A much more common problem is that a transfusion may be withheld because the extent of blood loss has not been recognized. Severe organ damage may occur from low blood volume. A significant number of patients with no kidney disease may develop kidney failure as a complication of inadequate or delayed transfusion. Physicians are faced with a difficult choice of administering a transfusion which may cause infection or other complications or withholding a transfusion from a patient who may suffer complications from low blood volume. Seventy percent are reported to be inadequately treated.
Vasoconstriction is an excessive tightening of the blood vessels.
Hypertension is treated with two types of medications, vasodilators, which relax the blood vessels, or diuretics, which cause the kidney to lose fluid and decrease blood volume. Presently, neither variable is measured. Treating high blood pressure is a trial and error process of choosing from more than 50 drugs currently approved for hypertension therapy. However, some Hypertensive patients may actually have a decreased blood volume. Giving such a patient a diuretic decreases the blood flow to the kidney, and may cause damage.