What physiological parameter is measured by a peak flow meter?

The peak flow meter measures the maximum speed of expiration, which is an important parameter for assessing lung function, particularly in conditions like asthma. This device gives a reading known as peak expiratory flow rate (PEFR), which indicates how quickly a person can exhale air from their lungs.

Monitoring the maximum speed of expiration can help identify changes in airway obstruction, allowing healthcare providers to evaluate the severity of respiratory conditions and determine the effectiveness of treatment plans. For individuals with asthma, for instance, regular use of a peak flow meter can provide crucial information about their airflow status and guide medication adjustments.

While the other choices reference important aspects of lung function, they do not directly relate to what a peak flow meter specifically measures. The volume of inhaled air pertains to tidal volume and inspiratory capacity but is not the focus of a peak flow meter. Total lung capacity refers to the maximum amount of air the lungs can hold, which is assessed using different devices such as spirometers. The effectiveness of breathing treatments can be inferred from various measures, but the peak flow meter specifically quantifies the rate of airflow during expiration rather than the broad effectiveness of treatments.