Induction agents part 2

What is a key characteristic of injectable anesthetics?

They can produce unconsciousness when administered alone.

What are the primary uses of injectable anesthetics?

They are mainly used as induction agents.

Can injectable anesthetics be used for sedation?

Yes, they are versatile and can be used as sedation/premedication.

What are injectable anesthetics best used with?

Other agents to produce the complete spectrum of effects of general anesthesia

Name an injectable anesthetic agent.

Propofol

Name another injectable anesthetic agent.

Etomidate

Name another injectable anesthetic agent.

Alfaxalone

Name another injectable anesthetic agent.

Ketamine

Name another injectable anesthetic agent.

Tiletamine/Zolazepam (Telazol)

What is a key benefit of injectable anesthetic agents?

They allow for a swift, smooth transition to unconsciousness and general anesthesia

What routes of administration can Alfaxalone, Ketamine, and Tiletamine/Zolazepam be given?

IM, IV, SQ, GV20

What routes of administration can Propofol and Etomidate be given?

IV only

Which injectable anesthetics can be used to maintain general anesthesia?

Propofol and Alfaxalone

What are the two methods of administering Total IV Anesthesia (TIVA)?

Intermittent bolus or Constant Rate Infusion (CRI)

How is injectable anesthetic administered IV 'to effect'?

The drug is given in small boluses until the desired level of anesthesia is reached.

What is the induction agent Propofol?

A fast-acting non-barbiturate injectable anesthetic/induction agent.

What is the clinical use of Propofol?

Induction and short-term maintenance of general anesthesia.

What is the typical dose of Propofol for induction?

3-6 mg/kg IV.

How should the dose of Propofol be administered?

Give ½ over 30-60 seconds, then titrate to effect.

What is the onset time for Propofol?

30-60 seconds.

How long does Propofol typically wear off?

Within 5-10 minutes.

What is the redistribution characteristic of Propofol?

Rapidly redistributed to muscle and fat.

What effect does Propofol have on muscle relaxation?

Causes very good muscle relaxation.

What is the recovery time associated with Propofol?

Smooth and rapid recovery time.

In which animals is Propofol mainly used?

Mainly used in small animals, exotics, and horses, but not ideal for large animals.

How can Propofol be administered?

As a Constant Rate Infusion (CRI) or as Total Intravenous Anesthesia (TIVA).

What is the recommended dosage of Propofol for CRI?

0.2-0.6 mg/kg/min IV.

What cardiovascular effects does Propofol have?

It causes significant hypotension and vasodilation by reducing sympathetic activity.

What happens to cardiovascular effects as Propofol metabolizes?

The effects resolve as Propofol metabolizes.

What potential cardiac issues can Propofol cause?

Bradycardia and decreased cardiac output.

What respiratory effects does Propofol have?

It causes respiratory depression and may cause apnea initially.

What precautions should be taken when administering Propofol?

Oxygen support and intubation are highly advisable.

What should you always be ready to do when using Propofol?

Be ready to intubate and possibly ventilate.

How is propofol administered?

Administered IV only and to effect.

What can occur if propofol is given too fast?

Apnea and respiratory depression.

In which patients should propofol be used cautiously?

Patients with preexisting hypotension.

What conditions should be considered when administering propofol?

Shock, blood loss, and dehydration.

What effects does propofol have on cardiac output?

Decreases cardiac output, may cause bradycardia and reflex tachycardia.

How does propofol affect intracranial and intraocular pressure?

Decreases both intracranial and intraocular pressure.

What caution should be taken with chronic use of propofol in cats?

It oxidizes red blood cells, leading to Heinz Body Anemia.

What can happen if propofol is given too slowly?

Transient excitement and muscle tremors (myoclonus) may occur during induction.

Does propofol provide analgesia?

No, it does not provide analgesia.

What is alfaxalone?

Alfaxalone is an ultra-short acting injectable anesthetic.

What type of anesthetic is alfaxalone?

Neuroactive steroid anesthetic.

What is the primary effect of alfaxalone?

CNS depression leading to sedation/anesthesia.

In which animals is alfaxalone mainly used?

Mainly used in small animals and exotics.

What is the route of administration for alfaxalone?

IV for induction of anesthesia and to maintain anesthesia using a CRI; IM if IV cannot be accessed.

What is the onset time for alfaxalone?

30-60 seconds.

What is the duration of IV dose of alfaxalone?

