8 - Pain 1 Flashcards
What is pain?
Unpleasant sensory and emotional experience associated w/ actual or potential tissue damage
What causes nociceptive pain?
Activation of pain pathways by ongoing tissue damage
What are the subcategories of nociceptive pain?
- Somatic
- Visceral
What is somatic pain?
- Pain arising in tissues of the body
- Sharp, sometimes burning, aching
What are examples of somatic pain?
- Osteomyelitis
- Osteoarthritis
- Bone fracture
What is visceral pain?
- Pain arising in organs of a body cavity
- Deep, aching, cramping, poorly localized
What are examples of visceral pain?
- Endometriosis (pelvis)
- Crohn’s disease (abdomen)
- Angina (thorax)
Can visceral pain be managed w/ OTC products?
No, so require referral
What causes neuropathic pain?
- Direct nerve damage
- Abnormal processing of a pain signal in CNS pain pathways
What is neuropathic pain generally described as?
Burning, tingling, shock-like, or shooting pain
What are some examples of neuropathic pain?
- Diabetic neuropathy
- Post-herpetic neuralgia
- MS
- Phantom limb pain
What is hyperalgesia?
When a stimulus that would normally cause discomfort causes significant pain
What is allodynia?
Pain due to stimulus that doesn’t normally evoke pain
What is phantom pain?
Pain in a limb that is no longer there
What is the difference between acute, sub-acute, and chronic pain?
- Acute lasts 2-4 weeks
- Sub-acute lasts 4-12 weeks
- Chronic lasts longer than 12 weeks
What is break-through pain?
- A temporary increase in pain greater than moderate intensity that occurs on a baseline pain of moderate intensity or less
- Ex: px after surgery that is on an analgesic has a dressing change
What is incident pain?
Type of breakthrough pain that is made worse by movement
What tools can be used to assess pain?
- Numerical rating scale (appropriate for adults)
- Visual analogue scale (horizontal line w/ left side meaning no pain and right side meaning worst pain)
- Wong-Baker FACES pain rating scale (appropriate for children and px that don’t speak english)
What is the most accurate evidence of pain/intensity?
Px description and self-reporting
What are the 4 main pieces essential to pain information gathering?
- Severity of pain
- Location of pain
- Onset and how long pain lasts
- Quality of pain (description– dull ache, sharp pain, tingling or burning)
What is OTC pain medication effective at treating?
- Mild to moderate somatic pain from skin, muscles, and joints
- Dysmenorrhea
- Headache
Are OTC pain meds effective in tx neuropathic pain?
For some px
What are the types of OTC pain meds?
- NSAIDs (ibuprofen, ASA, naproxen)
- Non-anti-inflammatory analgesics (acetaminophen)
- Opioids (codeine 8 mg)
- Other (caffeine, muscle relaxants, topical counter-irritants)
How does acetaminophen prevent pain?
- Central inhibition of prostaglandins
- Peripherally blocks generation of pain impulses
What is acetaminophen a first line therapy for?
- Mild to moderate pain (low back pain, osteoarthritis, some headaches)
- Fever
What is the duration of acetaminophen?
4-6 hours
When does acetaminophen produce a ceiling effect?
Over 1000 mg
What can contribute to acetaminophen toxicity?
- Overdose
- Disease and lifestyle issues (hepatitis, cirrhosis, chronic alcohol use, binge drinking)
What is the minimum toxic single dose of acetaminophen in a healthy adult and in children?
- 7.5-10 g in adults
- 150 or more mg/kg in children
- Over an 8 hour period
What are the sx of acetaminophen overdose?
- Early sx = N/V, drowsiness, confusion, sweating
- Biochemical evidence of liver damage after 24-48 hours
- Hepatic damage may not be apparent for 4-6 days
Why can alcoholism lower the threshold for acetaminophen liver damage?
- Possible induction of enzymes
- Hepatic dysfunction
- Decreased stores of glutathione
Severe liver damage may occur in adults who drink ___ alcoholic drinks/day while taking acetaminophen
3 or more
What are the pharmacological properties of NSAIDs?
