Pain in surgery

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Pain in surgery

  1. 1. PAIN IN SURGERY MS Surgery – Part I May 2008
  2. 2. LECTURE PLAN <ul><li>Definitions </li></ul><ul><li>Pain pathways </li></ul><ul><li>Modifications – Current thinking </li></ul><ul><li>Pain control </li></ul>
  3. 3. PAIN <ul><li>Sherrington : “ the physical adjunct of an </li></ul><ul><li>imperative protective reflex ” </li></ul><ul><li>Merskey : “ Pain is an unpleasant sensory and </li></ul><ul><li>emotional experience associated with actual or </li></ul><ul><li>potential tissue damage or described in terms of </li></ul><ul><li>such damage” </li></ul>
  4. 4. Acute Pain <ul><li>International Association for the Study of Pain </li></ul><ul><li>“ An unpleasant sensory or emotional experience </li></ul><ul><li>associated with actual or potential tissue damage, </li></ul><ul><li>or described in terms of such damage” </li></ul><ul><li>“ Pain is always subjective; & it is unquestionably a </li></ul><ul><li>sensation in a part of the body ” </li></ul>
  5. 5. <ul><li>Acute pain …… </li></ul><ul><li>Survival value </li></ul><ul><li>Chronic pain …… </li></ul><ul><li>No value </li></ul>
  6. 6. Pain Pathways <ul><li>Previously – 3 components </li></ul><ul><li>1. First order neurone </li></ul><ul><li>peripheral receptor  …… </li></ul><ul><li>2. Second order neurone </li></ul><ul><li>crosses midline  spinothalamic tract  thalamus </li></ul><ul><li>3. Third order neurone </li></ul><ul><li>projects to post-central gyrus </li></ul>
  7. 7. Pain Pathways <ul><li>Now </li></ul><ul><li>Peripheral receptors </li></ul><ul><li>Neural pathways </li></ul><ul><li>Spinal cord mechanisms & long tracts </li></ul><ul><li>Brain stem, thalamus, cortex & other areas </li></ul><ul><li>Descending pathways </li></ul>
  8. 8. Pain Response <ul><li>First pain </li></ul><ul><li>Second pain </li></ul>
  9. 9. Nociceptors
  10. 10. Neurogenic Inflammation
  11. 11. Nociceptors <ul><li>silent nociceptors </li></ul><ul><li>silent antinociceptors </li></ul>
  12. 12. Pain Perception <ul><li>thresholds constant </li></ul><ul><li>response and tolerance differ </li></ul>
  13. 13. Neural Pathways
  14. 15. Spinal Cord Pathways <ul><li>Initial connections </li></ul>
  15. 16. Spinal Pathways <ul><li>Initial Connections </li></ul><ul><li>Important second order neurones </li></ul><ul><li>1. Wide Dynamic Range (WDR) cell </li></ul><ul><li>“ wind up ” </li></ul><ul><li>2. Nociceptive specific neurones </li></ul><ul><li>3. Complex neurones </li></ul>
  16. 17. Spinal Pathways <ul><li>Local </li></ul><ul><li>Interconnections </li></ul><ul><li>Gating </li></ul>
  17. 18. Ascending Pathways <ul><li>Spino-reticulo-diencephalic pathway </li></ul><ul><li>Spinothalamic tract </li></ul>
  18. 19. Descending Pathways <ul><li>Origin </li></ul><ul><li>Cortex </li></ul><ul><li>Thalamus </li></ul><ul><li>Brain stem – periaqueductal grey matter </li></ul>
  19. 20. Noxious stimuli
  20. 21. Response to Pain <ul><li>Visceral Pain </li></ul><ul><li>Tonic muscular spasm </li></ul><ul><li>Somatic pain </li></ul><ul><li>Withdrawal of affected part </li></ul><ul><li>☼ Autonomic effects </li></ul>
  21. 22. Response to pain <ul><li>Fast & slow pain </li></ul><ul><li>Deep & superficial pain </li></ul><ul><li>Referred pain </li></ul>
  22. 23. C-fos <ul><li>Proto oncogene that codes for protein fos. </li></ul><ul><li>Expressed in response to painful peripheral </li></ul><ul><li>stimuli </li></ul><ul><li>Molecular memory of pain </li></ul>
  23. 24. <ul><li>PAIN CONTROL </li></ul>
  24. 26. PAIN CONTROL <ul><li>Primary analgesics </li></ul><ul><li>opioids – receptors – sites, types </li></ul><ul><li>drugs </li></ul><ul><li>routes of administration </li></ul><ul><li>side effects </li></ul>
  25. 27. PAIN CONTROL <ul><li>Primary analgesics </li></ul><ul><li>simple analgesics and NSAID’s drugs – inhibit COX </li></ul><ul><li>routes of administration </li></ul><ul><li>contraindications </li></ul><ul><li>COX 2 selective inhibitors – parecoxib, valdecoxib </li></ul>
  26. 29. PAIN CONTROL <ul><li>Primary analgesics </li></ul><ul><li>Local anaesthetics </li></ul><ul><li>drugs </li></ul><ul><li>uses </li></ul><ul><li>toxic effects </li></ul><ul><li>others - Tramadol </li></ul><ul><li>- clonidine </li></ul>
  27. 30. PAIN CONTROL <ul><li>Secondary analgesics </li></ul><ul><li>antidepressants </li></ul><ul><li>anticonvulsants </li></ul><ul><li>anxiolytics </li></ul><ul><li>muscle relaxants </li></ul><ul><li>Ca channel blockers </li></ul><ul><li>steroids </li></ul>
  28. 31. PAIN CONTROL <ul><li>Interventional therapy </li></ul><ul><li>TENS/acupuncture </li></ul><ul><li>neurolytic agents </li></ul><ul><li>radiofrequency/heat treatment </li></ul><ul><li>surgery </li></ul>
  29. 32. PAIN CONTROL <ul><li>Psychological treatment </li></ul><ul><li>psychological support </li></ul><ul><li>behavioural therapy </li></ul>
  30. 33. PAIN CONTROL <ul><li>pre emptive analgesia </li></ul>
  31. 34. Jan 1996 <ul><li>2. Discuss the physiological basis of the different methods of pain control. </li></ul>
  32. 35. <ul><li>Thank you </li></ul>

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