Forced inspiratory nasal flow-volume curves: A simple test of nasal airflow

Objective: To observe and describe normal and abnormal inspiratory nasal flow-volume patterns. Patients and Methods: In this observational case series, individuals with and without nasal symptoms underwent forced inspiratory nasal flow-volume (FINFV) curve measurements. The participants were volunteer adults from the staff and patients of a pulmonary subspecialty private practice office. To examine the flow patterns from the FINFV curves, definitions of normal and abnormal were established. Normal curves were defined as those from participants who had no nasal symptoms and a peak inspiratory nasal flow greater than 2.5 L/s. Abnormal curves were defined as those from participants who had 1 or more nasal symptoms, a peak inspiratory nasal flow lower than 2.5 L/s, and normal oral inspiratory flow. Results: Study participants consisted of 10 staff and 58 patients. Fourteen individuals (21%) met the definition of normal and had FINFV curves that mimicked the shapes of normal oral flow-volume curves; 39 (57%) met the definition of abnormal and had FINFV curves that mimicked the patterns of abnormal oral flow-volume curves. The abnormal curves showed both fixed (33/39 [85%]) and variable (6/39 [15%]) patterns of obstruction. Fifteen participants (22%) did not meet either established definition. Conclusions: Forced inspiratory nasal flow-volume curves are a potentially useful clinical tool to measure nasal airflow. Normal and abnormal flow patterns are easily identifiable.