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THE INS AND OUTS OF PAIN Kyle P. Edmonds, MD Fellow, Scripps Health & The Institute for Palliative Medicine at San Diego Hospice Adapted from the Palliative Care International Curriculum Series Editor, Frank R. Ferris, MD

The Ins and Outs of Pain

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Geared towards advanced pain nurses for the hospital-based and evidence-based management of pain. Overview of physiology, pathophysiology, assessment and management.

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Page 1: The Ins and Outs of Pain

THE INS AND OUTS OF PAIN

Kyle P. Edmonds, MDFellow, Scripps Health & The Institute for Palliative Medicine at San Diego

Hospice

Adapted from the Palliative Care International Curriculum Series

Editor, Frank R. Ferris, MD

Page 2: The Ins and Outs of Pain

OBJECTIVES

• Review the definitions, pathophysiology & classifications of pain.

• Perform a standardized assessment of pain and state why it is important for team communication.

• State how Cmax and half-life relate to opioid dosing.

• Describe the hallmark of addiction and the low likelihood of occurrence in pain management.

Page 3: The Ins and Outs of Pain

International Association for the Study of Pain ( IASP ):

“An unpleasant sensory and emotional experience

associated withactual or potential tissue damage.”

PAIN

Page 4: The Ins and Outs of Pain

Margo McCaffery:

“Pain is whatever the person says it is…”

PAIN

Page 5: The Ins and Outs of Pain

TOTAL PAINCICELY SAUNDERS 1964

Patient

with Pain

Physical

Emotional

Existential

Social

Page 6: The Ins and Outs of Pain

MECHANISM OF PAIN- DESCARTES

Page 7: The Ins and Outs of Pain
Page 8: The Ins and Outs of Pain

NOCICEPTOR

• Nerve cell

• Activation• Thermal • Chemical• Mechanical

• Transmits signal

Page 9: The Ins and Outs of Pain

NOCICEPTION

• Activation of receptors

• Transmitting

• Processing

• Leads to pain perception

Page 10: The Ins and Outs of Pain

BASIC STEPS: PAIN PROCESSING

• Transduction

• Transmission

• Perception

• Modulation

Page 11: The Ins and Outs of Pain

Mechanical Thermal

Chemical

Judith A. Paice, AAHPM, 2008

Aδ or C fibers

PAIN TRANSDUCTION

Page 12: The Ins and Outs of Pain

TRANSMISSION

• Stimulus to cord

• Cord to brain stem

• Brain stem to higher cortex

Page 13: The Ins and Outs of Pain

Thalamus

Somatosensory Cortex

Associative Cortex

Judith A. Paice, AAHPM, 2008

TRANSMISSION

Page 14: The Ins and Outs of Pain

PERCEPTION

• Experience• Conscious

• Multidimensional

• Interaction of transmission/transduction

Page 15: The Ins and Outs of Pain

MODULATION

• Changing

• Inhibiting

• Spinal cord level

Page 16: The Ins and Outs of Pain

PAIN PROCESSING

• Transduction

• Transmission

• Modulation

• Perception

Page 17: The Ins and Outs of Pain

CLASSIFICATION OF PAIN

• Physiologic• Nociceptive

• Neuropathic

• Mixed

• Temporal• Acute

• Chronic

Page 18: The Ins and Outs of Pain

NOCICEPTIVE PAIN

• Somatic

• Visceral

• “Sharp” “Aching” “Throbbing”

Page 19: The Ins and Outs of Pain

NEUROPATHIC PAIN

• Damaged or dysfunctional nerves

• Central

• Peripheral

• “Burning” “Tingling” “Numbness” “Electric”

Page 20: The Ins and Outs of Pain

MIXED PAIN

• Experiencing • nociceptive

and

• neuropathic

Page 21: The Ins and Outs of Pain

CLASSIFICATION OF PAIN

• Physiologic• Nociceptive

• Neuropathic

• Mixed

• Temporal• Acute

• Chronic

Page 22: The Ins and Outs of Pain

TEMPORAL CLASSIFICATION: ACUTE

• Sudden or recent onset

• Identifiable cause

• Short duration

• Sympathetic response

Page 23: The Ins and Outs of Pain

TEMPORAL CLASSIFICATION: CHRONIC

• Persistent

• May have no obvious cause

• Prolonged functional impairment

• No sympathetic response

Page 24: The Ins and Outs of Pain

INTERVAL SUMMARY

Understanding the pathophysiologyleads to improved assessment and

targeted management that will improve outcomes

Page 25: The Ins and Outs of Pain

PAIN ASSESSMENT

1. Location2. Description (type)3. Change over time4. Severity (0 – 10)5. Effect of

treatments• Benefit (+)• Unwanted effects (-)

Page 26: The Ins and Outs of Pain

1. LOCATION

• Where is it ? • Does it move ?

