Hemodilution During CPB

Описание: Hemodilution is a medical technique used to decrease the concentration of red blood cells and other components in the blood by adding a diluting fluid. This method is commonly employed during surgeries, particularly in procedures involving extracorporeal circulation (like cardiopulmonary bypass), to reduce the need for blood transfusions and maintain adequate blood flow while protecting the organs.

Types of Hemodilution:
Acute Normovolemic Hemodilution (ANH):

Blood is removed from the patient just before surgery, and the blood volume is replaced with crystalloid or colloid solutions to maintain normovolemia (normal blood volume).
The removed blood is stored and can be reinfused later, which reduces the need for transfusions during surgery.
Intraoperative Hemodilution:

During surgery, fluids (usually crystalloids or colloids) are infused to dilute the patient’s blood. This dilution reduces the concentration of red blood cells (RBCs) temporarily but allows for easier management of blood loss.
Hypervolemic Hemodilution:

In this technique, extra fluid is given without the removal of blood. The increased volume reduces blood viscosity, improving flow but diluting the concentration of RBCs.
Purpose and Advantages of Hemodilution:
Reducing Blood Transfusion Requirements:

By diluting the blood, fewer RBCs are lost during surgery, reducing the overall need for transfusions.
Transfusion avoidance lowers the risk of transfusion-related reactions and infections.
Improving Microcirculation:

Hemodilution reduces blood viscosity, making it easier for blood to flow through capillaries, thus improving oxygen delivery to tissues.
This can be especially helpful during procedures like cardiac surgery where extracorporeal circulation is used.
Decreasing Blood Viscosity:

Lower viscosity enhances perfusion and reduces strain on the heart, which can be particularly beneficial in surgeries where cardiac function is compromised or during hypothermic cardiopulmonary bypass.
Organ Protection:

During hemodilution, adequate blood flow and oxygen delivery can help prevent organ damage, such as renal or neurological injury, by ensuring perfusion even under low hematocrit levels.
Fluids Used for Hemodilution:
Crystalloids:

Normal Saline (0.9% NaCl): Commonly used to expand blood volume.
Lactated Ringer’s Solution: Contains electrolytes and buffers that help maintain acid-base balance.
Colloids:

Albumin: A natural plasma protein that increases oncotic pressure and helps retain fluids in the vascular compartment.
Hydroxyethyl Starch (HES): A synthetic colloid used to maintain blood volume and pressure during surgeries.
Gelatin-based Solutions: Used to expand blood volume while maintaining colloid osmotic pressure.
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