Anesthesiology - Quiz 1-3

drraythe's version from 2016-02-23 00:04

Opioids (basics)

Question Answer
Do opioids provide analgesia?OH YESSSS they are the GOLD STANDARD of analgesia!
Explain Opiate vs OpioidOPIATE: Naturally occurring opium derivative, like Morphine (I ATE the poppy)
OPIOID: Natural or synthetic compound binding to opioid receptors
The μ (mu) receptor (aka OP_?) has what effects when activated?(OP3) *This is the strongest & most important receptor.
It results in:
Resp depression
Inhibition of gut motility
(AMERIca has the highest % of opiod addiction)
The κ (kappa) receptor (aka OP_?) has what effects when activated?(OP2)
*Less powerful than the mu receptors
The δ (delta) receptor (aka OP_?) has what effects when activated?(OP1)
Resp depression
*Least important receptors
Where do the opioid receptors (mu, kappa, delta) live in the body?Brain
Spinal cord
Peripheral tissues
Nerve terminals (joints, cornea...)
... there is species variation tho
List some of the opiates in order of analgesic potency (This was in a chart, not sure how important)(Least) Meperidine < Butorphanol < Morphine/Methadone < Hydromorphone/Oxymorphone < Buprenorphine < Fentanyl (Most) (Metallic Blue MerMaids Hump Orange Bouys Faster)
Do opiates provide sedation?Mild sedation in dogs... BUT! excitement/ ↑ locomotor activity in cats & horses
How do opioids affect body temperature?There can be hypERthermia in cats & horses (HypOthermia in dogs)
Do opiates cz emesis or anti-emesis?Emesis
Which opiates can be used as antitussives?Codeine, Butorphanol (weak ones - horse w/ a cough)
How do opiates affect the resp. system?Dose dependent resp. depression
How do opiates affect the CV system?MINIMAL effects on CV system! It will ↓ HR w/ high doses tho (↓ sympathetic tone)
How are histamine & opioids related? (Explain what happens)Morphine & Meperidine IV cz a histamine release, which leads to hypOtension & reflex tachycardia
What are the GI effects of opioids? (spp diffs)Small animals: Nausea & vomiting
Large animals: ↓ in GI motility, (Ileus & colic in horses, ruminal atony in ruminants)
(both in humans!)
Which opioids are MOST LIKELY to cz emesis?Morphine - Chemoreceptive trigger zone affected. Route of admin plays a role - IV usually worse than IM
What is the therapeutic window like for opioids? (sp diffs)In DOGS there is a LARGE therapeutic window
In HORSES/CATs there is a SMALL therapeutic window
Mu receptor, full agonists → (read the) list (of) these(Basically the ones she cared about)
Meperidine (Pethidine)
Mu receptor full agonists → what is their affinity? Intrinsic activity? Does effect depend on dose? What schedule are they?HIGH affinity & intrinsic activity, they are dose dependent & schedule II drugs
2 super awesome reasons we like to use opioids(1) Reduce amount of anesthetic needed to maintain better CV fxn
(2) They provide WIND UP/ CENTRAL SENSITIZATION (remember, they dont perceive pain during anesthesia but they can still nocicept, which remodels pain perception in the CNS which will lead to ↑ pain perception while awake)
Explain why pregnancy/babies & opioid use is trickyCan cross placental barrier & cz resp. depression in newborn if used for C-section. Also can go into milk to cz problems like 'failure to thrive'
Do opiates cz miosis or mydriasis?Miosis (Except in cats then it czs Mydriasis)

