Background: Suction pressure is one variable that can affect the efficiency of red blood cell (RBC) recovery for intraoperative autotransfusion. This study compared a constant-suction-pressure system with a device that is expected to minimize hemolysis by automatically varying the suction pressure.
Study design and methods: Twenty-two 50-mL reconstituted whole-blood samples were collected from a flat surface with either a constant-pressure suction device (BRAT 2 autologous blood recovery system, COBE Cardiovascular) set to a pressure of -200 mmHg or a variable-pressure suction device (SmartSuction Harmony surgical suction pump, Haemonetics, Inc.). Time of blood collection was recorded and plasma free hemoglobin (PFHb) was spectroscopically measured in the aspirated blood. Postcollection blood was subjected to RBC mechanical fragility test to characterize potential sublethal blood trauma. Relative hemolysis and the mean fragility index (MFI) were calculated.
Results: Hemolysis was significantly reduced with the variable-pressure suction compared to the constant-pressure suction (2.17% vs. 3.20%, respectively; p < 0.001). There was no significant difference between both suction devices in either the MFI of RBCs (0.632 vs. 0.673, respectively; p > 0.05) or the collection time at -200 mmHg (54.2 seconds vs. 52.8 seconds, respectively; p > 0.05).
Conclusions: Although the variable-pressure device produced a significant reduction in hemolysis during one-pass blood collection, the clinical significance of this reduction is not clear. In relative terms, the variable-pressure device would recover an extra 10 mL of RBCs for every liter of salvaged RBCs, which is negligible compared to the blood loss in major surgery.