Pain Flashcards
Is pain limited to actual tissue damage?
Nope… Can be “potential tissue damage” as well.
1 / __ people over the age of 65 in Canada deal with chronic pain.
1/3
How can pain manifest into negative outcomes on one’s life?
-Decreased QOL
-Mental Health Toll
-Increased Suicide Risk
-Reduced Cognitive Function
-Work / School Absence
Define Nociceptive Pain.
-Caused by bodily tissue damage.
-Described as “sharp”, “aching”, “throbbing” pain.
-Can arise from direct tissue injury, disease, inflammation.
Define Neuropathic Pain.
-Caused by direct damage to the Nervous System.
-Typically originates in the Peripheral Nervous System (can be Central).
-Numbness, tingling, burning, shooting or radiating pain.
Define Nociplastic Pain.
-Caused by functional Neuron changes (as opposed to direct nervous system damage).
-Description of the pain is similar to Neuropathic.
Is Visceral (ie. Internal Organ) Nociceptive Pain typically localized?
Nope… Hard to localize where the pain is coming from. Somatic Nociceptive Pain is much more easily localizable.
What are the fast nerve fibers (as it pertains to nociceptive pain conductance)? Slow nerve fibers?
Fast: A-Delta
Slow: C
What is the brain’s relay station in the Ascending Nervous System?
Thalamus
What substances strengthen electrical pain signals coming down from the Descending Neural Pathway? Inhibit pain signals?
Strengthen: Substance P, Glutamate
Inhibit: GABA, NE, Serotonin, Endogenous Opioids
Nociceptor activation involves Voltage-Gated ___+ Channels.
Na+
Given that A-Delta nerves are fast, what type of pain would you expect them to respond to?
Sharp, Localized Pain
Given that C nerve fibers are slow, what type of pain would you expect them to respond to?
Achy, Poorly Localized Pains
Within what part of the Spinal Cord do we see A-Delta & C nerve fiber synapses? What excitatory neurotransmitters are released here?
Dorsal Horn; Glutamate & Substance P.
N-Type Voltage-Gated __+ Channels regulate the release of excitatory neurotransmitters at the Dorsal Horn of the Spinal Cord.
Ca2+
What would be some examples of conditions that cause Peripheral Neuropathic Injury? Central Neuropathic Injury?
Peripheral: Post-Herpetic Neuralgia, Diabetic Neuropathy, Chemo-Induced Neuropathy.
Central: Post-Ischemic Stroke, MS.
Is Neuropathic Pain associated with a noxious stimuli?
Nope!
Nociplastic Pain is defined by the term “_________”, (ie. Nervous System Rewiring) which causes mismatched pain stimulation / inhibition & leads to increased firing of Dorsal Horn Neurons.
neuroplasticity
What would be examples of predisposing risk factors for somebody who might experience Nociplastic Pain?
-Family Hx Pain
-Hx Recurrent Pain
-Mental Health Disorder
-Abuse / Prev. Trauma
What is the typical duration (in mths) of Acute Pain?
< 3 - 6mths
Acute Pain is typically what form of pain (ie. Nociceptive / Neuropathic / Nociplastic)?
Nociceptive, sometimes Neuropathic
What are some systemic responses to Acute Pain?
-HTN
-Tachycardia
-Sweating
-Pupillary Dilation
-Skin Whitening
What are some potential signs one might be experiencing Cauda Equina Syndrome?
-Bladder / Anal Sphincter Dysfunction
-Neurologic Dysfunction in Legs
-Major Motor Weakness in Lower Extremities
-Saddle Anesthesia
What other red flags associated with back pain would warrant automatic referral?
-Presence of possible infection (ie. Patient experiencing chills / has fever).
-Back pain beyond 3mths in length; AM Stiffness > 30mins; Night Pains (possible inflammatory condition).
-Severe pain lying down / worst at night (possible cancer).
-Major trauma present (possible fracture).
What are some “Yellow Flag” symptoms with back pain?
-Pain is perceived to be “harmful” or “severely disabling” to patient.
-Avoiding movement / activity.
-Withdrawal from social interactions / low mood.
Within 48hrs of an acute injury, is cold or heat best?
Cold; Heat beyond 48hrs.
Do Passive methods of Non-Pharm Therapies (ie. Acupuncture, Massage, Physio) work best for Chronic or Acute Pain management?
Acute > Chronic
What is the proposed MOA of Acetaminophen?
Inhibit Prostaglandins (Central), block pain impulse generation (Peripherally).
Outright CIs to Acetaminophen?
1) Ace-Induced Liver Dx
2) Allergy to Ace
Adverse effects of Acetaminophen?
-Hepatotoxic
-Increase BP (3-4mm Hg)
-Neutro / Thrombocytopenia (rare)
Maximal daily intake of Ace?
4g / day
Pediatric Tylenol Weight-Based Dosing?
10 - 15mg / kg / dose q4-6hrs
DO NOT EXCEED 75mg / kg / day!!!
If a patient is on chronic Ace usage for pain management, what should we drop the daily intake value to? If Cirrhosis / Chronic Alcohol Use Disorder?
Chronic Use: 3200mg/d
Cirrhosis / CAUD: 2600mg/d
MOA of NSAIDs?
Inhibit COX1 / COX2 enzymes, so less PG precursor formation.
Which COX enzyme does Celecoxib inhibit?
COX2
CIs of NSAIDs?
-CrCl < 40mL / min
-Hyperkalemia
-Liver Impaired / Cirrhosis
-Gastric Ulcers
-Unctrl’ed HF
-MI
-Thrombocytopenia
-Transplant
Who do we caution NSAID use in?
