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Spinal anatomy and_intrathecal_drugs

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  • 1. Interventional Pain Management Spinal anatomy and Intrathecal Drug Delivery Amitabh Gulati MSKCC Dept. of Anesthesiology and Critical Care
  • 2. Objectives
    • The Anatomy
    • Intrathecal medications
    • Trialing and dosing
  • 3.  
  • 4. The Spine
  • 5. The Spinal Cord
  • 6. Cord anatomy
  • 7. Cord anatomy
  • 8. The Rexed lamina
    • I – Marginal layer, pain and heat
    • II- sensory and pain (sub P)
    • III and IV- interneurons
    • V – visceral pain and wide dynamic range neurons
    • VII – Autonomic and visceral motor
  • 9.  
  • 10. Ascending Spinosensory tracts
    • Medial lemniscus system
      • Discriminative touch
      • Conscious proprioception
      • Cross in caudal medulla
    • Spinothalamic system
      • Simple touch, warmth, cold, pain
      • Crosses midline at root level
    • Both go to VPM and VPL of thalamus
  • 11. Descending inhibition
    • Reticulospinal tract
    • In medulla
    • Stimlated by PAG
      • Seratonergic
    • Pain modulation
  • 12. Brachial plexus
  • 13. Lumbar plexus
  • 14. Sacral Plexus
  • 15. The Autonomic Nervous System
  • 16. Visceral innervation
  • 17.  
  • 18. Intraspinal techniques Permanent Epidural, DuPen Intratehcal implantable pump
  • 19. Opiate receptor
    • Used by narcotic analgesics and endogenous opiates
    • mu (μ)
      • Analgesia, euphoria, respiratory/physical depression, miosis, dec GI motility
        • Mu 1 = supraspinal location and mediate analgesia
        • Mu 2 = mediate respiratory depression
    • delta (δ)
      • spinal/supraspinal analgesia, dysphoria, hallucinations, antagonistic respiratory and psychomotor stimulation
    • kappa (κ)
      • spinal analgesia, sedation, miosis, respiratory depression, dysphoria
        • Kappa 1 = spinal anesthesia
        • Kappa 3 = supraspinal anesthesia
    • sigma (σ)
      • psychotomimetic effects, dysphoria, dilation of the pupil
  • 20. Opiate effects
    • CNS
      • Narcosis
      • Euphoria
      • Nausea/ emesis
    • Cardiovascular
      • Vasodilation
      • Inhibition of baroreceptors
    • Dermatologic
      • Histamine release
    • Genitourinary
      • Spasm and retention
    • Respiratory
      • Decreased TV and RR
    • Gastrointestinal
      • Decreased motility
      • Decreased secretions
      • Constipation
      • Biliary colic
    • Cough suppressant
  • 21. Epidural administration
    • Pig epidural infusion of morphine
    • Epidural at L3
    • Intravenous measurement
    • Spinal CSF measurement at C-6, T-12, and L-5
    Bernards et al. Anesthesiology 2003 Epidural Spread Intrathecal spread
  • 22. Epidural Opiates
    • Target
      • Dorsal column of spinal cord
    • Diffusion
      • Through meninges
    • Epidural fat
      • Distribution of lipid soluble opiates
    Bernards et al. Anesthesiology 2003
  • 23. Spinal opiates
    • Redistribution
      • Lipid soluble opiates to epidural space
    • Caudal-rostral spread
      • Limited to few centimeters
    • CSF mixing
      • Compartmentalized
      • diastole
    • Leads to lower side effects
  • 24. Distribution of morphine
    • Pig anatomy with IT pump at T-10 and T-11
    • Morphine 0.48mg/day at 0.48ml/day
    • 14 days
    • Spinal cord sacrificed
    • Note decrease in concentration away from catheter
    Flack et al. A&A 2011
  • 25. Intrathecal opioids
    • Morphine
      • FDA approved for IT delivery
      • Maximum around 20 <60> mg/day
      • Side effects
        • Catheter granuloma
        • Hyperalgesia
        • Pruritus
        • Decreased sex hormones
    • Hydromorphone
      • 20 <40> mg/day maximum
      • Hyperalgesia
      • Fewer side effects
    • Fentanyl and sufentanil
    • Methadone
      • 30 mg/day max.
