Question

Assume that the ratio of total blood volume in liters to total body weight in kg is 0.07 and the blood consists of plasma and RBCs only. The plasma volume of a 70-kg man with 52% hematocrit is _____ L (rounded off to two decimal places).

Hint:

When estimating plasma volume, subtract hematocrit from 1 to determine the plasma fraction.

Answer 1

Correct Answer: 2.29

Given:
- Ratio of total blood volume = 0.07
- Total body weight = 70 kg
- Hematocrit = 52%
Total blood volume: \[ \text{Blood Volume} = 70 \times 0.07 = 4.9\ \text{L} \] Plasma volume is the part of blood excluding the RBCs: \[ \text{Plasma Volume} = \text{Blood Volume} \times (1 - \text{Hematocrit}) \] \[ \text{Plasma Volume} = 4.9 \times (1 - 0.52) = 4.9 \times 0.48 = 2.352\ \text{L} \] Thus, \[ \boxed{2.29\ \text{to}\ 2.41} \] Final Answer: 2.29–2.41 L