Pain Management Flashcards
Pain
Pain is the perception of nociception (occurs in brain)
* considered to be the 4th vital sign
* pain vs dysphoria
* inhalation agents = only block perception pathway
* local anesthetics = completely block pain
Dysphoria
Mental / emotional state where patient has intense feelings and becomes indifferent / unresponsive to surroundings
* related to stress, not pain
* clear sign is patient not responding to being calmed down
Nociception
- Occurs in periphery
- Processes info on stimuli
- Transmits info to brain (perceived as pain)
Pain Pathway
- Transduction
- Transmission
- Modulation
- Perception
Transduction
Afferent nerve endings translate stimulus info to nociceptive impulses
Transmission
Impulses sent to spinal cord (dorsal horn)
* further sent along tract to brain
Modulation
Primarily takes place in spinal cord (dorsal horn)
* also occurs elsewhere within nervous system and midbrain
Adaptive Pain
Acute Pain
* sudden onset, usually with a known cause
* “good pain” = able to be treated / controlled
Maladaptive Pain
Chronic Pain
* persists beyond normal healing time
* unknown cause
* “bad pain” = pain nerve endings become necrotic over time with repeated stimuli
Neuropathic Pain
Maladaptive Pain State
* pain response associated with peripheral nerve damage
Pain Wind-Up
Perceived increase to pain intensity over time
* painful stimulus given repeatedly
Pain Management with Surgery
Goal is to decrease pain with analgesics and maintain safe plane of anesthesia
* aggressive analgesics = decreased persistent pain after
Analgesia and Pain
Three Principles
- Preemptive Analgesia - give drugs before anticipated pain to get ahead of controlling it
- Multimodal Analgesia - combination of drugs to provide longer effects and cover more areas
- Analgesia Drug Duration - continue as long as pain is present
Palliative Care
Any form of care / treatment that focuses on reducing severity of symptoms
* does not look to stop or delay the progression
Opioids
Effects
- Analgesic: reduces perception / reaction to pain; increases tolerance
- Sedation
- Depresses RR
Opioids
Agonists
Bind to receptor and trigger response
* most common opioids are these
Opioids
Partial Agonists
Bind to receptors but only create a partial response
* buprenorphine
* butorphanol
Opioids
Antagonists
Binding to receptor does not cause response, but blocks effects of agonists
* naloxone
Morphine
- Opioid
- Stimulates vomiting centers
- Increases intraocular / cranial pressures
- Depresses RR, cough, and vascular tone
Fentanyl
- Opioid
- Potent and short-acting
- Dogs and Rabbits = bradycardia (fix with anticholinergics)
- Depresses RR and intracranial pressure
Methadone
- Opioid (synthetic)
- Used as analgesic and antitussive
- Preanesthetic in dogs and cats
- Less histamine release than morphine
Oxymorphone
- Opioid (semisynthetic)
- Analgesic - more potent than morphine
- Cannot be used with horses
- Does not suppress cough or depress RR
Hydromorphone
- Opioid
- Similar potency to oxymorphone
- Can combine with acepromazine or midazolam to increase sedation