Pressure equilibration of the middle ear during ascent

The capacity to equilibrate the middle ear with the ambient pressure depends on different factors. During descent when the clearing is active the technique is the most important factor. During ascent when the clearing is passive the status of the mucosal membranes lining the eustachian tube is believed to be of major importance. Horizontal position in air and head-up immersion in water to the neck have in earlier investigations shown to decrease the passive clearing capacity compared to vertical, head-up position in air. It was found in this study that a change from head-up position in water to prone in water did not change in clearing capacity, while head-down position in water gave a significant decrease of the clearing capacity. The results are discussed in terms of venous pressure in the neck veins in the different positions.