Transcript Red Cell Volume - people.vcu.edu

Red Cell Volume
Pictorial Guide To The RCV
Procedure
Blood Volume Determination
The fundamentals of the dilution principle are
based on the following equation and hold true for all
dilution type equations that are applied in vitro:
V = Q
C
V = Volume
Q = Dose of the activity injected
C = Sample of the activity extracted
Applications of formula
V = Q/C
Hence, by adding a known quantity of activity to an
unknown volume of liquid and extracted a sample from
the unknown liquid you can determine its volume.
This formula is the basis for all volume determinations
in nuclear medicine.
Equipment used Cr-51 Tag
 Identify materials for the






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tagging of the RBCs
ACD vial
Shielding for ACD vial
Ascorbic Acid
Cr-51
Shielding
Cups for Standard Prep
Tubes for collecting RBCs
Preparing the syringe
 Wet a 20 cc syringe
with 1 ml of ACD
Solution.
 Using a 19 gauge
needle take the syringe
and draw 15 ml of
whole blood from the
patient.
Preparing the blood for the tag
 After drawing 15 ml
of whole blood from
the patient slowly add
it to the ACD vial
Starting the tag
 Add 100 uCi of Cr-51
to the ACD vial
Mixing the contents
 Mix the contents in the
ACD vial after adding
contents
 Mix every 5 to 10
minutes after that for a
total of 30 minutes
Ampule of ascorbic acid
 Concentration of
ascorbic acid is 1000
mg/2ml
 Calculate a 50 mg
dose
Reducing the Cr-51
 After 30 minutes add
30 - 50 mg of ascorbic
acid
 Mix contents again
 This reduces the Cr-51
and locks it into the
RBCs
End Product - Labeled RBCs
 After waiting 5
minutes 10 ml is
withdrawn from the
ACD vial
 Labeled RBCs are
then injected into the
patient
 Dose circulates for 10
to 20 minutes before
withdrawing WB2
Preparation of Standards
 While the labeled
RBCs are circulating
in the patient make
your standard.
 99 ml of water is
measured twice and
added to two separate
containers.
The Standards
 1 ml of WB is added to
99 ml of H2O
 After collecting a 4 ml
blood sample it is spun
down and 1 ml of
Plasma is drawn off and
added to 99 ml of H2O
 2 - 4 ml samples from
each container is drawn
up to a test tube and
labeled WB1 and Pl1
Patient’s Whole Blood
 Using a 19 gauge needle
with a 20 ml syringe
approximately 20 ml of
whole blood is drawn
from patient
 4 - 4ml purple top tubes
are used to collect 4
equal samples of whole
blood.
 Three of these tubes are
spin down to collect 4
ml of plasma for Pl2
What about the other tubes?
 1 - 4 ml tube of patients
whole blood is collected
for WB2
 1 - 4 ml blood sample is
collected from ACD vial
to determine Hct1 from
ACD vial
 1 - 4 ml blood sample is
collected from pts to
determine Hct2
Time to count
 Count bkg for 20
minutes
 Count all tubes for 20
minutes
 Take them to the
formula
Now just plug in the counts
WB1 - Pl1(1 - Hct1)
x Hct2 x 1000 = RCV in ml
WB2 - Pl2(1 - Hct2)
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