16 - Intro to Pain Flashcards
List the 3 types of pain
Neuropathic Pain
Nociceptive Pain
Mixed Pain
Describe Neuropathic pain
Pain initiated or caused by a primary lesion or dysfunction in the nervous system (either peripheral or CNS)
Describe Nociceptive pain
Pain caused by injury to body tissues (MSK, cutaneous or visceral)
Describe Mixed pain
Pain with neuropathic and nociceptive components
Examples of neuropathic pain
- postherpetic neuralgia
- trigeminal neuralgia
- diabetic peripheral neuropathy
Common descriptors of neuropathic pain
- burning
- shooting
Examples of mixed pain
- lumbar radiculopathy
- cervical radiculopathy
- cancer pain
Examples of nociceptive pain
- pain due to inflammation
- limb pain after a fracture
- joint pain in OA
- postoperative visceral pain
Common descriptors of nociceptive pain
- aching
- sharp
- throbbing
List examples of pain that don’t fit into a previously listed category
- migraines
- tension headaches
- fibromyalgia
- interstitial cystitis
What is the goal in acute pain?
pain reduction
What is the goal in chronic pain?
functionality
What is the PQRST mnemonic ?
P: Provoking/preciptates?
-What brings it on and takes it away?
Q: Quality
-In the patient’s own words (prompt only if necessary - ex. dull, sharp, stabbing, burning, etc.)
R: Radiation, referral
- Does the pain move to another spot?
- Are there other symptoms associated with the pain (ex. nausea, SOB)
S: Severity
-Rate the pain on a scale of 1-10
T: Timing
- When did it start?
- Has it occurred before?
- Is it constant or does it come and go?
What is the problem with using exogenous opioids chronically?
we sacrifice normal healthy motivational behaviours, socialization & coping
What are some key questions to ask for pain?
- How does the patient look and mobilize?
- Are they able to perform valued activities?
- Are they dysphoric, irritable, depressed?
- How are they sleeping?
- Do they feel well enough to socialize?
- Are they enjoying life?
Acetaminophen:
Dose?
325-1000mg q4-6h
Acetaminophen:
Onset?
15-30 mins
Acetaminophen:
Max dose?
3-4g/day depending on age
Acetaminophen:
SE?
liver toxicity in high doses
*avoid with warfarin
Effectiveness:
Acetaminophen or Ibuprofen for headache?
same
Effectiveness:
Acetaminophen or Ibuprofen for post-dental surgery?
ibuprofen better
Effectiveness:
Acetaminophen or Ibuprofen for OA?
NSAIDs better for pain and function
Effectiveness:
Acetaminophen or Ibuprofen for back pain?
no effect vs placebo
Main concern with acetaminophen ?
hepatotoxicity
> 50% of serious liver injury associated with ________ overdoses
unintentional
Up to 1/5 of acetaminophen related liver injuries reported to Canada Vigilance mention doses of ?
<4 g/day
*but in many of these cases, patients had identifiable risk factors for acetaminophen liver injury (ex. alcoholism or viral liver disease)
______ stores are responsible for taking care of tylenol toxicity
glutathione
When should we decrease the daily dose to 3g/day ?
- Old age
- Poor nutritional status
- Fasting/anorexia
- *Lead to lower glutathione stores
Concurrent use of glucuronidation inhibitors and/or CYP2E1-inducing drugs (ex. phenobarbital, primidone, probably isoniazid, and possibly St. John’s wort). Chronic alcohol use
When is acetaminophen contraindicated?
severe hepatic impairment
Pros of NSAIDs
- Analgesic & anti-inflammatory
- More effective than acetaminophen for certain conditions
- Can be given topically (less systemic absorption)
- Many to choose from (10 different classes)
- Minimal differences in effect, a few differences in harms
- Ibuprofen & naproxen available OTC
Cons of NSAIDs
- No readily available injection
- Affects gut, kidneys, and heart
NSAID Harms:
What increases risk for GI event (ulcer or bleed) ?
- age > 65
- use of anticoagulants
- use of steroids
- history of PUD
- high dose of NSAID
- presence of H. pylori
NSAID Harms:
What can reduce the risk for GI bleed while on NSAIDs?
- PPI co-therapy
- celecoxib
- H. pylori treatment
- misoprostol cotherapy
NSAID Harms:
Any better than others for reducing renal event (AKI) ?
not likely
NSAID Harms:
What increases the risk for renal events (AKI) ?
- volume depletion
- CHF
- ACEi, ARB use
- renal disease, cirrhosis
- > 70 yrs old
NSAID Harms:
What are the NSAIDs that are worst for cardiac events?
- diclofenac
- high dose celecoxib
NSAID Harms:
What NSAIDs appear CV “neutral” ?
- low-dose naproxen (750-850 mg/day)
- ibuprofen (1200-2000mg/day)
- celecoxib (<200 mg/day)
NSAID Harms:
Again, absolute CV risk depends on other risks such as ?
- CHF
- CAD
- high risk for CVD (smoker, high cholesterol, etc.)
NSAID Effectiveness:
Is it effective for dental surgery?
