Pain Management Flashcards

1
Q

Pathophysiology of Pain

Stimulation

A
  • Receptors (nociceptors) are activated by stimuli
  • May differ for different painful conditions
  • Neurotransmitters and ions are released:
    • Serotonin
    • Norepinephrine
    • Baradykinin
    • Prostiglandin
    • Histamin
    • Substance P
    • Neurokinin
    • Potassium and hydrogen
  • Release of these substance in the periphery “activates” further neurons reducing the threshold for further inputs
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2
Q

Pathophysiology of Pain

Transmission

A
  • Process by which pain signals ascend throught the spinothalamic tract
  • Primary neurotransmitters involved are:
    • glutamate/aspartate
    • substance P
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3
Q

Pathophysiology of Pain

Perception

A
  • the process that occurs in the cortex allowing an awareness of the experience of pain
  • nonpharmacological therapies are based on modifying the patient’s perception of his or her pain
    • CBT
    • meditation
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4
Q

Pathophysiology of Pain

Modulation

A
  • process of modification of pain signals
  • can occur through the ascending or descending pathway
  • endogenous systems of modulation include inhibitory neurotransmitters/receptors
    • Endogenous opioids
    • Blockade of NMDA (N-methyl-D-spartate)
    • Serotonin
    • GABA (Gamma- aminobutyric acid
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5
Q

Pathophysiology of Pain

Centralization or central sensitization

A
  • an amplification of pain signals originating in the periphery.
  • this amplification over time imprints or sustains the pain in the CNS
  • thought to explain pain syndroms such as phantom limb pain, reflex sympathetic dystrophy, and hyperalgesia
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6
Q

Pathophysiology of Pain

Allodynia

A

presence of pain from stimuli that are not normally painful

e.g. a patient with diabetes who experieces pain when placing socks on feet

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7
Q

Pathophysiology of Pain

Hyperalgesia

A
  • normal pain stimuli produce exaggerated pain responses in patients with peripheral or central sensitization
    e. g. an immunization in the deltoid muscles cuases patients to experience extreme pain for many days, preventing them from lifting their arm. The injection site has no obvious erythema or signs of an injection site reaction
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8
Q

Acute Pain

A

1) pain is typically a result of an acute disease process (may be part of an mixed disease process - acute or chronic) and is typically managed as a symptom
2) Pathophysiology is primarily inflammation
3) Treatment goals include cessation of pain or substantial relief
4) Anticipatory anxiety may be involved - patients are worried that pain will worsen or that pain will reoccur when medication wears off.

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9
Q

Chronic Pain

A

1) a physiologic cause may not be determinable. Chronic pain should be managed as an independant disease state with a monitoring and treatment plan apart from other plans
2) Most types of chronic pain are mixed - somatic and neuropathic
3) Treatment goals include a reduction in pain and an improved quality of life. Patients do not usually achieve remission of their pain. Realistic expectations should be discussed
4) Anxiety and depression are often (30-50%) comorbidities of pain. Most patients develop a tolerance to and dependence on medications

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10
Q

Acute Pain Management

Mild

A
  • manage with acetaminophen or NSAIDs
  • consider around the clock dosing
  • may require adjuvants in certain situations
  • monitor and reassess
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11
Q

Acute Pain Management

Moderate

A
  • manage with acetaminophen or NSAIDs in combination with low dose opioids
  • consider around the clock dosing
  • may require adjuvants in certain situations as well as potentially agents for breakthrough pain
  • monitor and reassess
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12
Q

Acute Pain Management

Severe

A
  • long acting opioid analgesics and combinations with breakthrough medications
  • around the clock dosing
  • may require adjuvants in certain situations as well as potentially agents for breakthrough pain
  • monitor and reassess - patients are at higher risk for adverse effects and require stricter monitoring
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13
Q

Chronic Pain Therapies

Arthritis

A

Pharmacotherapy:

  • first-line agents: acetaminophen, oral and topical NSAIDs, intraarticular steroids
  • Tramadol

Nonpharmacotherapy

  • aquatic, aerobic, and resistance exercise
  • weight loss
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14
Q

Chronic Pain Therapies

Diabetic Neuropathy

A

Pharmacotherapy:

  • primary goal - maintain diabetic control. Agent with highest level of evidence: Pregabalin - most common side effect weight gain
  • Second tier agents/therapy - all are considered acceptable agents with weak levels of evidence and showed a significant number of adverse effects in trials
    • Gabapentin
    • Duloxetine
    • Sodium valproate
    • Venlafaxine
    • Dextromethorphan
    • Morphine sulfate
    • Tramadol
    • Oxycodone
    • Capsaicin

