Peak flow testing measures which of the following?

• A. The patient's maximum ability to exhale
• B. The heart rate
• C. The blood pressure
• D. The oxygen saturation

Answer: (A)

Peak flow testing measures the maximum speed of exhaled air, written as the peak expiratory flow rate. A peak flow meter captures how forcefully you can blow air out, which reflects how open your airways are. This is especially useful in asthma management to monitor control and detect changes in airway obstruction. It does not measure heart rate, blood pressure, or oxygen saturation, which are assessed with other tools and relate to different aspects of physiology. To perform it, you take a deep breath, place your lips tightly around the meter, and blow out as hard and fast as you can; the best effort from multiple attempts is recorded. Keep in mind that the result depends on effort and technique, and it’s most informative when compared to your own baseline or predicted values for your age, height, and sex.