Anaesthetics - Pain Flashcards by George Burton

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”

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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

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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

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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]

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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

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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

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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

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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

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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.

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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

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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

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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

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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

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What is the gate theory of pain?

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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)

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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

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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

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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?