essential pain management Flashcards
what is pain
unpleasant sensory and emotional experience associated with/resembling that associated with actual or potential tissue damage or described in terms of such damage
6 key notes - looking after patients with pain
- pain is a personal experience influenced by biological, psychological and social factors
- pain and nociception are different phenomena
- individuals learn the concept of pain through life experiences
- a person’s report of pain should be respected
- pain serves an adaptive role but may have adverse effects on function and psychological wellbeing
- verbal description is only one of several behaviours to express pain
how many people live with persistent pain
1 in 4
why is pain important to treat
persistent pain is common
basic human right
66% of people attending A&E seeking help w/ pain had made ~ 3 visits to HCP in proceeding weeks
pain results in poor QOL as bad as other neurological diseases
low back pain is the number 1 disease for yrs lost to disability worldwide
physical benefits of treating pain for the patient
improved sleep
better appetite
fewer medical complications e.g. MI, pneumonia
psychological benefits of treating pain for the patient
reduced suffering
less depression, anxiety
benefits of treating pain for the family
improved functioning as a family member e.g. as a parent
able to keep working
benefits of treating pain for society
lower health costs e.g. shorter hospital stay
able to contribute to the community
3 ways to classify pain
duration - acute, chronic, acute on chronic
cause - cancer, non-cancer
mechanism - nociceptive, neuropathic
what is acute pain
pain of recent onset and probable limited duration
what is chronic pain
pain lasting >3mths
pain lasting after normal healing
often no identifiable cause
what is cancer pain
progressive
can be a mixture of acute and chronic
what is non-cancer pain
many different causes
acute or chronic
what is nociceptive pain
obvious tissue injury or illness
aka physiological or inflammatory pain
protective function
description: sharp +/- dull, well localised
what is neuropathic pain
nervous system damage or abnormality
tissue injury may not be obvious
doesn’t have a protective function
description:
- burning, shooting +/- numbness, pins and needles
- not well localised
what are the 4 steps in pain physiology
periphery
spinal cord
brain
modulation
4 steps in pain physiology - periphery
tissue injury
release of chemicals e.g. prostaglandins, substance P
stimulation of pain receptors - nociceptors
signal travels in Adelta or C nerve to spinal cord - dorsal ganglia
4 steps in pain physiology - spinal cord
dorsal horn is the first relay station for pain
Adelta or C nerve synapses with 2nd nerve (usually in the spinothalamic tract)
2nd nerve travels up opposite side of spinal cord into the thalamus
4 steps in pain physiology - brain
thalamus is the 2nd relay station
connections to many parts of the brain - cortex, limbic system, brainstem
pain perception occurs in the cortex
what is the result of the pathway from the cortex to the thalamus
produce an expectation of pain
4 steps in pain physiology - modulation
descending pathway from brain to dorsal horn
usually decreases pain signal
done through many different types of neurotransmitters
what is the result of a very active descending pathway in pain modulation
less pain experience than those who have a less good descending inhibition
what is the gate theory of pain
by rubbing/massaging/application of heat etc stimulates the large peripheral Abeta fibres
this stimulates an inihibitory neurone
this switches off the nociceptive afferent signal from going into the dorsal horn
modulation pathway occurs at the periphery and at certain levels within the brain and spinal cord to modulate the pain pathway
what causes neuropathic pain
abnormal processing of pain signal
nervous system damage or dysfunction
needs to be treated differently
examples of neuropathic pain
nerve trauma, diabetic pain (damage)
fibromyalgia, chronic tension headache (dysfunction)
pathological mechanisms of neuropathic pain
increased receptor numbers - enhances pain signal and keeps it going for longer
abnormal sensitisation of nerves (peripheral, central) - pain signal is exaggerated all through the pathway
chemical changes in the dorsal horn - enhanced pain signal
loss of normal inhibitory modulation
drug classification for treating pain
simple analgesics:
paracetamol (acetaminophen)
NSAIDs - diclofenac, ibuprofen
opioids:
weak - codeine, dihydrocodeine, tramadol
strong - morphine, oxycodone, fentanyl
other
which opiates have the potential for addiction
both weak and strong
other analgesics
tramadol - mixed opiate and 5HT/NA reuptake inhibitor
antidepressants - amitriptyline, duloxetine
anticonvulsants - gabapentin
ketamine - NMDA receptor antagonist
local anaesthetics
topical agents - capsaicin
treatments for pain - periphery
non-drug - rest, ice, elevation
NSAIDs - reduce amount of prostagland
local anaesthetic
treatments for pain - spinal cord
non-drug - acupuncture, massage, TENS
local anaesthetics - epidural, nerve block
opioids - epidural, intrathecal, into CSF
ketamine - modulates pain signal in descending pathway
treatments for pain - brain
non-drug - psychological
drug - paracetamol, opioids, amitriptyline, clonidine
