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Pain Lec 3rd Year.


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Pain lecture for 3rd year medical college students.

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Pain Lec 3rd Year.

  1. 1. Pain Dr.Mohammad Shaikhani.
  2. 2. Pain <ul><li>An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage. </li></ul>International Association for the Study of Pain
  3. 3. Clinical Terms For The Sensory Disturbances Associated With Pain <ul><li>Dysesthesia – An unpleasant abnormal sensation, whether spontaneous or evoked. </li></ul><ul><li>Allodynia – Pain due to a stimulus which does not normally provoke pain, such as pain caused by light touch to the skin </li></ul><ul><li>Hyperalgesia – An increased response to a stimulus which is normally painful </li></ul><ul><li>Hyperesthesia - Increased sensitivity to stimulation, excluding the special senses. Hyperesthesia includes both allodynia and hyperalgesia . </li></ul>
  4. 4. Approach To Pain Control <ul><li>Thorough assessment by skilled and knowledgeable clinician </li></ul><ul><ul><li>History </li></ul></ul><ul><ul><li>Physical Examination </li></ul></ul><ul><li>D iscuss with patient/family the goals of care, hopes, expectations, anticipated course of illness,with consideration of investigations and interventions </li></ul><ul><li>Investigations – X-Ray, CT, MRI, etc - if they will affect approach to care </li></ul><ul><li>Treatments – pharmacological and non-pharmacological; interventional analgesia (e.g.. Spinal) </li></ul><ul><li>Ongoing reassessment and review of options, goals, expectations, etc. </li></ul>
  5. 5. TYPES OF PAIN NEUROPATHIC NOCICEPTIVE Deafferentation Sympathetic Maintained Peripheral Somatic <ul><li>bones, joints </li></ul><ul><li>connective tissues </li></ul><ul><li>muscles </li></ul>Visceral <ul><li>Organs – heart, liver, pancreas, gut, etc. </li></ul>
  6. 6. Acute vs. Chronic Acute Chronic Onset Abrupt Gradual Duration 1 second to 6 months Longer than 6 months Intensity Mild, moderate, severe Mild, moderate, severe Etiology Biologically identifiable May not be easily identified Physical response Increased BP, HR, RR, dilated pupils, pallor, nausea and vomiting, increase muscle tension and dry mouth No autonomic nervous system symptoms
  7. 7. Somatic Pain <ul><li>Aching, often constant </li></ul><ul><li>May be dull or sharp </li></ul><ul><li>Often worse with movement </li></ul><ul><li>Well localized </li></ul><ul><li>Eg/ </li></ul><ul><li>Bone & soft tissue </li></ul><ul><li>chest wall </li></ul>
  8. 8. Visceral Pain <ul><li>Constant or crampy </li></ul><ul><li>Aching </li></ul><ul><li>Poorly localized </li></ul><ul><li>Referred </li></ul><ul><li>Eg/ </li></ul><ul><li>CA pancreas </li></ul><ul><li>Liver capsule distension </li></ul><ul><li>Bowel obstruction </li></ul>
  9. 9. Neuropathic pain <ul><li>A variety of mechanisms: </li></ul><ul><li>Sensitized primary afferent nociceptors, damaged primary afferents, including nociceptors, become highly sensitive to mechanical stimulation and begin to generate impulses in the absence of stimulation. </li></ul><ul><li>There is evidence that this increased sensitivity and spontaneous activity is due to an increased concentration of sodium channels. </li></ul><ul><li>Damaged primary afferents may also develop sensitivity to norepinephrine&spinal cord pain-transmission neurons cut off from their normal input may also become spontaneously active. </li></ul><ul><li>So both central &peripheral NS hyperactivity contribute to neuropathic pain. </li></ul>
  10. 10. FEATURES OF NEUROPATHIC PAIN COMPONENT DESCRIPTORS EXAMPLES Steady, Dysesthetic <ul><li>Burning, Tingling </li></ul><ul><li>Constant, Aching </li></ul><ul><li>Squeezing, Itching </li></ul><ul><li>Allodynia </li></ul><ul><li>Hypersthesia </li></ul><ul><li>Diabetic neuropathy </li></ul><ul><li>Post-herpetic neuropathy </li></ul>Paroxysmal, Neuralgic <ul><li>Stabbing </li></ul><ul><li>Shock-like, electric </li></ul><ul><li>Shooting </li></ul><ul><li>Lancinating </li></ul><ul><li>trigeminal neuralgia </li></ul><ul><li>may be a component of any neuropathic pain </li></ul>
