Which of the following intravenous anesthetic agents causes highest incidence of nausea & vomiting:
**Core Concept**
Intravenous anesthetic agents cause nausea and vomiting due to their effects on the central nervous system, specifically the chemoreceptor trigger zone (CTZ) in the area postrema. The CTZ is sensitive to anesthetic agents and can trigger emetic responses.
**Why the Correct Answer is Right**
Propofol is known to cause a high incidence of nausea and vomiting due to its effects on the CTZ. Propofol is a phenol derivative that is highly lipophilic and can easily cross the blood-brain barrier, leading to its rapid onset of action. However, this lipophilicity also makes it more likely to stimulate the CTZ, leading to nausea and vomiting. Additionally, propofol can also cause histamine release, which can further contribute to nausea and vomiting.
**Why Each Wrong Option is Incorrect**
**Option A:** Etomidate is a short-acting intravenous anesthetic agent that is known for its minimal cardiovascular effects. While it can cause nausea and vomiting, its incidence is lower compared to propofol.
**Option B:** Ketamine is a dissociative anesthetic agent that can cause hallucinations and increased salivation, but it is not typically associated with a high incidence of nausea and vomiting.
**Option C:** Midazolam is a benzodiazepine anesthetic agent that is often used for sedation and amnesia. While it can cause some degree of nausea and vomiting, its incidence is lower compared to propofol.
**Clinical Pearl / High-Yield Fact**
When administering propofol, it is essential to use a lipid emulsion to prevent tissue lipid accumulation and to reduce the risk of nausea and vomiting.
**Correct Answer: C. Propofol**