Flashcards in Chpt. 3 - Key Points Deck (27):
What do preanesthetic agents do?
They reduce the required dose of general anesthetics, minimize adverse effects, ease induction and recovery, provide muscle relaxation, and reduce patient stress and discomfort.
What are atropine and glycopyrrolate used for?
Although they are not anesthetics, these anticholinergics are used to prevent bradycardia, bronchoconstriction, excessive salivation, and other parasympathetic effects.
These agents must be used sparingly, and with caution, as they can produce serious adverse side effects.
Name some tranquilizing agents.
- have a wide margin of safety
- may cause hypotension in some PTs
- have a calming effect on geriatric and debilitated animals
- excellent for prevention and Tx of seizures
e.g. Xylazine, Dexmedetomidine
- potent sedatives
- produce excellent muscle relaxation
- may cause serious CV and respiratory complications in some PTs
What may opioid agonists, partial agonists, and agonist-antagonists be used as?
They may be used as:
- preanesthetic agents
- neuroleptanalgesics (in combo w/tranquilizers)
- induction agents
Reversal for opiods
Reversal for alpha-2 agonists
Yohimbine (reverses Xylazine)
Atipamezole (reverses Dexmedetomidine)
Reversal for benzodiazepines
Are commonly used injectable and inhalation anesthetics safe?
They have a relatively good safety profile, but they also have the potential to produce significant CARDIOVASCULAR, RESPIRATORY, and THERMOREGULATORY SYSTEM DEPRESSION.
Name some injectable anesthetics.
*Dissociatives (Ketamine, Tiletamine)
*Barbiturates (Thiopental, Methohexital)
Barbiturates are divided into classes based on what?
Based on duration of action.
These classes differ in their lipid solubility, duration of effect, and distribution within the body.
Name the ultra-short-acting barbiturates
Thiopental (used for induction)
Methohexital (used for induction and maintenance)
Name the short-acting barbiturate
Pentobarbital (used to stop seizures and laboratory animal anesthesia)
Name the long-acting barbiturate
Phenobarbital (used for seizure control)
Contraindications/side effects of barbiturates
- Unusual potency in PTs that are acidotic, hypoproteinemic, or hypotensive
- may cause prolonged recoveries in sighthounds
How are most IV anesthetics administered?
By titration (or "to effect") to achieve the minimum effective dose.
How are injectable and inhalation anesthetics eliminated?
- by redistribution
- liver metabolism
- renal excretion
- primarily by exhalation from lungs
How do ketamine or tiletamine work?
Dissociatives such as ketamine and tiletamine produce a state of dissociative anesthesia characterized by
- intact reflexes
- CNS excitement
- apneustic respiration
- intact or increased muscle tone
**Concurrent use of a tranquilizer is recommended to promote muscle relaxation and to prevent excitement during recovery.**
A profound hypnotic state produced by the simultaneous administration of an opioid and a tranquilizer.
These agents provide relatively safe induction in debilitated PTs.
Name induction agents that can be given by repeat injection to maintain anesthesia.
Propofol, methohexital, and etomidate
What are the inhalation agents in common use?
Isoflurane and Sevoflurane
Both agents are administered by means of an anesthetic machine and either a mask or an endotracheal tube.
They are considered to have the greatest margin of safety and the shortest induction and recovery times.
How do inhalation anesthetics vary?
Inhalation anesthetic agents vary in their blood-gas partition coefficient, vapor pressure, and minimum alveolar concentration (MAC).
These properties affect the speed of induction and recovery, the type of vaporizer that should be used, and the vaporizer setting that is required for anesthetic induction and maintenance.
Side effects of inhalation anesthetics.
- Respiratory depression
- Decreased cardiac output
- Decreased blood pressure
(in addition, halothane may potentiate cardiac arrhythmias)
What can be given to hasten anesthetic recovery?
Reversal agents and analeptics