Pain control Flashcards
Define pain:
unpleasant sensory or emotional experience associated with actual or potential tissue damage or described in terms of such damage
Define nociception:
unconscious afferent response to traumatic or noxious stimuli
NOT pain as this is a conscious experience
What are the types of pain fibres?
C fibres = unmyelinated = transmit dull, poorly localised ill defined sensation
A delta fibres = myelinated = transmit fast, sharp, well localised sensation- synapse with 2nd order neurone in dorsal horn = plasticity = gate control theory of pain
What is encompassed in total pain?
physical = pain due to disease location, other symptoms (nausea), physical decline + fatigue
Social = relationships, families role, work life, financial problems
psychological = grief, depression, anxiety, anger, adjustment to condition
spiritual = existential issues, religious faith, meaning of life and illness, personal value as a human
When treating pain what is important to know?
knowing what has/hasn’t worked previously
- dose, compliance, side effects, suitable route and duration
What are the steps of the WHO pain ladder?
Step 1: paracetamol / NSAID
Step 2: codeine, dihydrocodeine, tramadol
Step 3: morphine, oxycodone, fentanyl, buprenorphone, hdyropmorphone
doses depend on patient and previous opioid hx
What are examples of adjuvants?
anti-depressants anti-convulsants smooth muscle relaxants steroids bisphosphonates radiotherapy / chemo or surgery
What is somatic pain?
Aching, often constant
dull or sharp
often worse on movement
well localised
musculo-skeletal e.g. bone metastases, arthritis, muscle sprain and spasm, fracture
How is somatic pain often treated?
NSAIDs
depends on degree of pain - often NSAIDs and opioids aren’t enough for bone metastases -consider RT
What is visceral pain ?
constant or crampy
aching
poorly localised
referred
abdominal organs e.g. cancer pancreas, bowel obstriction, liver capsule stretch, bladder spasm
How is visceral pain treated?
often responds well to opioids - although colic responds better to smooth muscle relaxants
also consider steroids e.g. dexamethasone 4-8mg daily for tumour oedema
What is neuropathic pain?
pain arising as a consequence of a disturbance of function or pathological change in a nerve or the nervous system
What is steady dysasethetic neuropathic pain like?
burning, tingling
constant, aching
squeeing, itching
e.g. diabetic neuropathy, post-herpetic neuroapthy
What is paroxysmal neuralgic neuropathic pain like?
stabing, shock like, shooting, lancinating
e.g. trigeminal neuralgia, nerve root compression
What signs suggest neuropathic pain?
- ” I just can’t describe it”
- burning and numbness
- allodynia
- cancer pain is often mixed
What are the treatment options for neuropathic pain?
partially respsonsive to opioids and to NSAIDs
other options:
- anti-depressants e.g. TCAs
- anti-convulsants e.g. gabapentin
- steroids - esp if loss of function
Beyond WHO ladder: ketamine, lidocaine, methadone
What is background and breakthrough pain?
constant nature
- needs long acting / regular analgesics
and then breakthrough pain requires additional analgesa
breakthrough = pain that occurs despite regular doses of modified release morphone = 1/6th of total daily morphine
What is incident pain?
e. g. pain precipitated by movement
- difficult to treat as may be very severe but short lived typically (45 mins or less)
- usual analgesics don’t work quickly enough but then analgesics may help but prolonged duration often leads to side effects
What is the usual treatment for incident pain?
traditional treatment = oral liquid morphine (10mg/5ml)
transmucosal opioids may be faster acting e.g. fentanyl lozenge
newer alternatives = sublingual and buccal fentanyl tablets/nasal spray
What are the different forms of morphone?
Oral morphine - immediate release -> oramorph liquid -> sevredol tablets = rapid onset 20-30 mins - duration 4 hours
- slow release
-> MST
-> Zomorph
= given eveyr 12 hours
What are the side effects of opioids?
constipation nausea sedation respiratory depression myoclonic jerks others: miosis, dry mouth, confusion, visual hallucinations, itching, euphoria
How can you treat the main side effects of opioids?
constipation = co-prescribe laxative permanently nausea= co-prescribe anti-emetic PRN first 5-7 days hallucinations = stop/reduce /switch - Drowsiness = assess - may pass/reduce but advise may need to temporarily stop driving
Define tolerance:
normal physiological phenomenon in which increasing doses are required to produce the same effect
Define physical dependence:
normal physiological phenomenon in which a withdrawal syndrome occurs when an opioid is abruptly discontinued
