08 pain lishangrong 2


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08 pain lishangrong 2

  1. 1. Pain Shangrong Li, MD Anesthesiology department Third hospital Sun Yat-sen University
  2. 2. Content <ul><li>Definitions </li></ul><ul><li>Basic of Pain </li></ul><ul><li>Categories and Assessment </li></ul><ul><li>Medicine </li></ul><ul><li>Nerve block </li></ul><ul><li>Acute pain </li></ul><ul><li>Chronic pain </li></ul>05/26/10
  3. 3. Definition of Pain <ul><li>Pain is whatever the experiencing person says it is, existing whenever the experiencing person says it does. McCaffery M. (1968) </li></ul>05/26/10
  4. 4. Definition of Pain <ul><ul><ul><li>Implies emotional component </li></ul></ul></ul>05/26/10 “ Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage.” IASP (1979) <ul><ul><ul><li>can exist without tissue damage. </li></ul></ul></ul>
  5. 5. Content <ul><li>Definitions </li></ul><ul><li>Basic of Pain </li></ul><ul><li>Type and Assessment </li></ul><ul><li>Medicine </li></ul><ul><li>Nerve block </li></ul><ul><li>Acute pain </li></ul><ul><li>Chronic pain </li></ul>05/26/10
  6. 6. 05/26/10 TRPV 辣椒素受体 TREK 钾离子通道 ASIC 酸敏感离子通道 DRASIC ACIC3 MDEG 退化蛋白通道 TRPM8 冷受体 8
  7. 7. 05/26/10 Somatosensory nerve fibers
  8. 8. Somatosensory nerve fibers 05/26/10 Fiber type Fiber characteristics Speed of conduction Associated with Aβ Large, myelinated 30-70 m/sec Mechanical stimuli Aδ Small, myelinated 12-30 m/sec Cold, fast pain, mechanical stimuli C Small, unmyelinated 0.5-2 m/sec Slow, heat, cold, mechanical stimuli
  9. 9. 05/26/10
  10. 10. 05/26/10
  11. 11. Pain Pathways 05/26/10
  12. 12. Content <ul><li>Definitions </li></ul><ul><li>Basic of Pain </li></ul><ul><li>Categories and Assessment </li></ul><ul><li>Medicine </li></ul><ul><li>Nerve block </li></ul><ul><li>Acute pain </li></ul><ul><li>Chronic pain </li></ul>05/26/10
  13. 13. Categories of Pain <ul><li>Somatic pain </li></ul><ul><ul><li>Examples: acute postoperative pain, bone fractures </li></ul></ul><ul><ul><li>aching, gnawing, and/or sharp in quality, well localized </li></ul></ul><ul><ul><li>initiated by nociceptor activation in cutaneous and deep tissues. </li></ul></ul><ul><li>Visceral pain </li></ul><ul><ul><li>Examples: abdominal pain due to constipation </li></ul></ul><ul><ul><li>dull and aching in quality and poorly localized </li></ul></ul><ul><ul><li>associated with tissue injury, specifically infiltration, compression, and distention of viscera. . </li></ul></ul><ul><li>Neuropathic pain </li></ul><ul><ul><li>examples: postherpetic neuralgia (PHN) and diabetic neuropathy. </li></ul></ul><ul><ul><li>shooting, electrical, or burning pain often is superimposed on a chronic background of burning and aching sensations. </li></ul></ul><ul><ul><li>results from injury to the peripheral or CNS. </li></ul></ul>05/26/10
  14. 14. Categories of Pain <ul><li>Acute pain: less than 6 months </li></ul><ul><ul><li>Highly correlated to damage </li></ul></ul><ul><ul><li>Example: Postoperative pain, Bone fracture </li></ul></ul><ul><li>Chronic pain: more than 6 months </li></ul><ul><ul><li>Often no correlated to damage </li></ul></ul><ul><ul><li>Example: Headache, Low back pain, Cancer pain </li></ul></ul><ul><li>Neuropathic pain </li></ul><ul><ul><li>alcoholic or diabetic neuropathy </li></ul></ul><ul><ul><li>partial spinal cord damage </li></ul></ul><ul><ul><li>postherpetic neuralgia (PHN) </li></ul></ul><ul><li>Complex regional pain syndrome (CRPS) </li></ul>05/26/10
