Pain Flashcards
A pain which:
-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 / WHO analgesic ladder is used
Is what type of pain?
Acute
A pain which:
-Comes on gradually
-Usually the result on a condition that is difficult to treat and diagnose
-Lasts longer than 6 months
-Difficult to find lasting relief
Is what type of pain?
Chronic
A pain which is:
-The traditional idea of pain
-Ability to detect and respond to painful stimuli
-Prevents or acts in the response to tissue damage
Is what type of pain?
Nociceptive pain
A pain which is:
-A malfunction in the nervous system or damage to the nerves, eg, diabetic neuropathy
-Central pain, peripheral neuropathy, complex regional pain syndrome
-Burning or electric shocks
Is what type of pain?
Neuropathic pain
A pain which is:
-Altered nociception in the absence of tissue or nerve damage
-Widespread intense pain
-Exercise / psychological / acupuncture could possibly help
-Antidepressants are used off label
Is what type of pain?
Nociplastic pain
What is stage 1 in the WHO analgesic ladder?
Non-opioid +/- Adjuvant
-Paracetamol
-NSAIDS/COX2-inhibitors
-Topical treatments
What is stage 2 in the WHO analgesic ladder?
Opioid for mild to moderate pain +/- non-opioid. +/- Adjuvant
-Codeine / Dihydrocodeine / Tramadol
= Limited potency at the Mu receptor
What is stage 3 in the WHO analgesic ladder?
Opioid for moderate to severe pain +/- non-opioid. +/- Adjuvant
Morphine / Diamorphine / Oxycodone / Fentanyl / Buprenorphine // Alfentanil
= Strong potency at Mu receptor
What anti-epileptic adjuvant therapies could be used for neuropathic pain?
-Gabapentin
-Pregabalin
-Carbamazepine
What anti-depressants can be used for pain?
Tricyclics
SSRI’s
Why would Dexamethasone be used in palliative care?
Bone pain
A patient who is a poor metaboliser would have what benefit from opioids?
No benefit - as codeine is converted to morphine in the liver by CYP2D6
A patient who is a super metaboliser would have what benefit from opioids?
Lots of benefit
Common side effects of Opioids?
Nausea, vomiting, constipation, drowsiness, sedation, respiratory depression
What laxatives should be given for Opioid induced constipation?
Stimulant + Osmotic
(Senna + Laxido)
What are the 6 signs of opioid overdose?
1) Pinpoint pupils
2) Unconsciousness
3) Shallow / slow breathing
4) Pale skin
5) Blue lips
6) Snoring / rasping breath
What is the reasoning behind pin point pupils?
-Stimulation of parasympathetic nervous system
-Contraction causes pinpoint pupils
What is the reasoning for pale skin / blue lips?
Hypoxia - low blood oxygen, low blood circulation
What are the pharmacological treatments for Musculoskeletal lower back pain?
-NSAIDS
-Weak opioids for acute pain if NSAID not useful
-DO not offer only paracetamol
What shouldn’t be offered for Sciatica?
-Gabapentin / Antiepileptics / Benzodiazepines
Should opioids be offered for chronic sciatica?
No
What are the long term management options for sciatica?
-Epidural injections
*Acute + Severe sciatica
*Local anaesthetic + Corticosteroid
-Spinal decompression surgery
What are the symptoms of Osteoarthritis?
-Pain
-Stiffness
-Tenderness
-Grafting sensation (noise)
-Swelling
-Bone spurs
What is the treatment for Osteoarthritis?
-Exercise
-Weight loss if needed
-Manual therapies
-Topical NSAIDS
-Paracetamol +/- Opioids
-Intra-articular corticosteroids
-Joint replacement
What drugs can be used for a patient descripting ‘shooting or burning’ pain?
*If one doesn’t work try another
-Amitriptyline
-Duloxetine
-Gabapentin
-Pregabalin
If someone with neuropathic pain can’t tolerate oral remedies what should be offered?
Capsaicin cream
What drug is used for Trigeminal neuralgia?
Carbamazepine
There is NO maximum dose of opioids in palliative care, true or false?
True
When someone is made palliative we start with anticipatory (PRN) injection medications , when would a patient be moved onto a syringe driver?
