Ventilation of the Paranasal Sinuses. A study using the 133-Xenon Washout Technique

Abstract: A noninvasive 133-xenon washout technique was used to evaluate the ventilation of the paranasal sinuses in healthy subjects and in patients with sinus disease. A mixture of air and 133-xenon is insufflated into the nasal cavities and passage into the sinuses is facilitated by a pressure increase created by letting the subjects inflate a balloon. A scintillation camera allowing single photon emission computed tomography (SPECT) was used to follow the washout of 133-xenon from not only the frontal and maxillary sinuses, but also the posterior ethmoidal and sphenoidal sinuses. The washout halftimes were used as a measure of the ventilation of the sinuses. Factors influencing the washout such as nasal patency, insufflation pressure and body possition were studied in healthy subjects and the reproducibility of the method was evaluated.The results show that 133-xenon washout in combination with SPECT has sufficient reproducibility and that variations in nasal patency, insufflation pressure and body position do not influence sinus ventilation. Other factors influencing the washout such as ostial size, sinus volume and nasal ventilation were studied in a nose-sinus model and the ostial size was found to be most import in the washout of 133-xenon. Sinus ventilation was evaluated in patients with sinus disease before and after endoscopic sinus surgery (ESS). The washout times are significantly longer in patients with polyposis than in healthy subjects, and the washout times were significantly shorter after ESS on patients with chronic sinus disease. Furthermore, sinus ventilation was measured in healthy subjects before and after the administration of oxymetazoline as nasal drops or using nasal bellows. No effect of decongestants on the ventilation of the paranasal sinuses was observed.