The air caloric test. A parametric study.

We studied the normal air caloric response's intensity and variability. Intensities of "preliminary standard" (47 C, 25 C, 60 seconds, 10 liters/min) air and standard bithermal water responses were the same, but the air responses were more variable. Control experiments suggested that the tendency of the air stream to equilibrate toward ambient may account for much of air's relatively high variability. Increasing the air irrigation's duration, flow rate, and separation from body temperature increased response intensity. Air's test-retest variability decreased when flow rate and duration increased and when temperature approached ambient. Therefore, we suggested that irrigating temperatures be chosen as close to ambient as possible and duration and flow rate be made as large as possible. From a table equating air and standard bithermal water responses, we selected tentative clinical air irrigation parameters of 27.5 C, 45.5 C, 100 seconds, and 13 liters/min.