3+ injections in 24 hours
*As per NNUH guidance
What is given if a patient is breathless when they are palliative?
Opioids / Midazolam - to slow breathing down, comfort patient as less distressed
What do you dilute the medicines with in a syringe driver?
Water for injection, remains stable over 24 hours and won’t precipitate
what factors could influence how post operative pain is managed?
Comorbidities, renal, liver, age, frailty, allergies
What group of medicines should be avoided if a patient has a fractured hip or pelvis surgeries and why?
NSAIDS - affects bone recovery
What should be monitored when a patient has a PCA?
Pain score & AVPU & Respiratory rate
When will a patient receive the loading does for a PCA?
In recovery
How much does a PCA deliver at a time (mg)?
1mg at a time
What is the benefit of a PCA?
Smaller dose, more frequently
What are the advantages of a PCA?
-Pt ownership and independence
-Faster alleviation of pain
-Reduces distress in waiting for nursing staff
-Less time consuming
-Easy to titrate according to response / need
What are the disadvantages of a PCA?
-Patient may not be responsive or dextrous enough to use
-Patient may lack understanding or be scared to use
-Reduced mobility
-Liable to abuse (lock out time)
-Side effects (N&V, low bpm drowsiness, constipation)
What should be monitored hourly for the first 8 hours post PCA insertion?
BP
Pulse
RR
Sedation
Pain score
Nausea
(Opioid effects!)
After the first 8 hours of hourly observation, when should they now be done and for how long?
Monitor every 2 hours for 24 hours
How is PCA induced nausea and vomiting managed?
Cyclizine / Ondansetron
How is PCA induced pruritis managed?
Chlorphenamine 4mg TDS
How is PCA induced respiratory depression (RR less than 8) managed?
-STOP PCA
-Oxygen and monitor sats
-Consider naloxone 200-400mcg (Short half life)
How should PCA induced excessive sedation be managed?
-Remove PCA
-Monitor: Sats, Pain and sedation score
-Ensure adequate non-opioid analgesia is prescribed
Administration of analgesics with or without anaesthetic into the epidural space, is known as what?
Epidural
What type of pain does an epidural dampen?
Nociceptive transmission
Morphine is in the epidural bag, what is the role of this?
-Diffuses into CSF
-Inhibits pain transmission in the spinal cord
-Acts at spinal opioid receptors
-Has no motor or sensory function
-Is reversible
-Doesn’t migrate
What is the role of Bupivocaine in a Epidural bag?
-Blocks nerve pulse and contraction
-Diffuses across myelin sheath into nerve cell
-Inhibits sodium channels, preventing depolarisation of the membrane
-Reversible,
-Doesn’t migrate
What two things do we not want an epidural to do?
1) Don’t want drugs to travel
2) Lowest concentration in the area we want
If drugs are dense what will happen to them when injected into the spinal column?
They will sink downwards
*If less dense will float and reach brain
=Need to find happy medium
Why is Ephedrine prescribed alongside an epidural?
RIsk of Hypotenstion
Why is Naloxone prescribed alongside an epidural?
It is reversible *just in case of overdose!
What are the advantages of an epidural?
-High amounts of pain relief at smaller opioid does than systemic
-Reduced incident of DVT
-Less sedation
-Post - op cover over 24 hours if infusion
-Improved pulmonary function
-Reduced cardiac morbidity and sepsis
-Faster re-establishment of oral intake
What are the disadvantages of an epidural?
-Accidental injection into the spinal cord (Total spinal block)
-Risk of permanent spinal damage
-Accidental IV administration
-Dural puncture headache
-Epidural bleed / haematoma
-Migration of drug can lead to respiratory paralysis
-Infection risk
Why is respiratory arrest a side effect on an epidural?
Migration of drugs to C3-C5 blocking phrenic nerves
Why can hypotension / hypothermia occur due to an epidural?
Vasodilation
Why can there be reduced cardiac output from an epidural?
If T1-T4 is affected
If overdose or given IV of the epidural what can this cause?
Depression of myocardial excitability
What are the more common side effects of an epidural?
