Midterm Flashcards
What are the reasons for using preanesthetic drugs prior to induction?
Reduce anxiety.
Relieve pain.
Reduce dose of anesthetic.
Provide smooth induction.
What mechanism is responsible for bradycardia induced by pressure on the eye?
Oculocardiac reflex
Which mechanism is responsible for further decreases in HR when atropine is administered to treat bradycardia?
Stimulation of central vagal nucleus in medulla
Why can’t glycoperrolate diffuse across the blood brain barrier easily?
Large molecular size
Which species does atropine cause a significant decrease in GI and ruminal motility that can result in ileus and ruminal stasis?
Horses, ruminants
Which species is least resistant to atropine toxicity?
pigs
What kind of drug is Ace classified as?
major tranquilizer
What action is responsible for hypotension after admin of Ace?
alpha-1 blockade
What are the pharmacological effects of Ace?
Anti-emetic
Anti-arrythmic
Decreased seizure threshold
Anti-histaminic effect
What should be given to treat the severe hypotension that results from epinephrine reversal after giving Ace?
Phenylephrine
What drug causes permanent penile paralysis in horses?
Ace
What pre-existing conditions are contraindicated for Ace admin?
Seziure, hypovolemia, hypotension, excessive hemorrhage
Which class of drugs produces good analgesia and muscle relaxation
Alpha 2 agonists
Rank the alpha 2 agonists from high to low for alpha 2:alpha 1 selectivity.
- Medetomidine (most selective)
- Romifidine
- Detomidine
- Clonidine
- Xylazine (least selective)
Changes in arterial BP after admin of xylazine are characterized by a biphasic response that increases BP initially then secondarily decreases. What is the mechanism behind this?
Initial increase is a result of stimulation of POSTsynaptic alpha 2 receptors and secondary decrease is a result of stimulation of PREsynaptic alpha 2 receptors.
What drug ca cause vomiting in dogs and cats?
xylazine
What drug can cause a significant increase in urine output and therefore should be used with caution in patients with urethral obstruction?
xylazine
Which alpha 2 agonist is often preferred for standing dentals because it causes less ataxia and less lowering of head position during sedation?
Romifidine
Which alpga 2 agonist is preferred for diagnostic procedures like Rads or CT scans that requires deep sedation but not general anesthesia in dogs?
Medetomidine
Which alpha 2 agonist is most likely to cause premature parturition in pregnant ruminants during the last trimester?
xyalzine
Which alpha 2 antagonists can be given to reverse the effects of alpha 2 agonists?
Atipamazole, tolazoline, yohimbine
What species is more sensitive to tolazolines? (ie have to use lower dose)
camelids and ruminants
Which alpha 2 antagonist is more effect in antagonizing CNS depression from alpha 2 agonists?
Atipamazole
Central muscle relaxation is produced by transmission of what location?
Internuncial neurons in the spinal cord
Which drugs can produce central muscle relaxtion?
Diazepam, midazolam, guafinesin, xylazine
Transient hypotension can occur following rapid IV admin of diazepam because of _______ which is used as a vehicle to increase solubility of the drug.
propylene glycol
Which tranq has minimal CV effects and is often used as part of an anesthetic regimen in high risk animals?
Diazepam
What drug can be used to produce reliable sedation when other tranq of sedatives fail?
chloral hydrate
What drug relies on it’s metabolite to produce CNS effects?
chloral hydrate
What drug is often administered to produce tranquilization in viscous dogs?
Innovar Vet
What is the primary pharm effect of diazepam?
Anxiolytic effect
What reflexes can animals maintain during ketamine anesthesia?
Palpebral, corneal, swallowing
What injectable anesthetic is used for it’s minimal CV depression?
Etomidate
What anestheic can be administered as a CRI at a subanesthetic dose to produce long duration of anesthesia?
ketamine
What receptors are responsible for the analgesic effect produced by ketamine?
opiate receptors and NMDA receptors
What injectable anesthetic increases ICP and thus is not an ideal anesthetic for use in patients with pre-existing ICP?
ketamine
What drug produces central muscle relaxation and is often used in combo with ketamine to improve muscle relaxation?
xylazine
What mechanism does recovery from anesthesia depend on?
Redistribution to peripheral muscle and fat tissue
Telazol is a proprietary combo of ______ and _______.
