Pain Management


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Pain Management

  1. 1. “Pain is a more terrible lord of mankind than death itself.” Albert Schweitzer
  4. 4. Pain… Definition: An unpleasant sensory and emotional experience associated with actual or potential tissue damage. May not be directly proportional to amount of tissue injury. Highly subjective, leading to under treatment
  5. 5. Major Categories of Pain Classified by inferred pathophysiology: 1. 2. Nociceptive pain (stimuli from somatic and visceral structures) Neuropathic pain (stimuli abnormally processed by the nervous system)
  6. 6. Why Don’t We Do a Better Job of Treating Pain?
  7. 7. Introduction Many, if not most, medical conditions cause pain.
  8. 8. Introduction Pain is a protective mechanism and occurs whenever any tissues of the body are being damaged.
  9. 9. Introduction Pain occurs whenever the cells or tissues are being damaged— whatever the underlying cause.
  10. 10. Introduction The reaction to pain may be rapid, as seen when one touches a hot pan.
  11. 11. Introduction Or slow, as when one has been seated in the same position for an extended period of time.
  12. 12. Introduction One of the oldest roles of medical practitioners is to help alleviate pain.
  13. 13. Introduction Analgesia • The relief of pain without a loss of consciousness.
  14. 14. Introduction Analgesia can be provided by: • • • • Drugs Surgical Procedures Physical Modalities Other
  15. 15. Introduction Analgesia: • Eliminate the source of the pain. • Block or attenuate the pathways that transmit pain impulses to the brain. • Combination of the two.
  16. 16. Introduction Pain elicits a strong emotional response that is often recorded in our memory.
  17. 17. Problems in Pain Management
  18. 18. Problems Pain appears to be under treated: • • • • Failure to assess pain. Failure to quantify pain. Fear of addiction. Legal constraints of utilizing controlled substances. • Ignorance
  19. 19. Problems Grady Memorial Hospital: • Black patients with isolated long-bone fractures were less likely to receive adequate analgesia when compared to their white counterparts. – Todd KH, Deaton C, D’Adamo AP, Goe L. Ethnicity and analgesic practice. Ann Emerg Med. 2000;35(1):11-16
  20. 20. Prehospital Pain Management is even worse!
  21. 21. Prehospital Pain Management Pain in the prehospital setting is often: • Not identified, • Under treated, • Both. – Ricard-Hibon A, Leroy N, Magne M, et al. Evaluation of acute pain in prehospital medicine. Ann Fr Anesth Reanim. 1997;16(8):945-9
  22. 22. Prehospital Pain Management Patients with extremity fractures receive inadequate analgesia. • Study of 1,073 patients found only 1.5% received analgesia in the prehospital setting. – White LJ, Cooper LJ, Chambers RM, Gradisek RE. Prehospital use of analgesia for suspected extremity fractures. Prehosp Emerg Care. 2000;4(3):205-8
  23. 23. Prehospital Pain Management Prehospital patients with lowerextremity fractures (including hip fractures): • Only 18.3% of eligible patients received analgesia. – McEachin CC, McDermott JT, Swor R. Few emergency medical services patients with lower extremity fractures receive prehospital analgesia. Prehosp Emerg Care. 2002;6(4):406-410
  24. 24. Prehospital Pain Management Femoral neck fractures are among the most common orthopedic injuries encountered in prehospital care.
  25. 25. Prehospital Pain Management Hip fractures: • Only a modest proportion of these patients receive prehospital analgesia for this painful and debilitating injury. – Vassiliadis J, Hitos K, Hill CT. Factors influencing prehospital and emergency department analgesia administration to patients with femoral neck fractures. Emerg Med (Fremantle). 2002:14(3):261-6
  26. 26. Types of Pain Acute pain: • Pain associate with an acute event Chronic pain: • Pain that persists after an acute event is over • Pain that last 6 months or more
  27. 27. Pathophysiology The generation of pain involves interaction between all parts of the nervous system.
  28. 28. Pathophysiology Perceiving pain: • Algogenic substances—chemicals released at the site of injury. • Nociceptors—Afferent neurons that carry pain messages. • Referred pain—pain that is perceived as if it were coming from somewhere else in the body.
  29. 29. Pathophysiology Nociception • Derived from the word noxious meaning harmful or damaging to the tissues. • Mechanical event that occurs in tissues undergoing cellular injury.
