Journal of Clinical Apheresis 00:00–00 (2014)

Brief Report

Calculations in Apheresis
Marleen M. Neyrinck1 and Hans Vrielink2*; on behalf of “the Joint Task Force
for Education and Certification”
1
AZ Delta, Roeselare, Belgium
2
Sanquin Blood Supply, Amsterdam, The Netherlands

It’s important to work smoothly with your apheresis equipment when you are an apheresis nurse. Attention should
be paid to your donor/patient and the product you’re collecting. It gives additional value to your work when you
are able to calculate the efficiency of your procedures. You must be capable to obtain an optimal product without
putting your donor/patient at risk. Not only the total blood volume (TBV) of the donor/patient plays an important
role, but also specific blood values influence the apheresis procedure. Therefore, not all donors/patients should be
addressed in the same way. Calculation of TBV, extracorporeal volume, and total plasma volume is needed. Many
issues determine your procedure time. By knowing the collection efficiency (CE) of your apheresis machine, you
can calculate the number of blood volumes to be processed to obtain specific results. You can calculate whether
you need one procedure to obtain specific results or more. It’s not always needed to process 33 the TBV. In this
way, it can be avoided that the donor/patient is needless long connected to the apheresis device. By calculating the
CE of each device, you can also compare the various devices for quality control reasons, but also nurses/operators.
J. Clin. Apheresis 00:000–000, 2014. V C 2014 Wiley Periodicals, Inc.

Key words: extra corporeal volume; total blood volume; collection efficiency

INTRODUCTION CALCULATION METHODS

For the stem cell transplant program of the hospital Total Blood Volume
you are working, the hematologist is requesting a Let’s start with the TBV of a human being. If you
hematopoietic stem cell product with 4 3 106 CD34 ask people what the TBV of a human is, many will
positive cells per kilogram of the patients’ body weight answer this is approximately 5 L. However, this cannot
from a male autologous donor (height 1.80 m, and be right for everybody. Looking round in the world,
bodyweight 88 kg) suffering from multiple myeloma. you will understand that there must be a big difference
In the meanwhile, a 39-year-old woman was presented between a tall and a small man, and a very obese man
at the emergency unit with a platelet count of 20,000/ will have a totally different blood volume compared to
mL (20 3 109/L), an hemoglobin level of 6.0 g/dL (3.6 a tiny woman. And also for babies and young children
mmol/L), and a lactate dehydrogenase (LDH) level of
1,080 U/L. The diagnosis of thrombotic thrombocyto-
penic purpura (TTP) was suggested, and therefore From the Proceedings of the 35th Annual Meeting of the American
emergently a total plasma exchange (TPE) with at least Society for Apheresis and the 15th Biennial Congress of the World
one total plasma volume (TPV) is requested. Apheresis Association, San Francisco, California, April 2014
Abbreviations used: AC, anticoagulant; BMI, body mass index;
For a correct, but also safe performance of these BSA, body surface area; CBC, complete blood count; CE, collection
requested apheresis procedures without harming donors efficiency; CE1, collection efficiency type 1; CE2, collection effi-
and or patients, various calculations are needed. In this ciency type 2; ECV, extra corporeal volume; Hb, hemoglobin; Hct,
article, covering calculations in apheresis, we will dis- hematocrit; RBC, red blood cell; T, thrombocyte count; TBV, total
cuss how to calculate the total blood volume (TBV), blood volume; TPE, total plasma exchange; TPV, total plasma vol-
ume; TTP, thrombotic thrombocytopenic purpura
the TPV, the body surface area (BSA), and the extra
*Correspondence to: Hans Vrielink, MD, PhD, Sanquin Blood Sup-
corporeal volume (ECV). Besides that, we will discuss ply, Department of Transfusion Medicine, Plesmanlaan 125, 1066
the collection efficiency of the apheresis machines, and CX Amsterdam, The Netherlands. E-mail: h.vrielink@sanquin.nl
in relation to that, how to calculate the number of Received 20 June 2014; Accepted 1 July 2014
TBVs to process to collect a specific number of cells Published online 00 Month 2014 in Wiley Online Library
with an apheresis machine. Finally, we will describe (wileyonlinelibrary.com).
the hematocrit in relation to the hemoglobin levels. DOI: 10.1002/jca.21347
C 2014 Wiley Periodicals, Inc.
V
2 Neyrinck and Vrielink

