A concentration in processed blood is only one part of a dose reconstruction. Zeilmaker-Roest and colleagues measured several perioperative drugs in blood collected for autotransfusion during congenital cardiac surgery.
The study included 18 cell-salvage runs in 18 children. The investigators used liquid chromatography–tandem mass spectrometry to compare blood in the collection reservoir with the processed blood prepared for return. The median processed-to-reservoir concentration ratio was 6% for midazolam and 34% for sufentanil. Cefazolin and propofol had different ratios under the same workflow.
These percentages compare concentrations. To estimate the amount returned to a patient, a reviewer needs the measured concentration and the volume actually infused. Timing, concurrent administration and the patient’s pharmacokinetics matter when interpreting a later observation. The small study documents drug carryover under one protocol. It does not establish a fixed reinfused dose or show that carryover caused sedation in a particular patient.