Certified Pulmonary Function Technologist (CPFT) Practice Exam

The minimum FEV1 decrease required for a mannitol challenge test to be considered positive is 15%. This threshold is significant because it indicates a clinically relevant bronchoconstrictive response to mannitol, which is a dry powder used in airway reactivity testing. The rationale behind using the 15% decrease is based on studies that demonstrate this level as a reliable cutoff for determining the presence of airway hyperresponsiveness, particularly in individuals with conditions such as asthma.

A decrease of 15% signifies a substantial enough change in lung function to warrant further clinical consideration and possibly more targeted management strategies. Testing below this threshold may not provide enough evidence of airway reactivity to inform clinical decisions.

In the context of the mannitol challenge test, values higher than 15% indicate stronger airway reactivity, while values below may lead to a reassessment of the patient's condition or management plan. Therefore, the focus on a 15% decline in FEV1 helps standardize the interpretation of results in clinical practice.