What is the primary function of a capnometer in polysomnography?

The primary function of a capnometer in polysomnography is to measure the level of carbon dioxide (CO2) in air samples. This measurement provides critical information about a patient's ventilatory status during sleep. Monitoring CO2 levels is vital for understanding how well the lungs are functioning in gas exchange and can help in assessing respiratory events such as apnea or hypopnea, which can significantly affect sleep quality and overall health.

By measuring the concentration of CO2 during the respiratory cycle, clinicians can evaluate the effectiveness of breathing and identify any potential issues related to ventilation. This information is particularly important in the context of sleep studies, as disrupted breathing patterns can have serious consequences for patients.

Other options focus on different parameters unrelated to the specific measurement provided by a capnometer. For instance, heart rate measurement relates to cardiovascular monitoring, sleep stage analysis pertains to the evaluation of brain activity during sleep, and airflow assessment involves monitoring the movement of air through the respiratory system. Each of these functions is crucial in its own right but does not reflect the primary capability of a capnometer, which is specifically centered on CO2 measurement.