Download Management Of Acute Pain

Management of Acute Pain
Shada Y. Elhayek
M.Sc. Clinical Pharmacy
Content
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Introduction
Types of pain
Management of pain
Patient evaluation
Monitoring
What is Pain?
• pain: an unpleasant sensory & emotional
experience associated with actual or potential
tissue damage or described in terms of such
damage
Pathophysiology
Pain
Nociceptive
Neuropathic
Neuropathic
Functional
Somatic
Visceral
Types of Pain
• Acute pain:
• Acute pain usually is nociceptive, but it can be
neuropathic in nature
• Common causes of acute pain: surgery, acute
illness, trauma, labor, & medical procedures
When should acute pain not be
treated?
• Traumatic head injury because medications
can interfere with cognitive function
• Acute abdominal pain until diagnosis is made.
Although several studies support early pain
management
• Chronic Pain:
• Pain persisting for > 6 months to years
• Persistent (chronic) pain serves no biologic
protective purpose & can cause undue stress
& suffering
• Can be nociceptive, neuropathic/ functional,
or both
Clinical Presentation of Acute Pain
• Pain attributes:
Clinical Presentation- Acute Pain
• General
• Obvious distress (e.g., trauma), infants may present
with changes in feeding habits, increased fussiness.
Those with dementia may exhibit changes in eating
habits, increased agitation, calling out. Attention also
must be given to mental/emotional factors that alter
the pain threshold. Anxiety, depression, fatigue, anger,
and fear in particular, are noted to lower this threshold,
whereas rest, mood elevation, sympathy, diversion,
and understanding raise the pain threshold.
• Symptoms
• • Can be described as sharp, dull, shock like, tingling, shooting,
radiating, fluctuating in intensity, and varying in location (these
occur in a timely relationship with an obvious noxious stimuli)
• Signs
• Hypertension, tachycardia, diaphoresis, mydriasis, and pallor, but
these signs are not diagnostic
• In some cases there are no obvious physical signs
• Comorbid conditions usually not present
• Outcome of treatment generally predictable
• Laboratory Tests
• • Pain is always subjective
• • There are no specific laboratory tests for pain
• • Pain is best diagnosed based on patient description and history
Pharmacological management
• Non opioid analgesics:
1. Paracetamol
2. Aspirin
3. NSAIDS
Paracetamol
• Has analgesic and antipyretic properties, and it is
recommended for use in minor pain.
• It has comparable effectiveness to aspirin, but it does
not have peripheral anti-inflammatory activity or
effects on platelet function.
• Acetaminophen has fewer GI and renal adverse effects
than NSAIDs.
• Hepatic toxicity has been associated with acute
acetaminophen overdose as well as with usual doses in
certain high-risk conditions or situations (e.g., alcohol
ingestion, cachexia or malnutrition, and concomitant
drugs that induce hepatic enzymes).
NSAIDS
• Drugs: aspirin, choline salicylate, diflunisal, meclofenamate,
mefenamic acid, etodolac, diclofenac, ibuprofen, fenoprofen,
ketoprofen, magnesium salicylate, naproxen, ketorolac) and
cyclooxygenase-II enzyme selective inhibitors (celecoxib)
• Recommended for mild to moderate acute pain.
MOA: NSAIDs relieve pain by inhibiting prostaglandin synthesis.
• They must be used with caution:
1. in patients who are at risk for GI bleeding (>60 years old, history
of a GI event, or taking medications, such as corticosteroids, that
may cause bleeding).
2. There is the possibility of increased cardiovascular events in
patients taking NSAIDs, and it has been recommended that
cyclooxygenase-II enzyme inhibitors only be used when there are
no other therapeutic options available, and that their dose and
duration of therapy should be limited.
Major concerns
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Sodium retention
GI ADR
CV risk
Bronchospasm and allergy
Nephrotoxicity
Opioids
• Morphine is 1st line for moderate to severe pain
• Administered oral, parenteral and rectal
• Pentazocin and butophanol are mixed agonistantagonists
MOA:
• Analgesia via inhibiting µ, ĸ, ɛ and δ opioid
receptors located in the central transmission and
peripheral nervous systems and block the of pain
and release of neurotransmitters that may be
responsible for transmitting pain
• Analgesia results because the perception of
pain within the CNS as well as the patient’s
emotional response to pain is altered,
therefore modifying the sensory and affective
response.
• Opioid classes include the phenanthrenes
(morphinelike), phenylpiperidine
(meperidinelike), and diphenylheptane
• (methadonelike).
ADRs
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Nausea, vomiting & constipation:
Urinary retention, sedation, altered mental status
Respiratory depression
Hypotension.
Tolerance to opioid induced side effects can be seen after a few
days of administration. If the side effects do not lessen over time,
adjunctive drug therapy, such as an antiemetic or stimulant, may
need to be initiated. Importantly, tolerance to constipation does not
occur and requires the use of routine stimulant laxatives for
persons requiring chronic opioid therapy.
• True type 1 hypersensitivity (anaphylactic) reactions uncommon
after administration of opioid agonists. If this does occur, an opioid
from a different chemical class may be prescribed under close
medical supervision
• The release of histamine resulting in itching (local or diffuse),
flushing, or urticaria. If appropriate, a trial of oxymorphone or
fentanyl may be an option because they have been associated with
less histamine release and therefore less itching and urticaria.
Premedication with antihistamines may also be helpful.
• Tolerance to the analgesic effects of opioids is a common
phenomenon, and its causes are complex and multifactorial.
Tolerance is suspected when larger doses of an opioid are required
to achieve the same level of analgesia once seen with lower doses.
• Physical dependence is commonly observed in patients requiring
chronic opioid analgesics and is manifested by signs and symptoms
of withdrawal after abrupt discontinuation or rapid dose reduction
of the medication.