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Chronic Pain Again. Dr. MC Chu Anaesthesia and Intensive Care PWH. Agenda. Remember the cases last time? Bear in mind the complexity of chronic pain Let’s try to treat them. Treatment principles. Pain as a symptom Find the cause and fix it Pathology oriented Works well in acute pain

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Chronic pain again

Chronic Pain Again

Dr. MC Chu

Anaesthesia and Intensive Care

PWH


Agenda
Agenda

  • Remember the cases last time?

  • Bear in mind the complexity of chronic pain

  • Let’s try to treat them


Treatment principles
Treatment principles

  • Pain as a symptom

  • Find the cause and fix it

  • Pathology oriented

  • Works well in acute pain

  • Well accepted by patient and doctor


Treatment principles1
Treatment principles

  • Pain as a symptom

  • Find the cause and fix it

  • Works well here


Treatment principles2
Treatment principles

  • Pain as a symptom

  • Find the cause and fix it

  • Does all headaches have a pathology?


Treatment principles3
Treatment principles

  • Pain as a symptom

  • Control the symptom

  • Passive

  • Long term effects and side effects

  • Case specific

  • What are the options?


Symptom control
Symptom control

  • Medications

  • Antipyretics (paracetamol)

  • NSAID

  • Opioids

  • Antidepressants

  • Anticonvulsants

  • Steroids, muscle relaxants, etc.


Symptom control1
Symptom control

  • Paracetamol

  • Effective in OA knees

  • Amadio Curr. Ther. Res. 1983

  • Effectiveness ~ Ibuprofen

  • Bradley N. Eng. J. Med. 1991

  • Safe and economical, NSAID sparing for elderly

  • Nikles Am. J. Ther. 2005


Symptom control2
Symptom control

  • Paracetamol

  • Evidence in OA only

  • Hepatic and renal toxicity do occur

  • Medication induced headache


Symptom control3
Symptom control

  • Medications

  • Antipyretics (paracetamol)

  • NSAID

  • Opioids

  • Antidepressants

  • Membrane stabilisers (anticonvulsants)

  • Steroids, muscle relaxants, etc.


Symptom control4
Symptom control

  • NSAID

  • Best evidence from rheumatoid arthritis

  • Also good for cancer pain

  • Effective in 5 out of 10 placebo-trials for LBP

  • Effective in 4 out of 9 Panadol-trials for LBP

  • Doubtful value for non-specific musculoskeletal pain

  • Koes Ann. Rheum. Dis. 1997

  • Eisenberg J. Clin. Onco. 1994


Symptom control5
Symptom control

  • NSAID

  • Annual GI bleed risk: 0.8-18% / year

  • Annual death rate: 0.03-0.1% / year

  • MacDonald BMJ 1997


Symptom control6
Symptom control

  • NSAID

  • Risk increase with age, > 4 week use,

  • history of GI bleed / ulcer / CVS disease

  • Least damaging: Ibuprofen

  • Only effective prophylaxis: PPI

  • Yeomans N. Eng. J. Med. 1998


Symptom control7
Symptom control

  • COX-2 specific NSAID

  • You know what happened to your patients


Symptom control8
Symptom control

  • COX-2 specific NSAID

  • You know what happened to your shares?


Symptom control9
Symptom control

  • Medications

  • Antipyretics (paracetamol)

  • NSAID

  • Opioids

  • Antidepressants

  • Membrane stabilisers (anticonvulsants)

  • Steroids, muscle relaxants, etc.


Symptom control10
Symptom control

  • Opioids

  • Gold standard for cancer pain management

  • (mostly) cheap and readily available

  • Administered at every route


Symptom control11
Symptom control

  • Opioids

  • Controversial for non-cancer pain

  • Limited (but positive) evidence of efficacy

  • Extensive side effects

  • Tolerance

  • Dependence

  • Divergence


Symptom control12
Symptom control

  • Opioids

  • Controversial for non-cancer pain

  • “Physicians should make every effort to control indiscriminate prescribing, even under pressure from patients…”

  • Ballantyne N. Eng. J. Med. 2003


Symptom control13
Symptom control

  • Opioids

  • Controversial for non-cancer pain

  • “Opioids are our most powerful analgesics, but politics, prejudice, and our continuing ignorance still impede optimum prescribing”

  • McQuay Lancet 1999


Symptom control14
Symptom control

  • Opioids

  • Practical guidelines for non-cancer pain

  • Exhaust other methods

  • Aim at functional improvement

  • Limit prescription authority, monitor behavior

  • Slow release, avoid injectables

  • Opioid contract


Symptom control15
Symptom control

  • Medications

  • Antipyretics (paracetamol)

  • NSAID

  • Opioids

  • Antidepressants

  • Membrane stabilisers (anticonvulsants)

  • Steroids, muscle relaxants, etc.


