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Source: Baumann TJ, Strickland
JM, Herndon DM. Pain Management. In: DiPiro JT, Talbert RL, Yee GC,
Matzke GR, Wells BG, Posey LM, eds. Pharmacotherapy:
A Pathophysiologic Approach. 8th ed. http://accesspharmacy.com/content.aspx?aid=7986332.
Accessed June 20, 2012.
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- Pain is an unpleasant, subjective, sensory and emotional
experience associated with actual or potential tissue damage or
described in terms of such damage.
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- Pain can occur from many causes, for example:
- Surgery
- Trauma
- Labor
- Medical procedures
- Illnesses
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- Nociceptive (acute) pain is somatic (from skin, bone,
joint, muscle, or connective tissue) or visceral (from internal
organs).
- Free nerve endings known as nociceptors
can be stimulated by mechanical, thermal, and chemical impulses.
- Action potentials transmitted along afferent nerve fibers
to spinal cord and then ascend to higher centers.
- The thalamus may act as relay station and pass impulses to
central structures, where pain is processed further.
- Body modulates pain through several processes, including endogenous
opioid system.
- Neuropathic and functional pain often described as chronic
pain.
- Neuropathic pain (e.g., postherpetic neuralgia,
diabetic neuropathy) results from nerve damage.
- Functional pain (e.g., fibromyalgia, irritable bowel syndrome,
tension-type headache) involves abnormalities in nervous system.
- Acute pain (e.g., surgery, trauma, labor, and medical procedures)
usually is nociceptive, but can be neuropathic.
- Chronic pain can be nociceptive, neuropathic/functional,
or both.
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- In a survey, 1 in 4 Americans reported pain that lasted
for >24 hours in previous month; in those reporting pain, 42% stated
that it lasted >1 year.
- 76.5 million Americans report they are in chronic pain.
- Each year, 25 million Americans experience acute pain due
to injury or surgery, and one-third of Americans experience severe
chronic pain at some point in their lives.
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- Patients may be in obvious acute distress or appear to
have no noticeable suffering.
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- Acute pain may be:
- Sharp or dull
- Burning
- Shock-like
- Tingling
- Shooting
- Radiating
- Fluctuating in intensity
- Varying in location
- Occurring in timely relationship with obvious noxious stimulus
- Chronic pain can present similarly and often occurs without
time relationship to noxious stimulus.
- Over time, chronic pain presentation may change (e.g., sharp
to dull, obvious to vague).
- Acute pain can cause:
- Hypertension
- Tachycardia
- Diaphoresis
- Mydriasis
- Pallor
- These signs seldom present in chronic pain.
- Neuropathic pain often chronic, not well described, and not
easily treated with conventional analgesics.
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Means of Confirmation
and Diagnosis
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- Pain is subjective sensation; diagnosis based on:
- Patient description
- History
- Physical exam
- Baseline pain description can be obtained by assessing PQRST
characteristics:
- Precipitating factors
- Quality
- Radiation
- Severity
- Temporal factors
- Pay attention to mental factors that may lower pain threshold,
example:
- Anxiety
- Depression
- Fatigue
- Anger
- Fear
- Behavioral, cognitive, social, and cultural factors may also
affect pain experience.
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- Perform individual tests as required to identify potential
underlying causes.
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- Performed as required to identify underlying causes.
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- Performed as required to identify underlying causes.
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Differential
Diagnosis
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