Contemporary rhinomanometry.

By contrast with the smoked drum and other mechanical systems, modern electronic rhinomanometers provide superior sensitivity and frequency response. They enable accurate measurement of nasal airflow resistance to be made and are commercially available. In addition to a rhinomanometer, nasal airflow measurements require a face mask fitted with a flow measuring device (a pneumotach connected to an electronic differential pressure transducer) or, as an alternative to a face mask, a head-out body plethysmograph. Concurrently with nasal respiratory airflow, transnasal pressures between the nostril and pharynx are measured via nasal or oral tubing by a second differential pressure transducer. The transduced electronic analogue signals are digitized, and nasal airflow resistances are computed from the ratio between transnasal pressure and airflow. At a single sitting, a series of measurements with modern rhinomanometry can determine (1) the response to topical decongestant of the mucovascular contribution to nasal airflow resistance at the time of examination and (2) in the decongested nose, the presence, side, site, and severity of structural obstruction. Rhinomanometry is not "medically necessary" in assessment of all cases of nasal obstructive symptoms, but, in many situations, it can provide valuable objective information in compliance with the requirements of evidence-based medicine. This article includes a table listing situations in which rhinomanometry is particularly useful.