Valsalva

Valsalva maneuver, named after the Italian physician Antonio Maria Valsalva, describes a forced exhalation against a closed mouth and pinched nose. The action raises intrathoracic pressure and alters venous return to the heart, producing characteristic cardiovascular responses that are useful in both diagnosis and treatment.

Physiologically, the maneuver is described as a four-phase process. Phase I involves a brief rise in arterial pressure as the chest and aorta are mechanically compressed. Phase II features reduced venous return and a fall in arterial pressure, often with reflex tachycardia. Phase III occurs on release, causing a short drop in blood pressure. Phase IV shows a rebound increase in blood pressure with a reflex bradycardia. The sequence reflects changes in preload, afterload, and autonomic tone, mediated mainly by baroreceptor pathways.

Clinical uses include assessment of autonomic function, particularly cardiovagal responses, and calculation of the Valsalva ratio during tilt-table testing. The maneuver is also used to terminate or slow certain supraventricular tachycardias by increasing vagal tone. In otolaryngology and aviation, a modified Valsalva helps to equalize middle ear pressure during pressure changes.

Safety and contraindications should be noted. The maneuver increases intracranial and intraocular pressures and can be hazardous in patients with raised intracranial pressure, glaucoma, severe cardiovascular compromise, or acute ear or sinus infection. It should be performed under appropriate clinical guidance, and variations or alternatives may be used depending on the medical context.