Potentially clinically relevant concentrations of Cefazolin, Midazolam, Propofol, and Sufentanil in auto-transfused blood in congenital cardiac surgery.

Background: Use of donor blood in congenital cardiac surgery increases the risk for post-operative morbidity and mortality. To reduce the need for allogenic blood transfusion a technique for peri-operative mechanical red cell salvage is applied. Blood from the operation site is collected in a reservoir, processed, passed through a lipophilic filter and returned to the patient. Influence of this cellsaver system on coagulation, fibrinolysis and inflammatory markers is known. To our knowledge no studies have been performed on the effects of autotransfusion on drug concentrations. A clinically relevant drug dose could potentially be returned to the patient through the auto-transfused blood, leading to unwanted drug reactions post-operatively. We aimed to measure drug concentrations in blood salvaged from the operation site and in the auto-transfused blood to determine if a clinically relevant drug dose is returned to the patient.

Methods: The study was performed at the Department of Cardiothoracic Surgery of a tertiary university hospital. Blood samples were taken from the reservoir, after processing before the lipophilic filter, the auto-transfused blood, and the waste fluid. Samples were stored at - 80 C and drug concentration for sufentanil, propofol, midazolam and cefazolin were measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Drug concentrations measured in the reservoir and the auto-transfused blood were compared and the relative reduction was calculated for each patient.

Results: Blood samples were taken from 18 cellsaver runs in 18 patients, age 0-13 years. Drug concentrations in the reservoir were comparable to concomitant concentrations in the patient. For sufentanil 34% (median, IQR 27-50) of drug concentration was retained from the reservoir in the auto-transfused blood, for midazolam 6% (median, IQR 4-10), for cefazolin 5% (median, IQR 2-6) and for propofol 0% (median, IQR 0-0) respectively.

Conclusion: Depending on the drug, up to 34% of the drug concentration salvaged from the operation site is returned to the patient through autotransfusion, potentially causing unwanted drug reactions post-operatively. Additionally, influence of a cellsaver system should be considered in pharmacological research during and after congenital cardiac surgery and could result in dose adjustments in the postoperative phase.

Trial Registration: Registration at the Dutch Trial Registry ( NTR3579 ) at August 14 2012.