy-induced neuropathy
Describe central neuropathic pain
arises from - central nervous system
described as - sharp shooting/radiating tingling, burning, freezing, itching
localization - poorly localized
examples - Post-ischemic stroke, multiple sclerosis
Describe the three steps of nociplastic pain
tissue or nerve damage
pain circuits rewire themselves
chronic pain
Describe tissue or nerve damage of nociplastic pain
Tissue damage or nerve damage may cause both peripheral and/or central changes in neurotransmission
PLUS predisposing risk factors: family history of pain, history of recurrent pain, mental health disorders, abuse/trauma, and many others not yet fully understood
Describe pain circuits rewire themselves of nociplastic pain
Neuroplasticity (rewiring of anatomical/biochemical nerve systems)
Produces a mismatch between pain stimulation/inhibition
Increases discharge of dorsal horn neurons
Describe tissue or nerve damage of nociplastic pain
Patient presents with episodic or continuous pain transmission, hyperalgesia, dysesthesias, and allodynia
Ongoing pain generator is not found
Pain is often widespread and/or migrating
What should you know about acute pain
Typically < 3-6 months
Due to tissue damage signaling harm or potential for harm
Serves a useful purpose (adaptive)
Often due to an identifiable cause
Common causes: surgery, acute illness, trauma, labour, medical procedures
Usually nociceptive, sometimes neuropathic
May outlive its biologic usefulness and have negative effects
Poorly treated, can increase risk of chronic pain syndromes, including nociplastic pain (maladaptive)
Assessment of Pain
Important to identify and treat acute pain effectively
pain management is most effective when validated and accurate pain assessments are carried out
What does PQRSTU stand for?
Provocative
palliative
quality
quantity
region
radiation
severity (scale)
timing
treatment
understanding
Acute Pain Tx Approach
Assess patient thoroughly, in collaboration with diagnostician(s)
Compare, contrast, and select treatment (therapeutic thought process)
Select the most effective analgesic with fewest ADEs/risk
Lowest dose for shortest duration, around the clock for first few days then prn
Identify non-pharm and interdisciplinary resources
Educate patient, including setting expectations
Communicate with others and document plans, including preparing for periods of transition (e.g., discharge from hospital, opioid exit strategy)
What is the Goal of Therapy for acute pain
primary goal depends on type of pain present and should be tailored to individual patient and circumstance
prevent or minimize ADEs
improve quality of life
List some non-pharmacologic therapies
education
distraction & relaxation
RICE
cold (<48 h)
heat (>48 h)
positioning
immobilization
massage
acupuncture
exercise
TENS (transcutaneous electrical nerve stimulation)
Risk Assessment for NSAID GI Toxicity
High Risk
- history of complicated ulcer especially recent or multiple (>2) risk factors
Moderate Risk (1-2 risk factors)
- older age >60 years
-NSAID use - high dose or multiple agents
- history of uncomplicated ulcer
-use with ASA, steroids, SSRIs
Low risk
- no risk factors