[The prevention of the ear barotrauma by positive pressure on nasopharynx].

Objective: To explore if the ear barotrauma could be prevented or not if the provided nasopharyngeal pressure is higher than the Eustachian tube resistance during the pressure increases in the hyperbaric chamber.

Method: Eight volunteers of healthy men were divided into 4 groups, with 2 persons in each group who were the tested and the control for each other. The positive pressure of 6kPa was given via mask to the nasopharynx of the tested, while the control took normal breath. The pressure in the hyperbaric chamber was increased by 5kPa with the velocity of 0.5kPa/s. No positive or negative measurement to open Eustachian tube was allowed for both tested and controls. The pressure within the tympanic cavity was measured. Similarly, the pressure in the hyperbaric chamber was increased by 20kPa with the same velocity. The tested were not allowed to adjust the Eustachian tube, while the controls could do so. The pressure within the tympanic cavity was measured once again.

Result: When 5 kPa in the hyperbaric chamber was reached, the pressure within the tympanic cavity of the tested and the control was -11.2 daPa and -168.6 daPa (P < 0.01), respectively. When 20 kPa was reached, the pressure within the tympanic cavity of the tested and the control was -8.3 daPa and -7.6 daPa (P > 0.05), respectively. Ear barotrauma could be prevented by providing positive pressure which is higher than the Eustachian tube resistance through mask to the nasopharynx.