What is the average pressure change with Valsalva (Valsalva maneuver)?

From the Guidelines

The average pressure change during the Valsalva maneuver is typically an increase of 30-40 mmHg in intrathoracic pressure. This increase in pressure is a result of the person forcefully exhaling against a closed airway, which causes a significant rise in intrathoracic pressure, affecting venous return to the heart, cardiac output, and blood pressure in a predictable pattern 1. The maneuver consists of four phases: initially blood pressure rises with increased intrathoracic pressure, then falls as venous return decreases, followed by a further drop when pressure is released, and finally a blood pressure overshoot as normal circulation resumes. This physiological response is used clinically to assess autonomic function, diagnose certain cardiac conditions, and evaluate baroreceptor sensitivity. Some key points to consider when performing the Valsalva maneuver include:

• The patient should be in the supine position
• The maneuver should be performed for 10 to 30 seconds
• The increase in intrathoracic pressure should be equivalent to at least 30 mmHg to 40 mmHg
• Carotid massage can be performed after the Valsalva maneuver if it is not successful
• The practice of applying pressure to the eyeball is potentially dangerous and has been abandoned. Individual responses may vary based on factors such as age, cardiovascular health, and technique used during the maneuver.

From the Research

Average Pressure Change with Valsalva

• The Valsalva maneuver results in an increase in intrathoracic pressure, which alters systemic and cerebral circulations significantly 2.
• The increase in intrathoracic pressure during the Valsalva maneuver incites a sequence of rapid changes in preload and afterload stress, with decreases in venous return to the heart and increases in peripheral venous pressures 3.
• Studies have shown that the Valsalva maneuver can produce an average pressure change of around 40 mmHg intrathoracic pressure, which is considered essential for the maneuver's effectiveness 4, 5.
• The pressure change during the Valsalva maneuver can vary depending on the method used to generate the pressure, with some studies suggesting that blowing into a 10 mL syringe can produce the required 40 mmHg pressure 4.
• The arterial pulse pressure response during the strain phase of the Valsalva maneuver has been proposed as a clinical tool for diagnosis, with studies showing that the aortic pulse amplitude ratio during the strain phase relates to baseline total arterial compliance and right heart filling pressures 6.

Factors Affecting Pressure Change

• The size of the syringe used to generate pressure can affect the pressure change, with a 10 mL syringe being the most appropriate size to achieve the recommended 40 mmHg pressure in some studies 4, 5.
• The plunger position of the syringe does not appear to make a difference in the pressure generated once the plunger is released 5.
• Individual variability in total arterial compliance and right heart filling pressures can also affect the pressure change during the Valsalva maneuver 6.