What does a peak flow meter measure?

A peak flow meter is used specifically to measure the maximum speed of expiration, which is the rate at which a person can exhale air from their lungs. This measurement is particularly useful for monitoring conditions such as asthma, as it helps determine how well the airways are functioning and how effectively air can be expelled from the lungs.

When a person uses a peak flow meter, they take a deep breath and then exhale forcefully into the device. The reading provided indicates the peak expiratory flow rate (PEFR), which is a vital sign of respiratory health. Monitoring this reading can alert individuals to changes in their condition, helping guide treatment decisions.

The other options involve aspects of respiratory health but do not accurately define the purpose of a peak flow meter. While the volume of air in the lungs and frequency of breathing are important parameters of lung function, they are not directly measured by this device. Similarly, evaluating the intensity of lung sounds pertains more to auscultation techniques rather than to the specific measurements that the peak flow meter provides.