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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. Incidence in Cancer. - PowerPoint PPT Presentation
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Basic Principles and Difficult Pain
Dr Pete NightingaleMacmillan 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.
Incidence in Cancer About ¼ of patients never
have pain Of those that do:-1. 1/3 have a single pain2. 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
AllodyniaPain due to a stimulus that does not normally provoke pain
DysaesthesiaAn 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 Neuropathic Pain
Pain pathways intact Anatomical or functional abnormality of pain pathway
In area of abnormal sensationSomatic Visceral
Pain TypesSomati
cVisceral Neuropathi
c
Source Skin or Deep
Tissues
Organs Damaged Nerves
Character
Dull or achingWell
localised
Tender pressurePoorly
LocalisedColic
Burning or Shooting
Intermittent
Causes TraumaBone Mets
MILiver Mets
Post-herpeticPhantom
Limb
Nociceptive Pain
SomaticActivation of pain receptors (nociceptors) by chemical stimuli in cutaneous or deep tissues
VisceralActivation of nociceptors as a result of infiltration/compression/extension or stretching of viscera (organs)
Neurophysiology Normal physiology of pain
CNS
DRG
Stimulus Response
Pain neurone
Normal Sensation
Low intensity stimulation
Innocuous Sensation
High Intensity Stimulation
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
DiagnosisSYMPTOMS SIGNS
Positive
•Pain
•Paraesthesia
•Hyperaesthesia
Negative
•Numbness
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.PQRSTResponse to previous treatmentNew 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?’
Assessing Consequences of Pain
depression Anxiety Ability to
interact socially
physical performance working ability
family income
PAIN MAY LEAD TO
Factors Affecting Pain ThresholdThreshold Threshold
Discomfort Relief of other symptoms
Insomnia Sleep
Fatigue Sympathy
Anxiety Understanding
Fear Companionship
Anger Creative Activity
Sadness Relaxation
Depression Anxiety
Boredom Mood
Mental Isolation Analgesics
Social abandonment Anxiolytics
Antidepressants
Principles of Pain Management
Treating the Underlying Cause
Palliative Anti-cancer TreatmentRadiotherapyChemotherapyHormone therapy
Modifying the effects of the diseaseCorrect HypercalcaemiaTreat LymphoedemaSurgery – spinal stabilisation
WHO Analgesic LadderWill 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
1/5th 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 added to a non-opioid
If a weak opioid is inadequate at regular optimal dose, change to morphine
Codeine is 1/10th as potent as morphine
Do not ‘kangaroo’ from weak opioid to weak opioid
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 – Laxative always required
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 1/6th of total daily morphine dose
Give the 1st dose of M/R morphine with the last regular dose of I/R
Patient Explanation1) The first goal is reduction in
discomfort (setting targets)
2) Common side-effects are sleepiness, nausea and constipation.
3) The drowsiness/nausea tend to wear off
4) Prophylactic Rx nausea and constipation
THEN REGULARLY REVIEW PATIENT
Alternative Strong Opiates
Choosing the right opioid
Subcutaneous infusion: diamorphine
Stable pain, unable to swallow: SC diamorphine or transdermal fentanyl
Afraid of using morphine: oxycodone or fentanyl
Infection with pyrexia: any can be used except transdermal fentanyl
Mild - moderate renal impairment: Possibly use hydromorphone
Severe renal failure: fentanyl
Liver impairment: 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
MST b.d. FENTANYL DOSE
5-20mg 30mg 25µg/h
25-35mg 90mg 50µg/h
40-50mg 120mg 75µg/h
55-65mg 180mg 100µg/h
70-80mg 240mg 125µg/h
85-95mg 260mg 150µg/h
100-110mg 330mg 175µg/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 Indication Example
NSAIDs Bone Pain Diclofenac
Steroids SOL/ Organ Infiltration
Dexamethasone
Anti-depressants
Neuropathic Pain Amitriptyline
Anti-convulsants Neuropathic Pain Gabapentin
Anti-spasmodics Colic Buscopan
Anti-spastics Skeletal Muscle Spasm
Baclofen
Benzodiazepines Muscle Spasm Diazepam
Non-drug Treatments (1) Nerve Blocks
Local Anaesthetic
Neurolytic (phenol)
NeurosurgeryCordotomy
ImmobilisationRest / Slings /Splints/ Corset
Walking Aids / Wheelchair
Non-drug Treatments (2) Psychology
IndividualGroup
RelaxationEducationCognitive TherapyMulti-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
CBTCognitive Behaviour
Therapy
PhysicalPain
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
THINKING EMOTIONS
PHYSIOLOGY
Our ever present internal states consist of:
Balloon challenge!
Non-drug Treatments (3) Counter-irritation
Massage – Gate Control TheoryTENS – Gate Control TheoryAcupuncture – stimulates release of
endorphins
PhysicalExercise and mobilityPhysiotherapyHydrotherapyMusic/ 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 StrategyAmitriptyline
Gabapentin
Ketamine
Spinal
??? Methadone
Pregabalin
Clonazepam
Sodium Valproate
(Carbamezpaine)
Steroids
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