5-10 minutes.

What is the duration of IM injection of alfaxalone?

20-45 minutes.

What is the recommended dose of alfaxalone for dogs?

1-3 mg/kg IM or IV.

What is the recommended dose of alfaxalone for cats?

2-5 mg/kg IM or IV.

What is a notable recovery characteristic of alfaxalone?

Rapid recovery time.

What is a common nickname for alfaxalone?

Clear Propofol.

What is a key characteristic of alfaxalone regarding analgesia?

Does not provide analgesia

What type of cardiovascular or respiratory effects can alfaxalone cause?

Mild cardiovascular/respiratory system depression

How does alfaxalone affect the induction process?

Smooth inductions - no excitement, or pain on IV injection

What happens if alfaxalone is injected perivascularly?

Does not result in tissue irritation

What muscle effects can occur with inadequate dosing of alfaxalone?

Some muscle spasms, twitching, and stiffness

What effects does alfaxalone produce that are similar to propofol?

Dose-dependent CNS depression, respiratory depression including apnea, +/- hypotension

What should be prepared when using alfaxalone due to its respiratory effects?

Oxygen support, and be prepared to intubate

alfaxalone: premeds and induction

Premed:

Methadone + dexmedetomidine IM

Induction:

Alfaxalone IV to effect

Route of induction for propofol and alfaxalone

IV only

IM + IV

CV effects of propofol

more bradycardia, hypotension

Cv effects of alfaxalone

mild depression

Respiratory effects of propofol

more apnea

resp effects of alfaxalone

mild depression/apnea

recovery with alfaxalone

can be rough

recovery for propofol

usually smooth

analgesia for propofol

none

analgesia for alfaxalone

none

CRI ability for propofol and alfaxalone

yes

What is the induction agent etomidate used for?

Etomidate is an ultra-short-acting sedative that produces hypnosis for the induction of anesthesia.

In which animals is etomidate mainly used?

Etomidate is mainly used in small animals, such as dogs and cats.

What are the cardiovascular and respiratory effects of etomidate?

Etomidate has minimal effects on the cardiovascular and respiratory systems.

Why is etomidate useful in high-risk patients?

Etomidate is very useful in high-risk patients due to its minimal effects on cardiovascular and respiratory systems.

What is the recommended dose of etomidate?

The recommended dose of etomidate is 1 - 3 mg/kg IV.

What is the onset and duration of etomidate?

Etomidate has a rapid onset of 5-15 seconds and a short duration of 3-10 minutes.

How should etomidate be administered?

Etomidate should be administered via rapid IV administration.

What is a consideration when using etomidate for induction?

It is recommended to use a co-induction agent, such as a benzodiazepine, for a smooth induction with muscle relaxation.

Is etomidate considered expensive?

Yes, etomidate is considered expensive.

What is a key characteristic of Etomidate regarding blood pressure?

It does not cause hypotension.

Who are the best candidates for Etomidate?

High-risk patients, including those with cardiac disease, hypovolemia, shock, or critically ill.

How does Etomidate affect the cardiovascular system?

It does not change the cardiovascular system.

What are the cardiovascular effects of Etomidate?

No bradycardia, no tachycardia, and no change in cardiac output.

What type of agent is etomidate?

Induction agent

How is etomidate administered?

IV only and to effect

What is a side effect of etomidate upon injection?

Painful upon injection

Does etomidate provide analgesia?

No, it does not provide analgesia

What substance in etomidate may cause RBC hemolysis in cats?

Propylene glycol

Is continuous rate infusion (CRI) recommended for etomidate?

No, CRI is not recommended

etomidate adrenal Suppression decreases ____ _____ and is more relevant in ____ ___/___ patients

decreases cortisol production

critically ill/septic patients

adverse effects of etomidate

Vomiting and muscle twitching, vocalizing, paddling

Does not provide analgesia*

What are two examples of dissociative anesthetics?

Ketamine, Tiletamine (in Telazol)

What is the primary use of dissociative anesthetics?

To create a 'disconnected' state, not true CNS depression

What type of receptors do dissociative anesthetics act as antagonists for?

NMDA receptors

What effects do dissociative anesthetics produce?

Amnesia and analgesia

What is the onset time for dissociative anesthetics when administered IV?

1-2 minutes

What is the onset time for dissociative anesthetics when administered IM?

About 10 minutes

What is the duration of effect for dissociative anesthetics?

About 20-30 minutes