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Basic Principles and Difficult Pain

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  1. Basic Principles and Difficult Pain Dr Pete Nightingale Macmillan GP

  2. Objectives By the end of this session I hope that you will have refreshed your ability to diagnose the type of pain a patient has and have in mind a strategy to deal with each pain.

  3. Incidence in Cancer • About ¼ of patients never have pain • Of those that do:- • 1/3 have a single pain • 1/3 have three or more different pains

  4. Overview of Pain Classification • Definitions • Classification • Nociceptive and Neuropathic

  5. Definitions

  6. Definitions of Pain • Pain An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage • Allodynia Pain due to a stimulus that does not normally provoke pain • Dysaesthesia An unpleasant abnormal sensation, whether spontaneous or evoked

  7. Causes of Pain • Pain caused by cancer and other medical illnesses may be caused by either direct effect of the disease OR • By the treatment associated with the disease which injure organs,muscles and nerves.E.G. Surgery, Chemo, XRT

  8. Classification of Pain

  9. Which type of pain could be classified as visceral nociceptive pain? • A Dull or aching, well localised • B Intermittant, burning or shooting • C Associated with an area of abnormal sensation • D Poorly localised, colic or sensation of pressure

  10. Classification of Pain Nociceptive Pain Neuropathic Pain Pain pathways intact Anatomical or functional abnormality of pain pathway In area of abnormal sensation Somatic Visceral

  11. Pain Types

  12. Nociceptive Pain • Somatic Activation of pain receptors (nociceptors) by chemical stimuli in cutaneous or deep tissues • Visceral Activation of nociceptors as a result of infiltration/compression/extension or stretching of viscera (organs)

  13. Neurophysiology • Normal physiology of pain DRG CNS Pain neurone Stimulus Response

  14. Normal Sensation Low intensity stimulation High Intensity Stimulation Innocuous Sensation PAIN

  15. Neuropathic Pain • Spontaneous firing of damaged nerves • Pain due to a disturbance or pathological change in a nerve • A form of pain that occurs in up to 1% of population. • Virtually any condition that damages neural tissue or causes neuronal dysfunction can result in neuropathic pain • Pain in an area of abnormal sensation

  16. Diagnosis SYMPTOMS SIGNS • Positive • Pain • Paraesthesia • Hyperaesthesia • Negative • Numbness • Normal • Motor • Distal Wasting • Absent reflexes • Sensory • Reduced Vibration/ light touch/ Pinprick

  17. Pain Assessment

  18. Assessment of Pain • History ‘ Pain is what the patient says it is’ There is evidence health workers tend to underestimate pain. PQRST Response to previous treatment New Pain or Exacerbation

  19. P P Q R S T • P Palliative factors ‘what makes it better?’ • P Provocative factors ‘what makes it worse?’ • Q Quality of pain ‘what exactly is it like?’ • R Radiation ‘Does it spread anywhere?’ • S Severity ‘How much is it affecting life?’ • T Temporal factors ‘Does the pain come and go?’

  20. Assessing Consequences of Pain PAIN MAY LEAD TO depression Anxiety Ability to interact socially  physical performance  working ability  family income

  21. Factors Affecting Pain Threshold

  22. Principles of Pain Management

  23. Treating the Underlying Cause • Palliative Anti-cancer Treatment Radiotherapy Chemotherapy Hormone therapy • Modifying the effects of the disease Correct Hypercalcaemia Treat Lymphoedema Surgery – spinal stabilisation

  24. WHO Analgesic LadderWill deal with 80% of Cancer Pain strong opioid (morphine) weak opioid (Codeine or Tramadol) non-opioid (Paracetamol) +/- Adjuvant

  25. Tramadol • Dual MOA • Via opioid receptors • By blocking 5HT and NA • 1/5th as potent as morphine orally • Less constipating than codeine/morphine • ?role in neuropathic pain • ?lowers seizure threshold

  26. Rules for Step 2 • A weak opioid should be added to a non-opioid • If a weak opioid is inadequate at regular optimal dose, change to morphine • Codeine is 1/10th as potent as morphine • Do not ‘kangaroo’ from weak opioid to weak opioid

