Clinical CNS Pain Flashcards
What are the questions to ask patients how to measure pain?
How long have they felt the pain?
What could have caused it?
Where is the pain?
What makes it better/worse time of day?
Does it come or go?
Does it vary with position?
What does the pain feel like?
What have they tried to help?
What are there ways of measuring a patient’s pain?
VAS (visual analogue scale) 0-10
NRS (numerical rating scale):
0-10 123= mild, 456=moderate, 789=severe
For younger patients can use facial expressions
What are aspects to examine on a patient in terms of pain?
Colour changes
Swelling
Tenderness
Asymmetry
Any weakness
Range of movement
Sensation
How do we classify pain?
Duration- acute/chronic
Underlying mechanisms
Physical origin
Cause e.g cancer/ post op
What are the underlying mechanisms of pain?
Nociceptive
Neuropathic
Nociplastic
What is the physical origin of pain?
Visceral (internal organs)
Somatic (external- bone, muscle)
Referred pain (e.g MI pain in arm/jaw)
Describe acute pain:
Comes on suddenly
Treated by resolving the cause of the pain
Usually due to trauma, injury or surgery
Lasts less than 6 months
OTC treatments/ analgesic ladder
Best to rest area
Describe chronic pain?
Comes on gradually
Usually, the result of a condition that is difficult to treat/diagnose
Lasts more than 6 months
Difficult to find lasting relief
Better to mobilise the area
Musculoskeletal pain 50-80% of UK pop at a time
What are the factors contributing to pain?
Social
Psychological
Biological
What is nociceptive pain?
E.g reflex arc, hand near flame
Nociception- the ability to detect painful stimuli via nociceptors that respond to painful stimuli
Preventing or in repsonse to tissue damage
What is neuropathic pain?
Malfunction in the NS or damage to the nerves e.g diabetic neuropathy
Central pain, peripheral neuropathy, complex regional pain syndrome
Burning, electric shocks, shooting pain
What is nociplastic pain?
Altered nociception in the absence of tissue or nerve damage
Widespread intense pain e.g fibromyalgia
Exercise/psychological/accupuncture
Antidepressants off label
Describe the first step in the WHO analgesic ladder:
Non-opioid:
Paracetamol
NSAIDs
Topical treatments (NSAIDs, lidocaine, capsaicin)
± adjuvant
Describe the second step in the WHO analgesic ladder:
Mild opioid as an alternative or an addition:
Mild to moderate pain
Codeine/ dihydrocodeine/ tramadol
Limited potency at the MU receptor
± adjuvant
Describe the third step in the WHO analgesic ladder:
Strong opioid to replace the mild opioid:
Moderate to severe pain
Morphine/ diamorphine/ oxycodone
Fentanyl/buprenorophine/ alfentanil
Strong potency at the MU receptor
± adjuvant
Name and give examples of adjuvant therapies in the WHO ladder:
Anti-epileptics (neuropathic)- pregabalin, gabapentin, carbamazepine (TN)
Anti-depressants- TCA, SSRIs
Other- dexamethasone, bone pain in palliative
Non pharmaceutical- physio, exercise, psychological
What is the evidence for the use of opioids?
Acute pain in palliative care
Limited evidence of efficacy in long term pain:
-if don’t achieve useful pain relief in 2-4 weeks unlikely to gain long term benefit
No efficacy with high dose (>120mg/ day morphine/ equivalent) due to lack of trial data
What are the risk of treatment with weak opioids?
Metabolism of weak opioids
Cyp2D6 enzyme- converts codeine into morphine
Interpatient variability dependent on gene expression (if a supermetaboliser and breastfeeding can pass more morphine to baby)
Unpredictable variation in efficacy and toxicity
What are the SEs of opioids?
N&V- likely to reduce with time
Constipation, drowsiness, sedation, resp depression
-use stim and osmotic
Renal function- increase morphine in body
Dependence/ addiction
What are the signs of overdose of an opioid?
Pinpoint pupils
Pale skin
Blue lips (cyanosis)
Unconscious
Shallow/slow breathing
Snoring/gasping for breath
Describe how pinpoint pupils are a sign of opioid overdose:
Stimulation of parasympathetic NS causes contraction pinpoint pupils
Less/no response to light or abnormal movements
Use eye examination and light test
Describe how pale skin and blue lips are a sign of opioid overdose:
Hypoxia- low blood oxygen, low blood circulation
Describe how unconsciousness and the breathing abnormalities are a sign of opioid overdose:
Resp depression
Activation of the µ-opioid receptors in the brain stem that co-ordinate respiratory rhythm
What are the aspects of the NEWS2 score that indicates an opioid overdose?
Resp rate <8bmp (normal= 12-20)
O2 sats can be <85% (96-99%)
HR= tachycardia
BP= high or low
Sedation score= VPU higher
What does VPU stand for in the NEWS2 score?
