Rhinomanometry is important in the diagnosis of nasal obstruction since it verifies the patient's complaint and provides information regarding the degree and site of obstruction. The nasal mirror, an old device for measuring nasal flow, is also useful, but objective evaluation of the results is difficult. In this study, we designed and tested a liquid cristal rhinoairflowmeter (LCR), which is a modification of the Glatzel nasal mirror, It is also very handy and can be equipped with an instant colour photo system for recording and analyzing the expiratory images on the LCR.
The LCR (8×15×0.4 cm) was constructed of four layers, namely, a polyester film layer, a microcapsule layer including liquid crystals, a black layer and a heat-insulating layer. LCR is capable of exhibiting five different colors between 27 and 31°C. As with the nasal mirror, the LCR is held immediately beneath the nose while the patient breathes quietly. The expiratory airflow produces an oval area of changing colors and expiratory patterns of varying colours.
The area of the expiratory image on the LCR correlated well (r=0.735) with the nasal conductance determined with a rhinomanometer (RION SR-11). These results confirm that the LCR is convenient and useful for diagnosis of nasal obstruction.
