Basic Principles and Difficult Pain Dr Pete Nightingale Macmillan GP

Objectives By the end of this session I hope that you will have refreshed your ability to diagnose the type of pain a patient has and have in mind a strategy to deal with each pain.

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Incidence in Cancer  About ¼ pain of patients never have Of those that do: 1/3 have a single pain 1/3 have three or more different pains

Overview of Pain Classification  Definitions  Classification  Nociceptive and Neuropathic

Definitions

Definitions of Pain  

Pain

An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage

Allodynia

Pain due to a stimulus that does not normally provoke pain 

Dysaesthesia

An unpleasant abnormal sensation, whether spontaneous or evoked

Causes of Pain  Pain caused by cancer and other medical illnesses may be caused by either direct effect of the disease OR  By the treatment associated with the disease which injure organs,muscles and nerves.E.G. Surgery, Chemo, XRT

Classification of Pain

Which type of pain could be classified as visceral nociceptive pain?

    A Dull or aching, well localised B Intermittant, burning or shooting C Associated with an area of abnormal sensation D Poorly localised, colic or sensation of pressure

Classification of Pain Nociceptive Pain Pain pathways intact

Somatic Visceral Neuropathic Pain

Anatomical or functional abnormality of pain pathway In area of abnormal sensation

Pain Types

Somatic Visceral Neuropathic Source Charact er

Skin or Deep Tissues Dull or aching Well localised

Causes

Trauma Bone Mets Organs Tender pressure Poorly Localised Colic MI Liver Mets Damaged Nerves Burning or Shooting Intermittent Post-herpetic Phantom Limb

Nociceptive Pain  Somatic Activation of pain receptors (nociceptors) by chemical stimuli in cutaneous or deep tissues  Visceral Activation of nociceptors as a result of infiltration/compression/extension or stretching of viscera (organs)

Neurophysiology 

Normal physiology of pain

DRG Stimulus Pain neurone Response CNS

Normal Sensation Low intensity stimulation High Intensity Stimulation Innocuous Sensation PAIN

Neuropathic Pain  Spontaneous firing of damaged nerves  Pain due to a disturbance or pathological change in a nerve  A form of pain that occurs in up to 1% of population.

 Virtually any condition that damages neural tissue or causes neuronal dysfunction can result in neuropathic pain  Pain in an area of abnormal sensation

Diagnosis SYMPTOMS

Positive

•Pain •Paraesthesia •Hyperaesthesia

Negative

•Numbness SIGNS

Normal Motor

•Distal Wasting •Absent reflexes

Sensory

•Reduced Vibration/ light touch/ Pinprick

Pain Assessment

Assessment of Pain

‘ i.

History Pain is what the patient says it is ’

There is evidence health workers tend to underestimate pain.

PQRST Response to previous treatment New Pain or Exacerbation

P P Q R S T       P Palliative factors ‘ what makes it better?

’ P Provocative factors ‘ what makes it worse?

’ Q Quality of pain ‘ what exactly is it like?

’ R Radiation ‘ Does it spread anywhere?

’ S Severity ‘ How much is it affecting life?

’ T Temporal factors ‘ Does the pain come and go?

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Assessing Consequences of Pain PAIN MAY LEAD TO  depression  Anxiety  Ability to interact socially  physical performance  working ability  family income

Factors Affecting Pain Threshold

Threshold

 Discomfort Insomnia Fatigue Anxiety Fear Anger Sadness Depression Boredom Mental Isolation Social abandonment

Threshold

 Relief of other symptoms Sleep Sympathy Understanding Companionship Creative Activity Relaxation  Anxiety  Mood Analgesics Anxiolytics Antidepressants

Principles of Pain Management

Treating the Underlying Cause  Palliative Anti-cancer Treatment Radiotherapy Chemotherapy Hormone therapy  Modifying the effects of the disease Correct Hypercalcaemia Treat Lymphoedema Surgery – spinal stabilisation

WHO Analgesic Ladder Will deal with 80% of Cancer Pain

strong opioid

(morphine)

weak opioid

(Codeine or Tramadol)

non-opioid

(Paracetamol)

+/- Adjuvant

Tramadol  Dual MOA  Via opioid receptors  By blocking 5HT and NA  1/5 th as potent as morphine orally  Less constipating than codeine/morphine  ?role in neuropathic pain  ?lowers seizure threshold

Rules for Step 2  A weak opioid should be opioid added to a non  If a weak opioid is inadequate at regular optimal dose, change to morphine  Codeine is 1/10 th as potent as morphine  Do not ‘ kangaroo ’ opioid from weak opioid to weak

Step3: Strong Opioids        Morphine Diamorphine Oxycodone Methadone Hydromorphone Fentanyl Alfentanil

Yet another A B C !

   A-Anti-emetic-usually Haloperidol 1.5mg for 7-10 days B- Breakthrough pain. Use 1/6 of daily dose (4 hrly equivalent) as ‘ rescue ’ C-Constipation required – Laxative always

Morphine preparations 

Modified Release:

Zomorph /MST Continus 12 hourly regularly MXL capsules 24 hourly regularly

Initiation of Morphine  For uncontrolled pain, start 4 hourly I/R morphine for rapid titration  Prescribe prn I/R at the same dose  If the patient responds to rescue doses, use them as needed  (? double night-time dose)

Conversion to long acting   Once pain controlled on 4 hourly dose I/R morphine, can convert to M/R morphine Tot up total daily morphine  For Zomorph: divide by 2 and prescribe Zomorph at this dose bd  For MXL: prescribe the total dose once daily

Conversion  Prescribe prn breakthrough dose 1/6 th daily morphine dose of total  Give the 1 st dose of M/R morphine with the last regular dose of I/R

Patient Explanation 1) 2) 3) 4) The first goal is reduction in discomfort (setting targets) Common side-effects are sleepiness, nausea and constipation.

