Search

BACKGROUND: Approximately every third surgical patient is anemic. The most common form, iron deficiency anemia, results from persisting iron-deficient erythropoiesis (IDE). Zinc protoporphyrin (ZnPP) is a promising parameter for diagnosing IDE, hitherto requiring blood drawing and laboratory workup. STUDY DESIGN AND METHODS: Noninvasive ZnPP (ZnPP-NI) measurements are compared to ZnPP reference determination of the ZnPP/heme ratio by high-performance liquid chromatography (ZnPP-HPLC) and the analytical performance in detecting IDE is evaluated against traditional iron status parameters (ferritin, transferrin saturation [TSAT], soluble transferrin receptor-ferritin index [sTfR-F], soluble transferrin receptor [sTfR]), likewise measured in blood. The study was conducted at the University Hospitals of Frankfurt and Zurich. RESULTS: Limits of agreement between ZnPP-NI and ZnPP-HPLC measurements for 584 cardiac and noncardiac surgical patients equaled 19.7 μmol/mol heme (95% confidence interval, 18.0-21.3; acceptance criteria, 23.2 μmol/mol heme; absolute bias, 0 μmol/mol heme). Analytical performance for detecting IDE (inferred from area under the curve receiver operating characteristics) of parameters measured in blood was: ZnPP-HPLC (0.95), sTfR (0.92), sTfR-F (0.89), TSAT (0.87), and ferritin (0.67). Noninvasively measured ZnPP-NI yielded results of 0.90. CONCLUSION: ZnPP-NI appears well suited for an initial IDE screening, informing on the state of erythropoiesis at the point of care without blood drawing and laboratory analysis. Comparison with a multiparameter IDE test revealed that ZnPP-NI values of 40 μmol/mol heme or less allows exclusion of IDE, whereas for 65 μmol/mol heme or greater, IDE is very likely if other causes of increased values are excluded. In these cases (77% of our patients) ZnPP-NI may suffice for a diagnosis, while values in between require analyses of additional iron status parameters.

BACKGROUND This study investigates the impact of preoperative calculated rivaroxaban (RXA) plasma concentration on perioperative red blood cell (RBC) loss. STUDY DESIGN AND METHODS In this retrospective single-center study, we identified patients with RXA intake according to a preoperative determination of RXA levels within 96 hours before surgery. RXA plasma concentration at the beginning of surgery was then calculated from the last RXA intake using a single-compartment pharmacokinetic model with four categories of RXA concentration (≤20, 21-50, 51-100, and >100 μg/L). Patients were classified into surgery with high (≥500 mL) or low (