1308 - Ex vivo Impact of Autologous Blood Transfusion (ABT) on Concentrations of Antibiotics used for Surgical Prophylaxis

Background: ABT is widely employed during surgical procedures involving high blood loss, such as liver transplantation and open heart surgery.  While ABT mitigates the need for allogeneic blood transfusions, an unintended consequence may be removal of drugs, including antimicrobials. Herein, we determined the ex vivo loss of antimicrobials utilized for surgical prophylaxis through an ABT system.

Methods: Experiments were conducted in duplicate to simulate processing of ABT blood during surgery.  Packed red blood cells and fresh frozen plasma (300ml) were acquired from banked blood and inoculated to achieve clinically-relevant plasma concentrations of vancomycin (VAN), the piperacillin (PIP) component of piperacillin/tazobactam, and the ampicillin (AMP) component of ampicillin/sulbactam. Inoculated blood was processed through a Cell Saver® Elite™ ABT system to fill a 125mL Latham bowl and washed with 500mL of normal saline. Processed fluid was directed to a reinfusion or waste bag; additional blood samples were collected from each. Drug concentrations were measured in all samples. The amount of VAN, PIP, and AMP infused through the Cell Saver (initial), and resulting in the reinfusion and waste bags was calculated.

Results: A range of 193-265mL of combined blood containing drug were processed in each experiment through the ABT system. Initial average plasma concentrations were 61, 107, and 172 mg/L for VAN, PIP, and AMP, respectively. When corrected for volume and hematocrit, plasma concentrations translated to a mean ± SD of 3 ± 1% of VAN in the reinfusion bag and 93 ± 2% in the waste bag. For PIP, plasma concentrations translated to 2 ± 1% of PIP in the reinfusion bag and 84 ± 13% in waste, while 2 ± 1% and 120 ± 5% of AMP was found in the reinfusion and waste bags, respectively. Unaccounted drug (0-14%) was considered sequestered in the device.

Conclusion: These ex vivo assessments of antibiotic removal during ABT are the first to demonstrate significant loss of antibiotics ( >95%) when processed through the ABT system.  Further studies measuring impact of ABT on drug concentrations in patients undergoing surgery are warranted.