Calculator Of Pulmonary Vascular Resistance (PVR)
What Is Pulmonary Vascular Resistance?
In order to get things started, let’s discuss what Pulmonary Vascular Resistance (PVR) is first. PVR reflects the change in the arteries that supply all the blood to the lungs. Whenever the pressure is abnormally high in the Pulmonary Vasculature, the right ventricle will have to work even harder to get the blood pumping through the pulmonic valve.
When this situation occurs, things can take a bad turn as the right ventricle could become diluted. As the right ventricle will be diluted, an additional volume will be needed to preload the needs of the left ventricle and this can complicate things.
How To Calculate Pulmonary Vascular Resistance
Calculating the Pulmonary Vascular Resistance is easy, just follow the steps mentioned.
Step 1: Enter Mean PA Pressure
Here you have to enter your mean pulmonary artery systolic pressure. A normal PA Pressure while resting is between 18-25 mm Hg. If we talk about the normal mean PA Pressure then it would be between 12-16 mm Hg.
Step 2: Enter Mean PAW Pressure
In the second step, you have to enter the pulmonary arterial wedge pressure (PAW Pressure). This is also known as the Pulmonary Artery Occlusion Pressure (PAOP). The PAW Pressure is very important because it gives you an indirect measure of the left ventricle.
This is the best way to check the cause of acute pulmonary edema.
Step 3: Enter Cardiac Output
In the last step, you just have to enter your cardiac output. This is the amount of blood the heart pumps in a minute.
What Will Be The Results?
Upon entering all the required information, you will be told about your Pulmonary Vascular Resistance. We already discussed that the normal PA pressure is between 12-16 mm Hg.
If there is too much pressure in the pulmonary arteries then this will cause pulmonary hypertension. The right ventricle will have to do more work and forcefully push the blood to the pulmonary vessels.
The Formula For PVR:
Pulmonary Vascular Resistance(dyne*sec/cm5) = ( 80 * (PAP – PCW) / C.O )
- PA = pulmonary artery pressure
- PCW = pulmonary Cap Wedge pressure
- C.O = Cardiac Output
What May Cause High PVR?
If you are experiencing High PVR, then it could be because of the following reasons:
- Vasoconstrictors
- Low PaO2
- High PaCO2
- Low blood pH levels
- Atelectasis
What May Cause Low PVR?
If you are experiencing Low PVR, then it could be because of the following reasons:
- Vasodilators
- High blood pH levels
- Low PaCO2
- Doing A Lot Of Exercises
References
https://www.ncbi.nlm.nih.gov/books/NBK554380/
https://en.wikipedia.org/wiki/Vascular_resistance
https://en.wikipedia.org/wiki/Pulmonary_wedge_pressure