- Analgesic
- Anti-platelet
- Anti-pyretic
- Anti-inflammatory
Is ASA a first line analgesic?
No
What is the mechanism of ASA?
Works primarily in periphery (anti-inflammatory)
What is the same and different btwn acetaminophen and ASA?
- Equally effective
- ASA has higher side effects (gastric irritation, nausea)
What is the dosing of ASA?
- 325-650 mg q4-6h
- Max 4g/ 24 h
What are some adverse effects of ASA?
- Abdominal pain w/ cramps
- Heartburn
- Dyspepsia
- GI irritation
What are the contraindications for ASA?
- Under 18 y/o
- Active GI lesions
- History of recurrent GI lesions
- Bleeding disorders
- Hypersensitivity
- Px relying on vasodilatory renal prostaglandins for renal function
What types of pain is ibuprofen indicated for?
- Minor pain
- Headache
- Common cold
- Toothache
- Fever
- Dysmenorrhea
How long does the analgesic effect of ibuprofen last?
6-8 hours
Can ibuprofen be given to a px w/ an ASA allergy?
No
Can naproxen be given to a px w/ an ASA allergy?
No
Mucosal damage through NSAID use is primarily a consequence of _____
COX-1 inhibition
Which px are at high risk of GI intolerability of NSAIDs?
- Peptic ulcer disease
- GI bleeds or perforation
- Concomitant alcohol
NSAIDs should always be taken w/ ____
Food
How can ASA cause damage to GI mucosa?
- Local irritant effect from drug contacting gastric mucosa
- Systemic effect from prostaglandin inhibition
What are some risk factors for upper GI bleeding?
- 60 y/o or older
- Concomitant use of alcohol
- Concomitant use of other NSAIDs, anticoagulants, antiplatelets, bisphosphonates, SSRIs, or systemic corticosteroids
- History of uncomplicated or bleeding peptic ulcer
- Rheumatoid arthritis
What affects do enteric coated forms of ASA have on the GI?
- Reduce risk of mucosal lesions and local irritation
- Don’t reduce risk of major GI bleeding
What are signs of GI bleeding?
- Black, tarry stool
- Blood in vomit
- Blood in stool
What are prostaglandins important for?
Maintenance of renal blood flow and tubular transport of electrolytes
When does prostaglandin release increase?
In response to increased levels of angiotensin 2 and norepinephrine
What is an important drug-drug interaction w/ NSAIDs?
Anti-hypertensive agents (ACE inhibitors, diuretics, beta blockers)
Which px are at risk of renal failure when using NSAIDs?
- Volume depletion states (dehydrated)
- Severe congestive heart failure
- Hepatic cirrhosis
- Creatinine clearance less than 30 mL/min
What is ASA-induced asthma?
Onset of asthma 30 mins to 3 hours post ingestion of ASA
Which px is ASA-induced asthma common in?
Asthmatics w/ concomitant allergic rhinitis or nasal polyps
What is the proposed mechanism for ASA-induced asthma?
Decreased prostaglandins causes increased leukotrienes
Can acetaminophen be given to px w/ ASA allergy?
Yes, but no more than 1g/day
What is white willow bark?
Natural health product similar to ASA
Can a COX-2 selective inhibitor (ex: celebrex) be used in px w/ ASA allergy?
Doesn’t affect levels of prostaglandins, so shouldn’t be a problem, but monitor closely
Which NSAIDs inhibit platelet aggregation?
ASA and ibuprofen
How long before surgery should ASA be discontinued? Why?
1 week to decrease risk of bleeding during and after surgery
How long before surgery should naproxen and ibuprofen be discontinued?
- Ibuprofen = 24 h
- Naproxen and other NSAIDs besides ASA = 3 days to err on side of caution
What is an important drug-drug interaction w/in the NSAID class?
- Regular use of ibuprofen 400 mg may interfere w/ cardioprotective effect of low dose ASA when taken at the same time
- Ibuprofen also has effect on naproxen
What should be done if ibuprofen must be taken w/ low dose ASA?
