Computer analyses of Rohrer's coefficients.

ABSTRACT

In the field of respiratory physiology computers have been used for theoretical and automatic analyses of the test results. The purpose of this paper is to clarify whether computers are available in measurement of the nasal resistance. The nasal cavities, simulated by an acryl resin model, were ventilated at various volumes and speeds. The pressure and flow changes were recorded by a data recorder and analyzed by a minicomputer according to the prescribed situations. Rohrer's formula P = K1V+K2V2 and its modification R = K1+K2V were used for calculation of K1 and K2. The calculated values differed significantly when sampling was made on a particular part of the respiratory excursion or sampling time was extraordinarily prolonged. They were also different from the ordinary values when too slow or too rapid ventilatory speed was applied. It was concluded that more than twenty samplings were necessary at regular intervals in a normal inspiratory or expiratory phase. Too slow and too rapid respiration should be avoided because of functional limitations of the measuring apparatus.