Preoperative hemostasis and its association with bleeding and blood component transfusion requirements in cardiopulmonary bypass surgery.

BACKGROUND: Variables of hemostasis before surgery might indicate an elevated risk of bleeding. We determined hemostasis tests and standardized bleeding history and their association with bleeding and transfusion requirements in cardiopulmonary bypass (CPB) surgery. STUDY DESIGN AND METHODS: In a prospective trial, variables from 104 patients were associated with postsurgical bleeding and with red blood cells (RBCs) and platelet concentrate (PC) transfusions. Variables included standardized bleeding history, prothrombin time (PT), fibrinogen, fibrin monomers, Factor VIII, von Willebrand factor (VWF), multiple electrode aggregation (MEA), and the day of aspirin or thienopyridine withdrawal before operation. RESULTS: Multiple linear regression revealed bleeding history score, ADP-induced MEA, CPB time, and hemoglobin (Hb) independently associated with postoperative bleeding and bleeding history, arachidonic acid (AA)-induced MEA, CPB time, and PT associated with RBC transfusions. The logistic regression model for the outcome of bleeding within 24 hours after operation indicated ADP-induced MEA, the day of aspirin withdrawal before operation, and CPB time as predictors. AA-induced MEA, CPB time, Hb, and PT were predictors of RBCs transfusion. ADP-induced MEA, the day of aspirin withdrawal, PT, and VWF were associated with PC transfusion. CONCLUSIONS: A standardized bleeding history may help to identify patients undergoing CPB surgery whose risk of bleeding is elevated. ADP-induced MEA appears to predict postoperative bleeding and PC transfusion requirements, while AA-induced MEA and preoperative Hb indicate the need for RBCs. The time of aspirin withdrawal before surgery influences perioperative blood loss and PC transfusion.

Sources of variation in factor VIII, von Willebrand factor and fibrinogen measurements: implications for detecting deficiencies and increased plasma levels.

OBJECTIVES: Differences in pre-analytical and assay conditions, inappropriate reference ranges, or inflammation may have the potential to impair clinical decisions based on measurements of factor VIII (FVIII), von Willebrand factor (VWF) and fibrinogen (Fg). This study examined the impact on FVIII, VWF and Fg in plasma of freezing and thawing, different citrate anticoagulant concentrations, and inflammation, as determined by high-sensitivity C-reactive protein (hsCRP). MATERIALS AND METHODS: FVIII was determined prior to freezing and after thawing using a one-stage clotting assay (FVIII:C), an amidolytic assay (FVIII:AM) and an enzyme immunoassay (FVIII:Ag). Samples were anticoagulated with 106 or 129 mmol/L of citrate. FVIII, VWF and Fg were quantified in 300 individuals to establish reference ranges and to investigate associations with hsCRP. RESULTS: Freezing and thawing reduced FVIII:C and FVIII:AM markedly. FVIII coagulant activities were not significantly different between samples anticoagulated with 106 or 129 mmol/L of citrate, respectively. FVIII, VWF and Fg were significantly associated with hsCRP. FVIII:C was greater than FVIII:AM and FVIII:Ag in all experiments, indicating that the presence of activated FVIII may lead to overestimation of FVIII:C. CONCLUSIONS: Standardized freezing and thawing of plasma samples appears to be indispensable if reliable FVIII results are to be obtained. Because inflammation can potentially mask deficiency states or mimic an increased risk of thrombosis, FVIII, VWF and Fg determinations should be supplemented by measurements of hsCRP.

Heparin monitoring during cardiopulmonary bypass surgery using the one-step point-of-care whole blood anti-factor-Xa clotting assay heptest-POC-Hi.

The activated clotting time (ACT) generally used for monitoring heparinization during cardiopulmonary bypass (CPB) surgery does not specifically measure heparin anticoagulant activities. This may result in heparin over- or under-dose and subsequent severe adverse events. A new point-of-care whole blood clotting assay (Heptest POC-Hi [HPOCH]) for quantifying heparin anticoagulant activity specifically was compared with ACT and anti-factor Xa (anti-Xa) heparin plasma levels (Coatest heparin) in 125 patients undergoing CPB surgery. The analytical reliability of the HPOCH and the influence of preanalytical variables on assay results were also examined. The ACT and HPOCH clotting times determined throughout the entire observation period correlated closely (n=683; r = 0.80; p < .0001). Similarly, there was a significant linear correlation between HPOCH and Coatest anti-Xa levels (n=352; r = 0.87; p < .0001). Pre- and post-CBP values of HPOCH, ACT, and anti-Xa plasma levels correlated closely with each other (correlation coefficients between r = 0.90 and r = 0.99; p < .0001). During CPB, there was no significant relationship between ACT and whole blood or plasma heparin levels determined by HPOCH (n=157; r = 0.19) and the chromogenic anti-Xa assay (n=157; r = 0.04), respectively. In contrast, HPOCH and anti-Xa plasma levels correlated strongly during CPB (n=157; r = 0.57; p < .0001). However, bias analysis showed that the HPOCH and Coatest heparin could not be used interchangeably. The HPOCH was well reproducible and not influenced by aprotinin, hemodilution, or other factors affecting ACT. The HPOCH seems to be a promising new tool for specific on-site measurement of heparin activities in whole blood during CPB.

Stratum corneum-derived caspase-14 is catalytically active.

Caspase-14, a cysteine protease with restricted tissue distribution, is highly expressed in differentiated epidermal keratinocytes. Here, we extracted soluble proteins from stratum corneum (SC) of human epidermis and demonstrate that the extract cleaves tetrapeptide caspase substrates. The activity decreased to below 10% when caspase-14 was removed by immunodepletion showing that caspase-14 is the predominant caspase in SC. In contrast to normal SC, where caspase-14 was present exclusively in its processed form, incompletely matured SC of parakeratotic skin from psoriasis and seborrheic dermatitis contained both procaspase-14 and caspase-14 subunits. Fractionation of extract from parakeratotic SC revealed that the peak caspase activity coeluted with processed caspase-14 but not with procaspase-14. Our results suggest that during regular terminal keratinocyte differentiation, endogenous procaspase-14 is converted to caspase-14 subunits that are catalytically active in the outermost layers of normal human skin.