What is an adverse effect of hemodilution?

• A. Increasing hematocrit
• B. Decreasing hematocrit
• C. No effect on hematocrit
• D. Increases blood viscosity

Answer: (B)

Hemodilution lowers the proportion of red blood cells in the blood, so the hematocrit falls. During processes like cardiopulmonary bypass, plasma volume is increased while the red cell mass stays the same, leading to a dilution of red cells. The main consequence is a reduced oxygen-carrying capacity of the blood, which can impair tissue oxygen delivery, especially to the heart and brain, and raise the risk of ischemia if hematocrit drops too far. While dilution also decreases blood viscosity—which can improve flow—the key adverse effect clinicians monitor is the fall in hematocrit and the associated potential for inadequate oxygen delivery. The other options don’t fit: increasing hematocrit would imply concentrating red cells, not dilution; no effect on hematocrit contradicts what dilution does; and viscosity typically decreases with dilution, not increases.