Comparison of the classic and Broms methods of rhinomanometry using model noses.

Calculation of nasal airway resistance (NAR) using rhinomanometry can be obtained using different methods of analysis of the pressure-flow curve. The two commonest methods for measuring NAR in rhinomanometry are the classic method at 75 and 150 Pa and the Broms method at radius 200. The objective of this study was to compare the unilateral NAR values measured using both classic and Broms method over four artificial model noses (R1, R2, R3 and R4). The study found that at low resistances (R1 and R2), NAR measurements of Broms were not significantly different from measurements of classic method at 75 Pa but were significantly different from measurements of classic method at 150 Pa. At high resistances (R3 and R4), NAR measurements of Broms were not significantly different from measurements of classic method at 150 Pa but were significantly different from measurements of classic method at 75 Pa. The magnitude of any change in resistance due to surgery or medical intervention is therefore also dependent on the method used to analyze the pressure-flow curves, with bigger change observed in Broms method at certain level of nasal resistances compared to classic measurements in the same patient. In conclusion, nasal airway resistance is not a standardized measurement like blood pressure. Clinicians need to be careful when comparing unilateral measurements of resistance from the classic and Broms methods because the two methods can give either similar or different measurements depending on the level of nasal resistance.