What is the function of an endotracheal tube?

The function of an endotracheal tube is to deliver anesthetic gases directly into the lungs. This is essential during surgeries requiring general anesthesia, as it ensures that the patient receives a steady supply of anesthetic agents and oxygen while preventing the risk of aspiration. The tube creates a secure airway, allowing for proper ventilation and gas exchange, which is critical for maintaining the patient's vital functions throughout the procedure. By placing the tube into the trachea, the anesthetist ensures that the anesthetic gases bypass the upper airway, which can be obstructed or compromised in some patients, thus maintaining a clear and effective path for anesthesia delivery.

The other choices provided do not accurately describe the primary function of an endotracheal tube. For example, ventilation through the nasal cavity is not a function of the endotracheal tube, and monitoring end-tidal CO2 levels is a separate process that involves additional equipment, not the tube itself. Similarly, blood pressure measurement involves different tools and methodologies, making these options incorrect in the context of the endotracheal tube's actual purpose.