  15. 15. Measuring Pain <ul><li>Physiological </li></ul><ul><ul><li>Symptoms, Signs </li></ul></ul><ul><ul><li>Unreliable </li></ul></ul><ul><li>Self-report </li></ul><ul><ul><li>Behavioral observations </li></ul></ul><ul><ul><li>Rankings </li></ul></ul><ul><ul><li>Pain questionnaires </li></ul></ul><ul><ul><li>Psychological tests </li></ul></ul>05/26/10 No one tool is suitable for all situations
  16. 16. Ranking <ul><li>Visual analogue scale(VAS) </li></ul><ul><ul><li>0-10 </li></ul></ul><ul><ul><li>Using widely </li></ul></ul><ul><li>Verbal rating scale(VRS) </li></ul><ul><ul><li>1-4, or 1-6 </li></ul></ul><ul><li>Numerical rating scale(NRS) </li></ul><ul><ul><li>Combined with VAS </li></ul></ul>05/26/10
  17. 17. 05/26/10
  18. 18. Content <ul><li>Definitions </li></ul><ul><li>Basic of Pain </li></ul><ul><li>Type and Assessment </li></ul><ul><li>Medicine </li></ul><ul><li>Nerve block </li></ul><ul><li>Acute pain </li></ul><ul><li>Chronic pain </li></ul>05/26/10
  19. 19. 05/26/10 Opioids (Narcotics, Narcotic analgesics)
  20. 20. 05/26/10 Blooming poppy flower
  21. 21. Opioid Receptor Subtypes <ul><li>Mu receptors: </li></ul><ul><ul><li>Mu 1 and Mu 2 receptors </li></ul></ul><ul><li>Kappa receptors: </li></ul><ul><ul><li>Kappa 1 , and Kappa 3 receptors </li></ul></ul><ul><li>Delta receptors: </li></ul><ul><ul><li>Delta 1 and Delta 2 receptors </li></ul></ul>05/26/10
  22. 22. Agonist and antagonist <ul><li>Agonists: Morphine( 吗啡) ,Codeine( 可待因), Meperidine (度冷丁) , Fentanyl (芬太尼) </li></ul><ul><li>Antagonists : Naloxone (纳洛酮) </li></ul><ul><li>Agonist-Antagonists: Butorphanol (布托诺啡), Buprenorphine (丁丙诺啡) </li></ul>05/26/10
  23. 23. Pharmacological Effects of Morphine <ul><li>Central </li></ul><ul><ul><li>Analgesia </li></ul></ul><ul><ul><li>Sedation </li></ul></ul><ul><ul><li>euphoria </li></ul></ul><ul><ul><li>Pupillary constriction </li></ul></ul><ul><ul><li>Cough suppression </li></ul></ul><ul><li>Depression of respiration </li></ul><ul><ul><li>Main cause of death from opioid overdose </li></ul></ul><ul><ul><li>Combination of opioids and alcohol is especially dangerous </li></ul></ul>05/26/10
  24. 24. Other properties <ul><li>Tolerance : need more doses to keep the effect </li></ul><ul><li>Toxicity : especially respiratory depression </li></ul><ul><li>Dependence : Physiological and psychological </li></ul>05/26/10
  25. 25. Clinical use <ul><li>The most commonly used in acute/chronic pain </li></ul><ul><li>Oral route: 10 mg/4 hr, less than 1000mg/24hr </li></ul><ul><li>Long-acting sustained-release: twice a day </li></ul><ul><li>doses are increased in a logical fashion </li></ul>05/26/10
  26. 26. Naloxone <ul><li>it has no agonist activity </li></ul><ul><li>it displaces morphine from all receptors, reverses all of the effects of morphine </li></ul><ul><li>its effects are immediate (3-5 min) </li></ul><ul><li>duration is 30-45 minutes must be reinjected often </li></ul>05/26/10
  27. 27. 05/26/10 NSAIDs
  28. 28. Pharmaceutical effects <ul><li>Antipyretic </li></ul><ul><li>Analgesia </li></ul><ul><li>Antiinflammatory </li></ul><ul><li>Antirheumatic </li></ul><ul><li>Anti-platelet aggregation </li></ul>05/26/10
  29. 29. Mechanism <ul><li>inhibiting the cyclooxygenase(COX) pathway, stops the production of various prostaglandins that can sensitize free nerve endings to painful stimuli. </li></ul>05/26/10
  30. 30. Charataristics <ul><li>limited of analgesic effect (Ceiling effect) </li></ul><ul><li>do not produce tolerance or physical dependence </li></ul><ul><li>A good adjuvant (with opioid) </li></ul><ul><li>no superior NSAID for pain control </li></ul>05/26/10
  31. 31. classiify <ul><li>Salicylates Salicylates Aspirin , Diflunisal, Choline Magnesium trisalicylate </li></ul><ul><li>Salicylate-Like Drugs Ibuprofen , Naproxen, Fenopren, Ketoprofen, Indomethacin, Celecoxib(COX 2) </li></ul>05/26/10
