Infusionstherapie und Transfusionsmedizin
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Bleeding is causally related to about 50% of postoperative deaths following liver resection. Main factors contributing to increased perioperative bleeding in liver surgery include surgical trauma, reduced activity of clotting factors and inhibitors due to impaired hepatic synthesis, low platelet count and poor platelet function as well as impaired clearance of activated clotting factors by the reticuloendothelial system of the liver (Kupffer cells). Hemostasis may be further impaired by transfusion of blood components, since citrate added for conservation is not adequately metabolized by the failing liver. ⋯ Thrombelastography is the leading method for diagnosis of hyperfibrinolysis, which can also be assessed by determination of D-dimer, fibrinogen and fibrin degradation products. Evaluation of primary hemostasis is frequently restricted to platelet count, which is only a rough parameter. In contrast, measurement of in vitro bleeding time and volume enables repeated quantification of platelet function in patients with impaired hemostasis.
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Infusionsther Transfusionsmed · Aug 1993
Comparative StudyPerioperative respiratory monitoring of oxygen transport.
Oximetry nowadays is understood as the in vitro measurement of O2 saturation (sO2, %) and hemoglobin (Hb) derivatives (%) using 4-7 wavelengths (CO- and Hem-oximeters). Pulse oximeters, using only 2 wavelengths, are designed for the continuous noninvasive measurement of the arterial partial O2 saturation (psO2, %) in vivo. Light-emitting diodes allow light to pass through the peripheral site of measurement with red and infrared light to enable a distinction between oxygenated and deoxygenated hemoglobin during a recorded pulse wave. ⋯ In the case of elevated methemoglobin (MetHb) concentrations, the situation is completely different. With increasing cMetHb, the psO2 is still the value required, but success depends on the concentration of MetHb: under normoxia psO2 is increasingly underestimated, whereas under hypoxia increasing overestimation must be anticipated. Provided there is a constant Hb concentration, knowledge of the initial sO2, and absence of the derivatives COHb and MetHb as well as of severe perfusion disorders, pulse oximetry is suitable for perioperative respiratory monitoring of oxygen transport.