Peak flow, or peak expiratory flow rate (PEFR), measures how quickly a person can exhale after taking a deep breath. Using a handheld peak flow meter, patients blow out as hard and fast as possible. Higher readings indicate better airflow, while lower readings suggest airway obstruction.
A recent commentary in the Journal of Emergency Medicine by researchers at the UC Riverside School of Medicine suggests that routine PEFR monitoring offers little added value in the emergency department (ED) management of acute asthma exacerbations.
The commentary examined a randomized controlled trial comparing PEFR-guided care with traditional symptom-based assessment. The original study found no meaningful differences in patient outcomes: both groups improved at similar rates, and ED length of stay, hospital admissions, treatment intensity, and return visits were comparable regardless of whether clinicians had access to PEFR measurements.
The UCR authors note that treatment decisions in acute asthma are driven primarily by a patient's symptoms, physical examination, vital signs, and response to therapy. Even when physicians received PEFR-based treatment recommendations, their management and disposition decisions remained largely unchanged.
The commentary also points out that PEFR testing can be difficult to perform reliably during respiratory distress and requires additional staff time and patient effort, raising questions about its value in busy emergency settings.
At the same time, the authors emphasize that peak flow measurements remain useful in outpatient asthma care, where tracking lung function over time can help monitor disease control.
“Effective emergency asthma care depends on the patient’s overall clinical picture rather than any single measurement,” said senior author Dr. Rajesh Gulati, a professor of medicine. “For most patients, symptom-based assessment provides the information physicians need to make safe treatment decisions.”
