The Valsalva Ratio is used to indirectly measure assess the blood pressure response to a Valsalva procedure, when direct arterial line measurement is not available. 

During the Valsalva maneuver, 4 phases are seen normally:

(1) phase 1: due to intrathoracic and intra-abdominal pressure there is aortic compression and an increase in peripheral resistance that results in a transient decrease in heart rate and an increase in blood pressure;

(2) phase 2: the increase in intrathoracic pressure results in a decrease in venous return and cardiac output, with a compensatory increase in heart rate

(3) phase 3: once the expiration stops, there is a further drop in blood pressure as the aortic compression stops;

(4) phase 4: the blood pressure increases as the cardiac output increases, resulting in a reflex bradycardia.


Patient Instructions: The patient exhales against a resistance of 40 mm Hg for 20 seconds.


Valsalva ratio =

= (longest R-R interval in phase 4) / (shortest R-R interval in phase 2)



• A ratio > 1:20 is normal.

• A ratio <= 1:20 is abnormal.

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