Washout of 133-xenon as an objective assessment of paranasal sinus ventilation in endoscopic sinus surgery.
Endoscopic sinus surgery (ESS) is today a common method for the treatment of chronic rhinosinusitis. Assessment of the results has been based mainly upon subjective evaluation, and only a few reports present objective measurements. In the present study, the 133-xenon washout technique was used for preoperative and postoperative evaluation of paranasal sinus ventilation in 12 patients selected for ESS. The postoperative half-times (T1/2) of 133-xenon washout were lower in the sinuses with abnormal preoperative half-times (T1/2), especially in the maxillary sinuses, where the postoperative T1/2 was 44 (22 to 150) minutes (median and quartiles, Q1-Q3) as compared with a preoperative T1/2 of 202 (94 to 278) minutes. The postoperative evaluation included a questionnaire and a follow-up visit with endoscopy and measurements of nasal nitric oxide. The results showed that patients who declared a marked reduction in symptoms exhibited significantly improved sinus ventilation. However, no direct correlation was found between improvement in ventilation and symptom improvement. Nine of the 12 patients showed improvement on endoscopy, and these patients also exhibited improved sinus ventilation. The postoperative nasal nitric oxide levels were within the normal range in 11 of the 12 patients; the other patient showed pathological T1/2 values for all paranasal sinuses. The 133-xenon washout technique is thus a method that can be used for objective evaluation of the ventilation of the paranasal sinuses before and after ESS procedures. However, the technique cannot be used to evaluate sinuses with totally obstructed ostia or postoperative sinuses with very wide neoostia, as rapid washout may lead to no activity remaining at the time of measurement.