Blood Transportation: Validation and Modeling of Current Practices

1
Blood Transportation Validation and Modeling of
Current Practices I. M. Croteau1, R.C.
Bannerman2, J. Irizar2, J.A.W. Elliott2, J. P.
Acker1,3 1Canadian Blood Services, Research and
Development 2Departments of Chemical and
Materials Engineering and 3Laboratory Medicine
and Pathology, University of Alberta, Edmonton,
Alberta
Introduction In the daily operation of a
national blood system, transport of blood is an
essential part of the supply chain. American
Association of Blood Banks (AABB) standards and
Current Good Manufacturing Practices (cGMP)
regulations state that blood must be stored
between 1-10 ºC during transport, and that
containers and procedures must be validated
before implementation.
Measurements of the RBC temperature (Tin) show
that the internal box temperature remains
constant (at Tin0) until all the ice melts. After
this event, the temperature inside the box
changes with time in an exponential fashion.
Figure 2 Mathematical modeling can be used to
predict product temperature as a function of time
and external temperature
Objectives In this study, we assessed the
suitability of the standard transport containers
and procedures used at CBS Edmonton Centre.
Packing configuration with 7 units
Temperature Measurement Set-up
Results
Methods We used expired RBC units, current CBS
shipping boxes (J-82), ice packs and packing
protocols as defined in the Centre Operating
Procedures. Thermocouples were distributed
throughout the box and in the blood, and the
packed box was exposed to various temperatures,
mimicking actual conditions encountered during
transport. The temperature was continuously
monitored using a computer, and temperature
profiles were generated for a 72 hour period.
Because the packing protocols differ depending on
how many units are being packed and the
temperature at which they are transported, we
chose two representative packing configurations
Figure 1 Internal product temperature profiles
at different external temperatures 7 units
Mathematical Model Using standard heat transfer
equations, it can be shown that at any given time
t after the ice in the shipping box has
completely melted the product temperature (Tin)
is given by This equation can be used to
determine the value for a. The value of a is a
constant for the system and is independent of the
external temperature. This model agrees well with
the experimental results (Figure 2) and allows us
to predict the product temperature for any
external temperature Tout at any time.
Tin Tout (Tin0 Tout)e-at
freezing
cardboard
Conclusions
styrofoam
ice pack
Current CBS packing methods maintain RBC within
the mandated temperature range for up to 72 h
when the external temperature is between 10 - 22
C. This greatly exceeds the conservative limit
of 24 h transit time that CBS currently imposes
on its blood shipments. External temperatures
greater than 35 C, or less than the 10 C
significantly shorten the time in which RBC
products are within the 1 - 10 C range. As
expected, the shipping box and selected packing
configuration provided only marginal temperature
control when the external temperature was less
than 4 C. Measuring product temperature as a
function of time and external temperature
provided the necessary data for the development
of a predictive mathematical model. Modeling will
greatly improve transport practices by providing
accurate information on expected blood
temperatures at various ambient temperatures.
Having this model will assist in making
evidence-based decisions when to discard blood,
which will improve blood usage, and the overall
service that CBS provides to its customers.
Packing configuration for external temperature
gt15 C, 3 units
cardboard dividers
Table 1 Effect of external temperature on the
time for product to reach out-of-range
temperature and the product temperature at 24 h
storage
crushed paper
gel pack
blood units
thermocouples
cardboard
styrofoam
crushed paper
Packing configuration for external temperature
gt15C, 7 units
ice pack
cardboard dividers
blood units
thermocouples
mean SD