QBC®
Autoreader®...
QBC Autoreader
is a registered
trademark of
QBC Diagnostics, who produces and sells this
instrument line. It
was designed to
provide a simple means of performing a complete blood count, or
"CBC" in point of care settings. Results are available in about
seven minutes, and only about 70µ of blood are required. Over
20,000 QBC systems have been sold to date; it is used worldwide as
the best means of providing hematologic testing in point of care
settings.
In 1975, we developed the
concept of
Centrifugal Hematology®, where a small
sample of
whole blood is placed into a capillary tube and centrifuged at high
speed for a few minutes until all of the blood's components are
separated according to their density. The red blood cells occupy a
relatively large percentage of whole blood, about 35% - 50% in a
healthy person. The other corpuscular components of the blood,
white blood cells and platelets, separate from the red blood cells
and form a tiny, buff-colored layer between the red cells and the
plasma called the "buffy coat", which gives us the acronym "QBC",
for Quantitative Buffy Coat analysis. This layer is very thin
however, and for the last 50 years, no one had found a simple way
to measure it and the components it contains. Our invention was a
way of accomplishing this measurement.
The
QBC tube is a high-precision glass capillary which contains a
plastic float occluding 90% of the tube's bore. The density of the
float is such that it floats on the compacted red blood cell layer, and
the buffy coat components, which also float on this layer, are forced
into the annulus formed between the float and the tube. The layers are
therefore linearly expanded by about 10-fold, so that they are long
enough to easily measure. Reagents in the tube cause the different
layers to fluoresce different colors, and there are also reagents which
enhance the separation of the buffy coat components from the red blood
cells. Detailed information can be found in the tube
patent.
The
original reader for the QBC tube relied upon the operator's locating
the correct cell bands in the tube. This was relatively easy, but it
still required a small amount of training. The QBC Autoreader was
developed to simplify the reading procedure and to increase its
accuracy. Using this instrument, all that is required of the operator
is to remove the tube from the centrifuge and place it into the reader.
The computer-controlled optics then takes about 64,000 individual light
intensity measurements from various locations on the tube, using
several fluorescent and transmittance wavelengths. If the instrument
determines that the tube was processed properly, it then calculates the
cell counts. A more detailed explanation can be found in the Autoreader
patent.
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