Tinnitus, headache, N&V, pruritis, sedation
Can an epidural cause reduced hepatic and renal perfusion?
Yes
If Bupivacaine is accidently given via IV what can be given?
Intralipid 20% to reverse cardiac arrest risk or life-threatening toxicity
If a dural puncture headache occurs, what should be given?
Blood patch: the patients own blood is injected causing a seal around the hole = no more CSF leakage
What are the contraindications of a epidural?
-Pt refusal
-Infection at proposed site of infection
-Clotting abnormalities
-Severe respiratory impairment
-Uncorrected hypovolaemia
-Raised intracranial pressure
-Neurological disease
-Difficult anatomy
Can a patient with tattoos have an epidural?
Yes/No
*Anaesthetist dependent
-Risk of ink entering epidural space
-If tattoo is old and healed no risk
What type of headache is caused by a muscle spasm in the neck, and could be caused by emotional stress such as tension, anxiety or fatigue,
-Also is non-throbbing, vice like, could be described as tightness or squeezing around the head or a weight pressing down on the head.
-Usually affects both sides of the head
-May worsen throughout the day and made worse by stress.
Tension headache
What type of headache is this?
-Excruciating severe unilateral headache
-Accompanied by red eye, lacrimation, nasal congestion, rhinorrhoea, facial sweating, miosis, droopy eye and eye lid oedema?
Cluster headaches
Who is more susceptive to a cluster headache?
Males
How long does a Cluster headache last?
Sudden onset, may way a patient from sleep.
Intermittent onset, can occur up to 8 times a day
-Lasts between 10 mins to 3 hours
What needs to be ruled out when a patient has cluster headaches?
Meningitis, bleed on head, fever, cranial arthritis
What is the dose of paracetamol for a patient aged 4-5?
250mg 4-6 hourly QDS
What is the dose of paracetamol for a patient aged 6-7?
240-250mg 4-6 hourly QDS
What is the dose of paracetamol for a patient aged 10-11?
480-500mg 4-6 hourly QDS
What are the symptoms of a migraine?
-Prodrome
-Aura
-Headache
-Postdrome - headache hangover
What is a headache, which is lateralised and pulsating, and can cause n&v / photophobia?
Migraine
A migraine which happens with an aura is called?
Classical migraine
A migraine which happens without an aura is called?
Common migraine
A migraine which involves GI symptoms and affects children is known as?
Abdominal migraine
What causes aura in a migraine?
Vasoconstriction across the brain = aura
What causes the headache in a migraine?
Vasodilation
What is the Brain hypothesis of a migraine?
An increase in extracellular potassium, decreases blood flow causing a wave of neuronal inhibition
What is the Sensory nerve hypothesis of a migraine?
Activation of the trigeminal nerve, meaning signals occur, releasing inflammatory mediators such as cytokines, prostaglandins this then causes pain and symptoms to occur.
What can be increased during a migraine?
Serotonin metabolites
What can trigger a migraine?
Foods, hormones, environmental,
When can a migraine occur?
After a stressful period of time
What is recommended for a migraine sufferer to do?
Keep a headache diary - behaviour, food and what they have done, to try identify triggers!
What is phase 1 of a migraine?
Prodrome - heightened sensations, foreboding
What is phase 2 of a migraine?
Aura
What is phase 3 of a migraine
Headache, photophobia, phonophobia, N&V,
What is stage 4 of a migraine?
Postdrome - washed out sleepy, post headache hangover
What is the diagnosis of a migraine?
At least 2 of:
-Unilateral pain
-Throbbing pain
-Aggravated by movement
-Moderate or severe intensity
At least one of:
-N/V
-Phone/photophobia
What are five attacks of a migraine called?
‘Migraineur’
A differential diagnosis for a migraine could be meningitis, what would indicate this?
-Non blanching rash *Glass test
-Neck stiffness
A differential diagnosis for a migraine could be Subarachnoid haemorrhage, what would indicate this?
Worst ever headache feel like they have been hit by a bus, it is in the occipital area (back of the head)
A differential diagnosis for a migraine could be temporal arteritis, what would indicate this?
Temple/scalp painful to touch, more likely to happen in an older patient.
