Chronic Pain Again Dr. MC Chu Anaesthesia and Intensive Care PWH.

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


Pain as a symptom


Works well here


Pain as a symptom


Does all headaches have a pathology?


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


NSAID

Opioids

Antidepressants

Membrane stabilisers (anticonvulsants)


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


NSAID

Opioids

Antidepressants



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


“Physicians should make every effort to control indiscriminate prescribing, even under pressure from

patients…”

Ballantyne N. Eng. J. Med. 2003

Symptom control

Opioids


“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


NSAID

Opioids

Antidepressants



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


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


NSAID

Opioids

Antidepressants



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


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

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 k

Usually deep seated

Anatomically diffuse l

Visceral functions .

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

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


Symptom control


Failed back surgery

Isolated neuropathy

Ischemic heart disease

Peripheral vascular disease

Pain relief as a therapy

Symptom control


de Jongste et al Br Heart J 1994

Symptom control


How does it compare with the “golden standard”?

Symptom controlAngina 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 control6-months cardiac mortality and morbidity

Mortality Morbidity Stroke

CABG (51) 7 7 8

SCS (53) 1 7 2

Mannheimer et al Circulation 1998

Symptom control


Only suitable for smart patients

Technical expertise and follow up facilities

Complications do occur

Symptom control


Cost: $ 80,000 HKD

Would you take it?


Pain as a symptom


Symptomatic control

Pain as a disease

How is this disease like?

Pain as a disease

Pain

Depression

Think negative

In-activity

MedicalDependence

InsomniaSocially deprived

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


Pain intensity (VAS)

0

1

2

3

4

5

6

7

8

9

Pre

Post

Pain as a disease


Depression (HADS)

0

5

10

15

20

Pre

Post

Pain as a disease


Catastrophising (PCS)

0

10

20

30

40

50

60

Pre

Post

Pain as a disease


40 meter carrying load (pounds)

0

2

4

6

8

10

12

Pre

Post

Pain as a disease


Analgesic consumption (types)

0

0.5

1

1.5

2

2.5

3

Pre

Post

Pain as a disease


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 Painwww.iasp-pain.org

HK College of Anaesthesiologistswww.hkca.edu.hk

Oxford pain Internet sitewww.jr2.ox.ac.uk/bandolier/booth/painpag/index.html

Chronic Pain Again Dr. MC Chu Anaesthesia and Intensive Care PWH.

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Transcript of Chronic Pain Again Dr. MC Chu Anaesthesia and Intensive Care PWH.