Page 27: The Ins and Outs of Pain

2. DESCRIPTION

• What does the pain feel like ?

• Does it ever feel burning or shooting ?

• How does the pain impact your life ?

Page 28: The Ins and Outs of Pain

• Constant

• Breakthrough

• Intermittentacute

3. CHANGE OVER TIME

Page 29: The Ins and Outs of Pain

4. PAIN SEVERITY = 5TH VITAL SIGN

29

Page 30: The Ins and Outs of Pain
Page 31: The Ins and Outs of Pain

5. EFFECT OF TREATMENTS

• Therapies tried• What worked ?• What didn’t work ? • Any affects you

didn’t like ?

Page 32: The Ins and Outs of Pain

EXAMINATION

• General exam• Changes in behavior• Focused exam• Psychological exam

Page 33: The Ins and Outs of Pain

INTERDISCIPLINARY TEAM

• Physician•Assess•Diagnose•Prescribe•Monitor•Communicate

• Nurse•Assess•Deliver•Monitor•Teach•Communicate

• Pharmacist•Assess•Provide•Monitor•Teach•Communicate

Page 34: The Ins and Outs of Pain

INTERVAL SUMMARY

Assessment of pain requires a thoughtful history and physical. Standardizing the

process helps prevent miscommunication.

Page 35: The Ins and Outs of Pain

PAIN MANAGEMENT: DEFINITIONS

• Opioid: anything that binds the opioid receptor

• Opiate: derived from the opium poppy (Papaver somniferum)

• Narcotic: archaic term, associated with illicit use

35

Page 36: The Ins and Outs of Pain

PAIN MANAGEMENT PRINCIPLES

• Don’t delay control

• Unmanaged pain nervous system changes

• Treat underlying cause

Page 37: The Ins and Outs of Pain

WHO LADDER

1, Pain 1 – 3

2, Pain 4 – 6

3, Pain 7 – 10

Morphine

Hydromorphone

Fentanyl

Oxycodone

Methadone

Levorphanol

± Adjuvants

Codeine

Tramadol

A / Codeine

A / Hydrocodone

A / Oxycodone

A / Dihydrocodeine

± Adjuvants

ASA

Paracetamol / Acetaminophen

NSAID’s

± Adjuvants WHO. Geneva, 1996.

Page 38: The Ins and Outs of Pain

Pla

sma

Co

nce

ntr

atio

n

0 Time

AbsorptionExcretion

First Order KineticsWhen biological effect

follows plasma concentration

Page 39: The Ins and Outs of Pain

Pla

sma

Co

nce

ntr

atio

n

0

Maximum Concentration ( Cmax )

20

10

= maximum concentration during the dosage interval

Cmax

Time ( hours )4

Page 40: The Ins and Outs of Pain

Pla

sma

Co

nce

ntr

atio

n

0 Time ( hours )

Time to MaximumConcentration ( t Cmax )

20

10

1 4

= time it takes to get to maximum concentration

Cmax MorphinePO / PR

Cmax = 1 hour

Page 41: The Ins and Outs of Pain

Pla

sma

Con

cen

trat

ion

0 Half-life (t1/2) Time

IV

PO / PR

SC / IM

Cmax

Time to MaximumConcentration ( t Cmax )

Page 42: The Ins and Outs of Pain

Pla

sma

Co

nce

ntr

atio

n

0

Half-Life ( t ½ )

Morphineall routes

t ½ = 4 hours

20

10

= time it takes for the body to excrete half the dose

Time ( hours )4

Page 43: The Ins and Outs of Pain

CLEARANCE CONCERNSMORPHINE

Liver

•Morphine M3G . . .

M6G . . .

Analgesia CNS

+ +++

++++

Collins SL, et al. J Pain Symptom Manage. 1998.Mercadante S, Arcuri E. J Pain. 2004.

