Which measurement is best for tracking deterioration in asthma?

The best measurement for tracking deterioration in asthma is FEV1, which stands for Forced Expiratory Volume in one second. FEV1 is a key component of pulmonary function testing that measures the volume of air that can be forcibly exhaled in the first second of a breath. This measurement is particularly sensitive to changes in airway obstruction, making it invaluable for monitoring asthma severity and the effectiveness of treatment.

As asthma worsens, FEV1 typically declines due to increased airway inflammation and bronchoconstriction. Healthcare providers often use FEV1 measurements to assess lung function over time, guiding therapeutic decisions and interventions. The ability to quantify airflow limitation allows for a more clear understanding of the patient's respiratory status and facilitates early detection of exacerbations.

While other measurements such as Peak Expiratory Flow (PEF), pCO2, and pulse oximetry provide useful information in managing asthma and assessing respiratory function, they do not offer the same direct insight into the degree of obstruction and lack the reliability that FEV1 provides in tracking changes over time. PEF can be a good tool for self-monitoring, especially in outpatient settings, but it is less standardized compared to FEV1. Pulse oximetry measures oxygen saturation but does not directly assess