Analgesia Flashcards
What are the 5 major classes of analgesic drugs used in vet med?
- opioids
- NSAIDs
- Alpha-2 agonists
- NMDA-receptor antagonists
- Local anesthetics
what are “pros” of opioids?
- excellent analgesia
- inexpensive
- many drug options to choose from
- minimal CV effects
- reversible (naloxone)
- sedation
what are the adverse effects / downsides of opioids?
- possible respiratory depression, but not typically at analgesic doses
- GI upset (vomiting, ileus) **
- histamine release
- sedation
- parenteral admin primarily
- abuse potential
What is the BEST use of opioids in the emergency setting?
These drugs are safe and effective and best used in cases of ACUTE, SEVERE pain.
They are NOT good for chronic pain management (>24-48hr) d/t GI side effects.
what are the “pros” of using NSAIDs in the emergency setting?
- excellent analgesia and lasts a while
- oral and parenteral
- many vet-approved products
- inexpensive
what are the adverse effects and downsides to using NSAIDs?
- possible GI ulceration
- contraindicated in patients with dehydration or hypovolemia (decreased RBF)
- NOT reversible
why are NSAIDs contraindicated in dehydrated, hypovolemic, or traumatic blood loss patients?
they have decreased renal blood flow AND renal auto-regulation is mediated by prostaglandins. Prostaglandins are blocked by NSAIDs so the kidneys are NOT able to adjust in the face of hypotension.
The risk of renal damage is higher.
What type of pain are NSAIDs BEST used for?
severe, chronic, and/or orthopedic pain
what are the “pros” of using alpha-2 agonists as analgesia in the emergency setting?
- effective analgesia (unsure how good)
- powerful sedation*’
- relatively inexpensive
- reversible (atipamezole)
Though alpha-2 agonists are great analgesics and sedatives to use in emergency analgesic management, what are the downsides/adverse effects that can occur with use?
- significant decrease in cardiac output (only use in stable patients)
- profound sedation
- respiratory depression
- parenteral admin only
why is the use of alpha-2 agonsits in the emergency setting restricted to STABLE patients only?
these drugs cause a significant DECREASE in cardiac output as well as respiratory depression.
T/F: alpha-2 agonists can cause significant decreases in cardiac out, so you should use lower doses in less stable patients to reduce the risk of CPA.
false – lower doses do NOT equal safer doses. Regardless of the dose, there is a 60-70% decrease in cardiac output within the first 2 minutes after administration.
These drugs should ONLY be used in stable patients.
T/F: alpha-2 agonsits are a good choice analgesic if you desire profound sedation for certain procedures such as radiographs.
true
T/F: NMDA receptor antagonist drugs such as ketamine are most effective if they are given BEFORE the painful stimulus
true
that is why these drugs rare starting intraoperatively before the first incision is made.
What is “wind up” pain?
an increase in pain intensity caused by the same stimulus over time.
NMDA receptor antagonist drugs such as ketamine prevent wind-up pain.
