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Because blood transfusions carry risks and because the blood
supply is limited, doctors try not to transfuse when possible. In some
cases, options other than blood product transfusions may be available.
Volume
expanders: When a patient has lost a lot of body fluids
but does not need red blood cells or other blood cells, shock may be
treated or prevented by solutions to keep the circulation going. The
most common solutions are normal saline (sterile water with a precise
amount of salt) and lactated Ringer's solution (saline plus other
chemicals). Other such solutions (called volume expanders)
include albumin, hydroxyethyl starch (HES), dextrans, and purified
protein fractions. All of these increase volume, but do not change the
number of blood cells.
Growth factors:
As described in the section "Why cancer patients might need blood
product transfusions," the body naturally makes hormone-like substances
called hematopoietic
growth factors that cause the bone marrow to make more
blood cells. Scientists have learned how to make some of these growth
factors in the lab to help people with low blood cell counts. Growth
factors can be used to boost red blood cell, white blood cell, or
platelet counts.
Growth factors may help patients who would otherwise need
transfusions. But they have some drawbacks that may limit their use in
some cases:
- Unlike transfusions, growth factors often take many days or
even weeks to raise blood counts, so they may not be useful in people
who need blood cell levels raised quickly, such as those with active
bleeding.
- People who have severe bone marrow disease may not respond
to the growth factors because they do not have enough blood-producing
cells in their bone marrow.
- Some growth factors might cause certain types of cancer
cells (such as lymphocytic leukemia, multiple myeloma, head and neck
cancer, breast cancer, cervical cancer, and some kinds of lung cancer
cells) to grow more quickly.
- Growth factors generally cost a lot more than transfusions.
Because of these drawbacks, certain growth factors are not
used in people whose treatment is expected to cure their cancer. And
when they are used, they are given for as short a time as possible.
Intra-operative
or post-operative blood salvage: Patients getting surgery
sometimes need transfusions to replace the blood lost during or after
the operation. In some cases this lost blood can be "salvaged" or saved
by collecting it with a special machine and giving it back into the
patient. Giving a person back his or her own (autologous) blood cuts
down on the need for transfusions from other donors. (Another type of
autologous transfusion is described in the "Blood
donation" section.)
Blood
substitutes: So far, there is no real substitute for human
blood. But researchers are working to develop a liquid that can carry
oxygen and replace blood, at least for a short time, in certain
situations. Products that are being tested include hemoglobin-based
oxygen carriers and perfluorochemical compounds. They can do some of
the work of red blood cells, such as carrying oxygen to tissues, but
cannot replace the many functions that human blood does. Of the
oxygen-carrying compounds that are being tested in U.S. clinical
trials, none has been approved by the FDA as of 2009.
Most blood substitutes are experimental and are rarely used.
They may be used as a short-term measure in patients whose religious
beliefs do not allow them to have blood product transfusions. They may
also help patients with rare blood types and those whose immune systems
would destroy donated blood. The substitutes may be used until matching
donated blood can be found, which in some cases might take several
days.
Last Medical Review: 07/13/2009
Last Revised: 07/13/2009
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