What is measured by a peak flow meter?

A peak flow meter is a device specifically designed to measure the speed of air that is forcibly exhaled from the lungs. This measurement is critical for individuals with respiratory conditions like asthma, as it provides valuable information about how well air can flow out of the lungs, which is directly related to airflow obstruction.

By monitoring peak expiratory flow rates, healthcare providers and patients can assess the severity of airway obstruction and make informed decisions about treatment plans. This information can help determine if a patient's condition is stable or if they are at risk of an asthma attack, enabling timely intervention.

The other options, while related to respiratory health, do not pertain to the function of a peak flow meter. For instance, the strength of a cough measures different aspects of respiratory function, the amount of blood in the lungs pertains to conditions like pulmonary edema and is typically assessed through imaging or blood tests, and oxygen saturation in the blood is measured using a pulse oximeter, which assesses how much oxygen the blood is carrying.