Anaesthetics - Pain Flashcards
What is pain?
Pain is “an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage”
Benefits of treating pain (for patient)?
- Physical
- Improved sleep, better appetite
- Fewer medical complications
- (e.g. heart attack, pneumonia)
- Psychological
- Reduced suffering
- Less depression, anxiety
Benefits of treating pain for the family?
- Improved functioning as a family member (e.g. as a father or mother)
- Able to keep working
- Socially this allows society to have lower health costs and contribute to society
What are the classifications of pain for: Duration, Cause and Mechanism?
Duration: Acute, Chronic, Acute on chronic
Cause: Cancer, non-cancer
Mechanism: Nociceptive (WHO pain ladder), neuropathic (need adjuncts)
[underlined is most useful]
Explain acute vs chronic.
Acute: Pain of recent onset and probable limited duration
Chronic: Pain lasting for more than 3 months, Pain lasting after normal healing, Often no identifiable cause.
Acute on chronic - an acute flare up of a chronic conditions
Explain cancer pain vs non-cancer pain.
- Cancer pain
- Progressive
- May be mixture of acute and chronic
- Non-cancer pain
- Many different causes
- Acute or chronic
Explain nociceptive pain.
- Obvious tissue injury or illness
- Also called physiological or inflammatory pain
- Protective function: if something hurts, we stop doing it etc
- Description
- Sharp ± dull
- Well localised
- Abdo visceral pain is slightly more difficult to localise
Explain neuropathic pain.
- Nervous system damage or abnormality
- Tissue injury may not be obvious
- Does not have a protective function
- Description
- Burning, shooting ± numbness, pins and needles
- Not well localised, all over kind of pain
What are the 4 steps of pain pathology?
- Periphery
- Spinal cord
- Brain
- Modulation
Patients pain response is driven by the cortex. If someone expects pain they are more likely to experience the pain.
Explain the peripheral step in pain pathology.
- Tissue injury
- Release of chemicals e.g. Prostaglandins, Substance P [these accentuate the pain pathway - amplify the signal]
- Stimulation of pain receptors (nociceptors)
- Signal travels in Aδ or C nerve to spinal cord
Explain the spinal cord step in pain pathology.
- Dorsal horn is the first relay station
- Aδ or C nerve synapses (connects) with secondary nerve
- Second nerve travels up opposite side of spinal cord
Explain the brain step in pain pathology.
- Thalamus is the second relay station: limbic for behavior, cortex for seeking help, brainstem for BP RR and other responses
- Connections to many parts of the brain
- Cortex
- Limbic system
- Brainstem
- Pain perception occurs in the cortex
Explain the modulation step in pain pathology.
- Descending pathway from brain to dorsal horn
- Usually decreases pain signal
- People who do more effectively have less pain
What is the gate theory of pain?
What are the features of neuropathic pain? Please include some examples.
- Abnormal processing of pain signal
- Nervous system damage or dysfunction
- Needs to be treated differently
- Examples
- Nerve trauma, diabetic pain (damage)
- Fibromyalgia, chronic tension headache (dysfunction)
What are pathological mechanisms that affect pain receptors in neuropathic pain?
Light touch of skin can cause a painful stimulus in these patients.
- Increased receptor numbers
- Abnormal sensitisation of nerves
- Peripheral
- Central
- Chemical changes in the dorsal horn: changes in neuromodulators
- Loss of normal inhibitory modulation
Give some examples of simple analgesics
- Paracetamol (underated hun xoxo)
- Non-steroidal anti-inflammatory drugs:
- diclofenac, iboprufen
- There is no antidote to these so be careful when administrating
- Can cause many issues such as kidney problems
- if you’re hingin take them both at the same time, rt to save a life
Give some examples of opiods:
- Mild
- Codeine, Dihydrocodeine
- Strong
- Morphine, Oxycodone, Fentanyl
What are some other commonly used analgesics?
- Tramadol ( Mixed opiate and 5HT/NA reuptake inhibitor)
- Antidepressants (e.g. amitriptyline, duloxetine)
- Anticonvulsants (e.g. gabapentin)
- Ketamine (NMDA Receptor antagonist)
- Local anaesthetics
- Topical agents (e.g. Capsaicin)
What are our treatment options for the periphery?
- Non-drug treatments
- Rest, ice, compression, elevation
- Non-steroidal Anti-inflammatory drugs (prostaglandin synthetase inhibitors)
- Local anaesthetics
What treatments do we use for the spinal cord?
- Non-drug treatments
- Acupuncture, massage, TENS
- Local anaesthetics - these are used centrally, epidural
- Opioids - work centrally and in brain
- Ketamine - also works in spinal cord
What analgesic options do we have for the brain?
- Non-drug treatments
- Psychological: chronic neuropathic pain, this therapy helps deal with chronic pain
- Drug treatments
- Paracetamol
- Opioids
- Amitriptyline
- Clonidine
Advantages and disadvantages of paracetamol?
