analgesia Flashcards
pain elicits…
protective motor action (biting), learned avoidance (fear), modifies species behavior (hiding)
untreated pain can effect…
heavior, psychology, metabolism, immune system
nociception
detection by the nervous system for potential tissue injury, protects animal from painful or noxious stimuli
physiological pain
ouch pain, little or no tissue injury, protects from injury
pathological pain
follows tissue injury, no useful function, causes suffering, acute or chronic
classification based on mechanism
inflammatory, neuropathic, cancer, idiopathic
classification based on origin
visceral (organ) or somatic (musculoskeletal)
classification based on severity
none, mild, moderate, severe
pain pathway step 1
transduction: transformation of stimuli into sensory electrical signals (action potentials)
pain pathway step 2
transmission: sensory impulses conducted to spinal cord
pain pathway step 3
modulation: impulses are either amplified or suppressed
pain pathway step 4
perception: impulses are transmitted to brain where they are processed or recognized
multimodal therapy
targeting two or more receptors
consequences of untreated pain
catabolism and muscle wasting, immune system suppression, inflammation and delayed wound healing, anesthetic risk, patient suffering
peripheral hypersensitivity
area around primary wound is sensitive and painful
secondary hyperalgesia
central nervous system hypersensitivity or windup, area of sensitivity is further away from site of tissue injury
neuroendocrine changes
can results in catabolic state and wasting, ACTH release, elevated cortisol, norepi, and epi, decreased insulin
sympathetic stimulation
can result in cardiac arrhythmias, vasoconstriction, increased myocardial work, increased O2 consumption
preemptive analgesia
administering meds before the pain, reduces requirements of analgesia and duration, prevents windup
behavioral responses
cats hide, dogs seeks owner comfort, herd animals separate themselves
physical evidence in pain
changes in gait, level of activity, reluctant to lie down, shifting position, vocalization (growl, howl, whine, hiss, groan), changes in facial expression
visual analog scales
left = pain
right= severe pain
with effective analgesia…
pain-associated behaviors with decrease and pain score will decrease
preemptive analgesia
pre op with pre meds, administered with anesthetic agents, fentanyl patch, NSAIDS
multimodal therapy
use of one or more drugs to control pain, cover multiple receptors, reduce dose of individual drugs
analgesia is needed at…
every stage of hospitalization and treatment
choice of drug depends on…
severity of pain, P general condition, route of delivery
using opioids as analgesics
often combined with tranquilizer, good for windup pain, not good for post op pain
sedatives and antianxiety drugs can cause _____ in horses and cats
excitement
post op opioids can be used
alone or with other drugs
opioids are metabolized in the
liver
morphine is used for…
moderate to severe visceral and somatic pain (pure agonists)
morphine is a schedule
II
side effects of morphine
GI stim in dogs and cats, colic in horses, miosis and hypothermia in dogs, mydriasis and hyperthermia in cats, bradycardia, ^ IOP, urine retention
oxymorphone
pure opioid antagonist, greater analgesic property and sedative effect than morphine, fewer side effects
what schedule is oxymorphone
II
hydromorphone
opioid agonist, less potency but similar duration to oxymorphone
hydromorphone schedule
II
methadone
synthetic opioid, similar to oxymorphone and hydromorphone, least likely to cause vomiting in cats and dogs
fentanyl
most potent analgesics known, rapid onset and short duration
fentanyl schedule
II
meperidine/pethidine
pure opioid agonist with less potent analgesic properties and shorter duration, wide margin of safety, used with NSAIDS for analgesia
meperidine/pethidine schedule
II
butorphanol
opioid agonist-antagonist, stims kappa receptors and blocks mu receptors, not as effective as pure agonists, less sedation, dysphoria, and resp depression
butorphanol can be used to reverse the effects of…
morphine and fentanyl
butorphanol schedule
IV
buprenorphine
partial agonist, produces some analgesia for mild to moderate pain, delayed onset of action and longer duration of action
buprenorphine schedule
III