Zolazepam and Tilatamine
What species experiences emergence hallucination or excitement during recovery when given telazol?
Horses
Regarding telazol, ______ lasts longer than ______ in dogs.
Tiletamine lasts longer than Zolazepam.
What anesthetic is often used in animals with severely compromised cardiac function?
Etomidate
Which anesthetic decreases cortisol secretion?
Etomidate
Propofol anesthesia is often accompanied by _______ _______ and ______.
Transient apnea, vasodilation
What is responsible for longer shelf life of propofol 28?
20 mg/mL benzyl alcohol
What occurs with guafenisin admin when 3-4xs appropriate dose is given in a short time period?
respiratory muscle paralysis
What barbituate is given to humanely euthanize animals?
pentobarbital
Why are local anesthetics less effective when injected into infected tissue?
More ionized form of local anesthetic in the infected area.
Concerning local anesethetics, which drug is more cardiotoxic between bupivicane, lidocaine, and mepivicane?
Bupivicane cardiotixicity»lidocaine and mepivicane
Rank local anesthetics based on duration of action from shortest to longest.
Lidocaine
- You are maintaining anesthesia on 20kg dog for spay. Iso is set to 2%. One hour of procedure notice that reservoir bag on circle system is deflated so you utilize O2 flush valve to refill reservoir. What effect can this have on inspired Iso concentration?
Will decrease it
An E tank has a pressure of 200 psi, how many liters of gas approximately does it contain?
70L
In the US, what color are medical air grade cylinders?
yellow
Storing a gas cylinder upright and unsecured constitutes risk of the cylinder becoming a ______.
missile
A modern Iso vaporizer is also compatible with which agents?
Nothing besides Iso, specific agents must be used
How is patient prevented from rebreathing CO2 when connected to a circle system?
Sodasorb scavenges CO2, valves prevent the patient from rebreathing CO2
What is an advantage of semi-open over semi-closed?
Less risk of mechanical failure
Which type of anesthesia breathing circuit would be most advantageous in a situation where there is limited supply of O2?
Closed
An activated charcoal canister used for active scavenging of inhalant anesthetics needs to be replaced when _____ changes.
weight
What are the benefits of using an endotracheal tube in an anesthetized patient?
Reduced risk of aspiration
Reduced risk of airway obstruction
Accuracy in monitoring expired CO2
What is the primary disadvantage of Sevo over Iso?
cost (sevo more expensive)
For maintenance of anesthesia, what advantages do inhalants have over injectables?
Safety, cost, rapid adjustment of effect
Based on blood:gas parturition coefficient, how do you determine which will give a more rapid induction?
Lowest blood:gas parturition coefficient will give most rapid (50:1 is faster than 2001:)
How is the amount of Sevo being given to a patient clinically measured?
Volume percent
Calculation question: Beginning anesthetic procedure with naïve machine…
- Circle breathing volume=6L
- Oxygen flowmeter set at 2L/min
- Iso vaporizer set at 1.5%
- How long till iso conc in circuit is 1.47%?
6L x 2L/min=3 min time constant
1.47%= about 4 time constants
4 TC x 3 min=12 minutes until Iso concentration is 1.47%
Calculation question: Administering anesthesia for 2 hr procedure…
- Breathing circuit volume=5L
- Oxygen flowmeter=0.5L/min
- Iso vaporizer=2%
- At the end of the procedure you turn of the vaporizer and inc fresh gas flow to 5L/min. What is inhalant conc one minute after you make the adjustment?
2% vaporizer turned down to 0%, so 2-0=difference of 2
Find new time constant:
5L/5L/min=1 min, new TC which is 63% change in concentration
Asking for concentration after 1 min, which is one time constant.
So multiply 2 x 0.63=1.26% CHANGE, so have to subtract this from original concentration.
2-1.26=0.74% for concentration after ONE MINUTE.
Calculation question: Administering anesthesia for 2 hr spay
- Breathing circuit volume=5L
- Oxygen flowmeter=0.5L/min
- Iso vaporizer=1%
- After uterus has been removed, you inc vaporizer to 2% to facilitate muscle relaxation. How long before patient is inspiring ~2% iso?
5L volume x 0.5L/min=10 min time constant
10 min x 4 TC=40 minutes until it’s at 2%
What is included in capacity volume when predicting the time constant?