Nonpharmacotherapy
- Percutaneous electrical stimulation

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15
Q

Diabetic Neuropathy adjuvants

Pregabalin

A

Dose: 300- 600mg

Common adverse effect: Sedation, weight gain

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16
Q

Diabetic Neuropathy adjuvants

Gabapentin

A

Dose: 1800 - 3600mg
Common adverse effect: Sedation, weight gain
Comment: dose should be reduced in renal dysfunction

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17
Q

Diabetic Neuropathy adjuvants

Duloxetine

A

Dose: 60-120mg
Common adverse effect: nausea, increase blood pressure, headache
Comments: Should not be used if CrCl<30; use with extreme caution with other serotonergic agents, rare LFT changes

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18
Q

Diabetic Neuropathy adjuvants

Venlafaxine

A

Dose: 75-225mg
Common adverse effect: hypertension
Comments: dose adjustment necessary if CrCl<50

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19
Q

Diabetic Neuropathy adjuvants

Desipramine, Nortriptyline

A

Dose: 25-150gm
Common adverse effect: Sedation, anticholinergic
Comments: Doses effective for pain may not be therapeutic for depression

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20
Q

Diabetic Neuropathy adjuvants

Topiramate

A

Dose: 50-200mg
Common adverse effect: Sedation, parasthesia, nopholithiases, secondary angle closure glaucoma, neurocognitive impairment, metabolic acidoses
Comment: titration by 25mg weekly will reduce work-finding difficulty and other neruocognitive effects

21
Q

Chronic Pain Therapies

Herpetic neuropathy

A

Pharmacotherapy - should e chosen on basis of comorbid conditions and location of the patient’s neuralgia

1) lidocaine patch
2) Duloxetine
3) Venlafaxine
4) Gabapentin
5) Pregabalin
6) Tricyclic antidepressants
7) Capsaisin 8% patch - Newer option
8) Opioids - short or long acting, depending on severity of pain

Nonpharmacotherapy
- current guidelines do not recommend nonpharmacotherapy

22
Q

Fibromyalgia

Diagnostic Criteria

A

1) Widespread pain index (WPI) of 7 or greater and symptom severity (SS) score of 5 or greater, or patients may have a lower WPI (3-6) if SS score is >9
2) Symptoms have been present for >3 months
3) There are not other diagnostic explanations for the pain/symptoms

WPI - - Number of anatomic areas with pain - scale ranges from 0-19

SS - patients are rated from 0-3 on fatigue, cognitive symptoms, waking unrefreshed and somatic symptoms. The final score is 0-12

23
Q

Fibromyalgia

Pharmacotherapy

A

1) Tramadol recommended for moderate to severe FM
2) acetaminophen or weak opioids can be considered
3) corticosteroids and strong opioids are not recommended
4) Antidepressants: amitryptyline, fluoxetine, duloxetine, milnapracin. Reduce pain and improve function
5) Pramipexole and pregabalin reduce pain

24
Q

Fibromyalgia

Nonpharmacotherapy

A
  • heated pool treatment with or without exercise is effective
  • patient specific exercise programs includine aerobic exercise and strength training (should be supervised to increase adherence and reduce injury)
  • CBT benefit to some patients. Strongest level of evidence among nonpharmacological therapies
25
Q

Chronic Back Pain

Risk factors

A

1) Obesity
2) Depression
3) Lifting associated with occupation

26
Q

Chronic Back Pain

Red Flags

A

symptoms of cauda equina syndrome or central canal spinal syndrome (medical emergency) - loss of bowel control

1) New-onset bladder incontinence
2) loss of weight
3) pain is worse at rest or in the middle of the night
4) new or worsening redicular symptoms - numbness or tingling
5) new-onset back pain in someone who is taking steroids or who has HIV
6) drop foot
7) focal neurologic deficitys

27
Q

Chronic Back Pain

Pharmacotherapy

A

1) !st line agents - acetaminophen and NSAIDs
2) 2nd tier agent - tramadol and long-acting opioids (should only be used for patients who are disables by their pain or not candidates for 1st line agents
3) Skeletal muscle relaxants are of limited benefit and have a high incidence of adverse effects, primarily their sedative properties
4) Patients with a neuropathic component involved my benefit from the addition of an SSRI or anticonvulsant. Duloxetine is approved for treatment of low back pain. Gabapentin has limited data to support its use.

28
Q

Chronic Back Pain

Nonpharmacotherapy

A

1) guidelines support the use of yoga, massage, acupuncture, relaxation, exercise and CBT
2) for patients who are obese, weight loss will improve outcomes.

