Pain and Pain Relief Flashcards by Chloe Mackle

What is pain, according to the International Association for the Study of Pain?

An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage

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What fraction of people live with persistent pain?

1 in 4

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What percentage of people attending A&E seeking help for pain will have made around 3 visits to their health care practitioner in the preceding weeks?

66%

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What is the number 1 disease for years lost to disability worldwide?

Low back pain

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What are the benefits of treating pain for the patient?

Physical
- improved sleep, better appetite
- fewer medical complications 
Psychological 
- reduced suffering 
- less depression and anxiety

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What are the benefits of treating pain for the family?

Improved functioning as a family member

Able to keep working

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What are the benefits of treating pain for society?

Lower health costs

Able to contribute to the community

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How is pain classified?

By;
Duration
Cause
Mechanism

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How is pain classified according to duration?

Acute
Chronic
Acute on chronic

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How is pain classified according to cause?

Cancer

Non-cancer

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How is pain classified according to mechanism?

Nociceptive

Neuropathic

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What is the difference between acute and chronic pain?

Acute pain is pain of recent onset and probable limited duration

Chronic pain is;

pain lasting for more than 3 months
pain lasting after normal healing
often no identifiable cause

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What is the difference between cancer and non-cancer pain

Cancer pain

progressive
may be a mixture of acute and chronic

Non-cancer pain

many different causes
acute or chronic

This classification is more about the context in which pain occurs and how this influences management

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What are the features of nociceptive pain?

Obvious tissue injury or illness
Also known as physiological or inflammatory pain
Protective function
Sharp/dull, well-localised

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What are the features of neuropathic pain?

Nervous system damage or abnormality - neuropathic dysfunction
Tissue injury may not be obvious
Does not have a protective function
Burning, shooting, numbness, pins and needles, not well-localised

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What are the 4 steps of pain physiology?

Periphery
Spinal cord
Brain
Modulation

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What is the mechanism of pain physiology in the periphery?

Nociceptors in the periphery
Tissue injury - results in release of chemicals e.g. prostaglandins
Signal travels in Aδ or C fibres to spinal cord

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What is the mechanism of pain physiology in the spinal cord?

Dorsal horn is the first relay station
Aδ or C nerve synapses with second nerve
Second nerve travels up the opposite side of the spinal cord

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What is the mechanism of pain physiology in the brain?

Thalamus is the second relay station
Connects to many parts of the brain - cortex, limbic system, brainstem
Pain perception occurs in the cortex

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What is the mechanism of pain modulation?

Descending pathway from brain to dorsal horn

Usually decreases pain signal

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What is the gate theory?

When transmission cell is stimulated, pain signal is transmitted to the brain
The inhibitor neurone switches off anything stimulating the transmission cell so signals that stimulate the inhibitor neurone will reduce pain transmission and pain sensation

Light touch and pressure turn on the inhibitor neurone
Noxious stimuli inhibit the inhibitor neurone

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Why does neuropathic pain occur?

Abnormal processing of pain signal
Nervous system damage or dysfunction
e.g. nerve trauma, diabetic pain, fibromyalgia

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What are the pathological mechanisms of neuropathic pain?

Increased receptor numbers
Abnormal sensitisation of nerves - peripheral or central
Chemical changes in dorsal horn
Loss of normal inhibitory modulation

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What are the simple analgesics?

Paracetamol

NSAIDs

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What are the opioids used?

Mild - codeine, dihydrocodeine | Strong - morphine, oxycodone, fentanyl

What are other drugs used as analgesics?

``` Tramadol Anti-depressants e.g. amitriptyline Anti-convulsants e.g. gabapentin Ketamine Local anaesthetics Topical agents e.g. capsaicin ```

What are the non-drug treatments for peripheral pathologies causing pain?

Rest Ice Compression Elevation

What are the drug treatments for peripheral pathologies causing pain?

NSAIDs | Local anaesthetics

What are the non-drug treatments for spinal cord pathologies causing pain?

Acupuncture Massage TENS

What are the drug treatments for spinal cord pathologies causing pain?

``` Local anaesthetics Spinal anaesthetics Epidural Opioids Ketamine ```

What are the non-drug treatments for brain pathologies causing pain?