advantages of paracetamol
cheap
safe
route: oral, rectal, IV
good for: mild pain by itself, mod-severe pain with other drugs
disadvantages of paracetamol
liver damage in overdose
examples of NSAIDS
aspirin
ibuprofen
diclofenac
advantages of NSAIDs
cheap
generally safe
good for nociceptive pain - best given regularly with paracetamol (synergism)
disadvantages of NSAIDs
GI side effects
renal side effects - reduced blood flow
bronchospasm in some patients with asthma
advantages of codeine
cheap
safe
good for mild-moderate acute nociceptive pain
- best given regularly w/ paracetamol
disadvantages of codeine
constipation
not good for neuropathic pain
how does tramadol work
weak opioid effect
plus inhibitor of serotonin and noradrenaline reuptake
advantages of tramadol
less respiratory depression
can be used w/ opioids and simple analgesics
less constipating than opioids
disadvantages of tramadol
N+V
can be poorly tolerated by some pts, esp at bigger doses
controlled drug
disadvantages of tramadol
N+V
can be poorly tolerated by some pts, esp at bigger doses
controlled drug
advantages of morphine
cheap
generally safe
route: oral, IV, IM, SC, PR, intrathecally
effective if given regularly
good for: mod-severe nociceptive pain (e.g. post-op), cancer pain
not advised for neuropathic pain
disadvantages of morphine
constipation
respiratory depression in high doses
addiction and avoidance due to fear of addiction
controlled drug
oral dose needs to be increased if changing from IV/IM or SC routes as 3rd pass metabolism reduces the amount of morphine available
how does amitriptyline work
tricyclic antidepressant
increases descending inhibitory signals
advantages of amitriptyline
cheap
safe in low dose
good for neuropathic pain
also treats depression, poor sleep
disadvantages of amitriptyline
anti-cholinergic side effects e.g. dry mouth, glaucoma, urinary retention
long term use might be linked with cognitive decline and dementia
examples of anti convulsant drugs
carbamazepine
sodium valproate
gabapentin
also called membrane stabilisers
how do anti-convulsants work
reduce abnormal firing of nerves
good for neuropathic pain
how do anti-convulsants work
reduce abnormal firing of nerves
good for neuropathic pain
how do anti-convulsants work
reduce abnormal firing of nerves
good for neuropathic pain
gabapentin and addiction
pretty addictive
cocaine like effect
only start w/ good evidence for neuropathic pain
choosing route of delivery
patient may be NBM
if prescribing IM/SC consider how much the patient might require and if that is acceptable
S/C cannula might be more tolerable
oral route preferred where possible
types of delivery routes
oral rectal sublingual subcutaneous transdermal IM IV - boluses, possibly patient controlled systems or nurse administered intrathecal/epidural
delivery routes for LA
epidural (+/- opiates) intrathecal (+/- opiates) wound catheters nerve plexus catheters lidocaine patches for some neuropathic pain conditions
how do we assess pain
verbal rating score numerical rating score visual analogue scale smiling faces abbey pain scale (for confused patients) functional assessments
non-drug treatments for pain
physical:
- rest, ice, elevation
- surgery
- accupuncture, massage, physio
psychological:
- explanation
- reassurance
- counselling
choosing drug treatments for pain
acute pain: WHO pain ladder
neuropathic pain: alternative analgesics +/or psychological and non-drug treatments; not responsive to WHO ladder drugs
WHO analgesic ladder
step 1 (mild-mod pain): - non-opioids: aspirin, NSAIDs or paracetamol
step 2 (mod-sev pain):
- mild opioids: e.g. codeine
- w/ or w/o non-opioids
step 3 (severe pain):
- strong opioids: e.g. morphine
- w/ or w/o non-opioids
Link pain assessment to prescribing for acute nociceptive pain
mild pain - start at bottom of pain ladder
moderate pain - bottom of ladder plus middle rung
severe pain - bottom of ladder plus top, miss out the middle
it is okay to start at the top of the ladder for severe/unbearable pain
what to do as pain resolves
move from top to middle of ladder
continue bottom rung at all times
lastly, stop NSAIDs first then paracetamol (NSAIDs have more side effects)
clear instructions must be given regarding reduction of all opiates
RAT approach to pain management
Recognise
Assess - severity, type, other factors
Treat - non-drug and drug
recognising pain
does the patient have pain?
- ask
- look - frowning, moving easily, sweating
- functional ability e.g. move easily, cough, deep breath etc
do other people know the patient has pain
- other health workers
- family
Assessment of pain - severity
what is the pain score
- at rest
- with movement
how is the pain affecting the patient
- can the patient move, cough,
can the patient work
assessment of pain - type
take a pain hx
nociceptive or neuropathic
look for neuropathic features:
burning or shooting pain
phantom limb pain
other features - pins and needles, numbness
assessment - are there any other factors
- things that might make the patient more susceptible to pain or more difficult to treat w/ analgesia
- physical factors - other illness etc
- psychological and social factors - anger, anxiety, depression; lack of social support; prev drug use/addictive personality
what to do after RAT
reassess the patient
is the treatment working
are other treatments needed