muscle tissue. Depending on the group your patient is

belonging, the TBV must be calculated by multiplying
the patient’s body weight with the number as given in
Table I.
In other calculation methods, the age of the person
is the starting point. Similar to the formulas discussed
Fig. 1. Nadler’s formula to calculate the TBV of a human being
based on gender, height, and weight. above, the weight is multiplied with a number as given
in Table II. For adolescents and adults, a difference
between men and women is made. An adult man
weighing 80 kg will have a TBV of 80 multiplied with
TABLE I. Gilcher’s Rule of Fives 70, and therefore 5,600 mL. The female with the
Blood volume (mL/kg of body weight) same weight will have a TBV of 80 multiplied with
65, so 5,200 mL.
Obese Thin Normal Muscular
In the last calculation method discussed here, the
Male 60 65 70 75 body mass index (BMI) is taken into account. Based
Female 55 60 65 70 on the BMI the bodyweight of the person needs to be
Infant/child — — 80/70 — multiplied with a number as given in Table III to
achieve the TBV.
To calculate the BMI, the body weight in kilograms
TABLE II. Total Blood Volume in Relation to the Age should be divided by the square height in meters (Fig.
Approximate blood 2). So when you are 75 kg and having a 1.70 m, you
Age group volume (mL/kg) need to divide 75 by square 1.7, and will get a BMI of
26 kg/m2.
Premature infant, at birth 90–105
Term newborn infant 80–90
Children > 3 months 70–75
Adolescents and adults
Extra Corporeal Volume
Male 70 When somebody is talking about the ECV, he or
Female 65 she is talking about the volume of blood which is out-
side of the body. This is not only the anticoagulated
blood which is in the disposable, but also the volume
you can’t say that they will have a TBV of 5 L. of the collected blood component and the volume in
Because of the differences between the various human the tubes collected, for instance for laboratory tests.
beings, various formulas to calculate a more accurate For the safety of the donor or patient, it is suggested
TBV are published. Well known are Nadler’s formula that the ECV should be maximally 15% of the TBV.
and Gilcher’s rule of fives [1,2], but the approximate Therefore you absolutely need to know what, besides
TBV can also be calculated with various other formu- the TBV, the volume of the disposable you’re using is.
las. Nadler’s formula (see Fig. 1) is complicated, tak- Working with Cobe Spectra (Terumo BCT), you have
ing into account the height, weight, and gender of a to know that some specific disposable sets have a vol-
person. It should be noted that this formula cannot be ume of 285 mL. Assume that you will collect 300 mL.
used for children. It’s also important to know that most The ECV of the patient or donor will be therefore at
apheresis equipment is using Nadler’s formula to cal- least 285 1 300 mL is 585 mL. It must be realized that
culate the TBV. That’s also the reason that the 585 mL is 15% of 3,900 mL. Therefore, one should be
machine is asking to include gender, height, and alert to perform procedures with this disposable in chil-
weight of the donor or patient prior to a procedure into dren and smaller persons, having a lower TBV than
the parameter settings of the machine. 3,900 mL.
For children, Linderkamp et al. [3] published
already in 1977 model for the prediction of the blood
volume of the child depending on the age and gender Total Plasma Volume
of the child varying from 80 mL/kg for the newborn To calculate the TPV of a person, the TBV and the
to 70–75 mL/kg for the 11–14 years old child. hematocrit (Hct) are needed (see Fig. 3). The Hct is
In Gilcher’s rule of fives, first of all a choice for the volume percentage of red blood cells (RBCs) in
male, female, or child need to be made. After that, you the TBV. Females normally have an Hct between 36
need to take into account the physics of the person. and 46% (0.36–0.46 L/L). In males this is a little
There is a choice for obese, thin, normal, or muscular. higher namely 44–53% (0.44–0.53 L/L). When there
The reason for the difference is secondary to the differ- is, for instance, an Hct of 35%, the blood will consist
ence in vascularization between adipose tissue and of 35% of RBCs and 65% of plasma.
Journal of Clinical Apheresis DOI 10.1002/jca
 Calculations in Apheresis 3
TABLE III. Method to Calculate the Total Blood Volume collection volume since the relative plasma volume in
(TBV) in Relation to the Body Mass Index (BMI) donors with a higher Hct is lower. Therefore you
BMI < 18.5 BMI 18.5–24.9 BMI 25–29.9 BMI >30 will have a longer procedure time. On the other
hand, in patients we will collect not a fixed volume
Blood 80 mL/kg 70 mL/kg 65 mL/kg 55 mL/kg
volume of plasma, but for instance one TPV. Therefore, there
will be a longer procedure in patients with a lower
Hct, and also a higher volume of replacement fluids
is needed.

