Nasal airflow characteristics in a normal sample

Abstract

The present study aims to describe the characteristics of nasal airflow in terms of the relative contributions of laminar and turbulent flow to the total pressure drop across the nose. The sample comprised 20 dental students with no history of nasal airway obstruction. Rhinomanometric data were recorded by a Mercury NR6 rhinomanometer with a Rohrer programme by the anterior and posterior methods after decongestion. Rohrer equation coefficients were calculated for each respiratory cycle. Method errors ranged from 6.3 to 9.3 per cent of sample variances. At a threshold of 75 Pa, average unilateral NAR was about 300 Pa/l/s and average bilateral resistance about 250 Pa/l/s. Analysis of the Rohrer equation data showed average coefficients of laminar (k1) and turbulent (k2) flow of 113 and 807 in unilateral breathing, indicating a predominance of turbulent flow. In bilateral breathing a switching of airflow characteristics occurred, with k1 and k2 coefficients of 147 and 348 indicating a marked reduction in the turbulent component of flow. It is suggested that Rohrer equation coefficients might provide information about nasal airflow which are physiologically more meaningful than conventional resistance calculations based on a single point on the rhinomanometric pressure-flow curve.