Anaesthetics - Pain Flashcards
What are the benefits of treating pain?
Physical - improved sleep, appetite, fewer complications
Psychological - Reduced depression, anxiety
Family - functioning
Society - Lower health costs
What are the classifications of pain?
Duration - acute/chronic
Cause - cancer/non-cancer
Mechanism - nociceptive/neuropathic
What is nociceptive pain?
Obvious injury/illness
Physiological or inflammatory
Protective function
Sharp, well localised
What is neuropathic pain?
NS damage/abnormality Not obvious tissue injury Not protective Burning/shooting + numbness Not well localised
What are the steps in pain physiology?
Periphery
Spinal cord
Brain
Modulation
What is the function of the periphery in pain?
Tissue injury
Release of chemicals (prostaglandins, substance P)
Stimulates pain receptors
Adelta and C fibres to spinal cord
What is the function of the spinal cord in pain?
Second nerve travels up opposite side of cord
Dorsal horn is first relay station
What is the function of the brain in pain?
Thalamus is second relay station
Pain perception in cortex
What is the function of modulation in pain?
“Gate theory”
Descending pathway
from brain -> dorsal horn
Usually decreases the signal
What are the mechanisms for neuropathic pain?
Increased receptors
Abnormal nerve sensitisation
Chemical changes in dorsal horn
Loss of normal inhibitory modulation
What are the simple analgesics?
Paracetamol
NSAIDs
What are the opioids?
Mild - Codeine
Strong - Morphine, Fentanyl
Name some other drugs for analgesia not simple/opioid?
Tramadol Nefopam Antidepressants Anticonvulsants Ketamine
What pain treatments affect pain in the peripheral step?
RICE
NSAIDs
Local anaesthetics
What pain treatments affect pain in the spinal cord step?
TENS
Local anaesthetic
Opioids
Ketamine
What pain treatments affect pain in the brain step?
Psychological therapy Paracetamol Opioids Amitriptyline Clonidine
What are the advantages/disadvantages of paracetamol?
Adv: Cheap, safe, oral/rectal/IV
Dis: Liver damage in overdose
What are the advantages/disadvantages of NSAIDs?
Adv: Cheap + safe, nociceptive pain (+paracetamol)
Dis: GI/Renal/Bronchospasm
What are the advantages/disadvantages of Codeine?
Adv: Cheap, mild/moderate
Dis: Constipation, no use in chronic pain
What are the advantages/disadvantages of Tramadol?
Adv: less resp depression, used with analgesics
Dis: N+V
What are the advantages/disadvantages of morphine?
Adv: Cheap, safe, multi-routes
Good for chronic and severe acute pain
Dis: Constipation, resp depression, addiction
What are the advantages/disadvantages of amitriptyline?
Adv: cheap, safe, neuropathic pain, depression
Dis: Anti-cholinergic sides (glaucoma, urinary retention)
What are the advantages/disadvantages of anticonvulsant drugs for pain?
Adv: Neuropathic pain
Which anticonvulsants are used as pain med?
Carbamazepine
Sodium valproate
Gabapentin
What is the RAT approach to pain?
Recognise
Assess - severity, type
Treat - Drug/non-drug
How do you Recognise pain?
Ask patient
Look at patient
Ask people who know them
What are the pain assessment scores?
Verbal rating Numerical rating Visual analogue Smiling faces Abbey pain scale Functional pain
What pain scale is used in confused patients?
Abbey pain scale
How is pain assessed?
Pain score (at rest vs movement) How is pain affecting the patient
How do you assess pain type?
Acute or Chronic
Cancer or non-cancer
Nociceptive or neuropathic
What are the non-drug treatments for pain?
RICE
Nursing care
Surgery, TENS
Psychological
Outline the WHO pain ladder?
Mild = Paracetamol (+NSAIDs) Moderate = Paracetamol (+NSAIDs) + codeine/alternative Severe = Paracetamol (+NSAIDs) + morphine
How is neuropathic pain managed?
Don’t use WHO ladder
Other drugs
Non-drug treatments
