Valsalva maneuver

From Free net encyclopedia

A Valsalva maneuver is any attempted exhalation against a closed glottis or against a closed mouth and nose. It is also known as Valsalva's test and Valsalva's method, after Antonio Maria Valsalva, a famous Italian anatomist. Valsalva's initial intention for the maneuver was as a method of expressing pus from the middle ear.

A Valsalva maneuver performed against a closed glottis results in a drastic increase in pressure in the thoracic cavity, the airtight section of the torso that houses the lungs and heart. In normal exhalation, the diaphragm relaxes, pushing up and into the thoracic cavity. This increases pressure in the cavity and forces the air out of the lungs. However, when the air cannot escape, as when the glottis is closed in a Valsalva maneuver, pressure simply continues to build inside the thoracic cavity until the diaphragm relaxes or the air is allowed to escape. This reduces the amount of blood flow into the thoracic cavity, especially in the veins leading to the right atrium of the heart.

General uses

The Valsalva maneuver is used as a pressure equalization technique by scuba divers and airplane passengers to avoid barotrauma and discomfort inside their ears when they move to a higher pressure breathing environment.

A person using this technique pinches his or her nose, closes his or her mouth, and tries to exhale. The technique works by raising the pressure in the throat so that a small volume of air moves from the throat to the ears through the Eustachian tubes which connect them.

People inadvertently perform closed-glottis Valsalva maneuvers when blowing up a balloon or "bearing down" for a bowel movement. If the pressure is held for long enough, one will begin to feel as if pressure were building in the head, followed by dizziness and lightheadedness upon release of the maneuver.fr:Manœuvre de Valsalva