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A/S - preanesthetics


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Why are preanesthetics used?
calm/sedate (smooth induction & recovery), reduce/eliminate adverse effects of general anesthetics, dec amt of general anesthetic required, decrease pain during & after sugery
What are anticholinergics used for?
decrease parasypathetic responses produced by anesthetic drugs
What is the autonomic nervous system?
Part of nervous system that controls involuntary bodily functions
What are the two division of the autonomic nervous system?
sympathetic and parasympathetic
Define synapse
space between nerve ending and receptor
Define receptor
site stimulated to respond when it recs neurotransmitter from nerve ending
Define neurotransmitter
chemical that is released from nerve ending & travels across synapse, stimulating receptor
Define parasympathetic nervous system
stimulation produces response for "all OK - relax" situations
Define sympathetic nervous system
stimulation produces responses for "fight or flight" situations
What is the neurotransmitter that stimulates parasympathetic responses?
What is the neurotransmitter that stimulates sympathetic responses?
What are some parasympathetic responses?
increased saliva & tear production, HR slows, pupils contract, blood pressure dec, bronchi constrict, incr GI motility & secretions
What are some sympathetic responses?
inc saliva & tear production, pupils dilate, inc HR, inc blood pressure, bronchi dilate, dec GI motility & secretions
What does suffix ergic mean?
does the work of, stimulates
What does the suffix mimetic mean?
mimics, has similar effect
What does the suffix lytic mean?
prevents, tears down the effects of
What are anticholineric drugs used for?
prevent hypersalivation, prevent bradycardia
What are two examples of anticholinergics?
Atropine and Glycopyrrolate
Atropine and Glycopyrrolate are what kind of drugs
Do anticholinergics have sedative effects?
Not at therapeutic doses
Atropine is derived from what deadly plant?
Is Atropine expensive?
No, cheap
What is the onset of Atropine SC? IM?
SC - 20 min, IM - 10-15 min
What is the duration of Atropine?
60 min after SC admin
What are some precautions w/ Atropine
Markedly reduces tear secretion (use artificial tears), avoid in pts w/ pre-ex rapid HR, produces thick mucous airway secretions, reduces GI activity, crosses placental barrier
What are some signs of Atropine overdose?
tachycardia, peripheral vasodilation, dry MM, thirst, hyperthermia, excitment, dilated pupils
Glycopyrrolate has effects similar to ___ but costs __, has ___ duration, milder effects, and does not cross the placental barrier
similar to Atropine but costs more, has longer duration (2-3 hrs), milder effects, and does not cross placental barrier
Why are sedatives/tranquilizers used?
calming effect, smooth induction & recovery, dec amt of general anesthetic reqd, prev excitatory of some anesthetics in some species
Define sedative
drug that causes reduced mental activity and sleepiness
Define tranquilizer
drug that reduces anxiety but does not necessarily decrease awareness & wakefulness
What effects do phenothiazines have?
sedation, antiemetic, antiarrhythmic, antihistamine, peripheral vasodilation, personality effects, penile prolapse, LACK OF ANALGESIA
What is an example of a phenothiazine drug?
Acepromazine is what kind of drug?
Is Ace a controlled drug?
How long is the sedation provided by Acepromazine given IM?
2-8 hours
What are some benefits of Acepromazine?
not controlled, long sedation effect, antiemetic, antiarrhythmic
Do phenothiazines (Acepromazine) provide analgesia?
What are some precautions w/ Acepromazine?
no analgesia, prolapse of third eyelid, vasodilation(avoid in hypotensive pts), lower seizure threshold
What is the onset of Acepromazine given IM?
15 mins
How can Ace be given?
IM, SC, Oral, IV - with caution
Acepromazine, Diazepam, Midazolam, Zolazepam, Xylazine, and Medetomidine are all what?
Diazepam, Midazolam, and Zolazepam are what kind of drug?
What are the advantages of Benzodiazepines?
antianxiety/calming effect, excellent muscle relaxation, anticonvulsant, minimal cardiac and respiratory depression
Name three Benzodiazepines
Diazepam, Midazolam, Zolazepam
Are Benzodiazepines controlled?
What is a precaution of Benzodiazepines?
may cause excitement when used alone
What is the most commonly used preanesthetic sedative in veterinary medicine?
What is the "big feature" of Diazepam?
prevents seizures
Diazepam is ___ sensitive
Diazepam is painful if given IM so it is usually given __ or ___
IV or orally
The only anesthetic agent that is physically compatible w/ Diazepam is ___
When drawing up Diazepam and Ketamine in the same syringe ___ is drawn up first. Why?
Diazepam - do not want to get Ketamine into anything!
