Air Fx

With Air Fx, you aim the air stream at the eardrum through your patient's external auditory canal. This creates a differential in ear temperatures, which causes a convection current in the ear being stimulated. Depending on the temperature of the stimulus, this either excites or inhibits the cupula, thus initiating the vestibular-ocular reflex (VOR), which causes caloric nystagmus. If you combine Air Fx with Interacoustics' VNG software, you can record and observe these side-to-side eye movements from the moment you start the caloric test.

Before performing a caloric test, it is important to inspect your patient's ear canal, as perforations or similar disorders may impede the test. For this purpose, Air Fx includes an otoscope. The irrigator also features a bright white LED, which illuminates the tympanic membrane without obstructing the airflow or view of the tympanic membrane. Finally, Air Fx features a resistance temperature detector (RTD) temperature sensor at its speculum to ensure an accurate and stable air temperature.

Caloric irrigation stimulates each vestibular end organ independently. As such, you can determine whether one end organ is weaker than the other or whether neither end organ is providing sufficient vestibular information to the brain. Thus, analyzing the response of each vestibular end organ allows you to assess the symmetry of the bilateral peripheral vestibular system.

Caloric stimulation can identify several abnormalities, such as unilateral weakness or directional preponderance present in asymmetrical caloric responses. The asymmetry is reflected by a difference in the amount of right-beating nystagmus compared with the amount of left-beating nystagmus. A bilateral weakness presents in symmetrical, but weak, caloric responses from both ears.