Opioids: Specific drugs, Neuroleptoanalgesia

Question Answer
What are Morphine’s metabolites like?Active metabolite (M-6 glucuronide)
Does Morphine cz emesis?Yes! (So does Hydrocodone & Oxycodone)
What should you be careful about when administering Morphine via IV?Rapid IV injxn can lead to histamine release (hypotension, reflex tachycardia) (Morphine & Meperidine are the histamine ones... Marilyn Manson & the HISTAMINE band)
How do cats handle Morphine in their system?There is slow elimination & euphoria in cats (they cant glucoronidate so it takes longer) (cats make the worse kinda Morphine addicts)
Is Methadone synthetic or natural? What is the analgesia like that it provides?Synthetic. Its analgesia is similar to Morphine, BUT it has the additional analgesic mechanism of NMDA antagonism (good for producing analgesia also) (which is why methheads are still crazy on it :P)
Is Meperidine (Pethidine) natural or synthetic? How long is it effective for? What other effects does it have? How do you administer it?Synthetic, short acting (1hr), w/ a mild anticholinergic effect. DO NOT GIVE IV → HISTAMINE RELEASE (remember-Marilyn Manson & the Histamine band) (not really her 1st choice, she said) (this will MEP the floor w/ your shocked out cholinergically depleted body)
Is Fentanyl natural or synthetic? How strong is it? How long is it effective for? What are the uses for it?Synthetic. VERY potent, also fast & short acting (20min!!). Can use as CRI, intraoperative bolus, rapid onset sedative IV or IM, "Rapid sequence" induction. Can also use as patches!!
Fentanyl patches → what are the average doses? Who can you use it on? List some pros & cons12.5-100 micrograms per hour. Avail for dogs, cats, horses & sheep
PROS: LONG duration (2-3 days) & useful in practice
CONS: Variable time till onset (several hours)
Variable plasma concentration (unreliable)
Poor alternative to opioid CRI
Potential for abuse
Remifentanil → what is the potency like? What is onset like? How long is it effective for? How is it metabolized? What is something it's useful for?Potency similar to Fentanyl (effin strong), w/ a rapid onset. It is ULTRA SHORT ACTING! 3-4minutes which means you must give CRI. It also has a UNIQUE metabolism by plasma esterases*****NOT BY THE LIVER!!!**** So it is AWESOME for intraoperative use in PTx w/ liver dz. (*BE SURE to administer posteroperative analgesics on time!)
Which opioid is awesome for liver PTx??Remifentanil
Which receptor does Buprenorphine work on? What is its affinity & intrinsic activity for it?PARTIAL Mu agonist w/ high affinity & low intrinsic activity (high affinity → slow disassociation from receptor)
What is onset of action like for Buprenorphine? What is duration of action like?SLOW onset of action (20-45min)
LONG duration of action (4-6hr)
Longest duration opioid?Buprenorphine (lol longcat is long)
This opioid can be given orally for mucosal absorption in catsBuprenorphine
What is the analgesia like for Buprenorphine? Side effects? What schedule is it?MODERATE analgesia (it's only a partial mu agonist) so only use for moderate pain, it has minimal side effects & is a schedule III drug
What receptors does Butorphanol work on? What is it's analgesia like? Duration? Side effect?Mu ANTAGONIST, KAPPA AGONIST. Bc of this, it is only a weak analgesic. The duration is 2-3h. However, this also means minimal side effects
How is Butorphanol as a sedative? Can it be used for anything else? What schedule is it?Great sedation, good antitussive, mu antagonist. It is a schedule IV drug
What are the complete opioid antagonists? How long do they last?Naloxone & Naltrexone. Short duration of action.
What is the partial opioid antagonist? Why might you wanna use a partial?Butorphanol (mu antagonist, kappa agonist)...useful bc if you fully antagonize all the opioid, you also get rid of all the analgesic effects, so they is good for just a teensey weensie OD
What are the most commonly used opioids in horses?#1 is Butorphanol! (Registered for use & less side effects). You can also use Morphine, Meperidine & Methadone (mmm, horse butt)
What does neuroleptoanalgesia mean youre giving?HUMANS: A neurolept (which is a Phenothiazine or a Butyrophenones along w/ an opioid)
ANIMALS: Any sedative + opioid
What is neuroleptoanalgesia used for in vet med?Preanesthetic med (such as Acepromazine+Morphine) & for restraint for minor procedures

