Hyperventilation in a motion sickness desensitization program.

Introduction: In motion sickness desensitization programs, the motion sickness provocative stimulus is often a forward bending of the trunk on a rotating chair, inducing Coriolis effects. Since respiratory relaxation techniques are applied successfully in these courses, we investigated whether these repetitive trunk movements by themselves may induce hyperventilation and consequently add to the motion sickness.

Methods: There were 12 healthy subjects who participated in our study. In the Baseline condition, subjects sat relaxed on the stationary chair. In the Hypervent condition, subjects performed voluntary hyperventilation (the level was prescribed). In two other conditions subjects rhythmically bent their trunk on a stationary chair (Tilt-Stat condition) and on a rotating chair (Tilt-Rot condition). In all conditions we measured respiratory and cardiovascular activity (heart frequency, tidal volume, end-tidal CO2, and respiration frequency).

Results: Of the 12 subjects, 9 had to stop prematurely in the Tilt-Rot condition because of moderate nausea. Except for heart rate in the Tilt-Rot condition, the measured physiological parameters in these subjects in the Tilt-Stat and Tilt-Rot conditions were not statistically different from the Baseline condition. Only in the Hypervent condition were significant differences observed, but no nausea.

Discussion: The findings show that hyperventilation is not the main cause of nausea during the Coriolis effects. We conclude that during the pilot desensitization program with Coriolis stimuli, measurement of cardiovascular and respiratory parameters is not necessary; however, in those cases that do not respond to the intervention, we recommend paying attention to respiratory parameters because hyperventilation does occur on an individual basis.