-Patient need’s a course of steroids
If a patient has had a headache for more than 24 hours what should you do?
Refer to the GP
If a patient has a headache that eases as the day progresses, and effortlessly is vomiting in the morning what should you do?
The headache is caused by something else, possibly a tumour hitting the vomit centre
=Refer to GP
If a patient has a headache which is causing unsteadiness / clumsiness, especially in children, what should we do?
Refer to the GP
If a patient under 12 is presenting with a headache that is not easing what should we do?
Refer to the GP
If a patient has a headache which is a suspected adverse drug reaction, what should we do?
Refer to GP
How can we manage headaches?
1) Shared agreement
2) Eliminate triggers
3) Acute intervention
4) Prophylaxis if 4+ a month
What medications should be taken before a headache starts?
*Dispersible / effervescent preferred
Aspirin 900mg
Ibuprofen 400mg
Paracetamol 1000mg
Why are dispersible / effervescent preferred?
If patient is nauseated, the GI tract is not as affected, and therefore the medication can be rapidly absorbed,
Should you recommend migraleve to a patient with migraines?
NO
Has an antihistamine for sickness as makes the patient drowsy + paracetamol + codeine
*Can buy separate
What can be sold OTC to help with sickness in a migraine?
Buccastem - 3mg Buccal prochloperazine
How does Sumatriptan work?
It is a 5-GT1 agonist = constricts blood vessels making them go back to normal
Who cannot have Sumatriptan?
IHD, uncontrolled BP, over 65+
What are the side effects of Sumatriptan?
-Tiredness and dizziness
-Heaviness on the chest and throat**Counsel
If a patient has taken simple analgesics and a triptan and after 2 hours it still persists what can they do?
Can take another triptan if not responded and then sleep off the headache.
If a patient is taking 4 or more sumatriptan a month what should we do?
Refer to the GP
When should prophylaxis be given for headaches?
-Functional impairment
-2+ headaches a week
-Amount of acute medication used
-Will the patient comply
-Success or failure of previous therapy
Can b-blockers be used in migraine prevention?
Yes but can cause fatigue and bronchoconstriction
What 5-HT2 antagonist, antihistaminic can be used in prophylaxis of migraines?
Pizotifen but can cause weight gain and sedation.
What 5-HT2 antagonist can be used in prophylaxis of migraines?
Methysergide but can cause N&V, and rare fibrotic conditions
What prophylaxis medication is good for, prolonged or atypical migraines with aura (no headache)?
Valproate / Topiramate
How can BOTOX be used in the prevention of migraines?
-Relaxes muscles and blocks pain feedback
What two drugs are the future of headache medications?
-Serotonin receptor agonists
-Nitric oxide (NO) antagonists
What is pain?
A protective response, to raise awareness of damage and help to immobilise damaged areas to facilitate healing
A pain which comes from cutaneous / musculoskeletal tissue or peritoneal membranes. Most often post-operative, post-exercise or from mild trauma is what?
Somatic pain
A pain which is in the thoracic or abdominal organs. Most related to post-operative, cancer, or traumatic injury is what type of pain?
Visceral
A pain which is from injury to the PNS or CNS, most commonly from amputation or T2DM, is known as what type of pain?
Neuropathic
A pain which is a sensitisation of CNS which causes neuropathic-like pain in distribution of a sympathetic nerve, and can be complex regional pain syndromes (CRPS), is what type of pain?
Sympathetically-maintained pain
What are the three types of stimuli to pain?
-Mechanical
-Thermal
-Polymodal
What does polymodal mean?
Variety of damaging stimuli
What fibres carry noxious stimuli?
A and C fibres
Informative forces movement away from danger is classed as what pain?
First pain
Punishing pain that changes behaviour, is classed as what pain?
Second pain
What are the 4 processes of noiception?
1) Detection
2) Transmission
3) Perception
4) Modulation
When trauma activates nociceptors, chemical mediators from the brain are released, what are these?
ATP, Bradykinin, Prostaglandins, Histamine, 5-HT, H+
What do released chemical mediators do in the nociception pain?
Activate / sensitise nociceptors = depolarisation and action potential generated
What is the major kinin related to pain?
