Experimental study on the perilymphatic pressure.

The hydrostatic pressure was successfully and accurately measured through the round window membrane of the cat over a wide pressure range and long duration using glass micropipets of 1-5 micrometer tip inner diameter and an active nulling pressure measuring system. The dynamic changes in perilymphatic pressure occurring after inhalation of different gas mixtures (5 percent CO2 and 95 percent O2/carbogen, 5 percent and 10 percent CO2 in room air) were recorded. The maximal oxygenation of the perilymph combined with minimal increase in pressure was achieved following inhalation of carbogen. The correlation between variations of pressure of the perilymph and of the systemic blood circulation shows that a regulatory system is present in the inner ear vessels. The pressure measuring system used has proven to have all the requirements that are needed for its use in humans.