-
Advantages
- Cheap, safe
- Can be given orally, rectally or intravenously
- Good for:
- Mild pain (by itself)
- Mod-severe pain (with other drugs)
-
Disadvantages
- Liver damage in overdose
Advantages and disadvantages of NSAIDS?
- Aspirin, ibuprofen, diclofenac
- Advantages
- Cheap, generally safe
- Good for nociceptive pain
- Best given regularly with paracetamol (Synergism)
- Disadvantages
- Gastrointestinal and renal side effects plus sensitive asthmatics
- Can increase wheeze
Advantages and disadvantages of codeine?
- Advantages
- Cheap, safe
- Good for mild-moderate acute nociceptive pain
- Best given regularly in combination with paracetamol
- Disadvantages
- Constipation
- Not good for chronic pain
- Nausea
What is tramadol? Advantages and disadvantages?
- Weak opioid effect plus inhibitor of serotonin and noradrenaline reuptake (modulation)
- Advantages
- Less respiratory depression
- Can be used with opioids and simple analgesics
- Not a controlled drug
- Disadvantages
- Nausea and vomiting
Morphine advantages and disadvantages?
GETS you high af, #lit
Advantages
- Cheap, generally safe
- Can be given orally, IV, IM, SC
- Effective if given regularly
- Good for:
- Mod-severe acute nociceptive pain (e.g. post-op pain)
- Chronic cancer pain
Disadvantages
- Constipation
- Respiratory depression in high dose
- Misunderstandings about addiction
- Controlled drug
What is amitriptyline? Advantages and disadvantages?
It is a tricyclic antidepressant (TCA) and increases descending inhibitory signals
Advantages
- Cheap, safe in low dose
- Good for neuropathic pain
- Also treats depression, poor sleep
Disadvantages
- Anti-cholinergic side effects (e.g. glaucoma, urinary retention)
Give some examples of anticonvulsant drugs and what they are useful for.
- Carbamazepine (Tegretol)
- Sodium valproate (Epilim)
- Gabapentin (Neurontin)
- Also called membrane stabilisers
- Reduce abnormal firing of nerves
- Good for neuropathic pain
What are some delivery routes available to us?
- Oral - this is the preferred route
- Rectal
- Sublingual
- Subcutaneous
- Transdermal - more slow acting so not so good for nociceptive pain
- Intramuscular
- Intravenous – boluses, possibly patient controlled systems
What are delivery routes available for local anaesthetics?
- Epidural (+/- Opiates)
- Intrathecal (+/- Opiates)
- Wound Catheters
- Nerve Plexus Catheters
- Local Infiltration of wounds
What are some scores that we use to assess pain?
- Verbal Rating Score: 5 numbers, 5 being the worst
- Numerical Rating Score: 0-10: but best to try and let patient tell you as this will guide what treatments we use.
These are used less in clinical but more in studies:
- Visual Analogue Scale
- Smiling faces: used in paeds
- Abbey Pain Scale (for confused patients)
What is the WHO analgesic ladder?
How do we manage acute nociceptive pain?
Link Pain Assessment to prescribing for acute nociceptive pain
- Mild Pain: Start at Bottom of Pain Ladder
- Moderate Pain: Bottom of Pain Ladder plus Middle Rung
- Severe: Bottom of Pain Ladder plus Top of Ladder. Miss out the middle
- It is okay to start at the top of the ladder for severe/ unbearable pain!!!!
What do we do when the pain starts to resolve?
- Move from top to middle of WHO ladder
- Continue Bottom Rung drugs at all times
- Lastly stop NSAIDs, then Paracetamol as more adverse effects with NSAIDs
What is the RAT approach to pain management?
- Recognise
- Assess
- Severity?
- Type?
- Other factors?
- Treat
- Non-drug treatments
- Drug treatments
Explain the features of recognising pain:
- Does the patient have pain?
- Ask
- Look (frowning, moving easily, sweating?)
- Do other people know the patient has pain?
- Other health workers
- Patient’s family
How do we assess the severity (assessment)?
- 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?
What other factors need to be considered in assessment?
- Physical factors (other illnesses)
- Psychological and social factors
- Anger, anxiety, depression
- Lack of social supports
What are some of the non-drug treatments available?
- RICE
- Rest, ice, compression, elevation of injuries
- Nursing care
- Surgery, acupuncture, massage, TENS etc
- Psychological
- Explanation and reassurance
- Input from social worker / pastor
What do we do for nociceptive pain?
- Mild
- Paracetamol (± NSAIDs)
- Moderate
- Paracetamol (± NSAIDs) + codeine/ alternative
- Severe
- Paracetamol (± NSAIDs) + morphine
What do we do for neuropathic pain?
- Traditional drugs may not be as useful
- Use other drugs early
- Amitriptylline
- Gabapentin
- Duloxetine
- Don’t forget non-drug treatments
What do we do once RAT is completed?
- Reassess the patient
- Is your treatment working?
- Are other treatments needed?
