Nasal mucociliary function was evaluated by nasal scintigraphy in normal subjects. A microdrop of HSA or saline labelled with 99mTc was dripped into the middle part of each middle meatus in the nasal cavity and its clearance was observed by scinticamera. The accumulated concentration of ICI was determined every 30 seconds for 10 minutes. The changes of accumulated concentration were studied, and a curve of decreasing ICI-counts was obtained, with the “clearance rate” defined as 100% for the count at the initial 30 seconds and “half time” as the time when radioactivity was reduced to one half the initial count. Nasal resistance was measured by rhinomanometry with the oscillation method.
In nonsmokers, 10μl of saline was cleared (78.0±10.4%) significantly faster than 10μl of HSA (59.9 ±24.6%), and there was no significant difference in the clearance between 10μl and 5μl of HSA (55.9±27.7%). In smokers, the mucociliary clearance of lO1d of HSA and saline was significantly lower than in nonsmokers. The clearance of 10μl of HSA reflects a pathological state much better than that of 5μl.
In nonsmokers, there is a significant negative correlation between nasal resistance and clearance rate, suggesting that the more patent the nose, the faster the mucociliary clearance. When both nostrils were closed, the clearance rate was significantly depressed. When one nostril was closed, there was no significant effect on clearance. Nasal resistance was decreased by exercise with a bicycle ergometer. Nasal mucociliary clearance was slightly decreased after exercise but not significantly so.
Nasal patency may be one of the most important factors in mucociliary clearance, since it is slowed by nasal obstruction which would prolong inflammatory changes in the nose and paranasal sinuses.