Which of the following is an example of intravenous anesthesia?

Intravenous anesthesia refers to the administration of anesthetic agents directly into the bloodstream through an intravenous (IV) line, providing rapid onset of action and allowing for a quick adjustment of anesthetic depth. Propofol is a commonly used intravenous anesthetic that is well-known for its fast-acting properties and is often employed in both induction and maintenance of general anesthesia.

Its lipid-based formulation allows it to be rapidly distributed throughout the body, leading to a swift onset of sedation or anesthesia. Propofol also has the added benefit of a relatively short duration of action, which allows for quick recovery for patients after the procedure is completed.

In contrast, the other substances listed serve different purposes. Lidocaine, primarily a local anesthetic, is used to block sensation in a specific area rather than providing general anesthesia through intravenous administration. Halothane is a volatile anesthetic typically administered via inhalation rather than intravenously. Chloroprocaine is also a local anesthetic used mainly for peripheral nerve blocks and epidural anesthesia rather than as an intravenous anesthetic.

Thus, Propofol stands out as the correct answer due to its specific use and characteristics as an intravenous anesthetic agent.