Anterior and posterior rhinomanometry primarily differ in the location of the transducer used to measure posterior pharyngeal pressure. Anterior rhi-nomanometry may be affected by deformation of the anterior nares and/or valves, nasal cycling, and by the instrument inserted to the nares for measurement. Posterior rhinomanometry does not have Viagra Australia official site these disadvantages, but is more expensive and requires more patient cooperation, with approximately 15% of subjects being unable to place the probe properly in the oral cavity. Despite these drawbacks, it is an excellent tool for determining the degree of airflow obstruction before and after surgical procedures and medical interventions (Table 4). It may also help to distinguish functional causes of upper airway obstruction from structural causes. For example, decongestants or exercise will improve airflow due to inflammation and vascular engorgement, whereas fixed abnormalities such as concha bullosa do not change after exercise or decongestants. Rhino-manometric measurements before and after treatment with a potent intranasal decongestant agent are recommended.
Acoustic Rhinometry
Acoustic rhinometry, a technique used widely in Europe, evaluates nasal obstruction by analyzing reflected sound waves introduced through the nares. It is generally easy to perform, is noninvasive, and does not require patient cooperation like many of the other evaluation procedures. It produces an image that reflects variations in the cross-sectional dimensions of the nasal cavity and closely approximates nasal cavity volume and minimal cross-sectional area for Buy Viagra Online. The short measurement period (10 s) makes this procedure easy to use in all patients, even children. The results of parallel determinations by acoustic rhinometry and rhinoma-nometry are comparable; however, nasal airway resistance cannot be easily computed from acoustic rhinometry data. Acoustic rhinometry has been reviewed in detail elsewhere.