Anaesthetics: Pain and pain relief 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”
○ Pain is what the patient says it is ….
Why treat pain?
○ 1 in 4 people live with persistent pain
○ Basic Human Right
○ 66% of people attending A & E seeking help with pain had made around 3 visits to HCP in proceeding weeks
○ Person living with pain has poor quality of life as bad as other neurological diseases
○ Low Back Pain is the number 1 disease for years lost to disability worldwide
What are the benefits to treating pain?
○ For the patient - Physical □ Improved sleep, better appetite □ Fewer medical complications (e.g. heart attack, pneumonia) - Psychological □ Reduced suffering □ Less depression, anxiety ○ For the family - Improved functioning as a family member (e.g. as a father or mother) - Able to keep working ○ For society - Lower health costs (e.g. shorter hospital stay) - Able to contribute to the community
What are the different ways to classify pain?
- Duration • Acute • Chronic • Acute on chronic - Cause • Cancer • Non-cancer - Mechanism • Nociceptive • Neuropathic
What is the difference between acute and chronic pain?
- 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
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
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 protective function
- Description
□ Burning, shooting ± numbness, pins and needles
□ Not well localised
What are the 4 steps of pain physiology?
□ Periphery
® Tissue injury
® Release of chemicals e.g. Prostaglandins, Substance P
® Stimulation of pain receptors (nociceptors)
® Signal travels in Aδ or C nerve to spinal cord
□ Spinal cord
® 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
□ Brain
® Thalamus is the second relay station
® Connections to many parts of the brain ◊ Cortex ◊ Limbic system ◊ Brainstem
® Pain perception occurs in the cortex
□ Modulation
® Descending pathway from brain to dorsal horn
® Usually decreases pain signal
What is the reason reason for neuropathic pain?
- 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) - Pathological mechanisms
□ Increased receptor numbers
□ Abnormal sensitisation of nerves ® Peripheral ® Central
□ Chemical changes in the dorsal horn
□ Loss of normal inhibitory modulation
Give examples of simple analgesics
- Paracetamol (acetaminophen)
- Non-Steroidal Anti-inflammatory drugs
□ Diclofenac, ibuprofen
Give exaamples of opiods
- Mild
□ Codeine, Dihydrocodeine - Strong
□ Morphine, Oxycodone, Fentanyl
Give examples of analgesics other than simple analgesics and opiods
- 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 treatments for pain affect the peripheries
- Non-drug treatments
□ Rest, ice, compression, elevation - Non-steroidal Anti-inflammatory drugs
- Local anaesthetics
What treatments for pain affect the spinal cord?
- Non-drug treatments □ Acupuncture, massage, TENS - Local anaesthetics - Opioids - Ketamine
