Pain Flashcards
What is pain?
An unpleasant sensory and emotional experience associated with actual or potential issue damage, or described in terms of such damage Treating pain is humane and has many benefits
What are the benefits of treating pain for the patient?
– Physical • Improved sleep, better appetite • Fewer medical complications (e.g. heart attack, pneumonia) – Psychological • Reduced suffering • Less depression, anxiety
What are the benefits of treating pain for the family?
- Improved functioning as family member - Able to keep working
What are the benefits of treating pain for society?
– Lower health costs (e.g. shorter hospital stay) – Able to contribute to the community
What are the 3 main questions for pain?
- How long has the patient had pain 2. What is the cause 3. What is the mechanism
How can you class pain?
Duration Cause Mechanism
What are the duration classes of pain?
- Acute - Chronic - Acute on chronic
What are the cause classes of pain?
Cancer Non cancer
What are the mechanism classes of pain?
Nociceptive Neuropathic
How are acute and chronic pain different?
• Acute – Pain of recent onset and probable limited duration • Chronic – Pain lasting for more than 3 months – Pain lasting afternormal healing – Often no identifiable cause
How are cancer and non cancer pain different?
• Cancer pain – Progressive – May be mixture of acute and chronic • Non-cancer pain – Many different causes – Acute or chronic
What is nociceptive pain?
• Obvious tissue injury or illness • Also called physiological or inflammatory pain • Protective function • Description – Sharp ± dull – Well localised
What is neuropathic pain?
• Nervous system damage or abnormality • Tissue injury may not be obvious • Does not have a protecve function • Description – Burning, shooting ± numbness, pins and needles – Not well localised
What is acute non cancer pain?
• Examples – Fracture, appendici9s • Symptom of tissue injury or illness • Usually nociceptive • Occasionally neuropathic (e.g. sciatica)
What is chronic non cancer pain?
• Examples – Chronic back pain, arthritis • Injury may not be obvious • Complex, may be mixed nociceptive and neuropathic • Does not respond to usual drug treatment
What is cancer pain?
• Examples – Uterine cervical cancer, breast cancer • Features of acute and chronic pain – May be acute on chronic • Often mixed nociceptive and neuropathic pain • Usually gets worse over time if untreated
What is the difference between nociception and pain?
• Nociception – How signals get from the site of injury to the brain • Pain perception – How we “feel” pain
What is nociception in reference to pain?
What is the gross physioogy of pain?
4 steps:
- Periphery
- Spinal cord
- Brain
- Modulation
What happens in the periphery in pain sensation?
- Tissue injury
- Release of chemicals
- Stimulation of pain receptors (nociceptors)
- Signal travels in Aδ or C nerve to spinal cord
What happens in the spinal cord in a pain response?
- Dorsal horn is the first relay station
- Aδ or C nerve synapses (connects) with second nerve
- Second nerve travels up opposite side of spinal cord
What happens in the brain when feeling pain?
- Thalamus is the second relay station
- Connections to many parts of the brain
– Cortex
– Limbic system
– Brainstem
• Pain perception occurs in the cortex
What does modulation do in the pain pathway?
- Descending pathway from brain to dorsal horn
- Usually decreases pain signal
Why might placebo treatment be helpful?
- Psychological factors are important.
- If a placebo treatment works, this does not mean the patient did not have pain or was telling lies!
- Many factors affect how we “feel” pain.
– Psychological factors are very important.
• Different treatments work on different parts of the pathway.
– More than one treatment may be needed.
Why might there be pain pathology?
- 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 the pathological mechanisms in pain pathologies?
- Increased receptor numbers
- Abnormal sensitisation of nerves
– Peripheral
– Central
- Chemical changes in the dorsal horn
- Loss of normal inhibitory modulation
What are the non drug treatments of pain?
Physical
- Rest, Ice, compression, elevation
- surgery
- Acupuncture, massage, physiotherapy
Psychological
- Explanation
- Reassurance
- Counselling
What are the drug classifications in pain?
- Simple analgesics (e.g. paractemol, anti infl: Ibuprofen, diclofenac)
- Opioids (Mild: codeine, Strong: morphine, pethidine, oxycodone)
- Other (tramadol, TCAs, anticonvulsants, ketamine, local anaesthetics, clonidine)
How do we treat pain in the peripheral part of the pain pathway?
• Non-drug treatments
– Rest, ice, compression, elevation
- Anti-inflammatory medicines
- Local anaesthetics
How do we treat pain at the spinal cord level?
• Non-drug treatments
– Acupuncture, massage
- Local anaesthetics
- Opioids
- Ketamine
How do we treat pain at the level of the brain?
• Non-drug treatments
– Psychological
• Drug treatments
– Paracetamol
– Opioids
– Amitriptyline
– Clonidine
What are the advantages of paracetamol in pain relief?
