Pain control

Question 1

Define pain:

Answer 1

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

Question 2

Define nociception:

Answer 2

unconscious afferent response to traumatic or noxious stimuli
NOT pain as this is a conscious experience

Question 3

What are the types of pain fibres?

Answer 3

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

Question 4

What is encompassed in total pain?

Answer 4

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

Question 5

When treating pain what is important to know?

Answer 5

knowing what has/hasn’t worked previously

- dose, compliance, side effects, suitable route and duration

Question 6

What are the steps of the WHO pain ladder?

Answer 6

Step 1: paracetamol / NSAID
Step 2: codeine, dihydrocodeine, tramadol
Step 3: morphine, oxycodone, fentanyl, buprenorphone, hdyropmorphone

doses depend on patient and previous opioid hx

Question 7

What are examples of adjuvants?

Answer 7

anti-depressants
anti-convulsants
smooth muscle relaxants
steroids
bisphosphonates 
radiotherapy / chemo or surgery

Question 8

What is somatic pain?

Answer 8

Aching, often constant
dull or sharp
often worse on movement
well localised

musculo-skeletal e.g. bone metastases, arthritis, muscle sprain and spasm, fracture

Question 9

How is somatic pain often treated?

Answer 9

NSAIDs

depends on degree of pain - often NSAIDs and opioids aren’t enough for bone metastases -consider RT

Question 10

What is visceral pain ?

Answer 10

constant or crampy
aching
poorly localised
referred

abdominal organs e.g. cancer pancreas, bowel obstriction, liver capsule stretch, bladder spasm

Question 11

How is visceral pain treated?

Answer 11

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

Question 12

What is neuropathic pain?

Answer 12

pain arising as a consequence of a disturbance of function or pathological change in a nerve or the nervous system

Question 13

What is steady dysasethetic neuropathic pain like?

Answer 13

burning, tingling
constant, aching
squeeing, itching

e.g. diabetic neuropathy, post-herpetic neuroapthy

Question 14

What is paroxysmal neuralgic neuropathic pain like?

Answer 14

stabing, shock like, shooting, lancinating

e.g. trigeminal neuralgia, nerve root compression

Question 15

What signs suggest neuropathic pain?

Answer 15

• ” I just can’t describe it”
• burning and numbness
• allodynia
• cancer pain is often mixed

Question 16

What are the treatment options for neuropathic pain?

Answer 16

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

Question 17

What is background and breakthrough pain?

Answer 17

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

Question 18

What is incident pain?

Answer 18

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

Question 19

What is the usual treatment for incident pain?

Answer 19

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

Question 20

What are the different forms of morphone?

Answer 20

Oral morphine 
- immediate release
-> oramorph liquid 
-> sevredol tablets 
= rapid onset 20-30 mins - duration 4 hours 

• slow release
  -> MST
  -> Zomorph
  = given eveyr 12 hours

Question 21

What are the side effects of opioids?

Answer 21

constipation 
nausea
sedation 
respiratory depression 
myoclonic jerks 
others: miosis, dry mouth, confusion, visual hallucinations, itching, euphoria

Question 22

How can you treat the main side effects of opioids?

Answer 22

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

Question 23

Define tolerance:

Answer 23

normal physiological phenomenon in which increasing doses are required to produce the same effect

Question 24

Define physical dependence:

Answer 24

normal physiological phenomenon in which a withdrawal syndrome occurs when an opioid is abruptly discontinued

Question 25

Define psychological dependence:

Answer 25

pattern of drug use characterised by a continued craving for an opioid which is manifest as compulsive drug seeking behaviour leading to an overwhelming involvement in the use and procurement of the drug

Question 26

What are the symptoms of opioid toxicity?

Answer 26

intractable nausea
hallucinations 
drowsiness
myoclonic jerks = very suggestive opioid neurotoxicity 
pinpoint pupils 
depressed respiration 

metabolites of morphine can accumulte and lead to renal failure

Question 27

When are opioid patches useful?

Answer 27

if pain is stable 
difficulty taking oral meds 
compliance 
reduce medication load 
side effect profile = renal impariment, consitpation may be better with patches 

e.g. fentanyl patches or buprenorphine

Question 28

What are syringe drivers?

Answer 28

used when patient is unable to take oral medication - terminal stage, vomiting, bowel obstruction

Question 29

What are the advantages o syringe drivers?

Answer 29

portable
relatively non-invasive
combine several drugs