Eustachian tube patency refers to how much the eustachian tube is open. The eustachian tube runs between the middle ear and the throat. It controls the pressure behind the eardrum and middle ear space. This helps keep the middle ear free of fluid.
The eustachian tube is normally open, or patent. However, ear infections, upper respiratory infections, or altitude changes can increase pressure in the ear. This can cause the eustachian tube to become blocked.
O'Reilly RC, Sando I. Anatomy and physiology of the eustachian tube. In: Flint PW, Haughey BH, Lund LJ, et al, eds. Cummings Otolaryngology: Head & Neck Surgery. 5th ed. Philadelphia, PA: Elsevier Mosby; 2010:chap 131.
Update Date 8/30/2014
Updated by: Neil K. Kaneshiro, MD, MHA, Clinical Assistant Professor of Pediatrics, University of Washington School of Medicine, Seattle WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.