Lec.3 Preanesthetic Flashcards
How do premedication drugs affect the amount of anesthetics required?
They decrease the amount of injectable and inhalant anesthetics required.
What is the primary purpose of administering premedication drugs in anesthesia?
To minimize patient stress and anxiety, facilitate restraint, and enhance the safety of the patient and staff.
What benefit do premedication drugs provide during the transition between anesthetic phases?
They facilitate a smooth transition between anesthetic phases and improve cardiopulmonary stability.
What are phenothiazine derivatives classified as in the context of preanesthetic drugs?
Phenothiazine derivatives are classified as major tranquilizers and antipsychotic drugs (or neuroleptics).
What effects do phenothiazine derivatives have due to their action as dopamine antagonists?
- Calming effects
- Mood-altering (antipsychotic) effects
- Powerful antiemetic action, particularly against opioid-induced vomiting.
How does the degree of sedation produced by phenothiazine derivatives vary?
The degree of sedation produced varies between different phenothiazine drugs.
What is the primary mechanism of action of phenothiazine derivatives?
Phenothiazine derivatives act as dopamine antagonists and also block α1-adrenoceptors.
What is a potential risk associated with long-term dosage of phenothiazine derivatives?
Long-term dosage can lead to liver damage.
What are the major cardiovascular side effects of phenothiazines?
- Fall in arterial blood pressure due to peripheral vasodilatation
- Decrease in packed cell volume caused by splenic dilation.
What antiarrhythmic effect do phenothiazines exert on the heart?
Phenothiazines exert an antiarrhythmic effect on the heart that may be caused by a blocking action on the cardiac α - arrhythmic receptors.
What is the current understanding of the antiarrhythmic effect of phenothiazines?
Phenothiazines exert an antiarrhythmic effect on the heart, which may be due to a blocking action on cardiac α-arrhythmic receptors rather than a quinidine-like action.
What are the CNS effects of certain preanesthetic drugs?
- Induce CNS depression by affecting various brain structures
- Lack generalized hypnotic effect
- Do not produce analgesia
- Act as anti-emetic
- Can lower seizure threshold.
What is the effect of combining phenothiazines with opioids and hypnotics?
When combined with opioids and hypnotics, phenothiazines have an additive effect, which may lead to respiratory depression.
What happens to ventilation when large doses of phenothiazines are administered?
Large doses of phenothiazines can depress ventilation.
What are the respiratory effects of phenothiazines at therapeutic doses?
At therapeutic doses, phenothiazines have negligible respiratory effects.
What are some physiological effects of certain preanesthetic medications?
- Skeletal muscle relaxation
- Delayed gastric emptying with spasmolytic action on the gut
- Decreased body temperature
- Some anticholinergic activity.
Which preanesthetic medications exhibit anticholinergic activity?
- Acepromazine
- Promazine
- Chlorpromazine
- Propiopromazine
- Triflupromazine.
What is Acepromazine and how is it prepared?
Acepromazine is prepared as the maleate, a yellow crystalline solid.
For how long has Acepromazine been available and what are its uses in veterinary medicine?
Acepromazine has been available for over 50 years and is widely used in veterinary medicine for sedation, premedication, and non-anesthetic related indications.
How is Acepromazine metabolized and excreted?
Acepromazine is metabolized in the liver, and both conjugated and non-conjugated metabolites are excreted in the urine, with some detectable for a considerable period.
What protective effect does preanesthetic medication have against epinephrine?
It has antiarrhythmic effects and protects against epinephrine-induced fibrillation.
How does premedication affect the incidence of death associated with anesthesia and surgery in horses?
It significantly reduces the incidence of death associated with anesthesia and surgery.
What is the impact of premedication on anesthetic-related deaths in dogs?
Its use significantly reduces anesthetic-related deaths when compared with no premedication.
What potential risk does Acepromazine pose to horses during sedation?
Acepromazine poses a risk of physical damage to the dangling penis in horses.
How does Acepromazine affect the retractor penis muscle in bulls and stallions?
Acepromazine causes paralysis of the retractor penis muscle and protrusion of the flaccid penis from the prepuce.
What cardiovascular effect does Acepromazine cause in horses?
Acepromazine causes tachycardia in horses.
What is the effect of Acepromazine on ventilation in horses?
Acepromazine has little effects on ventilation in horses.
Why is Acepromazine often administered to bulls and stallions?
Acepromazine is often given to facilitate examination of the penis.
Can Acepromazine be used in conjunction with local anesthesia in ruminants?
Yes, Acepromazine can be used with local anesthesia in ruminants.
Why should Acepromazine not be given to ruminants if general anesthesia is to be administered?
Acepromazine relaxes the gastroesophageal junction, increasing the risk of regurgitation of ruminal content during induction and causing delayed recovery.
Why should acepromazine not be used in dogs with epilepsy?
