Quick biochemical markers for assessment of quality control of intraoperative cell salvage : a prospective observational study

Background
Intraoperative Cell Salvage (ICS), hereby referred to ‘mechanical red cell salvage’, has been widely used in adult elective major surgeries to reduce requirement for homologous red blood cell transfusion and its associated complications. However, amount of free haemoglobin (fHb) from ICS has been shown related to incidence of renal failure. fHb is the most important indicator of quality control of cell salvaged blood, thus monitoring the fHb concentration is imperative to minimise renal injury. However, currently there has been lacking quick biochemical markers to monitor the levels of fHb during ICS. The aim of this study was to screen quick biochemical markers for evaluating the amount of fHb during use of intraoperative cell salvage.

Methods
Twenty patients undergoing elective cardiovascular surgery were enrolled. Blood was collected and processed using a Fresenius continuous auto-transfusion system device. The concentration of fHb, albumin (Alb), and calcium (Ca) in three washing modes were measured, and their clearance rates were calculated. The correlations among the clearances and concentrations of fHb, albumin, and calcium were analysed.

Results
In three washing modes, concentrations of albumin and calcium are significantly associated with amount of fHb:fHb(g/L) = 0.111Alb(g/L) –0.108, R = 0.638, p = 0.000; fHb(g/L) = 1.721Ca(mmol/L) +0.091, R = 0.514, p = 0.000. Furthermore, the clearance rates of albumin and calcium significantly predict clearance of fHb, CR_fHb = 0.310CR_ALB + 0.686, R = 0.753, p = 0.000, CR_fHb = 0.073 CR _Ca+ 0.913, R = 0.497, p = 0.000.

Conclusions
In clinic practice, clearance rates of albumin, or calcium can be used to evaluate the quality of salvaged blood, fHb. Bed-side measurement of calcium could offer a more feasible means for clinicians to undertake a real-time assessment of fHb.