Collection Efficiency
Fig. 2. Formula to calculate the body mass index (BMI). When there is a need to collect a specified number
of cells with an apheresis procedure, for instance 4 3
106 CD34 positive cells per kilogram of the patient’s
body weight, you would like to know how much of the
donor’s/patient’s blood you need to process. Therefore,
Fig. 3. Calculation method for the total plasma volume (TPV). it is good to know the collection efficiency (CE) of the
machines you are using. This parameter can also be
used for quality aspects of your collection but also
within your collection facility. For instance, the various
By knowing the TBV and the Hct, the TPV of the collection machines, but also the various operators can
patient can be calculated. Since the plasma volume of be compared to each other.
the patient is higher in patients with a lower Hct, a In principle, the CE is the number of cells that is
higher volume of plasma need to be exchanged and collected from the total number of cells processed by
therefore more units of plasma or plasma replacement the apheresis machine. To simplify this, when for
fluids are needed. In case the patient has a TBV of instance 100 cells are processed by the machine and 50
5,000 mL and has an Hct of 50% there will be of 100 cells are collected in the storage bag, we have a
2,500 mL of plasma, and in case of an Hct of 30% CE of 50%.
3,500 mL. This will give a difference of 1,000 mL, In Figures 4 and 5, two formulas to calculate the
which is really influencing the duration of a plasma CE for a platelet collection are given. Of course the
exchange procedure. same formulas can be used for all different blood cells,
Also in a plasma collection in blood donors, the Hct for instance for CD34 positive cells. In the formula
is influencing the procedure, especially the procedure given in Figure 4, you need to know the platelet count
time. In blood donors, a fixed volume of plasma is col- prior and after the apheresis procedure and of course
lected with a plasmapheresis procedure. In the donor sit- also the number of platelets in the collection bag. Fur-
uation, usually discontinuous apheresis systems are
ther you need to know the processed absolute blood
used. In these systems, the plasma will be separated
volume, but note, this is the processed volume without
from the blood cells and stored in the plasma collection
the anticoagulant (AC) volume. With all these data, the
bag. Prior to the return of the cells to the donor, they are
efficiency with this machine for this procedure can be
stored temporarily in a reservoir. Let’s assume that this
reservoir can contain 200 mL. Of course, the blood in calculated accurately. Usually, this collection efficiency
the reservoir isn’t purely cells, but has an Hct of 80%, is named the CE1.
so there will be approximately 160 mL of RBCs in the When the post-count of the platelets isn’t known,
completely filled reservoir. In case the donors’ Hct is the 2nd formula (see Fig. 5) can be applied. However,
50%, you can collect 120 mL of plasma before a com- since the cell count during a procedure can change, the
plete filling of the 200 mL reservoir. At that time we CE calculated with the formula given in Figure 5 is
will have processed 320 mL of anticoagulated whole less accurate than calculation given in Figure 4. Usu-
blood, because 50% of this 320 mL is 160 mL of RBCs. ally, this collection efficiency is named the CE2.
With this 200 mL of blood with an 80% Hct in the reser- It’s totally not needed to process always 33 the TBV
voir, you need to process 400 mL of anticoagulated volume or always standard 15 L of the donor’s or
whole blood in donors with an Hct of 40%, because patient’s blood. Knowing the mean CE of your machines
40% of 400 mL is again the same 160 mL of pure RBCs in a cell specific collection, you can also calculate what
in the reservoir. volume of blood should be processed to collect a specific
So when the donors’ Hct is higher, you need to number of specified cells. With the formula as given in
process more donor blood to achieve the same Figure 6 you can calculate this for instance for CD34
Journal of Clinical Apheresis DOI 10.1002/jca
4 Neyrinck and Vrielink