29
Q

Tools for assessment of pain severity

A

1) Pain measurement: VAS
2) Brief Pain Inventory
3) McGill Pain Questionaire

30
Q

Pain measurement: VAS

A
  • 10cm line - patients indicate on where the line corresponds to their pain - yeild a number from 0-100
  • this scale may be difficult for some patients to understand
  • Pain numberic rating scale. 1-10 - Patients rank their pain. Patients become desensitized to this tool - “always a 20”
31
Q

Brief Pain Inventory

A
  • patients indicate on a diagram of the body wherey they experience pain
  • patients also rate the severity of their pain and the relief they obtain from currently prescribed agents.
  • this tool requires a higher education level
  • good for ongoing monitoring
32
Q

McGill Pain Questionaire

A
  • patients are asked to rate their pain and then choose descriptor works for their pain
  • this tool requires the patient to have a higher reading level
  • good for initial evaluation
33
Q

Testing methods for Chronic Opioid Therapy

Urine immunoassay

A

Advantages:

  • less expensive
  • longer detection window than serum
  • less invasive than serum

Disadvantages

  • May not detect all medications in class (e.g. synthetic opioids)
  • more false positives than GC-MS
34
Q

Testing methods for chronic opioid therapy

Urine GC-MS

A

Advantages

  • more precise results
  • longer detection window than serum

Disadvantages
- Costly

35
Q

Testing methods for chronic opioid therapy

Quantitative serum testing

A

Advantages

  • shows results for metabolites
  • in high-dose patient, may detect aberrant metabolism patter
  • provides documentation for provider of serum levels
36
Q

Opioid risk tool

A

1) five question tool completed by the patient
2) easily completed in office setting
3) particularly suited for those anticipated to be a low risk
4) patients are asked about family and personal history of substance abuse, mental health history and age
5) yes/no questions
6) tool was originally validated in patients who were not expected to have risks of misusing medications

37
Q

Diagnosis, intractability, risk, efficacy (DIRE)

A

1) seven item completed by patient interview
2) correlates with efficacy of long-term therapy
3) better evaluation of environmental factors, which may influence the success of chronic opioid therapy

38
Q

Cuurent opioid misuse measure (COMM)

A

1) 17 item questionnaire designed to assess patients for addiction, problematic behaviour, emotional volatility
2) designed to evaluation patients with a history of substance misuse to determine their level of risk while on chronic opioid therapy
3) the COMM is helpful in monitoring patient’s medication-related behaviour while receiving opioid therapy

39
Q

4A’s of opioid patient assessment

A

analgesia
adverse effects
aberrant behaviour
activity

40
Q

Equianalgesic doses of outpatient opioids

Morphine

A

Equianalgesic dose: 30mg
Brands: MS Contin, Oramorph SR, Long acting, Avinza, Kadian

Adverse effects often limit use - nausea, itching.
May require tid dosing in some patients
Should not be used in patients with renal compromise

41
Q

Equianalgesic doses of outpatient opioids
(Morphine 30mg)
Hydrocodone

A

Dose: 30mg
Brands: Lortab, Norco, Vicodin, Zydone, Lorcet (with acetaminophen), Reprexain (with iburpofen)

This short-acting agent may be suitable to test opioid responsiveness, but is not usually suitable for chronic opioid therapy

42
Q

Equianalgesic doses of outpatient opioids
(Morphine 30mg)
Codeine

A

Dose: 200mg
Brands: Various generic products

Patients often report itching and nausea < constipation with codeine
Conversion to morphine by 2D6 required for analgesia

43
Q

Equianalgesic doses of outpatient opioids
(Morphine 30mg)
Hydromorphone

A

Dose: 7.5mg
Brands: Dilaudid - short acting

44
Q

Equianalgesic doses of outpatient opioids
(Morphine 30mg)
Oxycodone

A

Dose: 20mg
Brands: Oxycontin, Percocet, others

45
Q

Equianalgesic doses of outpatient opioids
(Morphine 30mg)
Oxymorphone

A

Dose: 10mg
Brand: Opana

46
Q

Equianalgesic doses of outpatient opioids
(Morphine 30mg)
Tramadol

A

Dose: 120mg
Brand: Ultram, Ultram ER

Can cause nausea and dysphoria in some pts
Should be avoided with other serotinergic agents
Conversion to 0-desmethyl-metabolit through 2D6 required for analgesia
CIII in some states

47
Q

Equianalgesic doses of outpatient opioids

(Morphine 30mg)Tapentadol

A

Dose: 100mg
Brands: Nucynta and nucynta ER

Fewer overall GI adverse effects than other opioids
CII
Approved for both acute and chronic pain

48
Q

Conversion from morphine equivalents (mg/day) to fentanyl transdermal (mcg/hour)

A
60-136 : 25
135-224 : 50
225-314 : 75
315-404 : 100
405-494 : 125
495-584 : 150
585-674 : 175
675-764 : 200
49
Q

Opioid Nasal Spray

A

1) Butorphanol - useful for some patients with migraines for acute relief but can lead to medication overuse headaches and is not recommended by AAN guidelines
2) Fentanyl nasal spray - indicated only for cancer breakthrough pain in opioid tolerant patients