Yes
- effective vs placebo
- more effective than acetaminophen
NSAID Effectiveness:
Is it effective for OA?
Yes
- effective vs placebo
- similar pain decrease vs opioids
- better vs acetaminophen for pain, global improvement & function
NSAID Effectiveness:
Is it effective for chronic low back pain?
similar pain decrease vs opioids
Advantage of topical NSAIDs?
Major adverse effects comparable to placebo!
-2-15% systemically available vs oral NSAIDs
(but if you’re rubbing it over entire back, you will increase systemic absorption)
Disadvantage of topical NSAIDs?
- local skin reaction
- stickiness
What strength of topical NSAID (diclofenac) commonly used?
diclofenac 1% - 1.5% solution or gel most commonly studied, dosed BID - TID
Does increase % work better?
- He usually starts with 2% and then goes to 4%.
- Apparently now pharmacare will only cover 4% or higher ?
Are topical NSAIDs effective vs oral NSAIDs for OA for hands and knees?
equal effectiveness
Topical NSAIDs for back pain, neuropathic or widespread pain ?
no evidence
Are topical NSAIDs effective for acute pain (sprains, strains overuse injuries) ?
Yes:
- diclofenac or ketoprofen vs. placebo
- > 50% pain relief
Pros of opioids ?
- Highly effective for some pain types (ex. nociceptive)
- High dose ceiling for effect (in some cases - maybe cancer pain?)
- IV/SC doses for improved access and quicker onset
Cons of opioids?
- Addiction
- Significant dose-related day to day side effects
- Threshold for serious toxicity can be low in some
- Tolerance, dependence, hyperalgesia
- Abuse potential
- Long term SE (dry mouth - cavities, androgen deficiency)
- Triplicate Rx
Ever recommend tylenol 1’s ?
No
- They will prob just take a bunch
- Increasing the amount of tylenol and caffeine they’re getting
- They might as well just take tylenol #3
What 2 opioids are not to be used for opioid-naive, and not go be used for Tx of acute pain ?
- Fentanyl patch
- Methadone
Morphine:
Caution with accumulation in ____ dysfunction
renal
Morphine:
Caution with _____
cirrhosis
Morphine:
Can cause ____ release and cause patient to get itchy
histamine
Oxycodone:
No _____ or _____ forms
liquid or parenteral
Oxycodone:
Big _____ value
street
- don’t see why we would ever use oxycodone
- no advantages over morphine and hydromorphone and there is a big street value
Hydromorphone:
Caution in renal dysfunction, but less so than ______
morphine
Hydromorphone:
Caution with _____
cirrhosis
Hydromorphone:
Less _____ release than morphine
histamine
If a patient is feeling itchy on morphine, what do you do?
switch to hydromorphone
Describe the switching of opioids
- not an exact science
- safer to under-dose at first
- 50-75% of the calculated amount
- use global RPH website is good
**Monitoring is important. For the next few days and who else can monitor them (ex. in hospital, at home, etc?)
Should you recommend muscle relaxants for low back pain?
No - may consider as add-on for muscle spasm
Should you recommend OTC muscle relaxants for pain relief ?
Don’t bother with OTC unless patient has a history of good overall effect
If you are recommending an Rx muscle relaxant, which one and for how long?
cyclobenzaprine - benefit in the first 4-7 days, may use up to 2 weeks
Common limitation of muscle relaxants ?
drowsiness
What are some other adjuvants for pain?
- Anti-epileptics
- TCAs
- SNRIs
- Local corticosteroid
What are SNRI’s used for?
primarily neuropathic pain, but also in migraine prevention, fibromyalgia, sciatic/radiculopathy, etc.
What are local corticosteroid injections used for?
Knee (for OA)
Epidural (for sciatica)
What are local anesthetics/analgesics used for?
epidurals, nerve blocks, topical
Explain the impact of pain triad ?
- Pain
- Depression, Anxiety
- Sleep issues
Describe the input and output of pain
Input:
- Cognitive
- Emotion
- Sensory
Output:
- Pain
- Motor
- Stress
- Emotion
Non-pharms for pain
- heat/cold
- physiotherapy
- massage
- exercise (help or worsen)
- chiropractic
- acupuncture
- yoga
- CBT
- music
What is the PQRST ?
P: Provokes, precipitates Q: Quality (dull, sharp, stabbing) R: Radiation, referral S: Severity T: Timing
Monitoring ?
- Pain diary
- Function
What can uncontrolled pain in elderly result in?
malnutrition, weight loss, decreased mobility, falls, fractures, decreased socialization, depression, anxiety, increased alcohol consumption
Approach to pain in the elderly ?
- vigilant dose titration, start low (1/2 of usual starting dose), go slow and review often
- caution with oral NSAID use: increased risk of GI bleed, CV & renal events (add PPI if ongoing use, monitor renal function, use topical instead if indicated)
- caution with opioid use
- do a 3-day tolerance check after starting
- ask if they’re constipated (will not go away with time)
- dizziness/balance
- ensure care support
- assess for sedation, imbalance, confusion, constipation
When should we caution opioid use?
- elderly
- increased fracture risk
- renal or hepatic impairment
- COPD and sleep apnea
- cognitive impairment
