Clearance of the eustachian tube under negative middle ear pressure

The influence of negative middle ear pressure on clearance function of the eustachian tube was examined in cats. In experiment 1, mucociliary clearance of a colored fluid through the eustachian tube was examined under negative middle ear pressure. The results showed that negative pressure affects mucociliary clearance only at quite high levels. In experiment 2, muscular clearance of fluid under negative middle ear pressure was investigated during electrical stimulation of the tensor veli palatini muscle. It was found that massive discharge of fluid by the muscle activity occurs only when the negative middle ear pressure was low. For massive discharge of effusion, muscular clearance is more effective than ciliary clearance. The findings suggest that it is clinically important to maintain middle ear ventilation.