Flashcards in Pain and analgesia Deck (35):
What is the definition of pain?
An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage
What is adaptive and maladaptive pain?
Adaptive pain is protective, e.g. nociceptive pain or inflammatory pain
Maladaptive pain has no protective function, e.g. neuropathic pain
What is the definition of chronic pain?
Pain lasting longer than a month with a wide range of often subtle behavioral changes
What are the three processes in pain?
Nociception (sensory process by which a noxious stimulus is transmitted to the brain)
Perception (of noxious stimulus in the CNS
Behavioural response to pain (varies according to species) - important in assessing pain
What is hyperalgesia?
Pain sensitivity increases if noxious stimuli experienced repeatedly in a certain time period. Takes time after noxious even for pain sensitivity to return to the baseline. It will be elevated for a while
What are the implications of hyperalgesia in a clinical context?
Pain will be more severe
Analgesic drugs may be less effective if given once pain is present already
One type of analgesic drug may no longer be sufficient
How do we assess pain in animals?
Pain scoring systems available. Look at things like demeanour in kennel, response to exercise, behaviour, body language etc.
Want to be repeatable, simple, objjective
What are the two decent pain assessment systems in horses?
Composite orthopaedic pain scale (COPS)
Post Abdominal Surgery Pain Assessment Scale (PASPAS)
What is pre emptive analgesia?
Administration of analgesia drugs before the onset of noxious events (included in permed)
What are the benefits of using multi modal analgesia?
Better pain relief achieved, allows lower doses of each individual drug-reduces side effects
What are the 7 available systemic analgesia drugs/classes?
Oh No Kelly! Look At That Giraffe
Opioids, NSAIDs, Ketamine, Lidocaine, a2 agonists, tramadol, Gabapentin
What are the three classes.drugs used for local analgesia?
What is an opioid?
Any product natural or synthetic that binds to the opioid receptors and shares the properties of the naturall occuring endogenous opioids
What is an opiate?
Any naturally occuring opioid derived from opium (e.g. morphine, codeine)
What are the naturally occuring opioids?
Morphine & codeine
What are the semi-synthetic opioids?
Dihydromorphine, Diamorphine (heroin), hydro-morphine & Buprenorphine
What are the synthetic opioids?
What are the effects mediated by the delta opioid receptor?
Spinal and supraspinal analgesia
Reduced gastric motility
What are the effects mediated by the kappa opioid receptor?
What are the effects of the miu opioid receptor?
Sedation, analgesia, bradycardia, respiratory depression
What are the effects of NOP receptors?
What receptor do morphine, pethidine, methadone, fentanyl and buprenorphine all work at?
All are full agonists except buprenorphone which is partial
What receptor(s) does butorphanol work at?
agonist at kappa, antagonist at miu
What are the two opioid antagonist drugs?
Why should buprenorphine only be used for mild-moderate pain?
It is only a partial agonist of the miu receptor, cannot produce maximal effect
Which opioid can you not give IV?
Which species do opioids cause CNS depression in?
Dogs, monkeys and people
Which species do opioids cause CNS stimulation in?
cats, horses, ruminants
--> euphoria and dysphoria
What are the common side effects of opioids?
Vomiting and nausea due to stimulation of the CTZ (dogs mainly) - rarely if pain present
Variation in pupil size due to stimulation of oculomotor nuclei, NB not seen in cats as counteracted by circulating catecholamines
Thermoregulation - decrease in set point in dogs, panting seen. Can cause hyperthermia in cats, horses, pigs and ruminants due to increased muscle activity
Respiratory depression - miu mediated effect on respiratory centre, due to decreased responsiveness to CO2
Bradycardia-Vagal stimulation, responsive to anticholinergics. Pethidine is an exception
Which of the opioids does not cause bradycardia?
Pure agonists are schedule 2 controlled drugs and therefore..
Must be kept in a locked cupboard
Must be recorded when they are purchased and used
Must have a special prescription
Must be dosposed of according to legislation
Buprenorphine (partial agonist) is a schedule 3 drug and therefore..
Should be kept in a locked cupboard but no record of use necessary
Which opioid is currently exempt from legislation restrictions?
(probably why all the horse people like it so much!)
What receptor does Ketamine block?