General Medical Information

Clinical Technique of Rhinomanometry

Thomas V. Mccaffrey

Clinical rhinomanometry by means of the anterior technique. A nasal pressure catheter is used to measure transnasal pressure and a mask pneumotachograph to measure airflow. Pressure-flow relation and resistance are calculated with a computer at a standard pressure of 150 Pa.

This technique has been chosen for routine use because it is reproducible, can be performed with modest investment in equipment, and provides the data necessary for clinical evaluation of nasal resistance. Nasal airflow is measured as shown in Fig. 23.8 with a tightly fitting face mask applied to the face. The mask has a large central aperture connected to a low-resistance pneumotachograph flowmeter. The pneumotachograph converts the flow signal to a differential pressure that can be measured with an electronic pressure transducer.

Transnasal pressure is measured at the nostril (anterior rhinomanometry). The pressure-measuring catheter passes through the mask and is attached to the nostril with either tape or a soft sponge rubber bulb. It is important that a pressure-tight seal be achieved at the nostril. A second catheter is used to measure air pressure inside the mask. These two pressure catheters are attached to a differential pressure transducer to measure transnasal pressure. The outputs of the electronic pressure transducers are amplified and recorded as a pressure-flow diagram. Recording can be done with an oscilloscope, an X-Y plotter, or a computer equipped with appropriate interface electronics and software. Computer-based rhinomanometry systems meeting these specifications are produced by several manufacturers. A commercial unit chosen for clinical use should produce a pressure-flow diagram and standard nasal resistance. In addition to this basic function, several units provide features that may prove useful in particular circumstances.