Objective: This study was performed to evaluate the effect of a homemade autotransfusion pressure-control system on the regulation of negative pressure and to clarify the influence of different negative pressures on the recovered erythrocytes.

Methods: Fifty patients were randomly divided into five groups, and five different suction-generated negative pressures were applied. Before suction, 6 mL of blood was collected from the surgical field; after suction, 6 mL of blood was collected from the blood storage tank. The hemoglobin, hematocrit, mean corpuscular volume, newly generated standardized plasma free hemoglobin, and change in the hemolysis rate of erythrocytes before and after suction were compared. Additionally, the erythrocyte morphology was observed.

Results: The hemoglobin and hematocrit were significantly different before and after suction in all five groups. As the suction pressure increased, gradual increases were noted in the number of abnormal erythrocytes in the field of view, the newly generated standardized plasma free hemoglobin, and the change in the hemolysis rate.

Conclusions: The destruction rate of erythrocytes increased as the suction-generated negative pressure increased. When using a pressure-control system, a negative pressure of <200 mmHg should be applied to reduce the damage to the autotransfused blood.