Researchers conducted a study to determine how much blood is really used compared to what is reserved for major types of brain vessel surgeries, including carotid endarterectomy (surgery to clear blocked neck arteries) and aneurysm repair.
Before blood can be used in surgery, it must undergo several tests to ensure it is compatible with the patient’s blood. These tests include ABO and Rh typing (to determine blood type), an antibody screen and a cross-match. In a cross-match, the patient’s red blood cells (RBCs) are mixed with those of commercially purchased RBCs that express all the common clinically significant antigens.
“At many institutions, there are policies about how RBCs are ordered for vascular neurosurgery, but these policies vary widely,” says primary researcher Neal F. Kassell, M.D., department of neurosurgery, University of Virginia Health System, Charlottesville. “The policy is often based on tradition rather than a formal audit of the facility’s transfusion practices. The number of units of RBCs prepared in advance for surgery is always greater than the number of units actually transfused.”
While the percentage of blood that is reserved but never used varies by institution, it’s high enough – and the cost is high enough – that researchers recommend that each institution update its policy according to its current blood usage.
“Because of modern advances, we are using less blood than we used to, particularly in surgery,” says Kassell. “Changing blood-use policies can decrease costs and make better use of this scarce and important resource.”
Researchers examined the records of 301 patients having cerebrovascular neurosurgery at the University of Virginia. These surgeries included carotid endarterectomy (CEA) and repairs of cerebral aneurysms and arteriovenous malformations (AVM). AVMs are a disorder where arteries and veins are misconnected in such a way that blood can’t move freely from the arteries to the veins. Researchers noted the use of RBCs before, during and within three days after the surgeries.
They measured the ratio of cross-matched blood (C) to transfused blood (T) – the C/T ratio. “A high C/T ratio means more blood must be kept in inventory, which increases hospital costs, wastes personnel time and increases the likelihood of outdated blood products,” says Kassell.
At the University of Virginia, 126 people underwent CEA surgery. The hospital ordered 252 units of RBCs; 5 units were used postoperatively and none were used before or during surgery. This gives a C/T ratio of 50.4. The standard C/T ratio for this surgery is 2. For all 301 patients, 952 units were ordered. The total number of units transfused before, during or after surgery was 176. This gives a total C/T ratio of 5.41 for all surgeries analyzed.
Evidence suggests that RBCs lose their capacity to deliver oxygen to the body’s tissues with increased storage time. For each unit of RBCs ordered, a cross-match is performed. The costs for any product that is outdated because it has been prepared but not used must be absorbed by the hospital, the researchers write. Once blood is cross-matched for surgery, it is unavailable to other patients for 24 to 48 hours and the chance of the RBCs becoming outdated is increased. However, without cross-matching, RBCs can be stored for over a month.
Based on their results, the researchers recommend only an ABO-Rh type and antibody screen for aneurysm and AVM surgery – and no type or screen for carotid endarterectomy.
“A transfusion performed after a type and screen is still very safe, and there’s plenty of time after the patient leaves the operating room to order it,” says Kassell. “Everyone who is reserving more blood than they’re using needs to examine their guidelines and modify their standards.”
Co-authors of the study include Daniel E. Couture, M.D.; Dilantha B. Ellegala, M.D.; Aaron S. Dumont, M.D.; and Paul D. Mintz, M.D.
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