Blood plasma: Difference between revisions
NawlinWiki (talk | contribs) m Reverted edits by 165.138.231.200 (talk) to last version by 60.234.159.16 |
|||
| Line 20: | Line 20: | ||
==Dried plasma== |
|||
[[Image:Britain_and_us_plasma_packages_wwii.jpg|thumb|300px|Dried plasma packages used by Britain and US military during WWII]] |
|||
Dried plasma was developed and first used during [[World War II|WWII]]. Prior to the United States involvement in the war, liquid plasma and whole blood were used. The "Blood for Britain" program during the early 1940s was quite successful (and popular stateside) based in part on Dr.[[Charles Drew]]'s contribution. A large project was started in August 1940 to collect blood in New York City hospitals for the export of plasma to Britain. Dr. Drew was appointed medical supervisor of the "Plasma for Britain" project. His notable contribution at this time was to transform the test tube methods of many blood researchers, including him, into the first successful mass production techniques. |
|||
Nonetheless, the decision was made to develop a dried plasma package for the armed forces because it reduced breakage and made transport, packaging, and storage much simpler. <ref> http://history.amedd.army.mil/booksdocs/wwii/blood/chapter1.htm Transfusion before World War I]</ref> |
|||
The resulting Army-Navy dried plasma package came in two tin cans containing 400 cc bottles. One bottle contained enough distilled water to completely reconstitute the dried plasma contained in the other bottle. In about three minutes, the plasma would be ready to use and could stay fresh for around four hours. <ref> [http://history.amedd.army.mil/booksdocs/wwii/blood/chapter7.htm Plasma Equipment and Packaging, and Transfusion Equipment]</ref> |
|||
Following the Plasma for Britain project, Dr. Drew was named director of the Red Cross Blood Bank and assistant director of the National Research Council, in charge of blood collection for the United States Army and Navy. Drew argued against the armed forces directive that blood/plasma was to be separated by the race of the donor. Dr. Drew argued that there was no racial difference in blood and that the policy would lead to needless deaths as soldiers and sailors had to wait for "same race" blood. |
|||
By the end of the war the American Red Cross had provided enough blood for over six million plasma packages. Most of the surplus plasma was returned stateside for civilian use. [[Serum albumin]] replaced dried plasma for combat use during the [[Korean War]].<ref>[http://history.amedd.army.mil/booksdocs/wwii/blood/chapter11.htm The Plasma Program]</ref> |
|||
== References == |
== References == |
||
Revision as of 17:50, 16 October 2006
Blood plasma is the liquid component of blood, in which the blood cells are suspended. Plasma is the largest single component of blood, making up about 55% of total blood volume. Serum refers to blood plasma in which clotting factors (such as fibrin) have been removed. Blood plasma contains many vital proteins including fibrinogen, globulins and human serum albumin.
Plasma resembles whey in appearance (transparent with a faint straw colour). It is mainly composed of water, blood proteins, and inorganic electrolytes. It serves as transport medium for glucose, lipids, amino acids, hormones, metabolic end products, carbon dioxide and oxygen. (The oxygen transport capacity and oxygen content (CaO2) of plasma is much lower than that of the hemoglobin in the red blood cells; the CaO2 will, however, increase under hyperbaric conditions.) Plasma is the storage and transport medium of clotting factors. Its protein content is necessary to maintain the oncotic pressure of the blood, which "holds" the serum within the vessels.
Laboratory use of plasma and serum
For hematalogical, biochemical, blood bank-related, immunological and other kinds of tests, plasma is obtained from whole blood. To prevent clotting, an anticoagulant such as citrate or heparin is added to the blood specimen immediately after it is obtained. (Usually the anticoagulant is already in the evacuated blood collection tube (e.g. Vacutainer or Vacuette®) when the patient is bled.) The specimen is then centrifuged to separate plasma from blood cells. Plasma can be frozen below -20°C nearly indefinitely for subsequent analysis or use.
For many biochemical laboratory tests, plasma and blood serum can be used interchangeably. Serum resembles plasma in composition but lacks the coagulation factors. It is obtained by letting a blood specimen clot prior to centrifugation. For this purpose, a serum-separating tube (SST) can be used which contains an inert catalyst (such as glass beads or powder) to facilitate clotting as well as a portion of gel with a density designed to sit between the liquid and cellular layers in the tube after centrifugation, making separation more convenient.
Tests of coagulation (such as the INR and aPTT) require all clotting factors to be preserved. Serum, therefore, is inappropriate for these tests. A citrated evacuated blood collection tube (e.g. Vacutainer, Vacutube or Vacuette) is usually used, as the anticoagulant effects of citrate are dependent upon concentration and can be reversed for testing.
Serum is preferred for many tests as the anticoagulants in plasma can sometimes interfere with the results. Different anticoagulants interfere with different tests; using serum means the same sample can be used for many tests. In protein electrophoresis, using plasma causes an additional band to be seen, which might be mistaken for a paraprotein.
Serum is also commonly used as a supplement added to a particular cell culture media to ensure a successful growth of the cells. This is because the serum provides the cells with numerous proteins, nutrients, hormones and attachment factors that are beneficial.[1] One of the more common sera added is fetal calf serum (FCS).
Fresh frozen plasma
Fresh frozen plasma (FFP) is prepared from a single unit of blood. It is frozen after collection and can be stored for one year from date of collection. FFP contains all of the coagulation factors and proteins present in the original unit of blood. It is used to treat coagulopathies from warfarin overdose, liver disease, or dilutional coagulopathy. FFP that has been stored more than a standard length of time is re-classified as simply "frozen plasma", which is identical except that the coagulation factors are no longer considered completely viable.[2]