A technique for measuring the perception of added resistive loads during nasal breathing

The perception of resistive loads added to nasal breathing was assessed in ten healthy adults using established psychophysical methods previously described for oral breathing. Detection threshold, that is, the smallest incremental resistance that the subject could detect 50% of the time, was determined at three different time periods (0, 30, and 60 min) on two separate days to determine the reproducibility of values over time. Nasal airway resistance measurements were made before and after threshold determinations to determine the influence of baseline resistance on the ability to detect added loads as well as to assess any effects of the procedure itself on resting nasal airway resistance. Analyses of the data revealed that subject-to-subject differences were the largest source of variability in threshold values followed by time period-to-time period differences and day-to-day variability. Although it was the smallest variability source, day-to-day variability still was significantly greater than zero. In contrast to previously published reports on resistive load detection during mouth breathing, the degree of baseline resistance did not appear to influence the subject's ability to detect added resistive loads during nasal breathing. These techniques may provide a methodological basis for objectively evaluating the effects of pharmacologic agents on perceived nasal patency.