Final answer:
The tidal volume of an unresponsive patient is assessed by observing the patient's breathing, as it is an immediate way to evaluate respiratory health.
Step-by-step explanation:
The tidal volume of an unresponsive patient is rapidly assessed by observing the patient's breathing. Tidal volume is the amount of air that is inhaled or exhaled from the lungs during a single breathing cycle when the body is at rest. It is part of several parameters used to measure respiratory health. Observing the breathing of a patient allows for quick assessment of the respiratory effort and effectiveness without the need for specialized equipment.