Midazolam is expensive but is watersoluable so it can be administered ___.
Zolazepam is most commonly seen as part of TelazolĀ® - what is the other component?
Alpha 2 Agonists are also called what?
Thiazine derivatives
Thiazine derivatives are also called what?
Alpha 2 Agonists
What are 2 examples of Alpha 2 Agonists?
Xylazine & Medetomidine
Xylazine and Medetomidine are examples of what kind of drug?
Alpha 2 Agonists/thiazine derivatives
What are some advantages of Alpha 2 Agonists?
Potent sedation, good muscle relaxation, effective analgesia, reversible, and not controlled
Are Alpha 2 Agonists (xylazine & medetomidine) controlled?
Why are Alpha 2 Agonists only used in young, healthy patients?
Can have potent cardiovasular effects
Why is Atropine used w/ Alpha 2 Agonists?
prevent bradycardia
What are some other precautions of Alpha 2 Agonists (Xylazine & Medetomidine)?
can be absorbed through skin and MM, analgesia wears off before sedation, emesis in 50% of dogs and 90% of cats, poss bloat - avoid in GDV risk pt
What kind of drug causes emesis in 50% of dogs and 90% of cats?
Alpha 2 Agonists (Xylazine & Medetomidine)
What is the reversing agent for Xylazine? How is it administered?
Yohimbine, given IV
What are some contraindications for Alpha 2 Agonists?
pediatric, geriatric, pregnant, sick, diabetic, cardiovasular or resp dz, GI obstruction
How is Xylazine administered?
IM or IV
How long is the period of analgesia provided by Xylazine? The sedation?
20 minutes for anagesia, up to several hours for sedation
With Medetomidine there is a longer period of duration, but sudden ___ has been reported
What is the reversing agent for Medetomidine? How is is given?
Atipamezole, given IM
Reversing Alpha 2 Agonists do/do not reverse other drug that were given simultaneously
do not
When reversing an Alpha 2 Agonist, addtl pain med may be needed - why?
It is the Alpha 2 Agonist that is providing the analgesia in many cases - if reversed you need to administer something to take over that function
What are opioids derived from?
opium poppy
Opioids are a common component of preanesthetic protocols - why?
safe for high risk pts and provide excellent analgesia for painful surgeries
What are the most effective analgesics known?
An opioid mixed w/ a tranquilizer for arousable but profound sedation/analgesia is an example of what?
What are three common uses for opioids
preanesthetic, postoperative pain, and neuroleptanalgesia
What are some advantages of opioids?
most eff analgesia known, potent sedation, reversible, wide margin of safety
With opioids, they are given IV w/ caution in dogs, but you should avoid IV route in ___
What are the four types of opioid receptors?
Kappa, Mu, Sigma, Delta
What effects does the opioid receptor Kappa control?
Analgesia & cardiovascular stimulation
What effects does the opioid receptor Mu control?
Analgesia, euphoria, and CV depression
What effects does the opioid receptor Sigma control?
Analgesia & dysphoria
What effects does the opioid receptor Delta control
Analgesia & motor dysfunction
What do pure agonists do? Examples of?
Stimulate all 4 types of receptors - morphine, oxymorphone, fentanyl
What do mixed agonists do? Examples of?
Stimulate some types or receptors, block others - Butorphanol
What do pure antagonists do? Examples of?
Block all types of receptors - Nalaxone
What are some signs of opioid overdose?
Profound resp depression, bradycardia, extreme sedation or excitement, pinpoint pupils in dogs, dilated pupils in cats, facial swelling &/or hypotension due to histamine release excessive salivation
Are opioids controlled?
How is morphine administered?
SC, PO, slow IV (dogs only), IM
What is the duration of morphine?
about 2 hours
___ is the standard by which other opioids are compared
Is morphine expensive?
How is Oxymorphone administered?
IV, IM, SC(cats), epidural
Hydromorphone is more or less expensive than Morphine? Than Oxymorphone?
More expensive than Morphine but less expensive than Oxymorphone
What are some benefits of Oxymorphone over Morphine? Disadvantage?
Adv - longer duration (~4 hrs), more potent sedation & analgesia, fewer side effects
Disadv - more expensive
Hydromorphone is more/less potent than oxymorphone, more/less expensive, and has duration and side effects similar to morphine
slightly less potent, less expensive
Butorphanol provides minimal sedation, analgesia for ____ hours, has a __ safety index, but is ___
analgesia for 1-2 hours, high safety index, is expensive
How are opioid reversants administered?
IV, sublingual for neonates
The reversant Nalorphine is __% antagonistic
The reversant Naloxone is __% antagonistic
The opioid Fentanyl is administered how? For what?
By transdermal patch for postoperative pain

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