  30. 30. Pathophysiology Nociceptive stimulus is detected by free nerve endings in the tissues. Three type of stimuli excite pain receptors: • Mechanical • Thermal • Chemical
  31. 31. Pathophysiology Pain fibers are free fibers.
  32. 32. Pathophysiology Pain fibers principally located in the superficial layers of the skin. Pain fibers also located in: • • • • Periosteum Arterial walls Joint surfaces Falx and tentorium of the cranial vault.
  33. 33. Pathophysiology Deep structures: • Sparsely supplied with pain fibers • Widespread tissue damage still causes the slow, chronic, aching-type pain.
  34. 34. Pathophysiology Visceral Pain: • Ischemia • Chemical stimuli • Spasm of hollow viscus • Over distension of a hollow viscous
  35. 35. Pathophysiology Chemicals that excite pain receptors: • • • • • • • Bradykinin Serotonin Histamine Potassium ions Acids Acetylcholine Proteolytic enzymes
  36. 36. Pathophysiology Chemicals that enhance the sensitivity of pain endings, but do not necessarily excite them: • Prostaglandins • Substance P
  37. 37. Pathophysiology Types of pain: • Fast Pain: – Felt within 0.1 second after painful stimulus – Also called: sharp pain, pricking pain, electric pain and acute pain. – Felt with needle stick, laceration, burn
  38. 38. Pathophysiology Types of pain: • Slow Pain: – Felt within 1.0 second or more after painful stimulus – Also called: dull pain, aching pain, throbbing pain and chronic pain. – Usually associated with tissue destruction
  39. 39. Pathophysiology Pain fibers transmit impulse to spinal cord through fast or slow fibers: • A-δ (delta) fibers—small myelinated fibers that transmit sharp pain. • C fibers—small unmyelinated fibers that transmit dull pain or aching pain.
  40. 40. Pathophysiology Pain is often a “double” sensation as fast pain is transmitted by the Aδ fibers while a second or so later it is transmitted by the C fiber pathway.
  41. 41. Pathophysiology Pain impulses enter the spinal cord from the dorsal spinal nerve roots. Fibers terminate on neurons in the dorsal horns.
  42. 42. Pathophysiolgy Pain ultimately transmitted to: • Thalamus • Medulla oblongata • Somatosensory areas of the cerebral cortex.
  43. 43. Analgesia The brain’s opiate system: • Endorphins • Enkephalins
  44. 44. Assessment of Pain Pain, in most instances, is selfreported. This should be considered along with physical signs and symptoms when assessing pain.
  45. 45. Assessment of Pain Self-Report of pain: • Have patient describe how they feel. • For infants and children, rely on care givers. • Obtain important historical information
  46. 46. OPQRST-ASPN System Onset of Problem Provocative / Palliative factors Quality Region / Radiation Severity Time Associated Symptoms Pertinent Negatives
  47. 47. Assessment of Pain Behavioral Observations: • • • • Vocalizations (cry, scream, moan) Facial expressions (frown, grimace) Body posture (fetal position) Motor responses (decreased movement, restlessness)
  48. 48. Assessment of Pain Physiological measurements: • • • • • • Skin flushing Diaphoresis Restlessness Tachycardia Tachypnea Elevated BP
  49. 49. Assessment of Pain Physical examination will often give a clear indication of the source of the patient’s pain.