Vaporizer voume, patient tidal volume (sodasorb canister volume NOT included)
True/False: Uptake of volatile anesthetics by muscle is a beneficial effect.
False
What causes a patient with rapid, shallow breathing pattern to take longer to induce on Sevo than a patient with a normal breathing pattern?
Decreased depth of breath.
What subset of the population has been shown to be at increased risk to developing health problems due to exposure of waste anestethic gases?
NONE (not even pregnant ladies)
MAC is a standard _______ of ______.
Index of potency
MAC represents what portion of a population?
ED50
How can you reduce MAC?
Administer analgesics
True/False: MAC is inconsistent between species.
False
What is the MAC of Iso and Sevo in a dog?
Iso=1.3-1.6
Sevo=2.3-2.6
What characteristics will decrease the MAC of an inhalant?
Pregnancy
Hypothermia
Very old patient
Ace as a premed
What is the mechanism of inhalant anesthetics?
Not fully understood
What process results in action potential being created by a nociceptor?
Transduction
What pain fiber is responsible for transmission of slow, generalized, persistent nociception?
C fiber
What is the gold standard for assessing pain?
NONE
3 y/o MN lab returns for recheck for a recheck 6 mo after uncomplicated repair of tibial fracture. The fracture healed completely but the o reports that p still appears painful. During PE the patient screams when you pull at his hair on the affected limb. You hospitalize him and put him on CRI of fentanyl. After 24 hours the patient shows no signs of improvement. His signs are consistent with what type of pain?
Neuropathic pain
Modulation of the afferent pain input occurs where?
Spinal cord
What are the two main effects of eicosanoids on the peripheral tissue as related to the production of pain?
Sensitization of pain receptors
Vasodilation
What is labeled with peri-operative use in cats?
Robenacoxib
What drug is contraindicated for pre-op admin in the following situations:
- ->6 year old female spayed cocker spaniel presented for cutaneous mass removal. Patient has hx of immune modulated thrombocytopenia and has platelet count of 50,000 (low)
- ->11 year old DSH cat presenting for dental and extractions. Patient has 1 year hx of chronic RENAL FAILURE managed with diet and SQF. Patient is approx 7% DEHYDRATED at presentation.
NSAIDs
What NSAIDs inhibit the COX 1 enzyme?
phenylbutazone, flunixin, carprofen (all NSAIDs inhibit COX 1)
What does NOT describe the effects of eicosanoids in the CNS?
increases glutamine activity
it DOES increase Ca activity and activate microglia
What is butorphanol classified as?
Mu antagonist, Kappa agonist
What is the decreasing order of onset (slowest to fast)?
Hydropmorphone, remifentanil, morphine, fentanyl
Morphine–>hydromorphine–>fentanyl–>remifentanil
You have anesthetized a 1 year old female mixed breed canine for an OHE. As the surgeon breaks the suspensory lig the patient shows signs of nociceptive stimulation. You decide to treat with a rapid bolus of morphine given IV. The next vital sign readings show the patient has signs of low BP accompanied by a rapid HR. What is the most likely cause of this low BP?
Histamine release
What opioid receptors produce analgesia when stimulated?
Mu, Kappa
Opioids produce their analgesic effects at what step of the pain pathway?
Modulation
What are five disadvantages of NMBA blocking agents
Mechanical ventilation Monitoring Uncertainty of duration Residual weakness side effects
True/False: One of the side effects of Atracurium is myalgia.
False
How do edrophonium, neostigmin, and pyridostigmine antagonize the effects of NMDA?
Increases the level of chemical messenger (Ach) in the neuromuscular junction
What is the most commonly seen clinical side effect from admin of Neostigmine?
Bradycardia
What amount of nicotinic receptors need to be blocked by NMDA before a reduction in twitch strength is noted by peripheral nerve stimulation?
75%
Where is legal guidance for appropriate means of euthanasia documented?
State Practice Act
What can be used BY ITSELF to confirm death after euthanasia?
Rigor mortis
You perform an OVE on a bitch 55 days into gestation. Is it AVMA panel on euthanasia recommendation that you inject each fetus in the removed uterus with pentobarb to insure there is no suffering?
NO, false
What are acceptable causes of death following euthanasia?
Direct hypoxia
Indirect hypoxia
Chemical depression of neurons
Physical destruction of the brain
