Transcript Document

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
Well accepted by patient and doctor
Treatment principles
Pain as a symptom
Find the cause and fix it
Works well here
Treatment principles
Pain as a symptom
Find the cause and fix it
Does all headaches have a pathology?
Treatment principles
Pain as a symptom
Control the symptom
Passive
Long term effects and side effects
Case specific
What are the options?
Symptom control
Medications
Antipyretics (paracetamol)
NSAID
Opioids
Antidepressants
Anticonvulsants
Steroids, muscle relaxants, etc.
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 control
Paracetamol
Evidence in OA only
Hepatic and renal toxicity do occur
Medication induced headache
Symptom control
Medications
Antipyretics (paracetamol)
NSAID
Opioids
Antidepressants
Membrane stabilisers (anticonvulsants)
Steroids, muscle relaxants, etc.
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 control
NSAID
Annual GI bleed risk: 0.8-18% / year
Annual death rate: 0.03-0.1% / year
MacDonald BMJ 1997
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 control
COX-2 specific NSAID
You know what happened to your patients
Symptom control
COX-2 specific NSAID
You know what happened to your shares?
Symptom control
Medications
Antipyretics (paracetamol)
NSAID
Opioids
Antidepressants
Membrane stabilisers (anticonvulsants)
Steroids, muscle relaxants, etc.
Symptom control
Opioids
Gold standard for cancer pain management
(mostly) cheap and readily available
Administered at every route
Symptom control
Opioids
Controversial for non-cancer pain
Limited (but positive) evidence of efficacy
Extensive side effects
Tolerance
Dependence
Divergence
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 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 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 control
Medications
Antipyretics (paracetamol)
NSAID
Opioids
Antidepressants
Membrane stabilisers (anticonvulsants)
Steroids, muscle relaxants, etc.
Symptom control
Antidepressants
Analgesic at below mood altering doses
NNT for diabetic neuropathy ~ 3.4
Collins J. Pain & Sym. Manag. 2000
Symptom control
Antidepressants
Analgesic at below mood altering doses
NNT for post-herpetic neuralgia ~ 2.1
Collins J. Pain & Sym. Manag. 2000
Symptom control
Antidepressants
How good is NNT of 2.1 to 3.4?
It is not good for this
Symptom control
Antidepressants
How good is NNT of 2.1 to 3.4?
It is really good for pain
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 control
Medications
Antipyretics (paracetamol)
NSAID
Opioids
Antidepressants
Membrane stabilisers (anticonvulsants)
Steroids, muscle relaxants, etc.
Symptom control
Anticonvulsants
Carbamazepime for trigeminal neuralgia
NNT ~ 2.6
NNH ~ 3.4
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 control
Anticonvulsants
Gabapentin
Less organ damage
No drug interaction
Want to have a break?
Symptom control
Intervention
Nerve / joint block
Counter-stimulation
Symptom control
Nerve block
Where to cut
How to cut
What is left behind
Symptom control
Nerve block
Where to cut
How to cut
What is left behind
Symptom control
Nerve block
Where to cut
How to cut
What is left behind
Symptom control
Nerve block
Where to cut
How to cut
What is left behind
Symptom control
CNS nerve block
Physically protected, relatively immobile
Synapses are chemically vulnerable
Effects (and side effects) are wide spread
Symptom control
Peripheral nerve block
Thick bundles of conducting cables
Mobile, difficulties with catheters
Impairment is profound yet localised
Symptom control
Visceral nerve block
Contain visceral pain fibres
Usually deep seated
Anatomically diffuse
l
Visceral functions .
k
Symptom control
Nerve block in chronic non-cancer pain
Preferably purely sensory block
Chemical / thermal neurolysis
Minimal dysfunction
Symptom control
Nerve block in chronic cancer pain
Cover most abdominal viscera
90% good to excellent relief
Eisenberg et al A&A 1995
Symptom control
Joint block
Symptom control
Joint block
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 control
Spinal cord stimulation
Patient controlled
No medication
Permanent (almost)
Symptom control
Spinal cord stimulation
Symptom control
Spinal cord stimulation
Failed back surgery
Isolated neuropathy
Ischemic heart disease
Peripheral vascular disease
Pain relief as a therapy
Symptom control
Spinal cord stimulation
de Jongste et al Br Heart J 1994
Symptom control
Spinal cord stimulation
How does it compare with the “golden standard”?
Symptom control
Angina attacks per week
Preop
CABG (51) 16.2
Post-op
5.2
p-value
<0.001
SCS (53)
4.4
<0.001
14.6
Mannheimer et al Circulation 1998
Symptom control
6-months cardiac mortality and morbidity
CABG (51)
Mortality
7
Morbidity
7
Stroke
8
SCS (53)
1
7
2
Mannheimer et al Circulation 1998
Symptom control
Spinal cord stimulation
Only suitable for smart patients
Technical expertise and follow up facilities
Complications do occur
Symptom control
Spinal cord stimulation
Cost: $ 80,000 HKD
Would you take it?
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
Depression
Insomnia
Socially deprived
Medical
Dependence
Pain
Think negative
In-activity
Pain as a disease
Our contribution
“Degenerative”
“Bone spurs”
“Nothing wrong”
“It is in your mind”
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 disease
Need a multi-disciplinary approach
Clinical psychology
Physiotherapy
Occupational therapy
Nursing
Social work / vocational training
Pain as a disease
Need a multi-disciplinary approach
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 disease
Cognitive behavioral therapy
Pain intensity (VAS)
9
8
7
6
5
Pre
4
Post
3
2
1
0
Pain as a disease
Cognitive behavioral therapy
Depression (HADS)
20
15
10
5
0
Pre
Post
Pain as a disease
Cognitive behavioral therapy
Catastrophising (PCS)
60
50
40
30
20
10
0
Pre
Post
Pain as a disease
Cognitive behavioral therapy
40 meter carrying load (pounds)
12
10
8
6
4
2
0
Pre
Post
Pain as a disease
Cognitive behavioral therapy
Analgesic consumption (types)
3
2.5
2
1.5
1
0.5
0
Pre
Post
Pain as a disease
Cognitive behavioral therapy
Pain is the same, but
More active
Less depressed
Less doped
Before we move on to the last bit
Pain as a specialty
Anaesthesia and pain
Expertise in peri-operative pain relief
Analgesics
Regional nerve blocks
Pain as a specialty
Anaesthesia and pain
Dr. John J. Bonica
“Father of pain medicine”
Pain as a specialty
Getting established
IASP and its 65 global chapters
Over 300000 members of multiple specialties
Pain as a specialty
Anaesthesiology
Orthopediac surgery
Neurosurgery
Oncology / palliative care
Neurology
Rheumatology
Rehabilitative medicine
Psychiatry
Radiology
Pain as a specialty
… is to specialize in everthing!
Pain as a specialty
Opportunity to work with other doctors
Pain as a specialty
Other activities
Pain as a specialty
Training
Diploma in Pain Management (HKCA)
Fellowship in Pain Medicine (ANZCA)
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
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