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Opioid pain surgery2010

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  • 1. Pain Management Suzana Makowski, MD Palliative Medicine and Laura Lambert, MD Surgical Oncology
  • 2. Key concepts
    • Pain assessment
    • Opioid pharmacology
    • Pain management
    • Side effects of pain medications
  • 3. The 5 th Vital Sign
    • Pain
  • 4. What do most surgical patients have in common?
    • Pain
    • Pre-op
    • Post-op
  • 5. How do you assess pain?
    • L the exact Location of the pain and whether it travels to other body parts O Other associated symptoms such as nausea, numbness, or weakness C The Character of the pain, whether it's throbbing, sharp, dull or burning A Aggravating or Alleviating factors. What makes the pain better or worse? T the Timing of the pain, how long it lasts, is it constant or intermittent? E the Environment where the pain occurs, for example, while working or at home
  • 6. How do you assess pain?
    • Intensity
    • Categories:
    • Nociceptive (somatic and visceral), Neuropathic
  • 7. Acute vs. Chronic Pain
    • Acute pain
      • Identified event (onset)
      • Resolves in days-weeks
      • Usually nociceptive
    • Chronic pain
      • Cause often not easily identified, multifactorial
      • Indeterminate duration
      • Nociceptive and/or neuropathic
  • 8. Barriers to assessing and treating pain
    • Addiction:
    • means a person has lost control over the use of the drug and they continue to use it despite harmful consequences.
    • Tolerance:
    • the situation in which a drug becomes less effective over time and an increased dosage of the medication is required to maintain the same pain relief.
    • Dependence:
    • a person will develop symptoms and signs of withdrawal (e.g., sweating, rapid heart rate, nausea, diarrhea, goosebumps, anxiety) if the drug is suddenly stopped or the dose is lowered too quickly.
    • Pseudo-addiction:
    • refers to patient behaviors that may occur when pain is under-treated. This is different from true addiction because such behaviors can be resolved with effective pain management .
    • Substance-abusers
  • 9. What is the easiest pain to bear?
    • SOMEONE ELSE’S!
    • Don’t delay
    • Unmanaged pain leads to nervous system changes
      • Permanent damage
      • Amplification of pain
      • Development of chronic pain
  • 10. WHO step-ladder 1 mild 2 moderate 3 severe Morphine Hydromorphone Methadone Levorphanol Fentanyl Oxycodone ± Adjuvants A/Codeine A/Hydrocodone A/Oxycodone A/Dihydrocodeine Tramadol ± Adjuvants ASA Acetaminophen NSAID’s ± Adjuvants WHO. Geneva, 1996 . 1-3 4-6 7-10
  • 11. Opioid Pharmacology
    • Conjugated in liver
    • First pass metabolism
    • Excreted by kidney (90-95%)
    • First order kinetics
  • 12. Opioid kinetics Plasma Concentration 0 Half-life (t 1/2 ) Time IV PO/PR SC/IM C max 6-7 min 15-20 min 45-60 min
  • 13. Clearance Issues
    • Conjugated by liver
    • 90-95% excreted in urine
    • Dehydration, renal failure, severe hepatic failure
      • Decrease interval/dosing size
      • If oliguria/anuria
        • STOP routine dosing (basal rate) of morphine
        • Use ONLY PRN
  • 14. Opioid pharmacology
    • What is the half life (range) for IV opioids?
      • 2-4 hours
    • How many half lives to get to steady state?
      • 4-5
    • What do you base your scheduled dosing on: C max or T 1/2 ?
      • T 1/2
    • What do you base your breakthrough dosing on: C max or T 1/2 ?
      • C max
  • 15. Routine oral dosing: immediate release formulations
    • Scheduled dosing based on t 1/2
      • Q4 hours
    • PRN dosing based on time to Cmax
      • Q1 hour PRN
    • Adjust scheduled dose daily based on prn use
  • 16. Routine oral dosing Extended release preparations
    • Reason for use:
      • Improve compliance, adherence
    • Dose q8, q12, q24 hours (depending on product)
      • Don’t crush or chew
      • May use time-release granules (Kadian)
    • Adjust dose every 2-4 days (once steady state is reached.)
  • 17.  
  • 18. Equation: To convert from one opioid to another using same route FROM CHART: Opioid A dose (mg), route X opioid B route = opioid B dose (mg), route opioid A route ( )
  • 19. Coverting
    • Step 1: Calculate 24 hour dose of medication
    • Step 2: Choose 2nd medication
    • Step 3: Choose numbers from chart for ratio
    • Step 4: Calculate 24 hour dose of new opioid
    • Step 5: Divide 24 hour dose by new rate
  • 20. Example:
    • Mr. Jones is a 67 yo man with colon cancer, just had low anterior resection with diverting ileostomy. He is now NPO.
    • His home regimen is Oxycontin 40mg bid and oxycodone IR 10 mg q1 hour prn, which he uses twice a day.
