This term is commonly used to designate any forced expiratory effort against a closed airway, but refers to two methods or tests.
The one is a method to test the patency of the Eustachian tube. It consists of having the patient take a forced expiration with the nose and mouth closed, thus increasing the pressure in the Eustachian tube. If the tubes are patent, air will be forced into the middle ear. A useful manoeuvre in «clearing» ears that have become blocked during a descent from altitude, or to match increasing water pressure on the outside. It was originally used to remove foreign bodies from the ear and to improve hyperacusis.
The technique originally described by Valsalva was to forcibly exhale against a closed glottis, by closing the vocal cords together, as in a cough. This causes increased intrathoracic pressure, slowing of the pulse, decreased return of blood to the heart, and increased venous pressure. This technique would not equalize the ears.
- ”If the glottis be closed after a deep inspiration, and a strenuous and prolonged expiratory effort be then made, such pressure can be exerted upon the heart and intrathoracic vessels that the movement and flow of the blood are temporarily arrested.”
- A. M. Valsalva:
De aure humana tractatus. Bologna, 1704. Page 184.