1. What is Plasma Volume?

Plasma volume is the fluid portion of blood that remains after removal of the cellular components. It's an important parameter in various clinical settings including fluid management, pharmacokinetics, and blood volume assessment.

2. How Does the Calculator Work?

The calculator uses the Plasma Volume equation:

Where:

• \( PV \) — Plasma volume (mL)
• \( TBV \) — Total blood volume (mL)
• \( Hct \) — Hematocrit (fraction between 0-1)

Explanation: The equation calculates the non-cellular portion of blood by subtracting the packed cell volume (hematocrit) from the total blood volume.

3. Importance of Plasma Volume Calculation

Details: Plasma volume assessment is crucial for fluid resuscitation, pharmacokinetic dosing, understanding blood viscosity, and managing conditions like hypovolemia or hypervolemia.

4. Using the Calculator

Tips: Enter total blood volume in mL and hematocrit as a fraction (e.g., 0.45 for 45%). All values must be valid (TBV > 0, Hct between 0-1).

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between plasma and serum?
A: Plasma is the liquid portion of blood containing clotting factors, while serum is plasma without clotting factors (after blood clots).

Q2: What are normal plasma volume values?
A: Normal plasma volume is approximately 40-50 mL/kg in adults, but varies with body composition and gender.

Q3: How is total blood volume estimated?
A: TBV can be estimated as 70 mL/kg for men and 65 mL/kg for women, or more precisely measured with radiolabeled albumin or dye dilution techniques.

Q4: When is plasma volume measurement important?
A: Critical in burns, shock, heart failure, pregnancy, and conditions with abnormal fluid distribution like sepsis or liver disease.

Q5: Does hematocrit always reflect plasma volume?
A: No, hematocrit can be affected by both red cell mass and plasma volume changes. A low hematocrit could mean increased plasma volume or decreased red cell mass.