Urine90 – 95 %

Page 44: The Ins and Outs of Pain

PRINCIPLEFOR CONTINUOUS PAIN

For constant pain

• To achieve steady-state, dose routinely every

half-life ( t ½ )

Page 45: The Ins and Outs of Pain

CONTINUOUS PAIN PRINCIPLE

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Pla

sma

Co

nce

ntr

atio

n

0

Dosing every half-life ( t ½ )Oral morphine = 4 hours

164 8 12Time ( hours )20 24

50%75%

87.5%93.75%

97%100%

Page 47: The Ins and Outs of Pain

Pla

sma

Co

nce

ntr

atio

n

0 Time

Steady state after 5 half-livesMorphine ≈ 20 hours

Peak

TroughConcentration

needed to control pain

Concentration where side-effects

start to occur

Page 48: The Ins and Outs of Pain

PRINCIPLEFOR BREAKTHROUGH PAIN

• Dose once every Time to Cmax

• PO 1 h

• Dose =10% of total 24 hr routine dose

Page 49: The Ins and Outs of Pain

Pla

sma

Con

cen

trat

ion

0 Time

Cmax

Breakthrough Pain

PO / PR≈ 1 hr

Page 50: The Ins and Outs of Pain

OPIOID ADVERSE EFFECTS

Uncommon

• Bad dreams / hallucinations

• Delirium

• Myoclonus / seizure

• Pruritis / urticarial

• Respiratory depression

• Urinary retention

Common

• Constipation

• Dry mouth

• Nausea

• Sedation

• Sweats

Page 51: The Ins and Outs of Pain

EQUIANALGESIC DOSES

Oral/Rectal Analgesic IV/SC/IM

150 Codeine --

15 Hydrocodone --

15 Morphine 5

10 Oxycodone --

3 Hydromorphone 1

51

Page 52: The Ins and Outs of Pain

MORPHINE PO OXYCODONE POMorphine 15 mg PO = Oxycodone 10 mg PO

• Patient is on Morphine ER 90mg BID PO

• Oral Morphine Equivalent?

• (90 mg x 2 = )180mg

• This equals how much Oxycodone?

• ( 180 mg x 15 / 10 =) 120mg

• How much Oxycodone ER?

• 60mg PO BID

Page 53: The Ins and Outs of Pain

MORPHINE PO HYDROMORPHONE IV

Morphine 15 mg PO = Morphine 5 mg IV = Hydromorphone 1 mg IV

• Patient is on Morphine IR 20mg q2hrs PO PRN

• Now can’t take PO, how much HM?

• ( 20mg / 3 then 6.67 mg / 5 =) 1.3mg IV

Page 54: The Ins and Outs of Pain

MORPHINE PO HYDROMORPHONE IV

Morphine 15 mg PO = Morphine 5 mg IV = Hydromorphone 1 mg IV

• Patient is on Morphine ER 90mg BID (OME 180mg)

• How much IV Hydromorphone in a day?

• ( 180mg / 3 then 60 mg / 5 =) 12mg IV / 24hrs

Page 55: The Ins and Outs of Pain

MORPHINE PO HYDROMORPHONE IV

Morphine 15 mg PO = Morphine 5 mg IV = Hydromorphone 1 mg IV

• Patient is getting 8mg IV Morphine hourly PRN without relief

• What is this equal to in Hydromorphone IV?

• ( 8 mg / 5 =) 1.6 mg

Page 56: The Ins and Outs of Pain

INTERVAL SUMMARY

Understanding the way these medications enter and leave the body can help you safely and effective treat pain. Always

have someone independently check your work when changing medications.

Page 57: The Ins and Outs of Pain

SARAH, 43 YO

• Metastatic colorectal CA

• Sacral plexus destruction

• Multiple opioid trials• Pain 6 / 10

• Drowsiness

• Confusion

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58

“TOTAL PAIN”

