All of the following are used for intravenous induction except: March 2005
## Core Concept
Intravenous induction agents are used to induce general anesthesia rapidly. They work by affecting the central nervous system, specifically the **GABA receptors** and other neurotransmitter systems, to produce sedation, hypnosis, and amnesia.
## Why the Correct Answer is Right
Thiopental (Option ) is a barbiturate commonly used for intravenous induction of anesthesia due to its rapid onset and short duration of action. Propofol (Option ) is a widely used agent for induction and maintenance of anesthesia, known for its antiemetic properties and rapid recovery profile. Etomidate (Option ) is another intravenous agent used for induction, particularly in patients with cardiovascular instability, due to its minimal impact on cardiovascular function. Midazolam (Option ) is a benzodiazepine used for sedation, anxiolysis, and as an adjunct for anesthesia induction, but it is not typically used as a sole agent for intravenous induction of general anesthesia due to its slower onset and less potent hypnotic effects compared to the others.
## Why Each Wrong Option is Incorrect
* **Option A:** Thiopental is used for intravenous induction.
* **Option B:** Propofol is used for intravenous induction.
* **Option C:** Etomidate is used for intravenous induction.
## Clinical Pearl / High-Yield Fact
A key point to remember is that **Midazolam** is often used for procedural sedation and as an adjunct to other anesthetic agents rather than as a primary intravenous induction agent for general anesthesia.
## Correct Answer: D. Midazolam