What device is used to measure ventilation in a subject?

A spirometer is the correct device used to measure ventilation in a subject. It assesses the volume of air inhaled and exhaled, providing crucial data on lung function. This measurement is vital for evaluating respiratory health, diagnosing conditions like asthma, chronic obstructive pulmonary disease (COPD), and monitoring the effects of medication or therapy on lung capacity and airflow.

Spirometers work by detecting the amount of air a person breathes in and out over a specified period, effectively giving a graphic representation of lung capacity. This quantitative data helps health professionals understand both how efficiently a patient's lungs are functioning and the presence of any potential obstructions or abnormalities in airflow.

In contrast, peak flow meters measure the maximum speed of expiration but do not provide a full picture of lung volumes like spirometers do. Stethoscopes are used to listen to internal body sounds, such as heartbeats and lung sounds, but they do not measure the volume or flow of air. Endoscopes are instruments designed for visual examination of internal structures, not for measuring ventilation capacity.