-Asthmatics
-CVD / HTN
-Perioperative Pt.’s (must d/c prior to surgery as bleed risk is elevated)
T or F: COX1 / COX2 inhibition via Aspirin is irreversible.
True!
At the following doses, state Aspirin’s role:
< 300mg / day
300 - 2400mg / day
2400 - 4000mg / day
< 300mg / day: Platelet Aggregation Reductions
300 - 2400mg / day: Antipyretic / Analgesic (need 325 - 650mg q4h prn)
2400 - 4000mg / day: Anti-Inflammatory
Maximal daily intake of Aspirin?
4g / day (same as Tylenol)
Other name for Aspirin / ASA?
Entrophen
CI to Aspirin?
-NSAID Hypersensitivity
-CrCl < 40mL / min
-GI Ulcers
Signs of Aspirin toxicity?
-Tinnitus
-Vertigo
-Hyperventilation
-Resp. Alkalosis
-Hyperthermia
-Coma
What is the precursor molecule required for Prostaglandin & Thromboxane synthesis?
Arachidonic Acid
Thromboxanes are only synthesized by ____ (COX1 or COX2).
COX1 (COX2 is exclusively in PG synthesis).
Diclofenac, Ketorolac, & Naproxen all demonstrate relatively more _____ (COX1 or COX2) selectivity.
COX2
Ibuprofen, Aspirin, and Ketoprofen all demonstrate relatively more _____ (COX1 or COX2) selectivity.
COX1
Which NSAID demonstrates the greatest degree of GI Toxicity?
Ketorolac (aka Toradol)
What is the OTC daily intake limit for Ibuprofen? Rx daily intake limit?
OTC: 1200mg / day
Rx: 2400 - 3200mg / day
Why do we typically limit Toradol usage to five days?
Increased GI bleed risk!
Explain why Aspirin is cardioprotective in comparison to NSAIDs (which demonstrate cardiac risk).
-TXA2 (from COX1 pathway) = Platelet Aggregating & Vasoconstrictive; Prostacyclin (from COX2 pathway) = Platelet Inhibitor & Vasodilatory.
-Aspirin = More COX1 selective… Means Prostacyclin production is in excess of TXA2 (promoting vasodilation & inhibited platelet aggregation).
Why does Celecoxib demonstrate increased cardiac risk?
COX2»_space;> COX1 Inhibition… Suppressing Prostacyclin production, TXA2 production greatly in excess, leads to vasoconstriction & promotion of platelet aggregation (opposite of Aspirin).
What is the most cardio neutral NSAID?
Naproxen (at daily doses < 750mg / day)
Does low dose Celecoxib (ie. < 200mg / day) still demonstrate increased cardiac risk?
Nope… Is neutral. At doses above 200mg / day we see increased risk (dose related).
What other mechanisms (despite vasoconstrictive properties of TXA2) see NSAIDs invoking cardiac risk?
-Reduced Renal Blood Flow
-Increased Na+ / H2O Reabsorption
What can be given to NSAID users in order to reduce potential GI toxicity?
Misoprostol / PPIs
Combo Products:
-Arthrotec (Diclo & Miso)
-Vimovo (Nap & Eso)
Joan is a 65yr old woman, Post-MI patient. She’s on DAPT (ASA 81mg OD & Ticagrelor 90mg BID) as per post-surgical protocol, and before her hospital placement routinely utilized Ibuprofen 600mg q6h (typically takes 2.4g / day) for osteoarthritic pain management. What is her GI toxicity risk score (Low, Mod, High)?
High… Age > 60yrs (1), CVD from her recent heart attack (2), Concurrent ASA use from her DAPT (3), High Dose Ibuprofen (4).
-Any body with 2 or more moderate risk factors is high risk. She has four!
Greg is a 50yr old male with acute lower back pains. He is wanting OTC analgesic pain relief for it. You do some probing to assess GI Toxicity risk and find out he’s not on any other medications, has a history of uncomplicated ulcers and no CVD history. What is his GI toxicity risk score (Low, Mod, High)?
Moderate (due to history of Uncomplicated Ulcers). If he had a history of Complicated Ulcers, would automatically jump up to High Risk.
Best NSAID in High CV Risk, Mod GI Risk patients?
Naproxen (+ PPI or Misoprostol recommended)
What are the “Triple Whammy” drugs that invoke high degrees of Renal damage?
1) NSAIDs (constrict Afferent Arteriole)
2) ACEi / ARB (dilate Efferent Arteriole)
3) Loop Diuretics (Volume Depletion)
Detectable increases in serious CV related events due to Celecoxib administration takes place at doses of ____ mg BID.
200mg BID (400mg / day)
Concurrent NSAID / COXIB use with ______, _____, _____, ______, & ______ can increase these drug’s toxicity risks.
Lithium, MTX, Corticosteroids, Tenofovir, Warfarin
In addition to Warfarin, Heparin & Corticosteroids, what other drug class can we see increased GI bleed risk with co-admin of NSAIDs / COXIB drugs?
SSRIs
In Trimester 1, what types of problems can arise with NSAID / COXIB administration?
Birth Malformations & Miscarriage
In Trimester 3, what problem can arise with NSAID / COXIB use?
Premature Closure of Ductus Arteriosus
What pain drug has some pregnancy-related indications?
Low Dose Aspirin
Proven to be safest OTC pain drug during pregnancy & lactation?
Acetaminophen
If somebody is breastfeeding, what are suitable NSAIDs to use for pain?
Short t1/2 NSAIDs (ie. Ibuprofen, Diclofenac)
Which NSAID is an outright CI for those who have breastfeeding?
Ketorolac
Are muscle relaxants more efficacious than Ace / NSAIDs for treating acute low back pain?
Nope!