The Valsalva Maneuver and the Vagus Nerve
By Richard N. Fogoros, MD
The Valsalva maneuver is a breathing technique that involves pinching your nose and breathing out forcefully with your mouth closed. This can help slow your heart rate and temporarily increase pressure in the throat, sinuses, and inner ears.
The Valsalva maneuver has several practical uses in medicine and in everyday life. For instance, it is often used to cure hiccups and help scuba divers adjust to water pressure changes. Cardiologists often recommend the Valsalva maneuver to patients who have episodes of certain kinds of supraventricular tachycardia (SVT). The technique can stop the arrhythmia when it occurs.
This article will explain how to do the Valsalva maneuver, the effects it has on the body physiologically, and its medical and non-medical uses.
How the Valsalva Maneuver Is Done
The Valsalva maneuver (which is named after A.M. Valsalva, who first described it 300 years ago as a way to expel pus out of the middle ear), is performed by attempting to exhale forcefully against a closed airway.
The Valsalva maneuver can be done by keeping your mouth closed and pinching your nose while trying to exhale forcefully. This maneuver immediately increases pressure in the sinuses and inner ears.
The maneuver must be maintained a little longer in order to also achieve an increase in vagal tone, at least for 10 to 15 seconds.1
What It Does
The Valsalva maneuver greatly increases pressures inside the nasal sinuses, and especially in the chest cavity. In simple terms, the elevated chest pressure stimulates the vagus nerve and increases vagal tone.1
However, the Valsalva maneuver actually produces a fairly complex series of physiological events that doctors have employed over the years for several purposes.
Phases of the Valsalva Maneuver
- From a physiological standpoint, a 15-second Valsalva maneuver has four distinct phases:
- Phase 1: Acutely blowing against a closed airway increases the pressure inside the chest cavity, which immediately pushes blood from the pulmonary circulation into the left atrium of the heart. So, for a few seconds the amount of blood being pumped by the heart increases.
- Phase 2: The amount of blood being pumped by the heart suddenly drops. This drop in cardiac output occurs because the increased pressure in the chest cavity prevents any more blood from returning to the chest from the rest of the body, and therefore from returning to the heart. To compensate for this drop in cardiac output, the body’s blood vessels constrict, and blood pressure rises. This elevated blood pressure continues for the duration of the Valsalva maneuver.
- Phase 3: Occurs immediately upon resumption of normal breathing. The pressure within the chest suddenly drops, and the pulmonary circulation re-expands and fills with blood again. However, during this re-expansion of the chest (which lasts for 5-10 seconds), the cardiac output may drop further.
- Phase 4: The blood flow to the heart and lungs returns to normal, as does the cardiac output and blood pressure.
Doctors find the Valsalva maneuver useful in distinguishing among various kinds of valvular heart disease.1 Most heart murmurs will diminish during phase 2 of the Valsalva maneuver since less blood is flowing through the heart at this time. But the murmurs associated with both mitral valve prolapse and hypertrophic cardiomyopathy will often increase during phase 2 of the Valsalva maneuver. (With these two kinds of heart problems, less blood in the heart actually increases the amount of obstruction to blood flow, so the murmurs tend to become louder.)
Speaking more practically, the chief medical use of the Valsalva maneuver is to suddenly increase vagal tone (which also occurs mainly during phase 2). Increasing vagal tone slows the conduction of the cardiac electrical impulse through the AV node, and this transient slowed conduction is quite useful in terminating some types of SVT (in particular, AV-nodal reentrant tachycardia and atrioventricular reentrant tachycardia).2
This means that people who have recurrent episodes of these particular kinds of SVT (which are the two most common types) are often able to quickly and reliably stop the arrhythmia whenever it occurs by employing the Valsalva maneuver.
The Valsalva maneuver may help doctors to detect injury to the cervical spine. This maneuver transiently increases intraspinal pressures — so if there is nerve impingement (for instance, as a result of a damaged intervertebral disc), any pain being caused by the injury may momentarily increase.
Urologists may use the Valsalva maneuver to help them diagnose stress incontinence since the elevated abdominal pressure this technique produces can provoke urinary leakage.
There are also some non-medical uses of the Valsalva maneuver. The Valsalva maneuver is commonly used by scuba divers during descent, to equalize the pressures in the middle ear with the elevated ambient pressures underwater.
And many people find that they can get rid of an episode of hiccups by performing a Valsalva maneuver.3 This use of the Valsalva maneuver probably relies on increasing vagal tone, so the effort should be continued for 10 to 15 seconds. It may be that this is the most common and the most practical application of the Valsalva maneuver.
A Word From Verywell
The Valsalva maneuver is a method of transiently increasing pressure within the sinuses and middle ears, and of increasing vagal tone. It has practical applications in the practice of medicine and in daily life.