What Is Blood Plasma?
Plasma is the liquid part of the blood, in which the red and white blood cells float. It is the red oxygen carrying cells that give the blood its red color, the plasma itself is straw-colored. You may have seen some oozing out round a burn. Plasma is 95 percent water, with various dissolved proteins, (6–8%) (i.e.—serum albumins, globulins, and fibrinogen), glucose, clotting factors, electrolytes (Na+, Ca2+, Mg2+, HCO3−, Cl−, etc.), hormones, carbon dioxide (plasma being the main medium for excretory product transportation) and oxygen including the blood-clotting one, and salts dissolved in it.
Along with the red cells, the plasma helps to carry oxygen from the lungs to the body tissues which need it to break down their food. When the tissues have finished with the oxygen, the blood carries the carbon dioxide waste back to the lungs in order for it to be breathed out. It also carries food, at various stages of absorption, round the body to the tissues, and takes the waste away to the kidneys from where it is passed out of the body as water.
Plasma is also a vehicle for toxins and antitoxins, special substances designed to fight infection. It plays a vital role in an intravascular osmotic effect that keeps electrolytes in balanced form and protects the body from infection and other blood disorders. These substances with the white blood cells which destroy bacteria are in charge of defending the body against infection. So, despite the unassuming appearance of plasma, clearly it is extremely important to our bodies.
Blood plasma is prepared by spinning a tube of fresh blood containing an anticoagulant in a centrifuge until the blood cells fall to the bottom of the tube. The blood plasma is then poured or drawn off. Blood plasma has a density of approximately 1025 kg/m3, or 1.025 g/ml. Blood serum is blood plasma without clotting factors; in other words, “pure” blood. Plasmapheresis is a medical therapy that involves blood plasma extraction, treatment, and reintegration.
Fresh frozen plasma is on the WHO Model List of Essential Medicines, the most important medications needed in a basic health system. The use of blood plasma as a substitute for whole blood and for transfusion purposes was proposed in March 1918, in the correspondence columns of the British Medical Journal, by Gordon R. Ward. “Dried plasmas” in powder or strips of material format were developed and first used in World War II. 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 in the United States) based on Charles Drew’s contribution.
A large project began in August 1940 to collect blood in New York City hospitals for the export of plasma to Britain. 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 into the first successful mass production techniques. Nonetheless, the decision was made to develop a dried plasma package for the armed forces as it would reduce breakage and make the transportation, packaging, and storage much simpler.
The resulting dried plasma package came in two tin cans containing 400 cc bottles. One bottle contained enough distilled water to reconstitute the dried plasma contained within the other bottle. In about three minutes, the plasma would be ready to use and could stay fresh for around four hours. Following the “Plasma for Britain” invention, 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. Drew argued that there was no racial difference in human blood and that the policy would lead to needless deaths as soldiers and sailors were required 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 to the United States for civilian use. Serum albumin replaced dried plasma for combat use during the Korean War.