Injectable Anesthetics
Terms
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- What are the characteristics of an ideal injectable anesthetic?
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Rapid onset & recovery
Lack of tissue toxicity
Lack of adverse cardiovascular & respiratory effects
Rapid metabolism
Analgesia
skeletal muscle relaxation - What are barbiturates used for?
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sedation
general anesthesia
anticonvulsants
euthanasia - Do not barbiturates in what types of animals?
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Pregnant animals
Animals w/ cardiac disease
Hypoproteinemic animals
acidotic animals
shocky animals
Sighthounds (thiopental & pentobarbital - What barbiturates drug is short acting?
- Pentobarbital (Nembutal)
- What is the duration of Pentobarbital, a short acting drug?
- 30 minutes to 2 hours
- Which barbiturate drug has the slowest onset?
- Pentobarital (Nembutal)
- What are the side effects of Pentobarital?
- Rough (paddling and thrashing), prolonged recovery, which may take hours to days.
- What is pentobarital most commonly used for now.
- anticonvulsant or euthanasia
- Which barbiturate drug is ultra short-acting?
- Thiopental (Pentothal)
- What is the duration of Thiopental?
- 10-20 minutes
- What is the onset of action of Thiopental?
- 30-60 seconds
- How does recovery occur when using Thiopental?
- recovery occurs as the drug is redistributed to muscle and fat, followed by excretion via hepatic metabolism
- How long does recovery take when using Thiopental?
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1-2 hours
**recovery may be longer in sighthounds and thin, athletic drugs - Why do you bolus Thiopental 1/3 - 1/2 initial dose?
- Debilitated animals may only require 80%
- Don't use Thiopental on what type of animals?
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hypoproteinemic
acidotic - What Barbiturate drug is ultra short acting Methylated?
- Methohexital (Brevital)
- What is the duration of action of Methohexital?
- 5-10 minutes
- What is the onset of action of Methohexital?
- 15-60 seconds
- The recovery time of Methohexital is?
- 30 minutes
- What barbiturate drug is safe for sight hounds?
- Methohexital
- If Thiopental is a strongly alkaline solution is can cause what if injected perivascularly?
- severe tissue damage
- What happens in recovery when using Methohexital? What is recommended?
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excitement
recommend premedicate w/ sedative or tranquilizer - Why should you use Diazepam with Methohexital?
- may cause seizures in induction or recovery
- What drugs are the cyclohexamines?
- Phencyclidine, ketamine, tiletamine
- How do cyclohexamines work?
- They cause selective CNS stimulation
- What are the side effects of cyclohexamines?
- exaggerated reflexes - palpebral, pedal, corneal
- What type of drug has marked sensitivity to sound, light, and sensory stimuli?
- Cyclohexamines (ketamine, tiletamine)
- What is apneustic respiration and what type of drug can cause it?
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inspiration followed by a prolonged pause and short expiration.
Cyclohexamines (ketamine & tiletamine) - Why are cyclohexamines considered a heart supportive anesthetic?
- it does not depress cardiac rate or function
- Cyclohexamines has what type of analgesic effect?
- Analgesia to skin and limbs significant but visceral analgesia is poor (funky analgesic effect)
- Ketamine is primarily excreted through what in cats and dogs?
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kidneys in cats
liver in dogs - What is the onset of action of ketamine?
- 90 seconds IV
- Recovery from ketamine takes how long?
- 2-6 hours
- Why do dogs recover quicker than cats when using Ketamine?
- the hepatic metabolism in dogs is faster
- Why should ketamine be used in combination with a tranquilizer or sedative?
- aides in muscle relaxation and prevents excitement during recovery
- Why is ketamine/diazepam popular in cats and dogs?
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minimal cardiac depression
good muscle relaxation
superior recovery
less risk of seizure
some analgesia - Which drug causes less apneustic respiration than ketamine?
- Tiletamine
- What drug is only available with zolazepam in the drug Telazol?
- Tiletamine
- What is thed disadvantage of Tiletamine?
- long, difficult recoveries
- What is a neuroleptanalgesia?
- a combination of opioid and tranquilizing agent
- What is the advantage of a neuroleptanalgesia?
- reduces anesthetic dose needed
- What is Propofol used for?
- short procedures or anesthetic induction
- What is a disadvantage of Propofol?
- Expensive
- What drug has rapid onset but short duration of action?
- Propofol (Diprivan, Rapinovet)
- Why should Propofol be given slowly?
- can see apnea if injected rapidly IV
- What animals should Propofol not be used on?
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hypotensive
shocky
dehydrated
anemic - What is the greatest benefit of Propofol?
- smooth induction and recovery, free from excitement