7. Challenges to pain assessment
ā¢ Acute vs. chronic pain ā¢ Dependence
ā¢ Concerns about addiction and ā¢ Tolerance
abuse/misuse
ā¢ Addiction
ā¢ What else?
ā¢ Pseudoaddiction
8. Barriers to Pain Management
Physician-Related
ā¢ Limited knowledge of pain pathophysiology and assessment skills
ā¢ Biases against opioid therapy and overestimation of risks
ā¢ Fear of regulatory scrutiny/action
Patient-Related
ā¢ Exaggerated fear of addiction, tolerance, side effects
ā¢ Reluctance to report pain: stoicism, desire to āpleaseā physician
ā¢ Concerns about āmeaningā of pain (associate increased pain with worsening disease)
System-Related
ā¢ Low priority given to pain and symptom control
ā¢ Limits on number of Rxs filled per month & number of refills allowed
ā¢ Reimbursement policies
(American Pain Society, 2001; Glajchen, 2001; Lister, 1996; Portenoy RK, 1996; Weinstein et al, 2000)
9. Racial & Ethnic Barriers
ā¢ Language or cultural differences make pain assessment more difficult
ā¢ PhysiciansŹ¼ perceptions and misconceptions:
ā“minority-group patients have fewer financial resources to pay for
prescriptions
ā“higher drug-abuse potential among minority groups
ā¢ Patientsā lack of assertiveness in seeking treatment
ā¢ Lack of treatment expertise at many sites at which minority-group patients
are treated
ā¢ Relative unavailability of opioids in some communities
(Bonham, 2001; Glajchen, 2001)
10. Untreated pain can lead to worsening chronic pain
ā¢ In chronic pain, the nervous system remodels continuously in
response to repeated pain signals
ā¢ nerves become hypersensitive to pain
ā¢ nerves become resistant to antinociceptive system
ā¢ If untreated, pain signals will continue even after injury resolves
ā¢ Chronic pain signals become embedded in the central nervous system
12. Cancer pain
Highly prevalent:
ā¢ 30-50% in active treatment
ā¢ 75-90% in advanced illness
Principles of Assessment
Pain History
ā¢ chronicity
ā¢ intensity and severity
ā¢ pathophysiology and mechanism
ā¢ tumor type and stage of disease
ā¢ pattern of pain and syndrome
Physical and Neurologic Examination
Radiographic Findings
13. Cancer Pain Treatment considerations
Identify the cause of the pain
ā¢ Primary treatment if indicated
ā¢ WHO ladder combined with etiology-specific therapies for syndromes
ā“pharmacologic and nonpharmacologic interventions
ā“long-acting + short-acting opioids
ā“adjuvant medications for neuropathic pain
ā“NSAIDs and steroids can be helpful when there is an inflammatory
component to pain
14. WHO guidelines
ā¢ Step 3: Opioid for moderate
to severe pain
+/- adjunctive treatment
+/- non-opioid
Pain Persists
ā¢ Step 2: Opioids for mild to
moderate pain
+/- adjunctive treatment
+/- non-opioid
Pain Persists
ā¢ Step 1: Non-opioid
+/- adjunctive treatment
(Adapted from Portenoy et al, 1997)
15. Chronic Low Back Pain
ā¢ 60-85% lifetime prevalence
Clinical Characteristics
ā¢ Preoccupation with pain
ā¢ Consistently disabled from
pain
ā¢ Depression and anxiety are
common
ā¢ High incidence of psychiatric
diagnoses
ā¢ Drug misuse is common, but
addiction relatively rare
17. Osteoarthritis
ā¢ Affects over 80% of people over 55
ā¢ 23% have limitation of activity
Diagnosis
ā¢ History: age, functionality, degree of pain, stiffness, time of occurrence
(e.g., morning, at rest, during activity)
ā¢ Physical examination: range of motion, tenderness, bony enlargement
of joint
ā¢ Laboratory findings: radiograph, CBC, synovial fluid analysis
18. Osteoarthritis Treatment Considerations
ā¢ After comprehensive assessment of function and pain
Mild to moderate pain Acetaminophen
Moderate to severe pain COX-2 and NSAIDs
Severe arthritic pain (unresponsive
to non-opioid, or for elderly at risk Opioids
for renal insufficiency)
Drug therapy ineffective or
Surgery
debilitating pain/function
20. Opioids
ā¢ Pure (Full) Agonists: Preferred for Chronic Pain
ā¢ Bind to opioid receptor(s)
ā¢ No antagonist activity
ā¢ No ceiling effect
ā¢ Agonist-Antagonists
ā¢ Ceiling effect for analgesia
ā¢ Can reverse effects of pure agonists
ā“ mixed agonist-antagonists (butorphanol,
ā“ nalbuphine, pentazocine, dezocine)
ā“ partial agonists (buprenorphine)
ā¢ Antagonists
ā¢ Reverse or block agonist effects of pure opioids
ā¢ Naloxone has been used to treat opioid overdose, addiction
21. Oral Opioids
Short-acting Long-acting
Hydrocodone/APAP
Transdermal fentanyl
Oxycodone +/- APAP
methadone
Morphine
morphine ER
Hydromorphone
oxycodone ER
Oral transmucosal fentanyl
Cmax ~ 45 min
Cmax and T1/2 vary based on
T1/2 ~ 4 hours
formulation and drug
Except fentanyl
24. Opioid pharmacology
ā¢ Conjugated by liver
ā¢ 90-95% excreted in urine
ā¢ Dehydration, renal failure, severe hepatic failure
ā¢ Decrease interval/dosing size
ā¢ If oliguria/anuria
ā¢ STOP routine dosing (basal rate) of morphine
ā¢ Use ONLY PRN
25. Delivery of opioids
What is the half life (range) for opioids?
