Figure 1.
Temperature (left) and relative humidity (right) measurement during each subject exposure session.
The temperature in the cold air exposure box was significantly lower than in the other exposure boxes, and the RH in the dry air exposure box was significantly lower than in the others (both p<0.01). The temperature difference between room air and dry air and the humidity difference between room air and cold air were both non-significant.
Figure 2.
Air exposure boxes and the visual analog scale used in the study.
The visual analogue scale includes a negative range to account for subjects that may rate their nasal patency as completely clear and then experience even less congestion in later exposures.
Figure 3.
Flow chart of the test sequence for each participant: box exposure and patency rating (top), followed by rhinometry, rhinomanometry, and trigeminal assessment by butanol lateralization threshold (bottom).
Figure 4.
Bilateral and unilateral subjective patency ratings and standard errors in room air, dry air, and cold air exposure boxes.
Subjects perceived significantly less nasal congestion (greater patency), both unilaterally and bilaterally, in the cold air box and unilaterally in the dry air box, compared to the room air box (p<0.01), with the cold air box having a larger effect (p<0.01) (Wilcoxon match pairs test, with Holm–Bonferroni correction to control for multiple comparison.)
Table 1.
Significant contributors to unilateral patency ratings (forward step-wise multiple regressions).
Figure 5.
Averaged total nasal heat loss versus patency visual analog scale (VAS) ratings for the three exposure box conditions.
Nasal heat loss is calculated assuming that, at the end of the breath, inspired air is always warmed and humidified to 35°C and 90% RH [13], [14]. Data are averaged over subjects for the three exposure conditions.
Figure 6.
Within subject, there was a significant difference in perceived patency between the high and low resistance nostrils.
Figure 7.
Contour plot of nasal mucosal heat flux (J/m2) for a subject that received a nasal/sinus CT scan immediately before testing.
A CFD model was created for this subject using the method described by Zhao et al. [16] in which nasal airflow and mucosal heat exchange are then simulated. The wall boundary condition at the mucosal surface is set similar to that described by Naftali et al. [14]: fully saturated with water vapor and at body temperature, with an unlimited supply of heat and water vapor.