      • NMDA, NE, 5-HT
  • 26. Intrathecal bupivacaine
    • Starting doses
      • 3-10 mg/day
    • Maximum doses
      • 18-20 mg/day
    • Side effects
      • Weakness
      • Numbness
      • Urinary retention
    • Shown to lower morphine doses intrathecally and/or synergy
  • 27. Clonidine
    • Alpha-2 agonist
    • Start at 10-40 mcg/day
    • Side effects
      • Hypotension
        • Rebound HTN
      • Sedation
      • Confusion
      • Nausea and dry mouth
  • 28. Ziconotide
    • N-type Ca channel antagonist
    • Works on primary nociceptive transmission
    • Issues
      • Tolerability
      • Low starting dose(0.6- 1.2 mcg/day)
      • Weekly increases (0.3-0.6 mcg)
    • Side Effects
      • Allergy
      • Urinary retention
      • Altered mental status
      • Pyschiatric changes
      • weakness
  • 29. Baclofen
    • GABA-B agonist
    • Primary indication
      • Spasticity
      • Mixed pain syndromes (central pain)
    • Initial dose
      • 25-75 mcg/day
    • Side effects
      • Flaccidity
      • Weakness
      • Sedation
      • Urinary retention
    • Withdrawal syndrome
      • Watch for pruritus
      • Could be fatal
      • Supportive care
    • Overdose
      • Seizures
      • Respiratory depression
      • Could be fatal
      • Rx - physostigmine
  • 30. Consensus maximum doses
  • 31. Consensus algorithm
  • 32. The Controversy of Trialing
    • Single shot intrathecal
      • Typically morphine
    • Daily intrathecal boluses
      • Seen with ziconotide
      • 3-5 mcg in 3-5 ml
    • Intrathecal catheter
    • Epidural catheter
    • CSE technique
  • 33. Dose Conversions
    • Morphine
      • 300 mg PO = 100 mg IV = 10 mg epidural = 1 mg intrathecal
    • Dilaudid
      • 100 mg PO = 20 mg IV = 4 mg epidural = 0.8 mg intrathecal
    • Clonidine
      • 10-40 mcg/hr epidural roughly similar to 10-40 mcg/day
    • Fentanyl and sufentanil similar doses as intravenous and epidural dosing
  • 34. Epidural trial
    • Epidural instructions
    • Bupivacaine at 0.05-0.075%
    • Convert half of basal oral or IV opioid into epidural daily dose
    • Distribute opioid dose into epidural rate (say 4ml/hr)
    • Choose bolus rate (say 2mL every 30 minutes
    • An example
    • Patient taking MSContin 120mg PO TID (use ½ for calculations)
    • 180 mg/day PO = 60mg IV = 6mg epidural
    • 6 mg / 24 (hr/day) / 4 (ml/hr) = 0.0625 mg/ml
    • So can run an epidural at 62 mcg/ml morphine at 4 ml/hr with 2-4 ml bolus
  • 35. The CSE trial
    • Target lumbar region
      • Ziconotide is soluable in CSF and can spread easily
  • 36. Tips to convert to IT pump
    • IT pumps runs well between 0.2mL to 0.5mL a day
    • 20 mL pumps are common
    • Choose 40 mL pump if opioid requirement is high
    • Choose rate first (generally start low to titrate)
    • Pick initial opioid rate in mg/day
      • This will determine the opioid concentration in the solution
    • Add 6-8 mg/ day for bupivacaine
  • 37. An example
    • ABOVE patient got relief at 100mcg/hr of morphine
    • 10 mcg/hr intrathecal
      • Per day x 24 = 240mcg/day
    • Choose 0.2 ml/day for IT pump rate
    • Solution concentration is 240 mcg/day / 0.2 mL/day = 1200 mcg/mL
    • So morphine will be ordered as 1.2mg/mL
    • Choose bupivacaine as 6 mg/day
    • Concentration will be 6 mg/day / 0.2 mL/day = 30 mg/mL
  • 38. Continued
    • So final solution is 20mL of
      • 1.2 mg/mL morphine
      • 30 mg/mL of bupivacaine
    • This allows for doubling of rate with safety
      • Bupivacaine would be below 18-20 mg/day
    • PTM
      • Generally give 10% of daily rate
      • Two to three times a day q6 hours
      • Can be modified for patient preference
  • 39.  
  • 40. Questions

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