  32. 32. Content <ul><li>Definitions </li></ul><ul><li>Basic of Pain </li></ul><ul><li>Type and Assessment </li></ul><ul><li>Medicine </li></ul><ul><li>Nerve block </li></ul><ul><li>Acute pain </li></ul><ul><li>Chronic pain </li></ul>05/26/10
  33. 33. Nerve block <ul><li>Epidural </li></ul><ul><li>Trigeminal Nerve Block </li></ul><ul><li>Stellate Ganglion Block (Cervicothoracic Sympathetic Block) </li></ul><ul><li>Brachial plexus block s </li></ul><ul><li>Interscalene Block </li></ul><ul><li>Celiac Plexus Block </li></ul><ul><li>Lumbar Sympathetic Block </li></ul><ul><li>Femoral Nerve Block </li></ul><ul><li>Sciatic nerve block </li></ul>05/26/10
  34. 34. Local anesthetics <ul><li>Block the nerve impulse </li></ul><ul><li>Only use in epidural, or nerve block </li></ul><ul><li>Can used alone or with opioids </li></ul><ul><li>Lidocaine: 45-60min </li></ul><ul><li>Bupivacaine, Ropivacaine: 4-6hr </li></ul>05/26/10
  35. 35. Mechanism <ul><li>Produce transient loss of sensory, motor, and autonomic function in a discrete portion of the body </li></ul><ul><li>Primary site of action : sodium channel in cell membrane </li></ul>05/26/10
  36. 36. Methods of administration <ul><li>Oral </li></ul><ul><li>Intravenous (IV) </li></ul><ul><li>Intra Muscular Injection (IM) </li></ul><ul><li>Inhalation (gas) </li></ul><ul><li>Transdermal </li></ul><ul><li>Epidural </li></ul><ul><li>Regional Nerve Blocks </li></ul><ul><li>Patient Controlled Analgesia [ IV or epidural ] </li></ul>05/26/10
  37. 37. Patient Controlled Analgesia (PCA) Infusions 05/26/10
  38. 38. Patient controlled analgesia <ul><li>introduced by Dr. Philip H. Sechzer in the later 1960s and described in 1971 </li></ul><ul><li>By pushing a button, patients can self-administer precise doses of opioids on PRN basis </li></ul><ul><li>sites : intravenous, epidural, intraspinal </li></ul>05/26/10
  39. 39. 05/26/10
  40. 40. PCA : settings <ul><li>bolus dose (demand dose) </li></ul><ul><li>lockout interval </li></ul><ul><li>dosage limit (1 hr, 4 hr) </li></ul><ul><li>background infusion </li></ul><ul><li>recordable and programmable </li></ul>05/26/10
  41. 41. 05/26/10 Acute pain
  42. 42. Importance of pain control <ul><li>undertreatment of severe acute pain can have a number of harmful physiological and psychological effects </li></ul><ul><li>important for humanitarian reasons </li></ul><ul><li>significantly improve outcome </li></ul><ul><li>Unrelieved acute pain resulting in more complications, longer hospital stays, greater disability and potentially long term pain </li></ul>05/26/10
  43. 43. Postoperative pain management <ul><li>Oral </li></ul><ul><ul><li>Ibuprofen 200-400 mg q8h </li></ul></ul><ul><li>IV </li></ul><ul><ul><li>Morphine8-10mg q8h </li></ul></ul><ul><ul><li>Meperidine 50-100 mg q8h </li></ul></ul><ul><li>PCA </li></ul><ul><ul><li>Epidural(PCEA) morphine 4-8 mg/d+0.1~0.2 bupivacaine(or Ropivacaine) 2-4 ml/hr </li></ul></ul><ul><ul><li>IV(PCiA) Fentanyl 0.3~0.6 mg/d </li></ul></ul>05/26/10
  44. 44. 05/26/10 Labor Pain
  45. 45. Nature of Labor Pain – 1 st Stage <ul><li>Visceral pain </li></ul><ul><ul><li>Diffuse abdominal cramping </li></ul></ul><ul><ul><li>Uterine contractions </li></ul></ul>05/26/10
  46. 46. Nature of Labor Pain – 2 nd Stage <ul><li>Somatic pain </li></ul><ul><ul><li>Perineum </li></ul></ul><ul><ul><ul><li>Sharper and more continuous </li></ul></ul></ul><ul><li>Pressure or nerve entrapment (caused by the fetus ’ head) </li></ul><ul><ul><li>May cause severe back or leg pain </li></ul></ul>05/26/10
  47. 47. Lumbar Epidural Analgesia <ul><li>L4-L5, L3-L4, or L2-L3 interspace. </li></ul><ul><li>17 or 18 gauge needle </li></ul><ul><li>catheter is thread cephalad for 2-3cms </li></ul><ul><li>fentanyl & bupivacaine </li></ul>05/26/10
