4. 4
Introduction
Definition : An unpleasant sensory and
emotional experience associated with
actual or potential tissue damage.
Pain may not be directly proportional to
amount of tissue injury.
Highly subjective, leading to
undertreatment
5. 5
In cancer, the prevalence of pain in
advanced disease is 70-90%.
" In HIV disease, pain prevalence is
about 50%.
" Other illnesses may have significant
pain but no clear data.
8. 8
Injury, trauma, spasm or disease to skin, muscle, somatic
structures or viscera;
Perceived and communicated via peripheral mechanisms
(pathways)
Usually associated with autonomic response as well
(tachycardia, blood pressure, diaphoresis, pallor,
mydriasis (pupil dilation).
Acute Pain
9. 9
Usually subsides quickly as pain producing stimuli
decreases
Associated with anxiety-(decreases rapidly)
Can be understood or rationalized as part of the healing
process.
Cont.
10. 10
i. Non-malignant
Pain persists beyond the precipitating injury
Rarely accompanied by autonomic symptoms
Sufferers often fail to demonstrate objective
evidence of underlying pathology.
Characterized by location-visceral, myofacial, or
neurologic causes.
II. Chronic Pain
11. 11
ii. Malignant
Has characteristics of chronic pain as well as
symptoms of acute pain (breakthrough pain).
Has a definable cause, e.g. tumor recurrence
In treatment, narcotic habituation is generally
not a concern.
II. Chronic Pain
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Types of Pain
Somatic
Visceral
Bone
Neuropathic
Emotional/Spiritual
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I- Somatic Pain
Aching, often constant
May be dull or sharp
Often worse with movement
Well localized
Skin, Muscle, Joints, superficial or deep.
Eg:
o Bone & soft tissue
o chest wall
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II- Visceral Pain
Constant or crampy
Aching, burning
Poorly localized
Referred
Organs of Thorax & Abdominal Cavity.
Usually as a result of stretching, infiltration and
compression
Eg:
o Liver capsule distension
o Bowel obstruction
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Both Somatic & Visceral pain
travel along the same
pathways. Pain stimuli arising
from the viscera is perceived
as somatic in origin.
This can be confused by the
brain and is often described as
referred pain.
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III- Bone Pain
Poorly localized, aching, deep, burning.
Common with malignancy of Breast, Lung,
Prostate, Bladder, Cervical, Renal, Colon,
Stomach and Esophagus
Can lead to pathological fractures.
Vertebral Metastases can lead to cord
compression.
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IV- Neuropathic Pain
Caused by disturbance of function or pathological
changes in a nerve.
May arise from a lesion or trauma, infection,
compression or tumour invasion.
Described as burning, shooting, tingling.
Does not respond well to standard analgesics.
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Categories of Pain
Classified by inferred pathophysiology:
I. Nociceptive pain (stimuli from somatic and
visceral structures)
II. Neuropathic pain (stimuli abnormally
processed by the nervous system)
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I. Nociceptive:
Caused by invasion &/or destruction &/or pressure on
superficial somatic structures like skin, deeper skeletal
structures such as bone & muscle and visceral structures
and organs.
Types: superficial somatic, deep somatic, & visceral.
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II. Neuropathic:
Caused by pressure on &/or destruction of peripheral,
autonomic or central nervous system structures.
Radiation of pain along dermatomal or peripheral nerve
distributions.
Often described as burning and/or deep aching &
associated with dysesthesia or lancinating pain.
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Effects of pain
Sympathetic responses
o Pallor
o Increased blood pressure
o Increased pulse
o Increased respiration
o Skeletal muscle tension
o Diaphoresis
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Effects of pain
Parasympathetic responses
o Decreased blood pressure
o Decreased pulse
o Nausea & vomiting
o Weakness
o Pallor
o Loss of consciousness
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Pain History
The site of pain
Type of pain
Exacerbating & Relieving factors
How frequently
Impact on daily life
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Pain History
Other important additional questions to be asked.
o What is the response to past and current analgesic
therapy?
o Any kind of diary or record about the pain?
o Fears they have about analgesics?
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Factors to consider in choosing a
pain scale
1. Age of patient
2. Physical condition
3. Level of consciousness
4. Mental status
5. Ability to communicate
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Numeric Pain Rating Scale
Ask the patient to rate their pain intensity on a scale
of 0 (no pain) to 10 (the worst pain imaginable).
