What does a peak flow meter primarily measure?

A peak flow meter primarily measures the maximum speed of exhalation, which is an important aspect of assessing respiratory function, particularly in individuals with asthma or other respiratory conditions. This measurement evaluates how quickly air can be expelled from the lungs after taking a deep breath.

By capturing this peak expiratory flow rate (PEFR), healthcare providers can determine how well the lungs are functioning and monitor changes over time. It is particularly useful in managing asthma, as fluctuations in PEFR can indicate worsening airway obstruction or the need for adjustments in medication.

In contrast, measuring lung tissue volume assesses the total capacity of the lungs, which is not the focus of a peak flow meter. The level of carbon dioxide in the blood relates to gas exchange efficiency and is typically evaluated through blood tests rather than with a peak flow meter. Lastly, airflow resistance in the lungs is a broader concept that may involve multiple factors, including airway diameter and inflammation, and cannot be directly measured by a peak flow meter.