Anesthesia Chapter 3 Flashcards

Study Notes

Injectable Anesthetics

Induce unconsciousness but do not provide complete effects like analgesia or muscle relaxation.
Require combination with other agents to achieve full general anesthesia.
Key agents include Propofol, Etomidate, Alfaxalone, and Barbiturates.
Administered via IV injection "to effect" with small boluses until desired anesthesia is reached.

Propofol (Schedule IV)

An ultra-short-acting non-barbiturate with a wide safety margin.
Used as an IV bolus followed by CRI for status epilepticus in unresponsive dogs and cats.
Administered in macros or microemulsions for different solubility properties.
Enhances inhibitory neurotransmitter GABA’s effects; highly fat-soluble for quick onset.
About 95% to 99% of Propofol in blood is protein-bound; only 1% to 5% circulates freely to induce anesthesia.
Effectiveness increases in animals with lower plasma protein levels.

Propofol Effects

Provides rapid induction due to high lipid solubility.
Cardiac depressant leading to bradycardia and hypotension; may cause transient hypotension.
Potent respiratory depressant; high doses can lead to significant respiratory complications (apnea).
Notable effects in dogs: muscle twitching, relaxation, anti-emesis, decreased intraocular and intracranial pressure.
Can cause pain upon IV injection; adverse effects in cats include Heinz body formation and prolonged recovery.
Shelf life of unopened product is approximately 3 years; discard unused product within 6 hours of opening.

Lipid Solubility / Tissue Redistribution

Lipid solubility describes a drug's tendency to dissolve in fats and oils, also known as the partition coefficient.
Tissue redistribution affects drug distribution based on blood flow; high blood flow tissues (heart, brain, liver, kidneys) receive 75% of the drug, while muscle receives 20%.

Etomidate

A noncontrolled sedative-hypnotic imidazole drug, excellent for induction in high-risk patients.
Minimal cardiovascular and respiratory effects, useful in sensitive populations.
Notable adverse effects include pain on IV injection, nausea, and vomiting.
Works rapidly with a duration of action lasting 3 to 5 minutes; characterized by hypnosis with minimal analgesia.
Exhibits anticonvulsant properties and good muscle relaxation.
Potential complications: myoclonus during induction/recovery, hemolysis in cats, and transient hypotension or apnea post-induction.

Etomidate Administration

Myoclonus may occur; IV administration can be painful; consider using a running IV fluid line to reduce pain.
Rapid injections can lead to red blood cell hemolysis in cats but is typically non-significant unless hematocrit is critically low.
Using premedication can mitigate adverse effects, such as muscle twitching and vomiting, during administration.

Description

Dive into the essential concepts of injectable anesthetics with these flashcards from Anesthesia Chapter 3. Explore definitions, applications, and specific agents like Propofol and Etomidate that are crucial for producing unconsciousness during procedures.