  48. 48. 05/26/10 Chronic pain
  49. 49. 05/26/10 Low back pain (LBP)
  50. 50. Epidemiology <ul><li>Incidence of LBP: </li></ul><ul><ul><ul><li>60-90 % lifetime incidence </li></ul></ul></ul><ul><ul><ul><li>5 % annual incidence </li></ul></ul></ul><ul><li>90 % of cases of LBP resolve without treatment within 6-12 weeks </li></ul><ul><li>40-50 % LBP cases resolve without treatment in 1 week </li></ul>05/26/10
  51. 51. Notice <ul><li>Occult disease (e.g., retroperitoneal tumor) must be excluded </li></ul><ul><li>anatomic derangements (e.g., bony fragments) must be characterized </li></ul><ul><li>possible surgical options (e.g., decompression foraminotomy) must be considered before selecting nonsurgical management. </li></ul>05/26/10
  52. 52. Treatment <ul><li>Medications </li></ul><ul><ul><ul><li>NSAIDS Aspirin, Ibuprofen … </li></ul></ul></ul><ul><ul><ul><li>Membrane stabilizers: mexiletine( 美西律 ) </li></ul></ul></ul><ul><ul><ul><li>Muscle relaxers: chlorzoxazone (氯唑沙宗) </li></ul></ul></ul><ul><ul><ul><li>Narcotics: rarely indicated </li></ul></ul></ul><ul><ul><ul><li>Steroids: more useful for radiculitis </li></ul></ul></ul><ul><ul><ul><li>Non-narcotic analgesics: Tramadol </li></ul></ul></ul>05/26/10
  53. 53. 05/26/10 Cancer pain
  54. 54. incidence <ul><li>Early stage cancer: 30-45% with moderate to severe pain </li></ul><ul><li>Advanced (metastatic) cancer: 75-90% with moderate to severe pain </li></ul>05/26/10
  55. 55. consequences <ul><li>Depression / anxiety </li></ul><ul><li>Reduced quality of life </li></ul><ul><li>Insomnia </li></ul><ul><li>Fatigue </li></ul><ul><li>Reduced functional status </li></ul><ul><li>Decreased wound healing(?) </li></ul><ul><li>Decreased immune functioning(?) </li></ul>05/26/10
  56. 56. assessment <ul><li>Location </li></ul><ul><li>Quality: dull, aching, stabbing, shooting, burning, electric shock </li></ul><ul><li>Intensity: scales include 1-10; mild, moderate, severe; faces scale </li></ul><ul><li>Temporal characteristics </li></ul>05/26/10
  57. 57. 05/26/10 Pain Physical symptoms Psychological Social Cultural Spiritual Suffering Woodruff, 1999
  58. 58. WHO Analgesic Ladder <ul><li>Developed by WHO : a guide to pharmacological Rx for cancer/ chronic pain </li></ul><ul><li>Drug Rx :cornerstone of cancer pain Rx </li></ul><ul><li>70-90% of pts. obtain adequate pain relief from analgesic drugs alone </li></ul><ul><li>A further 20%will require additional interventions (Nerve block or sugical) </li></ul>05/26/10
  59. 59. 05/26/10 Mild pain (0-3) Moderate pain (4-6) Severe pain (7-10) By the mouth By the clock By the ladder Acetaminophen Codeine Morphine WHO pain ladder
  60. 60. Other treatment <ul><li>Intrathecal drug delivery system Most commonly used for severely chronic cancer pain, this device allows the use of narcotics while avoiding some of the significant side effects, such as constipation and sedation. </li></ul><ul><li>Celiac plexus block Visceral pain from the upper abdominal organs, including pancreatic cancer </li></ul>05/26/10
  61. 61. Questions <ul><li>Definition of pain </li></ul><ul><li>The difference about three kinds of fiber type </li></ul><ul><li>The characteristic of different kinds of pain </li></ul><ul><li>Some name of opioid </li></ul><ul><li>The main pharmacological effect of morphine </li></ul><ul><li>The main pharmacological effect of NSAIDs </li></ul><ul><li>The mechanism of labor pain </li></ul><ul><li>The ladder of treatment about cancer pain </li></ul>05/26/10
  62. 62. <ul><li>My email: [email_address] </li></ul>05/26/10
  63. 63. 05/26/10 Thank you for listening