    • The chief resident writes for a Dilaudid PCA with no basal and 0.1mg q6 minutes demand.
    • Within one hour after the surgery, you are called by the nurse in the PACU about the pain because the CR is back in the OR.
  • 21. Example
    • Step 1: calculate 24 hour dose –
      • Oxycontin 40mg bid = 80mg
      • Oxycodone 10mg 2x = 20 mg
      • Total 24 hour dose = 100 mg
    • Step 2: choose new opioid = hydromorphone
    • Step 3: look at the chart
  • 22.  
  • 23. Example continued
    • Step 3: select ratio from chart for formula
      • Hydromorphone IV = 1
      • Oxycodone PO = 10
    • Step 4: Calculate 24 hour dose of new opioid
    • 100mg oxy (PO/24 hrs) x (1/10) = 10 mg hydromorphine IV/ 24 hrs
    • Step 5: Calculate new rate
      • 10mg/24hrs = 0.4 mg hydromorphone IV per hour
      • At least!
  • 24.  
  • 25. Opioid Side Effects
    • Common
    • Constipation
    • Dry mouth
    • Nausea/vomiting
    • Sedation
    • Sweats
    • Less Common
    • Bad dreams or hallucinations
    • Delirium
    • Myoclonus
    • Seizures
    • Pruritus, urticaria
    • Respiratory depression
    • Urinary retention
  • 26. POP Quiz
    • Pharmacologic tolerance develops to all of the following side effects of opioid analgesics except :
    • constipation
    • nausea
    • respiratory depression
    • sedation
  • 27. Constipation
    • Common to all opioids
    • Due to effects on:
      • CNS, spinal cord, myenteric plexus of gut
    • Easier to prevent than to treat
      • Diet insufficient
      • Bulk forming agents not recommended
    • Always order bowel regimen with opioid:
      • Colace and senna if able to tolerate po
  • 28. Options to Treat Constipation
    • Stimulant laxative:
      • Senna, bisacodyl, glycerine, etc.
    • Stool softener
      • Docusate
    • Prokinetic agent
      • Metoclopramide
    • Osmotic laxative (from above or below)
    • Specific to peripheral opioid receptors
      • methylnatrexone
  • 29. Nausea/Vomiting
    • Onset with start of opioids, tolerance may develop
    • Prevent or treat with dopamine-blocking anti-emetics (avoid with long-QT):
      • Haloperidol 0.5-1mg every 6 hours
      • Droperidol 0.625 mg (PACU order set)
      • Metoclopramide 10mg every 6 hours
    • Alternative opioid if refractory
  • 30. Sedation
    • Onset with start of opioids
      • Distinguish from exhaustion due to pain*
      • Tolerance develops within days
    • Complex assessment in advanced disease
    • If persistent, may consider alternative opioid or route of administration
    • Psychostimulants may play a role as well
      • Methylphenidate 5mg qAM and 1 noon
  • 31. Delirium/Neuroexcitability
    • Presentation
      • Cognitive changes: CAM assessment
        • acute onset or fluctuating course,
        • inattention,
        • disorganized thinking/altered level of consciousness
      • Restlessness, agitation
      • Myoclonic jerks, seizures (may be repressed if on benzodiazepines)
      • More common in renal failure
  • 32. Respiratory Depression
    • Opioid effects differ among patients
      • Change in LOC occurs before respiratory suppression
      • Pharmacologic tolerance develops rapidly
      • Most studies of respiratory depression in opioids looked at patients with drug overdose
    • Management:
      • Identify and treat contributing causes
        • Reduce opioid dose and observe
      • If unstable vital signs:
        • Naloxone 0.1-0.2 mg IV q 1-2 min
  • 33. Opioid “allergies”
    • Nausea/vomiting, constipation, drowsiness, confusion
      • Adverse effects, not allergic reactions
      • Anticipated and managed
    • Anaphylactic reactions are only true allergies
      • Bronchospasms
    • Urticaria, pruritus – need careful assessment
      • Mast cell destabilization
      • Treat with routine long-acting, non-sedating antihistamines
  • 34. Adjunctive Analgesics
    • Supplement primary analgesics
    • May be primary analgesics
    • Use at any step of WHO ladder
  • 35. Adjunctive Analgesics:
    • NSAIDS
    • Local anesthetics - Topical - Regional - Systemic
    • Steroids
    • Radiation
    • Physical therapy
    • Psychological approaches
    • Complementary therapies
  • 36. Routes of Delivery
    • PO/enteral feeding tubes
    • Transmucosal
    • Rectal
    • Transdermal (fentanyl)
    • Parenteral: SC, IV, IM
    • Intraspinal: Epidural, Intrathecal
  • 37. Contacts
    • Acute Pain service at University:
      • Perioperative pain, interventional pain
      • OUCH pager
    • Interventional Pain service at Memorial:
      • Perioperative pain, back pain crisis, cancer pain requiring intervention
      • Christian Gonzalez, MD
    • Palliative Medicine Service:
      • Pain related to severe/life-limiting illness (cancer, cardiac, etc.)
