H Weber

Impact of tranexamic acid vs. aprotinin on blood loss and transfusion requirements after cardiopulmonary bypass: a prospective, randomised, double-blind trial.

Summary Introduction: Aprotinin (AP) reduces blood loss and transfusions after cardiopulmonary bypass (CPB), but may sensitise patients and is expensive. Tranexamic acid (TA) has less side-effects, but data regarding its efficacy are controversial. The aim of our prospective, randomised, double-blind study was to compare the impact of AP vs. TA on drainage blood loss and transfusion requirements in patients undergoing first time CABG on CPB. Materials and Methods: One hundred and twenty adult patients were randomised to receive either high-dose AP according to Hammersmith or a total of 2 g TA. Perioperative blood products were transfused in a standardised fashion. Blood loss was measured up to 24 h. Demographic and clinical patient data were collected until hospital discharge. Results: The data from 118 patients (TA: n = 58, TA appears to be a cost-effective alternative to AP AP: n = 60) who completed the study according to protocol were analysed. Blood loss at 24 h postoperation in TA patients was significantly higher (896 ± 354 ml) as compared to AP patients (756 ± 347ml; p = 0.03). TA patients received 1.5 ± 1.5 units of red blood cells (AP: 1.5 ± 1.7, p = 1.0), 1.3 ± 2.0 units of fresh frozen plasma (AP: 1.0 ± 2.0, p = 0.38) and 0.5 ± 1.4 units of platelets (AP: 0.2 ± 0.7, p = 0.15). Clinical data, including perioperative myocardial infarction rate, acute renal failure, mechanical ventilation, hospital stay and mortality, were not significantly different between either group. Conclusion: Our data show a difference in blood loss between TA and high-dose AP. Although statistically significant, it has little clinical relevance, because perioperative transfusion requirements were similar for both groups. Thus, TA appears to be a cost-effective alternative to AP in primary CABG patients.

The dose effect of human bone marrow-derived mesenchymal stem cells on epidermal development in organotypic co-culture

BACKGROUND A wealth of evidences have shown the participation and benefits of bone marrow-derived mesenchymal stem cells (BM-MSCs) in wound healing and skin tissue repair in vivo. However, their role in epidermal development and reconstitution is not clearly investigated. OBJECTIVE Here we examine the quantitative effect of human BM-MSCs on epidermal regeneration in vitro. METHOD Human keratinocytes and BM-MSCs are cultured at ratios from 0% to 100% on top of a fibroblast-embedded collagen gel in a three-dimensional organotypic co-culture model at an air-liquid interface up to 20 days and analyzed by histochemical and immunochemical staining of filaggrin, involucrin and keratin 10 on days 14 and 20. Human BM-MSCs were tracked with quantum dots in organotypic co-cultures. RESULTS It was found that epidermal development is strongly influenced by the percentage of co-cultured BM-MSCs. A strong chemotactic effect between keratinocytes and MSCs was seen in the group with 50% of BM-MSCs, which resulted in an impaired epidermal development, whereas at a low percentage of BM-MSCs (10%), a stratified epidermal structure resembling native skin was established on day 14 of culture. Moreover, the immunostaining studies revealed that BM-MSCs in the low percentage (10%) participated in the basal periphery of reconstructed epidermis and a similar pattern characteristic of native epidermis was demonstrated in this experimental group, which was superior to all other experimental groups in terms of the thickness of stratum corneum and the expression profile of epidermal differentiation markers. CONCLUSION This study indicates the advantage of using a new skin equivalent model incorporating a small fraction of MSCs to develop biologically useful tissues for maintaining homeostasis during skin regeneration and wound healing process.

Comparison of the flow downstream two prototypes of a new monoleaflet artificial aortic heart valve by means of PIV visualization

Monoleaflet artificial heart valve prosthesis are commonly used for heart valve replacement. Although there are several manufacturers of these monoleaflet heart valve prosthesis, also known as tilting disc valves, the optimal hemodymamic solution is still not available. The differences of the flow pattern among these heart valve prosthesis are given related to the miscellaneous geometry of the hinges and occluder. In this experimental study, flow downstream of two new prototypes of monoleaflet disc artificial aortic heart valve (University of Lodz, Poland) were investigated by means of Particle Image Velocimetry (PIV).

Applied physics of compressible and incompressible fluids

Intensive care monitoring and therapy is nowadays usually associated with measurement, control and monitoring techniques using complex medical equipment. Fundamental knowledge of the measurement units, measurement techniques and their physiological relationships forms the basis for a correct interpretation of the biological signal. Therefore, the basics of the physics of pressure in fluids and gases are pointed out, and examples of application are given.