Injectable general anesthetics cont. + Preanesthetic medications Flashcards Preview

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Flashcards in Injectable general anesthetics cont. + Preanesthetic medications Deck (18)
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1
Q

What is propofol

A

• an intravenous anesthetic used for induction and maintenance of anesthesia
Popular in veterinary
medicine due to its smooth induction and recovery.

2
Q

Mechanism of action of propofol

A

• effect on the inhibitory GABA receptor - ↓the rate of GABA dissociation from
its receptors - ↑ opening of chloride channels - hyperpolarization of postsynaptic cell membranes and inhibition of the postsynaptic neurons - hypnosis and amnesia.

3
Q

Propofol indications

A
  • induction of general anesthesia (followed with inhal. anesthesia)
  • maintenance of anesthesia (via CRI)
  • short-term sedation, long-term sedation (e.g., ventilator patients),
  • treatment of status epilepticus
  • used almost exclusively in small animals for economic reasons
4
Q

Effect of propofol on the muscles

A

Excellent muscle relaxation

5
Q

Proposal and analgesia

A

Does not provide analgesia

6
Q

Name the 2 dissociative anesthetics

A

Ketamine and Tiletamine

7
Q

What are dissociative anesthetics

A

• have been extensively used in vet. medicine and may still be the most common class of anesthetics in use.
• Newer phencyclidine derivatives
– ketamine HCl - drug of abuse in humans
– tiletamine HCl - only in combination with zolazepam
• When anesthetized with ketamine, patients appeared to feel dissociated from or unaware of their environment, but did not always appear asleep (cataleptic).
– Later it was determined that these drugs did indeed dissociate the thalamocortical and limbic systems causing the change in awareness.

8
Q

Mechanism of action of dissociative anesthetics

A

-noncompetitive antagonists at N-methyl-D-aspartate (NMDA) receptors - prevent the binding of glutamate at the NMDA receptor- depressed activity at the thalamocortical and limbic systems and depression of nuclei in the reticular activating system
• Anesthesia with dissociatives produces an altered consciousness or catalepsy - drugs make them “not care” about what is going on around them.
• produce analgesia!!! which partially mediated through activation of mu and kappa opioid receptors. The NMDA receptor is also involved in pain processing

9
Q

Effect of dissociative anesthetics on the muscles

A

little muscle relaxation and may cause muscle rigidity

10
Q

Dissociative anesthetics and analgesia

A

provide a significant amount of analgesia

11
Q

Dissociative anesthetics and the eyes

A

Many patients do not close their eyes, can have muscle tone and muscle movement, and often do not look “asleep”. It is important to protect the corneas

12
Q

Dissociative anesthetics indications

A
  • chemical restraint, rapid induction of anesthesia, and to provide analgesia;
    • can safely be used in most species
13
Q

What species can dissociative anesthetics be used in?

A

All except for New Zealand White rabbits

14
Q

Describe neurosteroids

A

Include alphaxalone and alphadolone
• Neuroactive steroids are agonists at the γ-aminobutyric acid (GABA) receptor. This results in inhibition of pathway activation controlling arousal and awareness.
• great for very short surgical anesthesia in dogs and cats ( about 5-10 minutes)
– ~ 25% of cats will have edema of feet, ears, and muzzle, which resolves usually within 2 hours

15
Q

What are preanesthetics agents?

A

A preanesthetic agent is a drug that is given before the administration of an anesthetic agent to decrease anxiety and to obtain a smoother induction of, maintenance of and recovery from anesthesia.
• usually administered to animals 15-45 min. before induction of general anesthesia.
- Basically, they are any drugs except for general anesthetics that are used before general anesthesia

16
Q

What are the primary and secondary aims of using preanesthetic anesthesia

A

• The primary aims of preanesthetic medication are to calm the animal, to facilitate handling, and to relieve preoperative pain.
• Secondary goals are:
– to minimize undesirable reflex autonomic nervous system activity
• parasympathetic: vagal nerve, salivary and bronchial secretions;
• sympathetic: arrhythmic and arterial blood pressure alterations,
– to supplement general anesthesia (to add to level of analgesia, sedation and to reduce
anesthetic requirement),
– to minimize undesirable postanesthetic recovery complications,
– to prevent infection and to continue treatment of intercurrent disease.

17
Q

Advantages of preanesthetic agents

A
-reduced stress of animal, 
• smoother induction and recovery,
• decreased amount of induction and possibly maintenance agent 
• analgesia intra and postoperatively, 
• reduced secretions,
• reduced autonomic reflexes,
• handler safety!!!!!!!!!!
18
Q

Name the groups of preanesthetic medications

A
  • anticholinergics - parasympatholytics
  • tranquilizers
  • alpha-2 agonists
  • opioids
  • phencyclidines
  • neuroleptanalgesics