Measurement of nasal patency using a Vitalograph.

A standard Vitalograph was used to measure the volume of air inspired through the mouth (M-FIV0.5) and nose (N-FIV0.5) in 0.5 sec. The ratio of these parameters was used as a nasal patency index (NPI) and the characteristics of NPI and N-FIV0.5 investigated in terms of reproducibility and sensitivity. Both indices were significantly reduced by intranasal histamine (100 micrograms and 200 micrograms) and it is concluded that NPI and N-FIV0.5 are reproducible and sensitive indices of nasal patency.