HX1.2 - Cancer Pain Management Flashcards
What percentage of cancer patient experience pain?
(60-80%)
What is pain?
Unpleasant sensory and emotional experience associated with actual / potential tissue damage
What are the two processes at work when pain is experienced?
- Cognitive Process
2. Emotional Process
How does emotional process affect sensitivity/perception of pain?
These influence pain processing at the level of the spinal cord.
What is the result of the physical and emotional process of experiencing pain?
Pain is an individual experience.
What are the goals of assessing pain?
- Classify the pain
- Determine the cause
- Estimate severity
- Impact on patient
What are the steps in assessing pain?
- History
- Examination
- +/- Investigations
How do we classify pain?
- Type of pain
2. Time course
Who is the primary assessor of pain?
Patient
What should be elicited in the pain Hx?
SOCRATES
Site Onset Character Radiation Associations Time course Exacerbating / Relieving factors Severity
What are the two broad types of pain?
- Nociceptive
2. Neuropathic
What are the subcategories of nociceptive pain?
NOCICEPTIVE=
- Visceral
- Somatic
What brings about Visceral pain? What is its character?
Diffuse, achy, cramping
Results from the activation of nociceptors of the thoracic, pelvic, or abdominal viscera (organs). Visceral structures are highly sensitive to distension (stretch), ischemia and inflammation, but relatively insensitive to other stimuli that normally evoke pain such as cutting or burning
What brings about Somatic pain? What is its character?
Well-localised, throbbing, achy.
These specialized nerves, called nociceptors, pick up sensations related to temperature, vibration and swelling in the skin, joints and muscles.
What brings about Neuropathic Pain? What is its character? What may accompany neuropathic pain?
Burning / tingling
+/- referred
+/- altered sensation
What are the two types of neuropathic pain?
Peripheral (Due to Nerve Damage)
Central (Spinal Cord Damage)
In what patterns might neurogenic pain occur?
Spontaneous Discharge (due to degeneration of nerve sprouts)
Evoked
What causes the spontaneous pattern of neurogenic pain?
Degeneration of nerve sprouts
What is the name given to neurogenic pain caused by the reduced activation threshold of fibres?
Allodynia
What is the name given to neurogenic pain caused by the shift to the left of the stimulus response curve?
Hyperalgesia
Can pain be more or less neuropathic?
Yes can exist on a spectrum, Can be mixed.
How do we diagnose neurogenic pain?
Tools = LANSS Scale (Local Assessment of Neuropathic Symptoms and Signs).
Clinical = Pain in an area of altered sensation is pathogenomic.
How do we classify the time course of pain?
Acute
Chronic
Background
Breakthrough (Incident e.g. on walking, Spontaneous)
What are the broad causes of pain (in cancer care?)
- Cancer
e. g. Bony involvement, nerve compression - General Debility
e. g. Constipation, pressure sores - Treatment
e. g. Mucositis with chemotherapy - Concurrent disorder
e. g. Osteoarthritis
How do we assess the severity of pain?
Children: Wong Baker Scal
Adults: 0-10
How do we assess the impact of pain on a patient?
We Ask -_-
What are the consequences of uncontrolled pain?
Distress, anxiety, fear, low mood
Loss of mobility, independence
Poor quality of life
Admissions to hospital; need for practical assistance at home
Spiritual, Social, Psychological aspects.
What are the problems regarding the evidence base for cancer pain management?
- Trials are difficult to perform
- Level of evidence available often low
- Evidence often drawn from post-operative and chronic non-malignant pain experience
What are the 3 broad strategies for pain control?
- Modification of Pathology
- Non-Pharmacological
- Pharmacological
Give examples of how we might modify the pathology to help manage pain?
Chemotherapy
Radiotherapy
Hormone therapy
Surgery
Give examples of some non-pharmacological methods of managing cancer pain?
Radiotherapy
Physical methods – TENS, physiotherapy, acupuncture
What are the 3 broad categories of pharmacological pain management?
Opioid analgesics
Non-opioid analgesics
Adjuvant agents – antidepressants, anticonvulsants, local anaesthetics, ketamine, capsaicin
What is the main supporting framework for cancer pain relief? Strength?
The WHO Ladder
Not rigorously validated in trials but extensive experience and validation in practice
What is the saying for effective cancer pain management?
By the mouth, by the clock, by the ladder, individual assessment, and attention to detail
What is step 1 on the WHO ladder?
Step 1 - non-opioid analgesia
NSAIDs and paracetamol for cancer pain
Which NSAID?
No clear evidence for superior safety / efficacy of one NSAID over another.
What is the efficacy of combining NSAIDs to opioid regimes?
Paracetamol
No additional benefit with strong opioids
What are the side affects of NSAIDs?
Ulcers, bleeding, kidney failure, and, rarely, liver failure.
High dose diclofenac or ibuprofen (>1200mgs) associated withl increased risk of thrombotic / CV events
What is Step 2 on the WHO ladder?
Weak opioids
At what dose is Codeines ceiling effect reached?
240mgs / day
What race are poor metabolizers of codeine? What are the implications?