Take ibuprofen at least 2 hours after ASA/naproxen
What can happen if warfarin and ASA are taken together?
Increased INR and bleeding risk
What can happen if warfarin and ibuprofen/naproxen are taken together?
- No effect on INR
- GI irritation, so increased risk of bleeding
When is acetaminophen considered a first line therapy?
- ASA-sensitive asthma
- Gastritis or PUD
- Increased risk of bleeding
- Px w/ renal dysfunction
- CV or hypertensive px
- Multiple concurrent drug therapy
- Pregnant or breastfeeding (esp. 3rd trimester)
What is the active analgesic metabolite of codeine?
Morphine
How is codeine use preferred?
Short term, as adjunctive therapy
When should a px be referred who is taking codeine?
If no benefit for moderate pain in 2-3 days
What effect does caffeine have as an analgesic?
Enhances analgesic effects of ASA and acetaminophen
What is the recommended tx for pain that is 1-4 (mild to moderate)?
- Acetaminophen, ASA, ibuprofen, or naproxen at OTC doses
- Monitor according to type of pain and agent selected
What is the recommended tx for pain that is 4-8 (moderate to severe)?
- Consider addition of codeine combination or alternative (2-3 days)
- May need to switch to T3 or tramadol (weak opioids)
What is the recommended tx for pain that is 8-10 (severe)?
- Refer depending on acute/chronic situation, px history, and red flags
- Likely requires stronger opioids
What are some general red flags for pain?
- Escalating
- Unresponsive to appropriate therapy
- Severe
- Px is pregnant
- Px uses concurrent therapies or has other illnesses
Why shouldn’t medications be mixed in a bottle of milk or formula?
If child doesn’t finish the entire bottle then you don’t how much medication they received
What is thought to occur after a migraine is triggered?
- Dilation of intracranial and extracerebral blood vessels
- Activation of trigeminal sensory nerves
- Leads to pain signals in brain
An aura is thought to be due to ____
Neuronal dysfunction
How long do auras typically last? How long after an aura will a migraine occur?
- Typically last less than 1 hour
- Migraines occur w/in 60 mins of aura ending
What is the potential pathophys of tension headaches?
Thought to occur due to mental stress and tension
What is the location for a tension headache, migraine headache, and cluster headache?
- Tension = bilateral
- Migraine = mainly unilateral, can spread to bilateral
- Cluster = only unilateral
What is considered a chronic tension headache?
Headaches on 15 or more days per month
Which products most often cause medication-overuse headaches?
- Caffeine and/or opioids
- Acetaminophen or ASA
What are the sx of medication-overuse headaches?
Mimic tension headaches
What is the tx for medication-overuse headaches?
- Discontinue implicated drugs
- Relieve withdrawal sx
- Tx recurrent headaches w/ appropriate Rx migraine therapies (so would refer)
What are red flags for headaches?
- Severe or abrupt onset
- Age of onset over 40 y/o
- Recent head trauma
- Medication-overuse
- Progressive severity and/or increased frequency
- Neurological signs or symptoms (stiff neck, fever, reduced consciousness)
- Systemic sx
- Nocturnal occurrence
- Onset w/ exercise or exertion
- Chronic tension headaches
What are some non-pharms for migraine headaches?
- Cryotherapy
- Relaxation techniques (quiet, dark room, sleep)
- Massage, acupuncture
- Stress management
- Exercise (helps some, worsens others)
- Avoid triggers
When are OTCs used for migraines headaches?
Px w/ mild to moderate migraine pain
When is Rx therapy required for migraine headaches?
- OTC doesn’t work
- Tx being used more than 15 days per month
What are the Rx options for migraines?
- Acute tx w/ triptans (sumatriptan, zolmitriptan)
- Prevention (propranolol, amitriptyline)
What should be monitored w/ headaches?
- Relief of pain w/in 2 hours after taking medication
- If additional sx present, relief of those sx should also occur in that time