Psychological treatment

What are the drug treatments for brain pathologies causing pain?

Paracetamol (most effective when used in adjunct with other pain treatments) Opioids Amitriptyline Clonidine

What are the advantages of paracetamol?

Cheap, safe Can be given orally, rectally or intravenously Good for mild pain when used alone, and moderate-severe pain when used with other drugs

What are the disadvantages of paracetamol?

Liver damage in overdose

What are the commonly used NSAIDs?

Aspirin Ibuprofen Diclofenac

What are the advantages of NSAIDs?

Cheap Generally safe Good for nociceptive pain (works best when given regularly with paracetamol)

What are the disadvantages of paracetamol?

Gastrointestinal and renal side effects | Can aggravate asthma

What are the advantages of codeine?

Cheap Safe Good for mild-moderate acute nociceptive pain Works best when given regularly with paracetamol

What are the disadvantages of codeine?

Constipation | Not good for chronic pain

How does tramadol work?

Weak opioid effect plus inhibitor of serotonin and noradrenaline reuptake

What are the advantages of tramadol?

Less respiratory depression Can be used with opioids and simple analgesics Not a controlled drug

What are the disadvantages of tramadol?

Nausea | Vomiting

What are the advantages of morphine?

``` Cheap Generally safe Can be given orally, IV, IM or SC Effective if given regularly Good for moderate-severe acute nociceptive pain e.g. post-op, chronic cancer pain ```

What are the disadvantages of morphine?

Constipation Respiratory depression in high dose Misunderstanding about addiction Controlled drug

What is the safest way to administer morphine? Why?

Titration is generally the safest way to administer it as safety is dose-dependent

How does amitriptyline work?

Tricyclic antidepressant, increases descending inhibitory signals

What are the advantages of amitriptyline?

Cheap Safe in low doses Good for neuropathic pain Also treats depression and poor sleep

What are the disadvantages of amitriptyline?

Anti-cholinergic side effects | Many other side effects

What are some anti-convulsant drugs?

Carbamazepine Sodium valproate Gabapentin

How do anti-convulsants work?

Reduce abnormal firing of nerves (membrane stabilisers) - good for neuropathic pain

What are the possible delivery routes for analgesia?

``` Oral Rectal Sublingual Subcutaneous Transdermal Intramuscular Intravenous ```

What are the possible delivery routes for local anaesthetics?

``` Epidural Intrathecal Wound catheters Nerve plexus catheters Local infiltration of wounds ```

What can be used for pain assessment?

``` Verbal rating score Numerical rating score Visual analogue scale Smiling faces Abbey pain scale ```

What are the non-drug treatments that can be offered for pain?

Physical - rest, ice, compression, elevation (RICE) - surgery - acupuncture, massage, physiotherapy Psychological - explanation - reassurance - counselling

What type of pain is not responsive to the WHO pain ladder drugs?

Neuropathic

How does the WHO pain ladder link assessment to prescribing for acute nociceptive pain?

Mild pain - start at bottom of ladder Moderate pain - bottom of ladder plus middle rung Severe pain - bottom of ladder plus top of ladder, miss out middle As pain resolves, move down the ladder, passing the middle rung first, continue bottom rung drugs at all times Lastly, stop NSAIDs then paracetamol

What is the RAT approach to pain management?

Recognise - does the patient have pain - do other people know the patient has pain (family etc.) Assess - severity (pain score) - type i.e. acute or chronic, cancer or non-cancer, nociceptive or neuropathic - other factors e.g. how it is affecting the patient Treat - non-drug treatments - drug treatment

What features should you look for when assessing a patient's pain?

Neuropathic features - burning or shooting pain - phantom limb pain - pins and needles, numbness

What other factors might affect a patient's pain?

Physical factors e.g. other illnesses | Psychological and social factors e.g. anger, anxiety, depression, lack of social support

What are the drug treatments advised on WHO pain ladder?

Mild - paracetamol (+/- NSAID) Moderate - paracetamol + codeine/alternative (+/- NSAID) Severe - paracetamol + morphine (+/- NSAID)

What drugs (not on WHO pain ladder) should be used early in neuropathic pain treatment?

Amitriptyline Gabapentin Duloxetine