1. Non Imaging In Vivo
Plasma Volume

2. Plasma Volume Usually performed in conjunction with RBC Volume.
It also aids in the diagnosis of polycythemia
Occasionally it is performed for fluid balance

3. Plasma Volume
The technique for measuring plasma volume is similar to that for RBC Volume.
I125 RISA or HAS
I125 labeled to albumin
I125 has an energy of 32keV
Thus plasma volume is performed prior to RBC volume, Cr 51 has an energy of 320 keV

4. Technique for Plasma Volume
Recommended to administer Lugol’s solution 4-5 days, everyday prior to administration of I125
Prevents thyroid uptake of Iodine
Inject uCi in a 1.5 ml volume into the contralateral arm that samples will be drawn.
Count syringe in well counter to get CPM
Post injection count empty syringe
Withdraw three 15 ml blood samples at 15, 25, and 35 minutes post injection.
Centrifuge samples and divide into 5 ml aloquats.

5. Formula for Calculating PV
PL Volume = (Full syringe - empty syringe) x CF
Patient counts per sample drawn
CF = cpm/ml from 5 ml volume x 2000
cpm from syringe above well
CF is predetermined and maintained using specific procedure that may vary according to department or manufacturer.

6. Total Blood Volume
Total Blood Volume can be calculated after the plasma volume has been determined.
TBV = PL Volume
1 - (Hct x 0.97 x 0.91)
1 - (Hct x 0.97 x 0.91) is equal to the corrected PLcrit
The correction factor is needed due to the F-cell ratio. This is the relationship between venous hematocrit and the whole blood hematocrit. The hematocrit of smaller vessels differs from that of larger vessels.

7. Formula Calculations Plasma Volume (mL)= Net Standard Count x 4000
Net Plasma Count
WB Volume (mL)= Net Standard Count x 4000
Net Whole Blood Count
RC Volume (mL) = Whole Blood Volume - Plasma Volume
Radioactive Hematocrit = Red Cell Volume
Whole Blood Volume

8. Recalculating Plasma Counts
Approximately 10% of the injected plasma dose will leak out of the vascular pool per hour. Therefore a correction must be applied.
Take two separate blood samples form the patient and extrapolate the data.
10 minutes = 20.5k
20 minutes = 16.5k
Extrapolate to 0 time = 26k

9. Normal Findings
Males and females ml/kg

10. Condition Evaluations
Decreased PV
Addison’s Disease
Possible dehydration
Bacteremia
Bacteria take up part of plasma volume
Burns
Loss of fluid from burned area
Dehydration
Polycythemia
Shock, hemorrhage, and trauma
Sodium deficiency
Responsible for regulating water balance
Increased PV
Primary aldosteronism
Due to reduced blood flow to kidneys
Cushing’s Disease
Due to edema
Splenomegally
Can’t destroy damaged cells
Starvation
Waldenstrom’s macroglobulinemia
Malignant disorder, one symptom is bleeding disorders

11. Return to the Table of Content
Errors in PV
Not getting the nuclide in the vein
Wrong hematocrit
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