Symptom control16
Symptom control

  • Antidepressants

  • Analgesic at below mood altering doses

  • NNT for diabetic neuropathy ~ 3.4

  • Collins J. Pain & Sym. Manag. 2000


Symptom control17
Symptom control

  • Antidepressants

  • Analgesic at below mood altering doses

  • NNT for post-herpetic neuralgia ~ 2.1

  • Collins J. Pain & Sym. Manag. 2000


Symptom control18
Symptom control

  • Antidepressants

  • How good is NNT of 2.1 to 3.4?

  • It is not good for this


Symptom control19
Symptom control

  • Antidepressants

  • How good is NNT of 2.1 to 3.4?

  • It is really good for pain


Symptom control20
Symptom control

  • Antidepressants

  • Major problem: side effects

  • NNH (minor) ~ 2.7

  • No consensus which one is best

  • Classically TCA

  • SSRI: seemed more specific on mood


Symptom control21
Symptom control

  • Medications

  • Antipyretics (paracetamol)

  • NSAID

  • Opioids

  • Antidepressants

  • Membrane stabilisers (anticonvulsants)

  • Steroids, muscle relaxants, etc.


Symptom control22
Symptom control

  • Anticonvulsants

  • Carbamazepime for trigeminal neuralgia

  • NNT ~ 2.6

  • NNH ~ 3.4


Symptom control23
Symptom control

  • Anticonvulsants

  • NNT for diabetic neuropathy (red) ~ 2.7

  • NNT for post-herpetic neuralgia (white) ~ 3.2

  • Collins J. Pain & Sym. Manag. 2000


Symptom control24
Symptom control

  • Anticonvulsants

  • Gabapentin

  • Less organ damage

  • No drug interaction



Symptom control25
Symptom control

  • Intervention

  • Nerve / joint block

  • Counter-stimulation


Symptom control26
Symptom control

  • Nerve block

  • Where to cut

  • How to cut

  • What is left behind


Symptom control27
Symptom control

  • Nerve block

  • Where to cut

  • How to cut

  • What is left behind


Symptom control28
Symptom control

  • Nerve block

  • Where to cut

  • How to cut

  • What is left behind


Symptom control29
Symptom control

  • Nerve block

  • Where to cut

  • How to cut

  • What is left behind


Symptom control30
Symptom control

  • CNS nerve block

  • Physically protected, relatively immobile

  • Synapses are chemically vulnerable

  • Effects (and side effects) are wide spread


Symptom control31
Symptom control

  • Peripheral nerve block

  • Thick bundles of conducting cables

  • Mobile, difficulties with catheters

  • Impairment is profound yet localised


Symptom control32
Symptom control

  • Visceral nerve block

  • Contain visceral pain fibres k

  • Usually deep seated

  • Anatomically diffuse l

  • Visceral functions .


Symptom control33
Symptom control

  • Nerve block in chronic non-cancer pain

  • Preferably purely sensory block

  • Chemical / thermal neurolysis

  • Minimal dysfunction


Symptom control34
Symptom control

  • Nerve block in chronic cancer pain

  • Cover most abdominal viscera

  • 90% good to excellent relief

  • Eisenberg et al A&A 1995


Symptom control35
Symptom control

  • Joint block


Symptom control36
Symptom control

  • Joint block


Symptom control37
Symptom control

  • Transcutaneous Electrical Nerve Stimulation

  • (TENS)

  • Product of Gate theory

  • Better than placebo in short term

  • Minimal side effects

  • No long term benefit


Symptom control38
Symptom control

  • Spinal cord stimulation

  • Patient controlled

  • No medication

  • Permanent (almost)


Symptom control39
Symptom control

  • Spinal cord stimulation


Symptom control40
Symptom control

  • Spinal cord stimulation

  • Failed back surgery

  • Isolated neuropathy

  • Ischemic heart disease

  • Peripheral vascular disease

  • Pain relief as a therapy


Symptom control41
Symptom control

  • Spinal cord stimulation

  • de Jongste et al Br Heart J 1994


Symptom control42
Symptom control

  • Spinal cord stimulation

  • How does it compare with the “golden standard”?