  11. 11. Referred Pain:
  12. 12. Pain Assessment
  13. 13. <ul><li>“ Describing pain only in terms of its intensity is like describing music only in terms of its loudness” </li></ul>von Baeyer CL; Pain Research and Management 11(3) 2006; p.157-162
  14. 14. Pain Assessment Subjective Data <ul><li>Comprehensive pain history includes COLDERR </li></ul><ul><ul><li>C haracter </li></ul></ul><ul><ul><li>O nset </li></ul></ul><ul><ul><li>L ocation </li></ul></ul><ul><ul><li>D uration </li></ul></ul><ul><ul><li>E xacerbation </li></ul></ul><ul><ul><li>R elief </li></ul></ul><ul><ul><li>R adiation </li></ul></ul>
  15. 15. PAIN HISTORY <ul><li>Description: severity, quality, location, temporal features, frequency, aggravating & alleviating factors </li></ul><ul><li>Previous history </li></ul><ul><li>Context: social, cultural, emotional, spiritual factors </li></ul><ul><li>Meaning </li></ul><ul><li>Interventions: what has been tried? </li></ul>
  16. 16. Example Of A Numbered Scale
  17. 17. <ul><li>Dose </li></ul><ul><li>Route </li></ul><ul><li>Frequency </li></ul><ul><li>Duration </li></ul><ul><li>Efficacy </li></ul><ul><li>Adverse effects </li></ul>Medication(s) Taken
  18. 18. Physical Exam In Pain Assessment Inspection / Observation <ul><li>Overall impression.? </li></ul><ul><li>Facial expression: Grimacing; furrowed brow; appears anxious; flat affect </li></ul><ul><li>Body position and spontaneous movement: there may be positioning to protect painful areas, limited movement due to pain </li></ul><ul><li>Diaphoresis – can be caused by pain </li></ul><ul><li>Areas of redness, swelling </li></ul><ul><li>Atrophied muscles </li></ul><ul><li>Gait </li></ul><ul><li>Myoclonus – possibly indicating opioid-induced neurotoxicity </li></ul>“ You can observe a lot just by watching” Yogi Berra
  19. 19. Physical Exam In Pain Assessment Palpation <ul><li>Localized tenderness to pressure or percussion </li></ul><ul><li>Fullness / mass </li></ul><ul><li>Induration / warmth </li></ul>
  20. 20. Physical Exam In Pain Assessment Neurological Examination <ul><li>Important in evaluating pain, due to the possibility of spinal cord compression, and nerve root or peripheral nerve lesions </li></ul><ul><li>Sensory examination </li></ul><ul><ul><li>Areas of numbness / decreased sensation </li></ul></ul><ul><ul><li>Areas of increased sensitivity, such as allodynia or hyperalgesia </li></ul></ul><ul><li>Motor (strength) exam - caution if bony metastases (may fracture) </li></ul><ul><li>Deep tendon reflexes – intensity, symmetry </li></ul><ul><ul><li>Hyperreflexia and clonus: possible upper motor neuron lesion, such as spinal cord compression or cerebral metastases. </li></ul></ul><ul><ul><li>Hyoporeflexia - possible lower motor neuron impairment, including lesions of the cauda equina of the spinal cord or leptomeningeal metastases. </li></ul></ul><ul><li>Sacral reflexes – diminished rectal tone and absent anal reflexes may indicate cauda equina involvement of by tumour </li></ul>
  21. 21. Physical Exam In Pain Assessment Other Exam Considerations <ul><ul><li>Further areas of focus of the physical examination are determined by the clinical presentation. </li></ul></ul><ul><ul><li>Eg: evaluation of pleuritic chest pain would involve a detailed respiratory and chest wall examination. </li></ul></ul>
  22. 22. Pain Treatment
  23. 23. Non-Pharmacological Pain Management <ul><li>Acupuncture </li></ul><ul><li>Cognitive/behavioral therapy </li></ul><ul><li>Meditation/relaxation </li></ul><ul><li>Guided imagery </li></ul><ul><li>TENS </li></ul><ul><li>Therapeutic massage </li></ul><ul><li>Others… </li></ul>
  24. 24. +/- adjuvant Non-opioid Weak opioid Strong opioid Pain persists or increases W.H.O . ANALGESIC LADDER +/- adjuvant +/- adjuvant By the Clock 1 2 3
