Pain Management (KEY POINTS) Flashcards
Describe somatic pain
Arises from skin, bone, joint, muscle, or CT
Throbbing, well localized
Describe visceral pain
Arises from internal organs s/a intestine or pancreas
Localized or referred pain
What are the free nerve endings (nociceptors) stimulated by?
Mechanical, thermal, & chemical impulses
What fibers = large diameter? What do they evoke?
Myelinated Aδ fibers
Sharp, well-localized pain
What fibers = small diameter? What do they evoke?
Unmyelinated C fibers
Dull, aching, poorly localized pain
How is pain modulated by the body?
Endogenous opiate system
Blockage of N-methyl-D-aspartate (NMDA) receptors
The endogenous opiate system contains what receptors?
μ, δ, and κ
The CNS also contains a highly organized…
descending system for control of pain transmission.
What NTs in the CNS are involved in pain control?
Endogenous opioids
Serotonin
NE
GABA
What functions can modify pain?
Cognitive & behavioral
What type of changes in our neurobiochemical makeup can worsen pain?
Depression & anxiety
What is inflammatory pain?
The body shifting from: preventing tissue damage –> promotion of healing
What does the inflammatory process lead to?
Reduced pain threshold
Injured area becomes more sensitive to pain
Decreased movement
What is inflammatory pain associated with?
Increase in excitability or responsiveness of neurons within the CNS (central sensitization)
What are major causes of hypersensitivity to pain after injury?
Peripheral & central sensitization
Neuropathic pain is a result of…
nerve damage
What can be thought of as an abnormal operation of the nervous system?
Functional pain
How is neuropathic & functional pain described?
Burning, tingling, shock-like, shooting
Hyperalgesia (painful response to noxious stimuli)
Allodynia (painful response to normally nonnoxious stimuli)
Which type of pain often manifests long after the actual nerve-related injury or when no actual injury is identified?
Neuropathic & functional pain
What are non-pharm therapies in acute & chronic pain?
Physical manipulation Heat or cold Massage Exercise TENS Cognitive, behavioral, social
What is the tx goal in acute vs chronic pain?
Acute = pain reduction
Chronic = functionality
What are sx of acute pain?
Sharp, dull, shock-like, tingling, shooting, radiating
Flunctuates in intensity, varies in location
Occurs in a timely relationship w/ a noxious stimuli
Describe chronic pain
Can appear to have no noticeable suffering
Attention to mental/emotional factors that alter the pain threshold
What are sx of chronic pain?
Sharp, dull, shock-like, tingling, shooting, radiating
Flunctuates in intensity, varies in location
Occurs w/out a temporal relationship w/ a noxious stimuli
What are non-opioid analgesics?
Salicylates: ASA,
Choline & Mg trisalicylate
Acetaminophen
Ibuprofen
Ketorolac (Pyrrolacetic acid)
Celecoxib (Cox2 selective)
What is the max daily dose of ibuprofen?
3200mg - inflammatory
1200mg - analgesic/fever/dysmenorrhea
How is ketorolac administered?
Parenterally
In cardiac pts where low dose ASA is indicated, when should celecoxib be given?
After the ASA dose
What are 2 ADEs of NSAIDs?
Upper GI bleed
Acute renal failure
What should you monitor in pts taking NSAIDs?
CBC
Guaiac (if black tarry stools)
Serum creatinine
What is an ADE of acetaminophen?
Hepatotoxicity
What should you monitor in pts taking acetaminophen?
Transaminases (ALT/AST)
Liver tests (PT/INR, albumin)
Acetaminophen [ ]
When are NSAIDs/acetaminophen/ASA used?
Mild-Mod pain
What drugs are phenanthrenes?
Morphine
Hydro-morphone/codone
Oxy-morphone/codone
Codeine
What are characteristics of both morphine and codeine?
Naturally occurring
Histamine release
What is the drug of choice for severe pain?
Morphine
When do you use codeine?
In mild-mod pain & cough suppression
What does codeine depend on for metabolism to morphine?
CYP450 2D6
When do you use hydrocodone & oxycodone?
Mod/severe pain
What drugs are phenylpiperidines? (used in severe pain)
Meperidine (Demerol)
Fentanyl (Sublimaze, Duragesic, Actiq)
What is a contraindication of meperidine?
Renal failure
What are ADEs of meperidine?
Tremors, myoclonus, seizures
Mydriasis
What is meperidine’s active metabolite?
Normeperidine
When should you NOT use fentanyl transdermal?
Acute pain
What drug is a diphenylheptane?
Methadone
What drug causes QT prolongation?
Methadone
Titrations of methadone should be avoided more frequently than…
every 2 wks
What drugs are agonist-antagonist or partial agonists?
Pentazocine
Butorphanol
Nalbuphine
Buprenorphine (Butrans, Subutex)
What are characteristics of buprenonorphine?
2nd line for mod-severe pain
Detailed dosing conversion
Must complete training to Rx
Buprenorphine may precipitate…
withdrawal in opiate-dependent pts
Is naloxone effective in reversing resp. depression?
May not be
What are central analgesic?
Tramadol*
Tapentadol
What are ADEs of opioids?
Resp. depression
Constipation
Sedation (decreases over time)
N/V (decreases over time)
Who is at higher risk of developing resp. depression when taking opioids?
OSA
COPD
What is an opioid antagonist?
Naloxone (Narcan)
What is important to know about pregabalin (Lyrica) ?
Exerts antinociceptive & anticonvulsant activity
What adjunctive therapies are available for chronic pain?
TCAs, SSRIs, SNRIs (topical)
Duloxetine (Cymbalta)
What is the MOA of duloxetine?
Potent inhibitor of serotonin & norepinephrine reuptake
What are NSAIDs & skeletal muscle relaxants recommended for?
Acute low back pain
What are 1st line & 2nd line agents for chronic low back pain?
1st = NSAIDs 2nd = Duloxetine & tramadol
What is NOT recommended for tx of fibromyalgia?
Opioids!
What drugs are rarely effective for neuropathic pain?
Acetaminophen & NSAIDs
What is a true allergy? Give an examples.
IgE-mediated or T-cell mediated
Ex. bronchospasm
Is angioedema a true allergy?
Usually, but pseudoallergy is also possible
What is pseudoallergy? What causes it?
Common rxn to opioids
Histamine release, a nonimmunologic effect
What are sx of pseudoallergy?
Itching, flushing, sweating
