Comparison of rhinomanometric values expressed by rate--validity and normal range

Abstract

The nasal patency during respiration is today usually expressed by the nasal resistance. However, the nasal resistance is not the same throughout the total respiratory phase. Therefore, the reference point to express the resistance is therefore necessary to facilitate the mutual comparison of the data. The international committee for standardization of rhinomanometry has been paying a great effort to decide where this reference point should be set up, but has not yet reached the final consensus. The purpose of this study is to present a new method to estimate nasal respiratory conductivity, regardless of the reference point. Pressure flow curves during nasal respiration are quite similar in nature and rarely cross one another. The parabolic curves which do not cross each other can be superimposed by multiplying the standard equation, V = n.f(P). Accordingly, n is only one parameter in comparing these curves. A standard curve is decided as follows. Rohrer's equation was examined by polynomial regression analysis and concluded to be adequate to simulate a pressure flow curve. Rohrer's equation is converted to the function of P. Integration of this equation along P gives the value of the area under the curve (AUC). The total AUC can be obtained by simply adding the AUC of right and left sides. Definite integration from the origin to 1.0 and 2.0 on the abscissa gives the numerical value of AUC in each curve. The mean AUC is easily calculated by simple mathematical averaging of the data. K1 and K2 of the standard curve are calculated by solving simultaneous equations using mean AUC. K1 and K2 during expiration and inspiration are calculated, respectively. 718 subjects who had not been recently suffered from nasal diseases were examined by active anterior rhinomanometry. 47 functionally normal subjects in twenties were selected for calculation of the standard curve using the above mentioned method. In expiration, the values of K1 and K2 were 0.5476 and 1.3653, respectively. In inspiration, they were 0.4080 and 1.4750. Individual curve can be expressed by only one parameter. The normal range during nasal respiration is considered to be more than 0.7. The method presented in this study is convenient for the mutual comparison of the data both in clinical and basic research.