7% of Caucasians are poor metabolisers leading to poor or absent analgesic effect
What is the efficacy of combining weak opioids with Adujvent Analgesics?
Combined preparations (60mgs codeine / paracetamol 1g) more effective than paracetamol alone or 8mgs codeine / paracetamol)
What is the MOA of Tamadol?
Mu-receptor agonism (M1 metabolite)
Serotonin reuptake inhibition (tramadol)
Norepinephrine reuptake inhibition (tramadol)
What is the efficacy of Tramadol v Codeine/Paracetamol?
Evidence that is safe and well-tolerated but…
No evidence that is superior to codeine / paracetamol combination for management of cancer pain
What is step 3 on the WHO ladder?
Strong opioids
What are the mainstay of strong opioid therapies?
Morphine,
Oxycodone,
hydromorphone
What are valid alternative opioid therapies?
Fentanyl and Buprenorphine
Why is methadone not a first line opioid?
Methadone not first line due to side effect profile
Which type of pain will likely require adjuvant intervention to strong opioid to be managed properly?
Neuropathic pain – yes +/- other interventions
By what routes can strong opioids be delivered?
Oral (First line)
Subcutaneous
Intravenous
Transmucosal (Rapid onset, rapid offset)
Transdermal (Fentanyl / buprenorphine, Stable analgesia only)
Outline some of the approaches to determining formulation of analgesic drugs?
Multiple possible different approaches (e.g. rapid IV titration, subcutaneous infusion)
Oral titration
No evidence of superiority of starting with either oral immediate-release preparation or modified-release preparation
Dose titrated to pain; reassess at least daily if uncontrolled severe pain
What is breakthrough pain?
‘abrupt, short lived and intense pain that ‘breaks through’ the around the clock analgesia that controls persistent pain’
What are the subcategories of breakthrough pain?
Incident (Voluntary/Involuntary)
Spontaneous
End of dose failure
What is the Tx for breakthrough pain?
Dose of 1/6 of total daily opioid dose
When should background pain prompt analgesia to be reviewed?
Background analgesia should be reviewed if more than 4 breakthrough episodes / day
What are the S/E’s of opioid use?
- Dry mouth
- Transient drowsiness x 24 hours – driving
- Nausea and vomiting – 40%, 3 – 5 days after initiation
(NB co-prescribe anti-emetic PRN – metoclopramide) - Constipation
(NB NB co-prescribe laxative regularly) - Respiratory depression
(Exceptionally rare….)
What should be discussed with the patient prior to prescribing opioids?
What are the patient’s beliefs / fears?
Explain anticipated side effects
- Prescribe laxative
- Anti-emetic as needed
Encourage them to persevere despite initial side effects
Which is the active component of Morphine? S/E’s?
M6G
-Mu receptor agonist – ‘useful’ analgesic metabolite
=Drowsiness, nausea, respiratory depression as crosses blood brain barrier
What is the inactive (analegsicless) component of morphine?
M3G
-No analgesic effect
=May cause neuropsychological side effects within the CNS
What are the neurophysiological S/E’s of morphine?
Sedation Cognitive impairment Myoclonus Hallucinations Hyperalgesia
How common is psychological dependence on opioids?
extremely rare
How common is physical dependence? How is it mitigated?
Does occur but manageable
Gradual withdrawal if pain reduces e.g. post RT
How common is respiratory depression? How is the risk mitigated?
Respiratory depression – exceptionally rare
-Careful titration
Pain = antagonist to opioid effects on respiration and conscious level
How can opioid toxicity be managed/avoided?
Avoid stopping abruptly
Infection or renal failure? Reduced need following RT?
Treat cause (Hydrate)
What steps can be taken if pain becomes uncontrolled?
Switch / rotate opioid +/- reduce dose
Complex – seek senior help
How does opioid toxicity differ from overdose?
Toxicity Confused / drowsy Myoclonus Hallucinations (Pinpoint pupils irrelevant)
Suspected illicit opioid overdose Injected iv (fast) No control of dose taken Arrive unresponsive Pinpoint pupils = key clue Not breathing / v low RR
What is the Tx in opioid overdose? Indications? Other steps to be taken?
Toxicity = RR and SpO2 OK, Reduce opioid + monitor OD = Resuscitate, Naloxone iv +/- infusion
Which other drugs have analgesic effects but are not strictly analgesics?
ANTIDEPRESSANT
Amitriptyline
Neuropathic pain
ANTI-CONVULSANT
Gabapentin, pregabalin
Neuropathic pain
CORTICOSTEROID
Dexamethasone
Pain due to oedema
ANTISPASMODIC
Hysocine butylbromide
Colic
NMDA-RECEPTOR BLOCKER
Ketamine
Neuropathic pain
BISPHOSPHONATES
Zoledronic acid
Pain due to bone mets
When should a cancer patient be referee to palliative care for pain management?
Difficult to manage symptoms
Psychological / spiritual distress
Ethical difficulties
What are the steps to be taken when prescribing opioids?
Titrate according to pain severity
Co-prescribe appropriately
Always prescribe a breakthrough option with a regular opioid