  50. 50. Adult Pain Visual “Ten Scale”:
  51. 51. Pain Management
  52. 52. Pain Management Priorities are priorities! • • • • Scene safety BSI Treat any life-threatening illness of injury Treat pain
  53. 53. Pain Management Strategies: • Removing or correcting the source of the pain
  54. 54. Pain Management Strategies: • Blocking or attenuating the transmission of pain impulses to the brain
  55. 55. Pain Management Strategies: • Or, a combination of both
  56. 56. Pain Management Non-medication therapies: • • • • • • • Recognition and empathy Distraction Muscle relaxation Position of comfort Temperature regulation Physical therapies Treat underlying cause
  57. 57. Pain Management RICE: • • • • Rest Ice Compression Elevation
  58. 58. Pain Management Medications that relieve pain are called analgesics Medication therapies: • Peripherally-acting agents • Centrally-acting agents
  59. 59. Pain Management Peripherally-acting agents • Considerable reaction locally to cellular and tissue damage: – Pain – Swelling – Inflammation
  60. 60. Pain Management Peripherally-acting agents: • Corticosteroids • Non-steroidal anti-inflammatory agents (NSAIDs) • Local Anesthesia
  61. 61. Pain Management Peripherally-acting agents: • • • • Methylprednisolone Acetaminophen Ibuprofen Aspirin
  62. 62. Pain Management NSAIDs • Effective for pain and inflammation • Good side-effect profile • Second generation NSAIDs have better side-effect profiles • Inhibit prostaglandins and other mediators of pain and inflammation
  63. 63. Pain Management Centrally-acting agents: • Opiates • Anesthetic gasses used in analgesic quantities • Atypical agents (ketamine)
  64. 64. Opiates Mainstay of analgesic practice Originally derived from the opium poppy plant Many now synthetically manufactured
  65. 65. Opiate Receptors Μu (μ ) receptors Kappa (κ) receptors Delta (δ) receptors Actions: • • • • Inhibit pain Cause sedation Respiratory depression Cardiovascular depression
  66. 66. Opiates Actions: • Act on CNS and organs containing smooth muscle • Analgesia without loss of consciousness
  67. 67. Opiates Effects: • • • • • • • • Analgesia Suppresses cough reflex Respiratory depression Mental clouding Mood changes Euphoria Dysphoria Nausea and vomiting
  68. 68. Opiates Effects: • Meiosis • Decreased gastric, biliary and pancreatic secretions • Reduce gastric motility • Delay digestion of food in the small bowel • Decreases peristalsis in the colon (constipation)
  69. 69. Opiates Effects: • Certain opiates (morphine) cause an increase in biliary tract pressure • Certain opiates (morphine) cause peripheral vasodiation • Histamine release (red eyes, pruritis, flushing)
  70. 70. Opiates Morphine
  71. 71. Morphine Named after Greek god Morpheus—god of sleep and dreams
  72. 72. Morphine Onset of action: < 5 minutes IV Peak effects: 20 minutes Duration: 7 hours Typical IV dose: 2.5-10.0 mg
  73. 73. Opiates Synthetic opiate agonists / antagonists • Nalbuphine • Butorphanol
  74. 74. Synthetic Mixed Opiates Sub-class of opiates with both agonistic and antagonistic property Activate some opiate receptors while blocking others Reportedly decreases the likelihood of abuse and respiratory depression Not controlled in many states
  75. 75. Synthetic Mixed Opiates Nalbuphine
  76. 76. Nalbuphine Most common mixed agent used in prehospital care Antagonistic properties decrease the potential for abuse.
  77. 77. Nalbuphine Initial studies indicated it was an effective alternative to morphine. – Chambers JA, Guly HR. Prehospital intravenous nalbuphine administered by paramedics. Resuscitation. 1994;27-153-8. – Stene JK, Stofberg L, MacDonald G, et al. Nalbuphine analgesia in the prehospital setting. Am J Emerg Med. 1988;6(6):634-9.
  78. 78. Nalbuphine Subsequent studies seem to suggest not as effective as once thought. English study found it offered poor pain control to a high proportion of patients in the prehospital setting. – Wollard M, Jones T, Vetter N. Hitting them where it hurts? Low dose nalbuphine therapy. Emerg Med J 2002;19:565-570.
  79. 79. Nalbuphine Because of antagonistic properties, prehospital nalbuphine usage appears to be responsible for increased opiate requirements once patients arrive in the ED. – Houlihan KPG, Mitchell RG, Flapan AD, et al. Excessive morphine requirements after prehospital nalbuphine analgesia. J Accid Emerg Med 1999;16:29-31
  80. 80. Nalbuphine Also appears to interfere with general anesthesia and maintenance. – Robinson N, Burrow N. Excessive morphine requirements after pre-hospital nalbuphine analgesia. J Accid Emerg Med. 1999;16:1237.
  81. 81. Nalbuphine Probably should have a limited role in emergency medicine and EMS.
  82. 82. Nalbuphine Onset of action: 2-3 minutes IV Peak effects: < 30 minutes Duration of effect: 3-6 hours Typical IV dose: 5-20 mg
  83. 83. Gasses Nitrous Oxide (N2O): • • • • • Anesthetic at high concentrations Analgesic at low concentrations Initially used in dentistry and obstetrics Introduced into EMS in the 1970s. Effective in treating virtually all types of pain.
