Which of the following best describes the function of capnography?

Capnography serves a critical role in emergency care by providing real-time feedback on a patient’s ventilation status. It measures the concentration of carbon dioxide in exhaled air, known as end-tidal CO2 (EtCO2). By monitoring this measurement, EMTs can assess not only the effectiveness of a patient’s ventilation but also identify changes in their respiratory status, which can indicate conditions such as hypoventilation or hyperventilation.

This capability is invaluable during resuscitation efforts, as it helps assess the quality of chest compressions and the overall effectiveness of breathing interventions. In contrast, the other options do not accurately capture the primary function of capnography. For instance, measuring lung volumes pertains to spirometry and does not provide the same direct information about CO2 levels during acute distress. Assessing blood pH levels falls under different diagnostic tools and methods, such as arterial blood gas analysis, which is not the function of capnography. Lastly, while heart rate monitoring is an important component of patient assessment, it is typically measured through other means and is not the focus of capnography. Thus, the best description of capnography’s function is that it delivers real-time feedback on a patient's ventilation status.