A modification of the pressure-flow technique for measuring breathing of cold air and its effect on nasal cross-sectional area

The purpose of this article was to develop a method based on the pressure-flow technique for measuring cold air breathing and to observe the immediate reactions of breathing function to cold air inhalation in 40 subjectively healthy adults. The pressure-flow technique was used to measure airflow rate and oral/nasal pressure and to calculate the smallest cross-sectional area of the nasal airway. The equipment was modified to allow measurements both at room temperature and with cooled air by connecting the nasal mask to a freezer with a two-valve cylinder and tubing. Nasal cross-sectional area showed a significant decrease from 42.3 mm 2 at room temperature to 37.6 mm 2 with cooled air. Correspondingly, the airflow rate changed from 411 ml/s to 369 ml/s, whereas the differential pressure remained about the same, 1.2 and 1.3 cm H 2O, respectively. The interindividual variation was fairly large. The results suggest that the breathing of cold air seems to cause changes in nasal cross-sectional area and airflow rate. In general, the cross-sectional area diminishes, the change being quantitatively more pronounced in subjects with an initially large area. (A M J O RTHOD D ENTOFAC O RTHOP 1994;105:265-9.)