What does peak expiratory flow rate (PEFR) measure?

Peak expiratory flow rate (PEFR) is a measure specifically used to assess how quickly a person can expel air from their lungs. This measurement is particularly valuable for individuals with asthma, as it provides an indication of airway obstruction and can help monitor the effectiveness of asthma management and medication.

PEFR focuses on the maximum speed or flow rate of air during forced expiration after a full inhalation. By quantifying this airflow, healthcare providers can evaluate a patient's lung function and identify any significant changes over time, which may indicate an exacerbation of asthma or the need for intervention.

In contrast, the other options pertain to different aspects of respiratory function. The maximum air volume inhaled relates to the concept of lung capacity rather than flow rate. Total lung capacity incorporates the total volume of air the lungs can hold, which is not what PEFR measures. The resting respiratory rate refers to the number of breaths taken within a minute when at rest, and does not provide information about the speed of air expulsion or lung mechanics in real-time. Thus, option B accurately captures the purpose and function of measuring PEFR.