V= verbally
P= pain
U= unconscious/unresponsive
What is the non-pharmacological treatment for lower back pain (musculoskeletal)?
Exercise (aerobic) programmes and manual therapies- spinal manipulation, massage (as part)
Psychological therapies- CBT (as part)
Return to work programmes
What is the pharmacological treatment for lower back pain (musculoskeletal)?
NSAIDs- look at CI
Weak opioids for acute lower back pain if NSAIDs CI or ineffective
Do not offer paracetamol alone
What is sciatica?
Musculoskeletal pain
Leg pain 2º to lumbosacral nerve root pathology due to compression or irritation to the sciatic nerve- shooting pain
What is the pharmacological treatment for sciatica?
Do not offer gabapentinoids/antiepileptics/ benzodiazepines
If already prescribed, discuss problmes and withdrawal
Limited evidence of NSAID benefit
Do not offer opioids
Epidural injections (acute and severe sciatica)
What are the surgical treatments for sciatica?
Spinal decompression surgery
Other surgical intervention depending on cause
What are the symptoms of osteoarthritis?
Pain
Stiffness
Tenderness
Grating sensation
Swelling
Bone spurs
What is the non-pharmacological treatment for osteoarthritis?
Exercise/ physiotherapy
Weight loss if indicated to decrease pressure on joints
Manual therpaies
What are the pharmacological treatments for osteoarthritis?
Topical NSAID, if ineffective/ CI oral can be considered
Paracetamol and weak opioid may be considered
Intra-articular corticosteroid if others ineffective/unsuitable
Joint replacement
What are the main medications indicated for neuropathic pain?
Amitriptyline
Duloxetine
Gabapentin
Pregabalin
What should be the process of using medications for neuropathic pain?
Each indicated for things slightly different
If initial treatment ineffective/ not tolerated then try another
What are other medications that can be used for neuropathic pain?
Tramadol only if acute rescue therapy needed
Capsaicin cream for localised pain who with to avoid oral- normal for burning/stinging
Carbamazepine for trigeminal neuralgia
What is the initial pain relief in palliative care?
24 hour pain relief- simple analgesia or strong opioid, no max dose of opioid
Begin with anticipatory (PRN) injection
Name and state the doses of the anticipatory injection in palliative care:
Morphine SC 2.5-5mg 2-4 hrly (eGFR >60)
Oxycodone SC 1.25-2.5mg 2-4 hrly (eGFR 30-60)
Alfentanil SC 125-250mcg 2-4 hrly (eGFR <30)
When would a patient need a syringe driver in palliative care?
If needing 3 or more injections in a 24 hour period, may be less than 3 in certain situations
What is the treatment for breathlessness in palliative care?
Opioid/ midazolam- slows down breathing
What should be co-prescribed with opioids in palliative care?
Naloxone- toxicity
What are syringe drivers?
Battery powered pump delivering a 24hr continuous SC infusion of medication
Usually matches PRN injections
Need a diluent to provide volume- WFI/NaCl
Compatibility- can put other drugs in there as well
Which surgeries would NSAIDs not be used for pain and why?
Not in fracture of hip or pelvis as affects bone recovery
IV paracetamol is used
When would you use oral opioids for post-operative pain?
Moderate/severe pain expected- larger/complex procedure
Not with PCA or opiate epidural
Aids in recovery- get coughing relax back and mobilise pt quicker
When would gabapentin be used for post-operative pain?
If neuropathic post op pain- orthopaedic/ thoracic chest drain insertion (temporary treatment)
What is PCA?
Patient controlled analgesia
Pts determine when and how much analgesia they receive (presses button)
IV admin
Opiates most common
Loading dose in recovery then PCA
What are the monitoring requirements for patients on PCA?
BP/pulse/RR/sedation/pain score/nausea (opioid effects)
First 8 hours= hourly
8-24 hours= 2 hourly
48 hours- end= 4 hourly
What is the typical PCA admin?
100mg morphine in 100ml NaCl 0.9% (1mg/1ml)
-administers 1mg at a time
-lockout 5 mins
What are the benefits of PCA?
Patient ownership and independence
Faster alleviation of pain
Decrease distress in waiting for nursing staff
Less time consuming for nurse
Easy to titrate accoring to response
Fewer peaks/ troughs than bolus
What are the disadvantages of PCA?
Patient may to be responsive or dextrous enough
Patient may lack understanding or be scared to use
Decrease mobility
Liable to abuse (comes with lockout)
SEs- normal opioids
What should be administered for N&V in PCA?
Cyclizine (oral/IM prn)
Ondansetron (oral/IV/IM)
Can have protocols so nurse can give without prescribing
What should be administered for pruritis in PCA?
Chlorphenamine 4mg TDS