Anaesthetics: Essential Pain Management Flashcards
What is pain?
an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage
What are the physical benefits for the patient if we treat pain?
- improved sleep
- better appetite
- fewer medical complications (e.g. heart attack, pneumonia)
What are the psychological benefits for the patient if we treat pain?
- reduced suffering
- less depression, anxiety
What are the benefits for the family if we treat pain?
- improved functioning as a family member (e.g. as a father or mother)
- able to keep working
What are the benefits for society if we treat pain?
- lower health costs (e.g. hospital stay)
- able to contribute to the community
How can pain be classified?
duration: acute or chronic
cause: cancer or non-cancer
mechanism: nociceptive or neuropathic
What is acute pain?
pain of recent onset and probable limited duration
What is chronic pain?
- pain lasting for more than 3 months
- pain lasting after normal healing
- often no identifiable cause
Describe pain from cancer vs non cancer
cancer: progressive, a mixture of acute and chronic
non cancer: acute or chronic
Describe nociceptive vs neuropathic pain
nociceptive: sharp +/- dull, well localised
neuropathic: burning, shooting +/- numbness, pins and needles, not well localised
when does nociceptive & neuropathic pain occur?
nociceptive: obvious tissue injury or illness
neuropathic: nervous system damage or abnormality
What does nociceptive pain function as?
protective function
also referred to as inflammatory pain
What are the 4 steps in the physiology of pain?
- periphery
- spinal cord
- brain
- modulation
What physiology occurs in the periphery during the pain response?
- 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
What physiology occurs in the spinal cord during the 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 physiology occurs in the brain during the pain response?
- thalamus is the second relay station
- connections to many parts of the brain: cortex, limbic system and brainstem
- pain perception occurs in the cortex
What physiology occurs during modulation in the pain response?
- descending pathway from brain to dorsal horn
- usually decreases pain signal
What is the gate theory?
stimulation by non-noxious input is able to suppress pain by closing the ‘gate’ to painful input preventing pain sensation from travelling to the cortex
Give examples of neuropathic pain
- nerve trauma, diabetic pain (damage)
- fibromyalgia, chronic tension headache (dysfunction)
What is the pathology behind neuropathic pain?
- increased receptor numbers
- abnormal sensitisation of nerves (peripheral and central)
- chemical changes in the dorsal horn
- loss of normal inhibitory modulation
What types of drugs can be used for the treatment of pain?
- simple analgesics
- opioids
- other analgesics
Give examples of simple analgesics.
- paracetamol (acetaminophen)
- non-steroidal anti-inflammatory drugs (diclofenac, ibuprofen)
Give examples of opioid drugs
weak: codeine, dihydrocodeine, tramadol
strong: morphine, oxycodone, fentanyl
Other than simple analgesics and opioids, what other drugs can be used for pain?
- 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)
