What is a Blood Volume Test?

A blood volume test is a clinical procedure used to measure the total volume of blood within the body. The test may also be used just to determine the volume of plasma or of red cells in the blood and therefore also be known as a plasma volume test or a red cell volume test.

In the clinical setting, the test may also be referred to as an assessment of intravascular volume status. This assessment may provide critical information in the treatment of patients in intensive care as well as for the treatment of heart failure and kidney disease.

The blood volume test results help the medical doctor determine the cause of symptoms such as hypovolemia, hypervolemia or polycythemia.

The test results from the blood volume test help the planning of an efficient blood volume guided treatment. In acute heart failure and kidney disease the quantification of blood volume is documented to provide a superior clinical disease assessment and to decrease mortality rate in heart failure if treatment is based on blood volume status. The blood volume test is critical to distinguish true anemia from dilutional anemia.

While traditional radioactive methods can easily take 2-4 hours, the standard CO re-breathing blood volume test can be completed in less than 15 minutes with the same accurary. The shortest version of CO re-breathing test can be completed in as little as 10 minutes and requires only a capillary blood sample (finger prick).

In a clinical setting, the use of CO re-breathing does not require specialized equipment nor specialist personnel. The only requirements in addition to an automised CO Rebreather are the use a standard blood gas analyzer and the ability to perform simple blood sampling.