  25. 25. STRONG OPIOIDS <ul><li>most commonly use: </li></ul><ul><ul><li>morphine </li></ul></ul><ul><ul><li>Hydromorphone (Dilaudid ®) </li></ul></ul><ul><ul><li>transdermal fentanyl (Duragesic®) </li></ul></ul><ul><ul><li>oxycodone </li></ul></ul><ul><ul><li>Methadone </li></ul></ul><ul><li>DO NOT use meperidine (Demerol  ) long-term </li></ul><ul><ul><li>active metabolite normeperidine   seizures </li></ul></ul>
  26. 26. OPIOIDS and INCOMPLETE CROSS-TOLERANCE <ul><li>Tolerance to a specific opioid is fully “crossed over” to other opioids. </li></ul><ul><li>cross-tolerance unpredictable, especially in: </li></ul><ul><ul><li>high doses </li></ul></ul><ul><ul><li>long-term use </li></ul></ul><ul><li>divide calculated dose in ½ and titrate </li></ul>
  27. 27. Drug Equipotency with Morphine (Morphine:Drug) Hydromorphone 5:1 Oxycodone 1.5:1 to 2:1 Codeine 1:12 Methadone Daily Morphine Dose 30 – 90 mg 3.7:1 90 – 300 mg 7.75:1 > 300 mg 12.75:1 Fentanyl 80:1 to 100:1 (for subcutaneous dosing of each)
  28. 28. TITRATING OPIOIDS <ul><li>Dose increase depends on the situation </li></ul><ul><li>Dose  by 25 - 100% </li></ul>EXAMPLE: (doses in mg q4h)
  30. 30. TOLERANCE A normal physiological phenomenon in which increasing doses are required to produce the same effect Inturrisi C, Hanks G. Oxford Textbook of Palliative Medicine 1993: Chapter 4.2.3
  31. 31. PHYSICAL DEPENDENCE A normal physiological phenomenon in which a withdrawal syndrome occurs when an opioid is abruptly discontinued or an opioid antagonist is administered Inturrisi C, Hanks G. Oxford Textbook of Palliative Medicine 1993: Chapter 4.2.3
  32. 32. PSYCHOLOGICAL DEPENDENCE and ADDICTION A pattern of drug use characterized by a continued craving for an opioid which is manifest as compulsive drug-seeking behaviour leading to an overwhelming involvement in the use and procurement of the drug Inturrisi C, Hanks G. Oxford Textbook of Palliative Medicine 1993: Chapter 4.2.3
  33. 33. <ul><li>po / sublingual / rectal routes </li></ul><ul><li>SQ / IV / IM routes </li></ul>reduce by ½ Changing Route Of Administration In Chronic Opioid Dosing
  34. 34. Using Opioids for Breakthrough Pain <ul><li>Patient must feel in control, empowered </li></ul><ul><li>Use aggressive dose and interval </li></ul><ul><li>Patient Taking Short-Acting Opioids: </li></ul><ul><ul><li>50 - 100% of the q4h dose, given q1h prn </li></ul></ul><ul><li>Patient Taking Long-Acting Opioids: </li></ul><ul><ul><li>10 - 20% of total daily dose given, q1h prn </li></ul></ul><ul><ul><li>with short-acting opioid preparation </li></ul></ul>
  35. 35. Opioid Side Effects <ul><li>Constipation – need proactive laxative use </li></ul><ul><li>Nausea/vomiting – consider treating with dopamine antagonists and/or prokinetics (metoclopramide, domperidone, prochlorperazine [Stemetil], haloperidol) </li></ul><ul><li>Urinary retention </li></ul><ul><li>Itch/rash – worse in children; may need low-dose naloxone infusion. May try antihistamines, however not great success </li></ul><ul><li>Dry mouth </li></ul><ul><li>Respiratory depression – uncommon when titrated in response to symptom </li></ul><ul><li>Drug interactions </li></ul><ul><li>Neurotoxicity (OIN): delirium, myoclonus  seizures </li></ul>
  36. 36. OIN: Treatment <ul><li>Switch opioid (rotation) or reduce opioid dose; usually much lower than expected doses of alternate opioid required… often use prn initially </li></ul><ul><li>Hydration </li></ul><ul><li>Benzodiazepines for neuromuscular excitation </li></ul>
  37. 37. Adjuvant Analgesics <ul><li>First developed for non-analgesic indications </li></ul><ul><li>Subsequently found to have analgesic activity in specific pain scenarios </li></ul><ul><li>Common uses: </li></ul><ul><ul><li>Pain poorly-responsive to opioids (eg. neuropathic pain), or </li></ul></ul><ul><ul><li>With intentions of lowering the total opioid dose and thereby mitigate opioid side effects. </li></ul></ul>
