# Can I calculate the blood pressure and pulse based on a given blood loss

Is there a function, graph, guideline or rule where I can see how a change in blood volume changes other relevant values?

E. g. for every 1% of blood volume lost, heart rate rises 2 beats per minute, blood pressure decreases 120/80 mmHg. It probably isn't easy, but anything to give me a rough idea about how I can determine this will help.

Rough Calculations

Here you can find an example of what you are looking for.

Hemorrhagic shock is a condition of reduced tissue perfusion, resulting in inadequate blood oxygen and nutrients levels that are necessary for cellular function. Whenever cellular oxygen demand outweighs supply, both the cell and the organism are in a state of shock.

A hemorrhagic shock classification uses a patients body weight to determine the total volume of blood.

E.g. 7% of the a 70 Kg person is 4.9 kilograms. That can be converted to 4.9 liters of blood.

Next there are 4 stages of classification:

Class 1 - 15% of total blood volume - 750 mL Blood lost-
Class 2 - 15-30% of total blood volume - 50 mL to 1500 mL Blood lost-
Class 3 - 30-40% of total blood volume - 1500 mL to 2000 mL Blood lost-
Class 4 - >40% of total blood volume - no assigned value -

Attached here is a shock calculator that uses Systolic BP and Heart Rate/Pulse. A similar one can be found here.

Alternatively some blood loss calculations during birth may help.

These are some calculations:

• Calculated pregnancy blood volume = (0.75 ([maternal height (inches) X 50]+ [maternal weight in pounds X 25])
• Percent of blood volume lost = (Predelivery HCT- postdelivery HCT) / predelivery HCT.
• Calculated estimated blood loss (cEBL) = Calculated pregnancy blood volume X Percent of blood volume lost