      • Office: 334-8630; see call schedule for pager
  • 38. Take home messages
    • Treat the pain like it was your own
    • Remember to take into account pain medications being taken before surgery
    • Take an active approach to avoiding constipation!
    • Decrease dose/frequency in renal and hepatic failure – and just use PRN doses
    • Think of adjuncts (NSAIDS, steroids, topicals etc)
  • 39. Questions?
  • 40. Corticosteroids
    • May have a role in patients with advanced illness: when?
    • Dexamethasone
      • Long half-life (>35 hours), dose once / day
      • Minimal mineralocorticoid effect
      • Doses 2-20+ mg/day
    • Adverse effects
      • Steroid psychosis
      • Proximal myopathy
      • Other long-term adverse effects
  • 41. Interventional Pain Management
    • 14% cancer patients have pain unrelieved despite aggressive medical management.
    • Intraspinal therapies
    • Plexus nerve blocks: celiac, etc.
    • Nerve stimulation, ablation
    • Vertebral cementing
    • Memorial : Interventional Pain – Christian Gonzalez, MD
    • University : Acute Pain Service – OUCH pager
  • 42. Radiation Therapy
    • Studies show that high dose/fraction, low number of fractions is as effective as low fraction and high number of treatments in palliative settings.
  • 43. Non-pharmacologic interventions
    • Neurostimulation
    • Surgical
    • Physical therapy
    • Psychological approaches
      • Cognitive therapies
      • Biofeedback
      • Behavior therapy
    • Complementary therapies
      • Acupuncture
      • Massage
      • Meditation/relaxation: Refer to Center for Mindfulness
  • 44. Fentanyl patch (Duragesic)
    • Black box warning: why?
    • Not for opioid naïve patients
    • Not good for acute pain
    • Takes 24 hours to reach peak effect
    • Held in subcutaneous fat, thus takes >12 hours after patch is removed to leave system
    • Must not cut patch
  • 45. To start Fentanyl Patch
    • From oral morphine to patch:
    • Oral morphine 50-100 mg in 24 hours =
      • Fentanyl 25 mcg/hour transdermal patch
    • From IV Fentanyl to patch
    • 1:1 conversion
    • 25 mcg/hour = 25 mcg/hour patch
  • 46. Adjunctive Analgesics: Anticonvulsants
    • Gabapentin (Neurontin)
      • 100 mg PO daily to tid, titrate
      • Increase dose q 1-3 days - Usual effective dose 900-1800 mg/day
        • Max may be > 3600 mg/day
      • Minimal adverse effects
        • Drowsiness, tolerance develops within days
    • Pregabalin (Lyrica)
      • Start 50 mg tid, titrate over 7 days up to 600mg/day in divided doses
    • Carbamazepine
      • 100mg bid, titrate
    • Valproic acid – monitor drug levels
  • 47. Adjunctive Analgesics: Tricyclic Antidepressants
    • Amitriptyline
      • Most extensively studied - NMDA receptor
      • 10-25 mg po nightly, titrate ever 4-7 days
      • Analgesia in days to weeks
      • Monitor plasma levels
      • Adverse effects prominent (anticholinergic)
    • Desipramine
      • Fewer anticholinergic side effects
      • 10-25 mg po qhs, titrate
      • Tricyclic of choice in the seriously ill
      • Nortriptyline is an alternative
  • 48. Adjunctive Analgesics: SSNRI
    • Duloxetine (Cymbalta)
    • Venlafaxine (Effexor)
  • 49. Adjunctive Analgesics: NMDA Receptor Antagonists
    • Dextromethorphan
    • Ketamine
    • Methadone – opioid + NMDA r-antagonist
  • 50.
    • Dose interval for methadone is variable (q 6 h or q 8 h is usually adequate)
    • Biphasic pharmacology makes it more complex:
      • side effects may only show up day 3
    • Adjust methadone dose q 4-7 days
    • Do not use PRN dosing of methadone.
    Methadone
  • 51. Changing opioids…
    • Adjusting for cross-tolerance
      • Start with 50-75% of published equianalgesic dose
        • More if pain is uncontrolled
        • Less if there are adverse side effects of current opioid.
    • Methadone
      • Start with 10-25% of published equianalgesic dose and
      • Consult pain service for assistance.
    Ripamonti C, Zecca E, Bruera E. Pain . 1997.
  • 52. Adjusting for cross-tolerance
  • 53. Breakthrough dosing
    • Based on time to Cmax
      • PO/PR – q1 hour
      • SQ/IM – q20-30 min
      • IV – q 6-15 min
    • Use immediate release opioids 5-15% of 24 hour dose
  • 54. Relative strengths of routes
    • Significant first-pass metabolism of PO/PR dose
    PO/PR to SC, IV, IM 2-3 ~ 1
  • 55. Using a PCA
    • Basal rate
    • Bolus dose (PCA dose)
    • Lock-out
            • (See PCA form)

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