Symptom control43
Symptom control

  • Angina attacks per week

  • Preop Post-op p-value

  • CABG (51) 16.2 5.2 <0.001

SCS (53)14.6 4.4 <0.001

Mannheimer et al Circulation 1998


Symptom control44
Symptom control

  • 6-months cardiac mortality and morbidity

  • Mortality Morbidity Stroke

  • CABG (51) 7 7 8

SCS (53) 1 7 2

Mannheimer et al Circulation 1998


Symptom control45
Symptom control

  • Spinal cord stimulation

  • Only suitable for smart patients

  • Technical expertise and follow up facilities

  • Complications do occur


Symptom control46
Symptom control

  • Spinal cord stimulation

  • Cost: $ 80,000 HKD

  • Would you take it?


Treatment principles4
Treatment principles

  • Pain as a symptom

  • Find the cause and fix it

  • Symptomatic control

  • Pain as a disease

  • How is this disease like?


Pain as a disease
Pain as a disease

  • Pain

Insomnia

Depression

Socially deprived

Medical

Dependence

Think negative

In-activity


Pain as a disease1
Pain as a disease

  • Our contribution

  • “Degenerative”

  • “Bone spurs”

  • “Nothing wrong”

  • “It is in your mind”


Pain as a disease2
Pain as a disease

  • Our contribution

  • Misunderstanding on Waddell’s signs esp. malingering

  • Incorrect attempts to test for placebo e.g. saline test


Pain as a disease3
Pain as a disease

  • Need a multi-disciplinary approach

  • Clinical psychology

  • Physiotherapy

  • Occupational therapy

  • Nursing

  • Social work / vocational training


Pain as a disease4
Pain as a disease

  • Need a multi-disciplinary approach


Pain as a disease5
Pain as a disease

  • Alleviate their depression

  • Motivate them to mobilise despite pain

  • Encourage active coping

  • Reduce dependency on medical input

  • Stop searching for a cause

  • Stop giving analgesics together with side effects

  • Cognitive behavioral therapy


Pain as a disease6
Pain as a disease

  • Cognitive behavioral therapy

  • Pain intensity (VAS)


Pain as a disease7
Pain as a disease

  • Cognitive behavioral therapy

  • Depression (HADS)


Pain as a disease8
Pain as a disease

  • Cognitive behavioral therapy

  • Catastrophising (PCS)


Pain as a disease9
Pain as a disease

  • Cognitive behavioral therapy

  • 40 meter carrying load (pounds)


Pain as a disease10
Pain as a disease

  • Cognitive behavioral therapy

  • Analgesic consumption (types)


Pain as a disease11
Pain as a disease

  • Cognitive behavioral therapy

  • Pain is the same, but

  • More active

  • Less depressed

  • Less doped



Pain as a specialty
Pain as a specialty

  • Anaesthesia and pain

  • Expertise in peri-operative pain relief

  • Analgesics

  • Regional nerve blocks


Pain as a specialty1
Pain as a specialty

  • Anaesthesia and pain

  • Dr. John J. Bonica

  • “Father of pain medicine”


Pain as a specialty2
Pain as a specialty

  • Getting established

  • IASP and its 65 global chapters

  • Over 300000 members of multiple specialties


Pain as a specialty3
Pain as a specialty

  • Anaesthesiology

  • Orthopediac surgery

  • Neurosurgery

  • Oncology / palliative care

  • Neurology

  • Rheumatology

  • Rehabilitative medicine

  • Psychiatry

  • Radiology


Pain as a specialty4
Pain as a specialty

  • … is to specialize in everthing!


Pain as a specialty5
Pain as a specialty

  • Opportunity to work with other doctors


Pain as a specialty6
Pain as a specialty

  • Other activities


Pain as a specialty7
Pain as a specialty

  • Training

  • Diploma in Pain Management (HKCA)

  • Fellowship in Pain Medicine (ANZCA)


Pain as a specialty8
Pain as a specialty

  • Pain centres at HK (2006)

  • AHNH PWH

  • QEH UCH

  • QMH PYNEH

  • Smaller scale ones at DK, PM, etc.


Resources for you
Resources for you

  • Internation Association for the Study of Pain

  • www.iasp-pain.org

  • HK College of Anaesthesiologists

  • www.hkca.edu.hk

  • Oxford pain Internet site

  • www.jr2.ox.ac.uk/bandolier/booth/painpag/index.html


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