Some patients are unable to do this with only verbal
instructions, but may be able to look at a number
scale and point to the number that describes the
intensity of pain.
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Wong-Baker FACES Pain Rating
Scale
Can be used with young children (sometimes as young as 3 years
of age)
Works well for many older children and adults as well as for
those who speak a different language
Explain that each face represents a person who may have no
pain, some pain, or as much pain as imaginable. Point to the
appropriate face and say the appropriate description. e.g. “This
face hurts just a little bit”
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Wong-Baker FACES Pain Rating
Scale
Ask the patient to choose the face that best matches how she or
he feels or how much they hurt.
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Color Pain Rating Scale
Ask the patient to point to the area on the scale that shows their
level of pain from white (no pain) to dark red (worst possible
pain).
Obtain a number corresponding to the area where the patient
points.
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Severity Assessment
McGill Pain Questionnaire
Scale from 0 to 5
From None to Severe Pain
for children or adults who understand numerical
relationships.
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Goals of Pain Management Therapy
1) Decreased pain
2) Decreased healthcare utilization
o Decreased “shopping” for care
o Decreased emergency room visits
3) Improved functional status
o Increased ability to perform activities of daily living
o Return to employment
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Analgesics
Non-opioid
e.g. aspirin,paracetamol
Opioids
e.g. codeine, morphine
Adjuvant
e.g. muscle relaxant, antidepressant, anti-epileptic
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Choosing the Appropriate Analgesic
Match the severity of pain to the strength of the
analgesic i.e. strong analgesics for severe pain.
The WHO has developed 3-step model to guide
analgesic choice depending on the severity of the
patient’s pain.
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Analgesics(Non-opioids)
Used in full doses for the most part.
All have a ceiling effect to their analgesia ( a
maximum dose past which no further analgesia can
be expected).
COX-2 inhibitors may be associated with fewer
side-effects
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Analgesics(Non-opioids)
Use cytoprotection with NSAIDs only in patients
who have symptoms suggestive of GI distress or
who are at high risk of ulcer formation. For
cytoprotection use sulcrafate or misoprostol.
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Analgesics(Weak Opioids)
Useful drugs:
o Codeine & codeine combination products
o Oxycodone combination products.
DO NOT USE:
o Dextropropoxyphene
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Analgesics(Strong Opioids)
Useful drugs:
o Morphine , hydromorphone, fentanyl, oxycodone ,
methadone.
DO NOT USE:
o Meperidine , anileridine , pentazocine
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Opioid Dosing
Opioid analgesia is most effective when titrated to effect.
Effective doses are highly variable between patients.
“Standard” doses may be insufficient.
When used properly for analgesia addiction occurs in less
than 1% of patients.
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Opioid Side Effects
Constipation :
o need proactive laxative use
Nausea/vomiting:
o consider treating with dopamine antagonists and/or
prokinetics (metoclopramide, domperidone,
prochlorperazine, haloperidol)
Urinary retention
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Cont.
Itch/rash
o worse in children; may need low-dose naloxone infusion. May
try antihistamines, however not great success
Dry mouth
Respiratory depression
o uncommon when titrated in response to symptom
Neurotoxicity: delirium, myoclonus seizures.
Drug interactions
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Adjuvant analgesics (coanalgesics)
Are medications that when added to primary
analgesics, further improve pain control.
may themselves also be primary analgesics (e.g.
tricyclic antidepressant medications for postherpetic
neuralgia).
They can be added into the pain management plan at
any step in the WHO ladder.
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Adjuvants for Neuropathic Pain
When pain is neuropathic there is good evidence for
treating with adjuvant medication rapidly.
Always remember the potential of using radiotherapy,
chemotherapy and surgery as adjuvant modalities with
neuropathic pain but they should not replace drug adjuvants
completely.
An adequate trial of 2-4 weeks at full dosage should be
tried for each drug
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Adjuvants for Neuropathic Pain
Cyclic Antidepressants:
o Amitriptyline - desipramine - nortriptyline –maprotiline
Anticonvulsants:
o carbamazepine - valproic acid - gabapentin
Local Anesthetics:
o mexiletine - lidocaine
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Other modalities
Nerve blocks, epidural blocks and ablative
neurosurgical procedures may be effective in pain
management.
Such procedures may be associated with return of
pain after a number of months so that timing of
procedures may be important.