Injectables: Intro+Barbiturates

Question Answer
Principal disadvantage of injectables?If administered, CANT BE CONTROLLED & are NOT IMMEDIATELY eliminated (once it is in there, you can't take it out!)
Dosing → what do you do for obese PTx?Calculate dose for ideal weight!
Dosing → what do you do for PTx in shock?They have reduced CO & centralization of blood, so SLOWLY TITRATE TO EFFECT & reduce dose
The ideal IV anesthetic will have high or low lipid solubility?HIGH! THE BRAIN IS MADE OF FAT!
Do you want active metabolites in an IV anesthetic?No, or it can build up in system
Which Barbiturate is ULTRA SHORT ACTING???Thiopental (Theo is not so great in bed, then...)
What is the short acting Barbiturate used for euthanasia?Pentobarbital
What is the long acting Barbiturate used as an anticonvulsant?Phenobarbital
Big caution w/ Thiopentone/Thiopental? What’s something you really should do if you inject Thiopental?If extravascular, NASTY TISSUE NECROSIS & SLOUGHING!! (It is very alkaline) You should ALWAYS flush w/ saline BEFORE & AFTER you admin
Thiopental comes as a yellow crystalline powder. What should & shouldn't you do in order to make it ready for administration? How good is it after you reconstitute it? How do you know when it isnt good anymore?Reconstitute w/ sterile water. DO NOT use LRS! IT PRECIPITATES OUT OF LRS!! prepared solution stable for approximately 1 week. If solution becomes turbid, it's lost its efficacy.
What is the plasma protein binding like for Thiopental? Where is it metabolized? Excreted?65-85% plasma protein bound (considered highly protein bound)
Metabolized in the liver (slow metabolism, even tho ultra-short acting)
Excreted in the urine
What should you know about repeated injxns of Thiopental?After repeated injxns, metabolism follows zero-order kinetics, which means there will be a prolonged recovery
What is the MOA for Thiopental??GABA-A agonism
Cl-ion channel → increasing the duration of the Cl-ion channel gate being open!
(Theo stands in the door holding it open the whole time)
How long will a single dose of Thiopental induce general anesthesia?5-10min
How does Thiopental affect the resp system? CV system?Depresses resp. system & ↓ CO & czs hypOtension. Also czs tachyarrythmias (VENTRICULAR BIGEMINY!)
Which Barbiturate can cz ventricular bigemeny, a special kind of tachyarrhythmia?THIOPENTAL (there is an example in the notes)
What are some of the CNS effects of Thiopental?Antiepileptic, neuroprotective
Species differences w/ anesthesia induction w/ Thiopental? (Any notes about admin in horses?)Can use as anesthesia induction in small animals, in horses can be used as anesthesia induction when in combination w/ Guaifenesin. When using as maintenance in horses, do bolus admin
Thiopental → what percent solution is used in small animals? Large animals?SM: 1.25%-2.5% solution
LG: 5-10% solution
*How do you administer Thiopental?Only use w/ IV catheter!! CHECK CATHETER BEFORE INJXN, Flush w/ saline before & after injxn.
If you perivascularly administer Thiopental what should you do?Inject the area w/ saline or lidocaine to dilute it (massage in)
Cooling in the local area affected
Possibly parenteral NSAIDs
What is the dose of Thiopental in small animals? How do you administer it?Dose is approx. 10mg/kg. You administer a 3rd to a 1/2 of the dose, wait for effect & then give the rest to effect... FLUSH CATHETER BEFORE & AFTER INJXN
What are the 6 contraindications of Thiopental?(1) PTx w/ hepatic dz
(2) Neonatal PTxs
(3) Greyhounds
(4) Cachexic PTx
(5) Cesarean section (any preggo animal really)
(6) Splenectomy (barbiturate congestion)
Why can't you give Thiopental to a PTx w/ hepatic dz?Metabolism is in the liver & the metabolism is slow
Why can't you give Thiopental to greyhounds?They have a defect in their metabolic pathways, their low % body fat affects their redistribution & they have an extremely long recovery bc of this
Why can't you give Thiopental to a cachexic PTx?No fat to redistribute to → higher plasma levels → higher risk of OD → higher risk of DEATH
Why can't you use Thiopental for performing a cesarean section?Mortality in fetus
Why can't you use Thiopental for anesthesia when you are doing a splenectomy?Barbiturates cz splenic relaxation & congestion, making the procedure more difficult. (When ppl say "Barbiturate effect" or "Barbiturate congestion" this is what they mean)
6 quick n dirty things you need to know about ThiopentalFast acting induction agent
Accumulation (slow hepatic metabolism)
MUST use IV catheter
Respiratory depression
Arrhythmias (ventricular bigeminy)
Avoid in hepatic dz PTxs & greyhounds
Does Thiopental provide analgesia?NO!!!!
How is duration of action affected in the body, for Thiopental?Thio is redistributed to fat, which limits the duration of action. This means it can also accumulate in fat w/ repeated admin & lead to prolonged recoveries
(In long notes) How do you treat Barbiturate overdose?Artificial ventilation (bc resp depression)
Maintain body temperature
Try not to have the body stagnate in any 1 position for too long (move every 2hr)
↑ excretion in urine via alkalinizing urine w/ bicarb (carefully) (thio is very alkaline so I'm not sure how this helps, but w/e)