2-4 hours
How many half lives to get to steady state?
4-5
What do you base your scheduled dosing on: Cmax or T1/2?
T1/2
What do you base your breakthrough dosing on:
Cmax or T1/2?
Cmax
26. Scheduling oral short-acting opioids
ā¢ Scheduled dosing based on t1/2
ā¢ Q4 hours
ā¢ PRN dosing based on time to Cmax
ā¢ Can be as frequent as Q1 hour PRN
ā¢ Adjust scheduled dose daily based on prn use
27. Scheduling long-acting opioids
(except methadone)
ā¢ Reason for use:
ā¢ Improve compliance, adherence
ā¢ Dose q8, q12, q24 hours (depending on product)
ā¢ Donāt crush or chew
ā¢ May use time-release granules (Kadian)
ā¢ Adjust dose every 2-4 days (once steady state is reached.)
28. Side effects of opioids
Common Uncommon
Bad dreams/hallucinations
Constipation* Delirium
Dry mouth Myoclonus
Nausea/Vomiting Seizures
Sedation Pruritus, urticaria
Sweats Respiratory suppression
Urinary retention
*No development of tolerance
29. Opioid side effects: Constipation
ā¢ Stimulant laxative:
ā¢ Senna, bisacodyl, glycerine, etc.
ā¢ Stool softener
ā¢ Docusate
ā¢ Prokinetic agent
ā¢ Metoclopramide
ā¢ Osmotic laxative (from above or below)
ā¢ Specific to peripheral opioid receptors
ā¢ methylnatrexone
30. Opioid side effects: Nausea/Vomiting
ā¢ Onset with start of opioids, tolerance may develop
ā¢ Mechanism: dopamine receptors and decreased motility
ā¢ Prevent or treat with dopamine-blocking anti-emetics (avoid with
long-QT):
ā¢ Haloperidol 0.5-1mg every 6 hours
ā¢ Droperidol 0.625 mg (PACU order set)
ā¢ Metoclopramide 10mg every 6 hours
ā¢ Alternative opioid if refractory
31. Opioid side-effects: Sedation
ā¢ Onset with start of opioids
ā¢ Distinguish from exhaustion due to pain*
ā¢ Tolerance develops within days
ā¢ Complex assessment in advanced disease
ā¢ If persistent, may consider alternative opioid or route of
administration
ā¢ Psychostimulants may play a role as well
ā¢ Methylphenidate 5mg qAM and 1 noon
32. Opioid side-effects: Neuroexcitability
ā¢ Presentation
ā¢ Cognitive changes: CAM assessment Reason to avoid ātitrate
to comfortā order at end-
ā¢ acute onset or fluctuating course, of-life
ā¢ inattention,
ā¢ disorganized thinking/altered level of consciousness
ā¢ Restlessness, agitation
ā¢ Can cause hyperalgesia
ā¢ Myoclonic jerks, seizures (may be repressed if on benzodiazepines)
ā¢ More common in renal failure
ā¢ Mechanism:
ā¢ Morphine/hydromorphone 6-glucoronide build-up
ā¢ Management:
ā¢ Benzodiazepines, fluids, and perhaps dialysis - antipsychotics
exacerbate symptoms
33. Opioid side-effects: respiratory depression
ā¢ Opioid effects differ among patients
ā¢ Change in LOC occurs before respiratory suppression
ā¢ Pharmacologic tolerance develops rapidly
ā¢ Most studies of respiratory depression in opioids looked at patients
with drug overdose
ā¢ Management:
ā¢ Identify and treat contributing causes
ā¢ Reduce opioid dose and observe
ā¢ If unstable vital signs:
ā¢ Naloxone 0.1-0.2 mg IV q 1-2 min
34. Summary
ā¢ Treat pain as though it were your own:
ā“remember under/untreated acute pain can lead to severe chronic pain
ā¢ Schedule routine opioids based on half-life
ā¢ Consider offering prns based on Cmax:
ā“IV=6-12 min;
ā“SQ=20-30min;
ā“PO=45-1hour
ā¢ When ordering opioids, always order bowel regimen to avoid constipation
ā¢ Watch for neurotoxicity in renal insufficiency - especially at end-of-life