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Blood transfusions have inherent risks and associated costs. For example, blood transfusions have been associated with an increase in mortality, length of stay in the hospital, and multiorgan system dysfunction, as well as continued increase in blood cost. In addition, potential known and unknown risks such as transmission of blood-borne pathogens are still a concern. Because of religious practices or personal preferences, some patients may seek alternative to a blood transfusion. Therefore, anesthesiologists should be familiar with the various effective strategies to minimize the use of allogeneic blood and alternatives to allogeneic blood transfusion.
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Because normal human blood has significant excess oxygen transport capability that is only used in cases of great physical exertion, patients can safely tolerate very low hemoglobin levels (about one-third in normal healthy patient). As such, a volume expander can be used to provide volume during surgical blood loss and can help prevent shock; the remaining red blood cells can still oxygenate body tissue. Crystalloids and colloids are the two main types of volume expanders. Crystalloids are aqueous solutions of mineral salts or other water- soluble molecules. The most commonly used crystalloid fluid is normal saline (0.9% NaCl solution). Others include Lactated Ringer’s and plasmaLyte. Colloids contain large insoluble molecules, such as gelatin; blood itself is a colloid. Colloid volume expanders include hydroxyethyl starch (hetastarch), albumin, dextran, and gelofusine. Limitations to the use of colloids include their cost, potential allergic reaction, and their effect on coagulation. Dextran can decrease platelet adhesiveness, depress von Willebrand factor (vWF) level, and can cause anaphylactoid reaction; it is rarely used as volume expander. Hetastarch can decrease fibrinogen, vWF, and factor VIII levels as well as decrease platelet function. Recent concerns about hetastarch will probably limit its use as volume expander.
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AUTOLOGOUS BLOOD SALVAGE
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This method is also known as autologous blood transfusion or cell salvage (cell saver). The technique involves recovering blood lost during surgery and reinfusing it into the patient. It is a major form of autotransfusion. This alternative to blood transfusion eliminates the need and associated risk of giving a patient blood collected through blood donation of an unknown person. It is also a useful method in patients whose religious belief (eg, Jehovah Witness) prohibits them from receiving allogeneic blood transfusion. Some of these patients may accept the use of autologous blood salvaged during surgery to restore their blood volume and homeostasis. Autologous blood salvage is frequently used in cardiothoracic and vascular surgery, or in other surgeries in which blood loss is anticipated to be high. It is generally restricted to clean surgical fields and nononcologic procedures because of the risk of reinfusing bacteria or tumor cells into the patients. Several medical devices have been developed to assist in salvaging the patient’s own blood in the perioperative setting. The final product— which is devoid of plasma, clotting factors, or platelets—is a ...