tion for the Hb in mmol/L is more difficult. You can cal-

culate the Hct by multiplying your Hb by 10, than divide
Fig. 4. Formula to calculate the collection efficiency 1 (CE1). by 2 and from this outcome you should subtract 2.
Let’s make this some what more concrete. You have
a Hb of 16.1 g/dL (10 mmol/L).
To calculate the Hct, you multiply the 16.1 by 3
and you will have a result of 48%.
Is your Hb in mmol/L, you need to multiply this 10
Fig. 5. Formula to calculate the collection efficiency 2 (CE2).
mmol/L by 10 and divide the outcome of 100 by 2
(550) and subtract 2, and also here your Hct is 48%.

SUMMARY
In summary, in this article, we discussed the TBV
Fig. 6. Calculation methods for the TBV to be processed to collect of a human being and the awareness that this varies
a specific number of CD34 positive cells.
per person. We learned to calculate the TPV from the
TBV based on the hematocrit. We mentioned the total
TABLE IV. CBC Results of Patient John Smith body mass index and the importance to know what the
Hemoglobin 9.7 g/dL 5.9 mmol/L extra corporeal blood volume during a procedure is.
Hematocrit 19% 0.19 L/L Further we calculated the CE of the apheresis machine
Platelets 159,000/mL 159 3 109/L and from that the total volume to be processed to
Leukocytes 8,800/mL 8.8 3 109/L
CD34 positive cells 23.6/mL 23.6 3 106/L
achieve a specific number of cells with an apheresis
procedure. Finally we mentioned the calculation of the
hematocrit from the known hemoglobin level.
positive cells. For instance, the hematologist is request- Having said all this, we go back to our patients. Mr.
ing 3 3 106 CD34 positive cells per kg of the patients’ John Smith is a multiple myeloma patient. An adequate
body weight, which is 65 kg. So you collect in total 3 3 number of CD34 positive cells needs to be collected
65 5 195 3 106 CD34 positive cells. The CD34 cell for a hematopoietic stem cell transplant. He will be his
count in the donor is 35 3 106/L and a mean CE of your own donor. Using Nadlers’ formula, you can calculate
machine is 45%. Therefore to collect sufficient CD34 that Mr. Smiths’ TBV is approximately 5,600 mL.
positive cells, you need to process 195/(35 3 Based on the outcome of the complete blood count of
0.45) 5 12.381 mL of uncoagulated blood of the donor. this morning (see Table IV), you will calculate that
By using these kinds of formulas and calculating the vol- with your machines (mean collection efficiency of
45%) you need to process 33 L (almost 63 the
ume to be processed it can be seen in advance that one
TBV) of the donors’ blood to achieve the 4 3 106
procedure will not be sufficient and that a second and/or
CD34 positive cells per kilogram of the patient’s body
third procedure is needed.
weight. So you need at least two consecutive collection
procedure days to achieve the requested goal.
Hemoglobin and Hematocrit Our second patient is Mrs. Jones. Using Nadlers’ for-
mula, you can calculate, based on the height and the
Hemoglobin (Hb) is the iron-containing oxygen-
body weight, that Mrs. Jones’ TBV is 4,300 mL. You
transport protein in the RBC. Depending on the center
already heared from the physician that the hemoglobin
or country your working, the units you’re working with
level is 6.0 g/dL (3.9 mmol/L). With the formula
for the Hb level in human being can vary. Some work
described above, you know now that the hematocrit will
with gram per deciliter (g/dL) and others with milli-
be 18% (0.18 L/L), and therefore the TPV will be
mols per liter (mmol/L). It’s not that difficult to know
3,500 mL. Therefore, in the plasma exchange proce-
what the Hb will be when for you usual unit is not
dure for this TTP patient you need to exchange between
used, because 1 g/dL equals to 0.6206 mmol/L, and the
3.5 and 5 liters of plasma [4].
other way around, 1 mmol/L equals to 1.61 g/dL.
Besides the Hb, we also have the hematocrit (Hct).
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Journal of Clinical Apheresis DOI 10.1002/jca