Page 59: The Ins and Outs of Pain

ADJUVANT THERAPIES

• Pharmacological• Interventional Anesthesia

• Non-pharmacological• Acupuncture

• Biofeedback

• TENS

• Counseling

• Integrative therapies

Page 60: The Ins and Outs of Pain

ADJUVANT EVIDENCE

• Therapies extrapolated from non-cancer pain

• Few RCTs

• Very few comparative trials

Page 61: The Ins and Outs of Pain

GUIDING THERAPY

• Diagnosis

• Assessment

• Efficacy

• Safety / tolerability

• Ease of use

• Cost

Page 62: The Ins and Outs of Pain

OPIOIDS

• Nociceptive pain > neuropathic pain

• First-line for mod to severe neuropathic pain

• Titrate to effect or side-effect

Page 63: The Ins and Outs of Pain

METHADONE

• Long half-life

• NOT first order kinetics

• Experienced palliative care / pain experts

• Coanalgesic: 2.5 – 5+ mg

• Cost PO << parenteral

Page 64: The Ins and Outs of Pain

GABAPENTINOIDS

• Sodium channel antagonist

• Positive RCT’s

• NNT less favorable than TCAs

• First-line 2º safety

Page 65: The Ins and Outs of Pain

• Trial gabapentin

•Start 100-300 mg qhs

•Daily, increase 100 mg q8h

•Effective 900 - 1800 mg / 24 hr

•Max 3600 - 5400 mg / 24 hr

• If ineffective, pregabalin

•Start 25-75 mg q12h

•Increase 25 mg q12h

•Effective 100-150 mg / 24 hr

•Max 300 - 600 mg / 24 hr

GABAPENTINOIDS…

Page 66: The Ins and Outs of Pain

ANTIDEPRESSANTS

• 3º amine TCAs (amitriptyline)

• 2º amine TCAs (desipramine, nortriptyline)

• Mixed SNRIs (duloxetine, venlafaxine)

• SSRIs (citalopram, paroxetine)

Page 67: The Ins and Outs of Pain

OTHER ANTICONVULSANTS

• excitation

• Limited data, trial-and-error

• Newer drugs have better safety profiles

Page 68: The Ins and Outs of Pain

CORTICOSTEROIDS

• Limited data, widely used in • Bone pain

• Neuropathic pain

• Lymphedema

• Other conditions

• Dexamethasone• Start high dose 8+ mg daily

• Taper to lowest effective dose

Page 69: The Ins and Outs of Pain

OTHER OPTIONS

• Lidocaine (IV or SC)

• Sodium channel blockade

• Good evidence

• Ketamine (PO, IV, SC)

• NMDA blocker

• Dose-limiting psychological effects

Page 70: The Ins and Outs of Pain

SARAH, 43 YO, CA COLON

• Touch

• Simplify meds ( ! )

• Address total suffering

• Feb 14…Pain 6 / 10

Page 71: The Ins and Outs of Pain

INTERVAL SUMMARY

Sometimes the best long-acting medicine for a patient may not be an opioid. Poor

opiate-responsiveness is a sign that multimodal therapies may be necessary

to achieve pain relief.

Page 72: The Ins and Outs of Pain

CLARIFYINGADDICTION

Page 73: The Ins and Outs of Pain

TOLERANCE

• Reduced effectiveness over time

• Not clinically significant with chronic dosing

• Suspect disease progression

Page 74: The Ins and Outs of Pain

PHYSICAL DEPENDENCE

• Process of neuro-adaptation

• Abrupt cessation withdrawal

• Titrate down if stopping

• Avoid antagonists

Page 75: The Ins and Outs of Pain

DRUG DIVERSION

• Regulation

• Record keeping

• Accountability

Page 76: The Ins and Outs of Pain

PSEUDO-ADDICTION

• Most common cause of apparent drug ‘ failure ’ is under-dosing

• Behavior LOOKS like drug seeking

Page 77: The Ins and Outs of Pain

ADDICTION: CHARACTERISTICS

• Psychological dependence

• Compulsive use

• Loss of control over drugs

• Loss of interest in pleasurable activities

Page 78: The Ins and Outs of Pain

ADDICTION: HALLMARK

• Continued use of drugs in spite of harm

• Rare outcome of pain management

Page 79: The Ins and Outs of Pain

SUBSTANCE USERS

• Can have pain too

• Treat with compassion

• Consultation with pain or addiction specialists

Page 80: The Ins and Outs of Pain

INTERVAL SUMMARY

True addiction is rare in the management of pain and pain can occur in those with a

history of substance use.

Page 81: The Ins and Outs of Pain

SUMMARY

81

• Pain may be nociceptive, neuropathic or both and the history tells you which.

• A standardized approach to the assessment of pain helps prevent miscommunication.

• For constant pain, dose on the half-life (q4hrs). For breakthrough pain, dose on the Cmax (route-dependent).

• True addiction is uncommon in pain management.

Page 82: The Ins and Outs of Pain

THE INS AND OUTS OF PAIN

Kyle P. Edmonds, MDFaculty, UCSD Division of Palliative Medicine

928.853.1483

[email protected]

Kylepedmonds.com