• Cheap, safe
– Can be given orally, rectally or intravenously
– Good for:
- Mild pain (by itself)
- Mod-severe pain (with other drugs)
What is the major disadvantage of paracetamol?
- Liver damage in OD
What are the pros and cons of anti inflammatory medicine?
- Aspirin, ibuprofen, diclofenac
- Advantages
– Cheap, generally safe
– Good for nociceptive pain
- Best given regularly with paracetamol
- Disadvantages
– Gastrointestinal and renal side effects
What are the pros and cons of codeine?
• Advantages
– Cheap, safe
– Good for mild-moderate acute nociceptive pain
- Best given regularly with paracetamol
- Disadvantages
– Constipation
– Not good for chronic pain
– Misunderstandings about addiction
What is the risk for opioids and addiciton?
- Pain is sometimes poorly treated because of concerns about addiction.
- Addiction is very rare in:
– Acute pain
– Cancer pain
• Addiction is more likely in chronic non-cancer pain.
What are the advantages of morphine?
– 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
What are the disadvantages of morphine?
– Constipation
– Respiratory depression in high dose
– Misunderstandings about addic9on
– Controlled drug
How much morphine is given?
Oral, 2-3 times
IV/IM/SC
What are the pros and cons of pethidine?
- Can be good for severe acute nociceptive pain but has more disadvantages than morphine
- Disadvantages
– Also a controlled drug
– Must be given more frequently than morphine
– Breakdown product (norpethidine) can cause convulsions
– Not good for chronic pain
What are the pros and cons of tramadol?
- 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
What are the pros and cons of amitriptylline?
- Tricyclic antidepressant (TCA)
- 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 reten9on)
Why are anticonvulsants used in pain treatment?
• Examples
– Carbamazepine (Tegretol) [Trigeminal neuralgia]
– Sodium valproate (Epilim)
– Gabapentin (Neurontin) [Nerve pain]
• Also called membrane stabilisers
– Reduce abnormal firing of nerves
• Good for neuropathic pain
How do the drugs compare to each other in different types of pain?
What is the RAT approach to pain management?
- Recognize
- Assess
– Severity?
– Type?
– Other factors?
• Treat
– Non-drug treatments
– Drug treatments
How do you recognise if the patient has 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 you assess severity?
• 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?
- Helps guide treatment
- Methods
– Verbal (e.g. mild, moderate, severe)
– Numerical
• 0 (no pain) to 10 (worst pain imaginable)
– Visual
- Visual Analogue Scale (VAS)
- “Faces” pain scale
How do you assess the pain type?
- Acute or chronic?
- Cancer or non-cancer?
- Nociceptive or neuropathic?
– Look for neuropathic features:
- Burning or shooting pain
- Phantom limb pain
- Other features (pins and needles, numbness)
What must you also think of when assessing pain?
- Physical factors (other illnesses)
- Psychological and social factors
– Anger, anxiety, depression
– Lack of social supports
Summarise the treatments of pain
- Non drug
- Drug for nociceptive pain
- Drugs for neuropathic pain
What is complex regional pain syndrome
- Can occur following minimal tissue damage
- Neuropathic pain
Summarise the non drug treatments of pain
- RICE
- Nursing care
- Surgery, acupuncture, massage
- Psychological (explanation and reassurance, input from social worker/ pastor)
What are the steps in treating nociceptive pain?
– Mild
• Paracetamol (± NSAID)
– Moderate
• Paracetamol (± NSAID) + codeine
– Severe
• Paracetamol (± NSAID) + morphine
What are the treatments of neuropathic pain?
– Traditional drugs may not be as useful
– Use other drugs early
- Amitriptyline
- Gabapentin / carbamazepine
– Don’t forget non-drug treatments
What do you do after RAT?
• Reassess the patient
– Is your treatment working?
– Are other treatments needed?
A 32-year-old man caught his right hand in machinery at work. He presents with a compound fracture of his hand.
How would you manage his pain using the RAT approach?
R- ask if he has pain, watch facial expression, ask others
A- Pain score, affect on patient, acute non cancer, nociceptive pain, ask about other factors
T- WHO pain ladder for acute pain
A 55-year-old woman presents with a large breast tumour with spread to her spine. She has severe pain.
How would you manage her pain using the RAT approach?
R- ask if he has pain, watch facial expression, ask others
A- Pain score, affect on patient, chronic cancer, neuropathic pain, ask about other factors
T- Other drugs (gabapentin, amitriptylline), WHO pain ladder
What is allodynia?
Pain provoked in response to a stimulus that does not normally cause pain
What is hyperalgesia?
Increased pain in response to something that causes pain
What types of pain response are linked to neuropathic pain?
Allodynia
Hyperalgesia
