Pain Management Flashcards
What is acute pain?
normal predicted physiological response to adverse stimulus that RESOLVES WITHIN 1 MONTH
What is chronic pain?
poorly managed acute pain that can produce pathophysiologic processes
- caused by sensitization of the nervous system due to neuroplastic changes resulting in allodynia & hyperalgesia
What surgical procedures are associated with chronic pain?
amputation of a limb
lateral thoracotomy
inguinal herniorrhaphy
What do we call a painful response to a non-painful stimulus?
allodynia
what is hyperalgesia?
an exaggerated pain response to a normally painful stimulus
What are nociceptors?
free nerve endings (first order neuron)
What fibers transmit first pain?
A-delta fibers
- sharp or stinging pain well localized
which fibers transmit second pain?
C fibers
diffuse pain
What is the difference between nociceptive pain & neuropathic pain?
NOCICEPTIVE NEUROPATHIC
- doesn’t cause nerve - injury or malfunction in the
damage peripheral or central
nervous system
- acute pain - chronic pain
- somatic: localized
or visceral: diffuse
What is the pain pathway?
1- stimulus 2- nerve ending 3- spinal cord ---> crossover 4- spino-thalamic tract (thalamus) 5- sensory cortex
How does the body process pain?
1- transduction: stimuli converted to action potential
2- transmission: action potential conducted through
nervous system
3- modulation: altering neural transmission
- inhibition or augmentation of pain signals
4- perception: integration of painful input into
somatosensory & limbic cortices
What is the point of preventive analgesia?
block the development of sustained pain to prevent chronic pain
What type of pain is postoperative pain?
nociceptive
What is the best method of treating nociceptive (acute) pain?
- opioids
- NSAIDS
How should mild pain be treated?
nonopiod +/- adjuvant therapy
How should mild to moderate pain be treated?
weak opioid +/- nonopioid +/- adjuvant therapy
How should moderate to severe pain be treated?
strong opioid +/- nonopioid +/- adjuvant therapy
What is the aim of multimodal analgesia?
- improves pain relief
- reduces opioid requirement & adverse effects
What analgesics are used in multimodal analgesia?
- opioid
- NSAID
- paracetamol
- local anesthesia
What is the acute pain service (APS)?
- a team providing pain service for post-op patients
- anesthesiologist
- surgeons
- nurses
- pharmacist
- physiotherapist
what are the analgesics that work on the level of the cortex?
- opioids
- alpha2 agonists (pesidex)
- acetominophen
- anticonvulsants
- NMDA antagonists (KETAMINE at low dose)
What are the analgesics that work at the level of the trauma?
- anti-inflammatory drugs
- local anesthetics
What are the analgesics that work on the level of the peripheral nerve (first order)?
local anesthesia
What are the analgesics that work at the level of the dorsal horn (second order neuron)?
- opioids
- local anesthesia
What is the gold standard for treatment of acute post-op pain?
morphine
Why is pethidine no longer used?
highly addictive
which opioid has the fastest onset?
fentanyl
has a short duration of action (45mins)
What are the adverse effects of opioids?
- nausea, vomiting, constipation
- urinary retention
- delirium, hallucinations, sedation
- respiratory depression
What is the function of NSAIDs?
voltarine & ibuprofen
- inhibit COX enzymes thus decrease the production of prostaglandin E2
What is the function of prostaglandin E2?
key mediator of peripheral & central pain sensitization
What are the side effects of old NSAIDs?
- platelet dysfunction
- gastrointestinal ulceration
- risk of nephrotoxicity
What is the function of paracetamol?
analgesic & antipyretic
centrally acting inhibitor of COX enzyme
What are the other nonopioid analgesic adjuncts?
- ketamine at very low doses
- lidocaine infusion
- dexmedetomidine
- gabapentin (anticonvulsant)