Acepromazine might reduce the threshold at which epileptiform seizures occur.
What is a potential use of very small doses of acepromazine in dogs and cats?
Very small doses of acepromazine have been used to treat behavioral problems, such as anxiety and noise phobias.
What is a notable effect of Chlorpromazine hydrochloride?
Chlorpromazine hydrochloride has a potent antihistaminic effect and its effects may last for 24 to 47 hours.
What is Propionyl promazine used for in veterinary medicine?
Propionyl promazine is used in combination with methadone for general sedation of all species of animals.
How do benzodiazepines achieve muscle relaxation?
Benzodiazepines achieve muscle relaxation through inhibition of the internuncial neurons at spinal levels.
What is the primary mechanism through which benzodiazepine compounds exert their sedative effects?
Benzodiazepine compounds exert their main sedative effects through depression of the limbic system.
At which receptors do benzodiazepines act selectively within the central nervous system?
Benzodiazepines act selectively at GABAA receptors within the central nervous system.
What is a notable characteristic of benzodiazepines regarding their effects on the cardiovascular and respiratory systems?
Benzodiazepines have minimum adverse effects on the cardiovascular and respiratory systems at therapeutic doses.
What are the primary actions provided by benzodiazepines?
- Antianxiety action
- Sedation and hypnosis
- Anticonvulsant effects
- Muscle relaxation
- Anterograde amnesia.
Can you name two examples of benzodiazepines?
- Diazepam
- Midazolam.
Which benzodiazepines are most commonly used as agonists in veterinary practice?
- Diazepam
- Midazolam
- Zolazepam.
What is the function of Flumazenil (Romazicon) in veterinary practice?
Flumazenil (Romazicon) is a benzodiazepine antagonist that works by competing for benzodiazepine inhibitory receptor sites.
What are the potential cardiovascular effects of rapid infusion of Diazepam due to propylene glycol?
- Hypotension
- Bradycardia
- Apnea.
What is a unique absorption characteristic of Diazepam?
Diazepam is absorbed by the plastic of the container it is stored in, which can lead to reduced efficacy if stored improperly.
Which drugs should not be mixed in a single syringe with Diazepam due to the risk of precipitation?
- Atropine
- Acepromazine
- Barbiturates
- Opioids.
What is the solubility characteristic of Diazepam and what is used to increase its solubility?
Diazepam is insoluble in water and requires propylene glycol to increase its solubility.
Can Ketamine be mixed with Diazepam in a single syringe?
Yes, Ketamine can be mixed with Diazepam in a single syringe.
What is the recommended dosage of Diazepam for dogs and cats?
0.2 - 1 mg/kg IV or SQ in dogs and cats.
How does the sedative effect of phenothiazines vary among individuals?
The sedative effect of phenothiazines varies considerably among individuals; it may produce calming effects in animals, but paradoxical excitement is also a possibility.
What is the effect of phenothiazines on anxiety?
Phenothiazines reduce anxiety without marked sedation.
What effect do phenothiazines have on memory in humans?
Phenothiazines produce amnesia in humans.
What parts of the brain do phenothiazines primarily work on?
- Limbic system
- Thalamus
- Hypothalamus.
What are the cardiopulmonary effects of diazepam at clinical doses?
At clinical doses, minimal cardiopulmonary effects prevail.
What can high IV doses of diazepam produce?
High IV doses may produce respiratory depression and decrease blood pressure.
What percentage of diazepam is protein bound?
Up to 96% of diazepam is protein bound.
What is the typical dosage range of Midazolam for dogs and cats?
0.1 – 0.5 mg/kg in dogs and cats.
How does the potency of Midazolam compare to Diazepam?
Midazolam is 2 - 5 times more potent than diazepam.
Why is Midazolam well absorbed from IM or SC injections?
Due to its good water solubility.
Is Midazolam physically compatible with many other solutions?
Yes, it is physically compatible with many other solutions.
What is a key physiochemical characteristic of Midazolam?
Midazolam is water soluble.
What is the clinical duration of midazolam compared to diazepam?
The clinical duration of midazolam is shorter than that of diazepam.
What are the cardiopulmonary effects of midazolam compared to diazepam?
Midazolam has similar cardiopulmonary effects to diazepam with minimum alteration, but it may be more respiratory depressant than diazepam.
How predictable is the onset of clinical effects for midazolam?
The onset of clinical effects for midazolam is more predictable than that of diazepam.
How does the metabolism and excretion of midazolam compare to diazepam?
The metabolism and excretion of midazolam is similar to that of diazepam.
What is Zolazepam used in combination with for its administration?
Zolazepam is used in combination with tiletamine in Telazol.
For what type of patients is the use of zolazepam and tiletamine popular?
Their use is popular for exotic patients.
What is the composition of each vial of Telazol?
Each vial contains 250 mg of zolazepam and 250 mg of tiletamine.