  84. 84. Acetaminophen – – – – Mechanism – unknown Route - PO, PR Onset - variable, half life = 2-3 h Side effects - hepatotoxicity, AIN/tubular necrosis – Contraindications • Relative—, liver disease (max daily dose reduction), renal disease (prolonged use) – History – 1894, 35% current pain med market, more ER visits for OD than all other pain meds.
  85. 85. NSAIDS – Mechanism - COX inhibitors, lipoxygenase inhibitors – Route - PO, PR, IV, IM – Side effects- platelet inhibition, PUD, dyspepsia, CNS dysfunction, headache, renal dysfunction – Contraindications • Relative - ASA/NSAID induced asthma, periop CABG, GI bleed, Renal dysfunction, liver disease.
  86. 86. NSAIDS
  87. 87. Mefenamic acid Global Standard of Pain Relief Mefenamic acid Inhibits prostaglandin (PG)synthetase Blocks prostaglandin action at receptor sites (Budoff P.W.JAMA. June 23,1979.volume 241.)
  88. 88. Anti Prostaglandin's MEFENAMIC ACID which blocks the action of cyclo-oxygenase are effective in checking MENORRHAGIA. (Menstrual disorders Pg 174 ,GYNAECOLOGY By ten Teachers ,Edited by GEOFFREY V P CHAMBERLAIN MD FRCS FRCOG , 16TH Edition , ELBS .)
  89. 89. Fenamates . Fenamates potentially inhibit cyclooxygenase and also block responses to certain PGs .The effect varies in different tissues but can be very potent. (Collier & Sweatman.)
  90. 90. Mefenamic acid a Global Standard of Pain Relief “Mefenamic acid produces highly significant reduction in menstrual blood loss in most women with Menorrhagia”. (Fraser etal Am.J.Obestet Gynecol 58-5-5543.Nov.1981.) Upto 45% reduction in median blood loss in Menorrhagia- The evidence • In a trial involving 22 patients, there was a significant reduction in blood loss from 137ml/cycle at present to 76ml/cycle on treatment. (Haynes,P.J. etal Update . Bri. J. Obstet Gyne 1979.)
  91. 91. Adjuvants/Other classes – – – – Gabapentin/Pregabalin, anticonvulsants neuropathic pain Tricyclics - neuropathic and chronic pain Caffeine - useful as an adjuvant with NSAIDS Things we shouldn’t use acutely • • Benzodiazepines: no role for acute pain relief unless due to muscle spasm Antihistamines, dextroamphetamine, steroids, intrathecal clonidine
  92. 92. Some analgesics relieve pain primarily by decreasing the sodium and potassium transfers at the neuron level, thereby slowing or stopping pain transmission. Examples—local anesthetics, anticonvulsants used for neuropathic pain, migraines.
  93. 93. Future Trends Methoxyflurane Inhalers Intranasal fentanyl Alfentanil (Alfenta) Tramadol (Ultram) Entonox Non-Pharmacological interventions
  94. 94. Tramadol Synthetic analogue of codeine. Has weak opioid agonistic properties. Slight abuse potential Non-controlled
  95. 95. Tramadol 1/10 as potent as morphine Onset of action: 1-5 minutes IV Peak effects: 15-45 minutes Duration: 4.5 hours Typical IV dose: 100 mg
  96. 96. Tramadol Analgesia and side-effects similar to morphine. Concluded tramadol is an effective alternative to morphine in the prehospital setting. – Vergnion M, Desgesves S, Garcey L, Magotteaux V. Tramadol, an Alternative to Morphine for Treating Posttraumatic Pain in the Prehospital Situation. Anest Analg. 2001;92:1543-6.
  97. 97. Topicals/Local – – – – Mechanism—local receptor effect Route—topical Side effects—local reaction, accidental IV injection, burning, erythema, hives, seizures, respiratory arrest, asthma Contraindications • Relative—liver dysfxn, renal dysfxn, heart block
  98. 98. Non-Pharmacological Interesting Austrian study for victims of minor trauma using acupressure. Patients randomly assigned to receive acupressure at “true points,” at “sham points” or “no acupressure.” Different values measured before and after treatment.
  99. 99. Acupressure At the end of transport, patients who received acupressure at “true points” had less pain, less anxiety, a slower heart rate, and greater satisfaction with the care provided. They concluded that acupressure is an effective and easy-to-learn treatment of pain in prehospital care. – Kober A, ScheckT, Greher M et al. Prehospital analgesia with acupressure in victims of minor trauma: a prospective, randomized, doubleblinded trial. Anest Analg. 2002;95(3):723-7.