  27. Step3: Strong Opioids • Morphine • Diamorphine • Oxycodone • Methadone • Hydromorphone • Fentanyl • Alfentanil

  28. Yet another A B C ! • A-Anti-emetic-usually Haloperidol 1.5mg for 7-10 days • B- Breakthrough pain. Use 1/6 of daily dose (4 hrly equivalent) as ‘rescue’ • C-Constipation – Laxative always required

  29. Morphine preparations • Modified Release: Zomorph /MST Continus 12 hourly regularly MXL capsules 24 hourly regularly

  30. Initiation of Morphine • For uncontrolled pain, start 4 hourly I/R morphine for rapid titration • Prescribe prn I/R at the same dose • If the patient responds to rescue doses, use them as needed • (? double night-time dose)

  31. Conversion to long acting • Once pain controlled on 4 hourly dose I/R morphine, can convert to M/R morphine • Tot up total daily morphine • For Zomorph: divide by 2 and prescribe Zomorph at this dose bd • For MXL: prescribe the total dose once daily

  32. Conversion • Prescribe prn breakthrough dose 1/6th of total daily morphine dose • Give the 1st dose of M/R morphine with the last regular dose of I/R

  33. Patient Explanation • The first goal is reduction in discomfort (setting targets) • Common side-effects are sleepiness, nausea and constipation. • The drowsiness/nausea tend to wear off • Prophylactic Rx nausea and constipation THEN REGULARLY REVIEW PATIENT

  34. Alternative Strong Opiates

  35. Choosing the right opioid Subcutaneous infusion: diamorphine Stable pain, unable to swallow: SC diamorphine or transdermal fentanyl Afraid of using morphine: oxycodone or fentanyl Infection with pyrexia: any can be used except transdermal fentanyl Mild - moderate renal impairment: Possibly use hydromorphone Severe renal failure: fentanyl Liver impairment: morphine (with care)

  36. Please rank the following in order of potency:- • A Codeine 60mg • B Tramadol 100mg • C Morphine 5mg • D Fentanyl 25mcg/hr patch.

  37. FENTANYL (eg Durogesic D Trans) • Alternative strong opioid (Change patch every 72 hrs) • Take 12-48hrs to achieve maximum blood levels • Oral Morphine used for breakthrough pain • Indications for use • Intolerable adverse effects of morphine • Tablet phobia or difficulty swallowing • Poor compliance with oral medication • When the patient won’t have anything called morphine!

  38. FENTANYL(e.g Durogesic D Trans)

  39. Oxycodone • MR – Oxycontin IR – Oxynorm • Oxycodone twice as potent as morphine • MST 10mg bd  Oxycontin 5mg bd • Tolerated better by some • More expensive

  40. Adjuvant Analgesics (1)

  41. Non-drug Treatments (1) • Nerve Blocks Local Anaesthetic Neurolytic (phenol) • Neurosurgery Cordotomy • Immobilisation Rest / Slings /Splints/ Corset Walking Aids / Wheelchair

  42. Non-drug Treatments (2) • Psychology Individual Group Relaxation Education Cognitive Therapy Multi-disciplinary Approach • Distraction • Hypnosis

  43. Mannix K et al Palliative Medicine 2006; 20:579-584 Cognitive Behaviour Therapy (CBT) can be used by palliative care staff to help patients. Training may become more widely available

  44. CBTCognitive Behaviour Therapy Physical Pain

  45. ABC of CBT! • A is the activating event • B is your beliefs and thoughts • C is the consequences, such as emotions you feel

  46. The Mercedes Model Our ever present internal states consist of: THINKING EMOTIONS PHYSIOLOGY

  47. Balloon challenge!

  48. Non-drug Treatments (3) • Counter-irritation Massage – Gate Control Theory TENS – Gate Control Theory Acupuncture – stimulates release of endorphins • Physical Exercise and mobility Physiotherapy Hydrotherapy Music/ Art therapy • Lifestyle Modification