Peptide Bradykinin which acts at GPCR’s
What kinin is important in Inflammation?
Bradykinin
What kinin is produced during tissue injury and produced by cleavage of precursor molecules?
Bradykinin
What kinin causes phosphorylation of the TRPV1 channel increasing the opening of the channel?
Bradykinin
What kinin causes the release of prostaglandins?
Bradykinin
What enhances the pain-producing effects of other substances such as bradykinin?
Prostaglandins
What does activation of PGE2 cause?
K+ channel activation and phosphorylation of TRPV1 via EP receptors
What ion channels are in Nociceptor terminals?
-TRPV1
-P2X
-ASIC
-TRPA1
-TRPM8
-NaV
-K+
What activates TRPV1?
Heat, chemicals, phosphorylation
What activates P2X?
ATP
What activates ASIC?
H+
What activates TRPA1 and TRPM8?
Cold and chemicals
-pH of less than 5.5
-Heat above 43 deg
-Mustard + Wasabe
-Capsaicin
What receptor plays a major role in body temperature regulation and if stimulated leads to a burning sensation?
TRPV1 receptor
What is the role of C Fibres in peripheral modulation?
Chemical mediators reduce the threshold of C fibres, making them more easily activated by a given level of stimulus
What is the role of Neuropeptides in peripheral modulation?
Increase activity of C fibres leads to the peripheral release of neuropeptides like Substance P and CGRP.
What is the role of inflammation in peripheral modulation?
These neuropeptides cause the release of inflammatory mediators and NGF, creating a positive feedback loop that increases the sensitivity of neurons
What is the role of hyperalgesia in peripheral modulation?
Sustained release of C Fibres, Neuropeptides and inflammation mediators can lead to hyperalgesia, which is an increased sensitivity to pain.
What is NGF?
Nerve growth factor
What is the function of NGF?
-Acts on TrkA receptors
-Causes upregulation of NaV channels
-Signals to increase TRPV1 activity via tyrosine kinase activity (Phosphorylation)
If a patient has a mutation in TrkA, what does this mean?
They have a congenital insensitivity to pain
What are the NaV channels essential for?
Action potential propagation
What does a mutation in Nav 1.7 do?
Causes erythromelaglgia and paroxysmal extreme pain disorder
What does loss of activity at Nac 1.7 do?
People do not feel pain
What interneurons are present throughout the dorsal horn and common in Substantia Gelatinosa?
Inhibitory
Activation of nociceptors in viscera result in somatic perception of pain, why does this happen and what causes it?
-Referred pain
Possibly due to convergence of multiple nociceptor afferents on a single spinothalamic tract via dorsal horn.
What type of pain is rare?
Visceral
What does the inhibitory interneuron do?
Closes the gate and alters info getting into the brain.
Neurons that are in the dorsal horn and modulate transmission at the first synapse, and those that also mediate inhibition of transmission are called what?
Short inhibitory interneurons
*Enkephalins are important here
What is Enkephalin?
Endogenous opiate
What is something that modulates transmission at the synapse, the pathways originate in the periaquaductal grey (PAG) (5-HT), and the locus ceruleus (NA). Enkephalins are important in stimulation here too!
Descending inhibitory pathways
Innocuous peripheral stimuli evokes painful sensations such as what?
-Hyperalgesia
-Allodynia
-Spontaneous pain
-Neuropathic pain
What cells can contribute to increased firing in neuropathic pain?
Glial
What are the four opioid receptors?
All GPCR’s
1) DOR - Delta
2) MOR - Mu
3) KOR - Kappa
4) ORL1 - Orphan
What do opioid receptors signal through?
Gai/O
= Inhibitory
To get morphine induced effects what do we need?
MOR
What type of drug is morphine?
Partial Agonist
How does Ziconotide work for neuropathic pain?
Inhibits Calcium Channels CaV2.2
How does Ketamine work for neuropathic pain?
NMDA receptor blocker - suppresses neurotransmission through central synapse
How doe Tricyclic antidepressants and SNRIs work for neuropathic pain?
Potentiate descending inhibition by modulating 5-HT and NA levels - prevent re-uptake enhance synaptic levels, enhance descending inhibition.
