General Medical Information

Anterior Rhinomanometry

Thomas V. Mccaffrey

Anterior rhinomanometry is measurement of transnasal pressure at the anterior end of the nose. If one nostril is occluded, the pressure in that nostril equals the pressure in the nasopharynx because the occluded airway can be considered a rigid tube with its proximal end exposed to nasopharyngeal pressure. If a differential pressure transducer is inserted into the occluded nostril, the difference between atmospheric pressure and nasal pressure equals the pressure difference between the nasopharynx and the air. This is the driving pressure for airflow through the unobstructed nostril. With this method, resistance can be measured in only one nostril at a time. Total nasal resistance can be calculated with one of the parallel resistance formulas previously described.

Anterior rhinomanometry has inherent limitations. It cannot be satisfactorily used in cases of complete occlusion of one nasal passage. Nasal septal perforation or marked flaccidity of the septum makes the measurements unreliable. Anterior rhinomanometry also produces the nonphysiologic condition that all airflow must occur through one side of the nose during measurement. This means that even under resting conditions the measurements can be made only over short time periods because breathing may be restricted when respiration occurs through only one side of the nose. To overcome this difficulty and allow measurement of nasal resistance of both nostrils simultaneously, the method of posterior rhinomanometry was developed.