The drowsiness/nausea tend to wear off Prophylactic Rx nausea and constipation

THEN REGULARLY REVIEW PATIENT

Alternative Strong Opiates

Subcutaneous infusion: Stable pain, unable to swallow: Afraid of using morphine: Infection with pyrexia: Mild - moderate renal impairment: Severe renal failure: Liver impairment:

Choosing the right opioid

diamorphine SC diamorphine or transdermal fentanyl oxycodone or fentanyl any can be used except transdermal fentanyl Possibly use hydromorphone fentanyl morphine (with care)

Please rank the following in order of potency:     A Codeine 60mg B Tramadol 100mg C Morphine 5mg D Fentanyl 25mcg/hr patch.

FENTANYL (eg Durogesic D Trans)  Alternative strong opioid ( Change patch every 72 hrs)  Take 12-48hrs to achieve maximum blood levels  Oral Morphine used for breakthrough pain      Indications for use Intolerable adverse effects of morphine Tablet phobia or difficulty swallowing Poor compliance with oral medication When the patient won ’ t have anything called morphine!

FENTANYL (e.g Durogesic D Trans)

4HRLY MORPHINE DOSE

5-20mg 25-35mg 40-50mg 55-65mg 70-80mg 85-95mg 100-110mg MST b.d.

30mg 90mg 120mg 180mg 240mg 260mg 330mg

FENTANYL DOSE

25 µ g/h 50 µ g/h 75 µ g/h 100 µ g/h 125 µ g/h 150 µ g/h 175 µ g/h

Oxycodone  MR – Oxycontin IR – Oxynorm  Oxycodone twice as potent as morphine  MST 10mg bd  Oxycontin 5mg bd  Tolerated better by some  More expensive

Adjuvant Analgesics (1)

Analgesic

NSAIDs Steroids

Indication

Bone Pain SOL/ Organ Infiltration

Example

Diclofenac Dexamethasone Anti-depressants Anti-convulsants Anti-spasmodics Anti-spastics Benzodiazepines Neuropathic Pain Neuropathic Pain Colic Skeletal Muscle Spasm Muscle Spasm Amitriptyline Gabapentin Buscopan Baclofen Diazepam

Non-drug Treatments (1)  Nerve Blocks Local Anaesthetic Neurolytic (phenol)  Neurosurgery Cordotomy  Immobilisation Rest / Slings /Splints/ Corset Walking Aids / Wheelchair

Non-drug Treatments (2)  Psychology Individual Group Relaxation Education Cognitive Therapy Multi-disciplinary Approach  Distraction  Hypnosis

Mannix K et al Palliative Medicine 2006; 20:579-584 Cognitive Behaviour Therapy (CBT) can be used by palliative care staff to help patients.

Training may become more widely available

CBT Cognitive Behaviour Therapy Physical Pain

ABC of CBT!

 A is the activating event  B is your beliefs and thoughts  C is the consequences, such as emotions you feel

The Mercedes Model Our ever present internal states consist of: THINKING EMOTIONS PHYSIOLOGY

Balloon challenge!

Non-drug Treatments (3)  Counter-irritation Massage – Gate Control Theory TENS – Gate Control Theory Acupuncture – stimulates release of endorphins  Physical Exercise and mobility Physiotherapy Hydrotherapy Music/ Art therapy  Lifestyle Modification

Reasons for Unresolved Pain  A belief that symptoms are untreatable  Fear or ignorance (docs/patients/carers)  Inadequate assessment  Inappropriate treatment  No adjuvants / wrong drug or dose  Total pain  Failure of patient and doctor to ask for help

Neuropathic Pain Management

What is a commonly accepted ‘ batting order ’ of drugs to treat neuropathic pain  A Gabapentin  B Amitriptyline  C Dexamethasone  D Ketamine

Neuropathic Pain  Pharmacological  Invasive/injection therapy  Physical therapies  Psychological therapy  Complementary therapy

WHO Ladder +/- NSAIDs  Compound analgesics  Nsaids- use for trial of 3-7 days and then review  Opioids do work  Responsiveness reduces with time  ?In combination with neuropathic agents  No evidence for one opioid above another except Methadone

Anti-depressants  Best evidence base is amitriptylline  Small NNT  High NNH  Usually well tolerated  Rapid response  1 wk to reach steady state

Anti-convulsants        

Gabapentin

Short acting Safe/ Good side-effect profile Can use in severe renal compromise Memory loss and reduced concentration More expensive Improved sleep pattern Mood enhancement  Clonazepam good for night pain

Ketamine  NMDA antagonist  Beneficial for incident related and pressure area pain  Can use as little as 2.5mg sublingual for procedure pain (effect within 10 minutes)  Breaking the cycle of pain with ketamine or spinal intervention

Methadone Indications for use  Intolerable side-effects with other opioids  Inadequate analgesia despite dose titration  Morphine hyperexcitability, allodynia  Morphine poorly responsive pain  Nociceptive & Neuropathic pain  Severe renal failure  Antitussive

Management Strategy

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Methadone Pregabalin Clonazepam Sodium Valproate (Carbamezpa ine) Steroids Amitriptyline Gabapentin Ketamine Spinal

Summary  Assessment of each pain is essential  Calm Reassuring Approach  Analgesic ladder and adjuvants  Non-drug measures  Realistic goals  Clear Plan of Action  Regular reassessment