  38. 38. Adjuvants Analgesics <ul><li>General / Non-specific </li></ul><ul><ul><li>corticosteroids </li></ul></ul><ul><ul><li>cannabinoids </li></ul></ul><ul><li>Neuropathic Pain </li></ul><ul><ul><li>Gabapentin </li></ul></ul><ul><ul><li>Antidepressants </li></ul></ul><ul><ul><li>Ketamine </li></ul></ul><ul><ul><li>Topiramate </li></ul></ul><ul><ul><li>Clonidine </li></ul></ul><ul><li>Bone Pain </li></ul><ul><ul><li>Bisphosphonates </li></ul></ul><ul><ul><li>(Calcitonin) </li></ul></ul>
  39. 39. <ul><ul><li> Inflammation </li></ul></ul><ul><ul><li> Edema </li></ul></ul><ul><ul><li> Spontaneous nerve depolarization </li></ul></ul> tumor mass effects CORTICOSTEROIDS AS ADJUVANTS }
  40. 40. CORTICOSTEROIDS: ADVERSE EFFECTS IMMEDIATE LONG-TERM <ul><li>Psychiatric </li></ul><ul><li>Hyperglycemia </li></ul><ul><li> risk of GI bleed </li></ul><ul><ul><li>gastritis </li></ul></ul><ul><ul><li>aggravation of existing lesion (ulcer, tumor) </li></ul></ul><ul><li>Immunosuppression </li></ul><ul><li>Proximal myopathy often >15 days </li></ul><ul><li>Cushing’s syndrome </li></ul><ul><li>Osteoporosis </li></ul><ul><li>Aseptic / avascular necrosis of bone </li></ul>
  41. 41. DEXAMETHASONE <ul><li>Minimal mineralcorticoid effects </li></ul><ul><li>po/iv/sq/?sublingual routes </li></ul><ul><li>perhaps can be given once/day; often given more frequently </li></ul><ul><li>If an acute course is discontinued within 2 wks, adrenal suppression not likely </li></ul>
  42. 42. Treatment of Neuropathic Pain <ul><li>Pharmacologic treatment </li></ul><ul><ul><li>Opioids </li></ul></ul><ul><ul><li>Steroids </li></ul></ul><ul><ul><li>Anticonvulsants – gabapentin, topiramate </li></ul></ul><ul><ul><li>TCAs (for dysesthetic pain, esp. if depression) </li></ul></ul><ul><ul><li>NMDA receptor antagonists: ketamine, methadone </li></ul></ul><ul><ul><li>Anesthetics </li></ul></ul><ul><li>Radiation therapy </li></ul><ul><li>Interventional treatment </li></ul><ul><ul><li>Spinal analgesia </li></ul></ul><ul><ul><li>Nerve blocks </li></ul></ul>
  43. 43. Gabapentin <ul><li>Common Starting Regimen </li></ul><ul><ul><li>300 mg hs Day 1, 300 mg bid Day2, 300 mg tid Day 3, then gradually titrate to effect up to 1200 mg tid </li></ul></ul><ul><li>Frail patients </li></ul><ul><ul><li>100 mg hs Day 1, 100 mg bid Day 2, 100 mg tid Day 3, then gradually titrate to effect </li></ul></ul>
  44. 44. Incident Pain Pain occurring as a direct and immediate consequence of a movement or activity
  45. 45. Circumstances In Which Incident Pain Often Occurs <ul><li>Bone metastases </li></ul><ul><li>Neuropathic pain </li></ul><ul><li>Intra-abd. disease aggravated by respiration </li></ul><ul><ul><li>“ incident” = breathing </li></ul></ul><ul><ul><li>ruptured viscus, peritonitis, liver hemorrhage </li></ul></ul><ul><li>Skin ulcer: dressing change, debridement </li></ul><ul><li>Disimpaction </li></ul><ul><li>Catheterization </li></ul>
  46. 46. Time Pain Having a steady level of enough opioid to treat the peaks of incident pain... ...would result in excessive dosing for the periods between incidents Incident Incident Incident
  47. 47. Fentanyl and Sufentanil <ul><li>Synthetic µ agonist opioids </li></ul><ul><li>Highly lipid soluble </li></ul><ul><ul><li>Transmucosal absorption; effect in approx 10 min </li></ul></ul><ul><ul><li>rapid redistribution, including in / out of CSF; lasts approx 1 hr. </li></ul></ul><ul><li>fentanyl » 100x stronger than morphine </li></ul><ul><li>sufentanil » 1000x stronger than morphine </li></ul>10 mg morphine  10 µg sufentanil  100 µg fentanyl
  48. 48. INCIDENT PAIN PROTOCOL (see also Step # Medication (50  g/ml) # Micrograms Sublingually 1 Fentanyl 50 2 Sufentanil 25 3 Sufentanil 50 4 Sufentanil 100
  49. 49. <ul><li>Fentanyl or sufentanil is administered SL 10 min. prior to anticipated activity </li></ul><ul><li>Repeat q 10min x 2 additional doses if needed </li></ul><ul><li>Increase to next step if 3 total doses not effective </li></ul><ul><li>Physician order required to increase to next step if within an hour of last dose </li></ul><ul><li>the Incident Pain Protocol may be used up to q 1h prn </li></ul>INCIDENT PAIN PROTOCOL ctd...