Elevated lactate levels and impaired lactate clearance during extracorporeal life support (ECLS) are associated with poor outcome in cardiac surgery patients.

The use of extracorporeal life support (ECLS) as part of cardio-circulatory support has increased rapidly in recent years. Severe hyperlactatemia is not uncommon in this group of patients. Lactate peak concentrations and lactate clearance have already been identified as independent marker for mortality in critical ill patients without mechanical device support. The aim of this study was to determine a supposed correlation between the variables lactate peak concentration and clearance in the blood and mortality in the ECLS context. Therefore, a total of 51 cardiac surgery ICU patients with ECLS therapy were included in this retrospective, clinical observational study (survivors n = 23; non-survivors n = 28). Lactate measurement was performed before, during and after ECLS therapy. Further, common ICU scores (SAPSII, SOFA, TISS28), the rates of transfusion and the different vasopressor therapies will be compared. Significant elevated peak lactate levels and poor lactate clearance were associated with higher mortality during ECLS therapy (p < 0.001). Deceased patients had higher SAPSII scores (p < 0.001), received more transfusions (p < 0.001) and presented with higher rates of epinephrine (p < 0.001). In conclusion, hyperlactatemia during ECLS therapy is a time sensitive emergency. Lactate cannot be cleared in all patients. Reversible causes should be explored and treated. In cases where the cause is irreversible, the prognosis of elevated lactate concentrations and reduced clearance is very poor.

Regurgitant jet evaluation using three-dimensional echocardiography and magnetic resonance.

BACKGROUND: Three-dimensional assessment of regurgitant jet volume is the prerequisite for stratifying valve insufficiency. However, systematic comparison of three-dimensional methods is lacking. Therefore, we evaluated magnetic resonance imaging and three-dimensional echocardiography experimentally. METHODS: An insufficiency chamber (22 x 18.5 x 27 cm; ostia 10, 16, and 20 mm; regurgitant volumes 2.3 to 25 mL) within experimental circulation (BioMedicus pump, tubes, pulsatile flow 0.2 to 1.9 L/min) was used for three-dimensional echocardiography (HP Sonos 2500) and magnetic resonance imaging (Siemens Magnetom Vision). Doppler flowmeter served as a gold standard. Segmentation used thresholding and surface integration of velocity vectors. Jet volume was evaluated qualitatively by polynom fitting. RESULTS: Jet volume calculated by magnetic resonance (r = 0.99, p < 0.0001) and by echocardiography (r = 0.99, p < 0.0001) correlated identically to the gold standard. Jet volume derived from imaging correlated with each other by r = 0.98 (p < 0.0001). Polynom fits indicated a more paraboloid shape of magnetic resonance jet volume. CONCLUSIONS: Experimentally, three-dimensional echocardiography and magnetic resonance imaging possess identical accuracy for determining regurgitant jet volume. Magnetic resonance imaging seems to provide qualitatively better image data for three-dimensional reconstruction.

Identification of pathogenic microbial cells and spores by electrochemical detection on a biochip.

BACKGROUND: Bacillus cereus constitutes a significant cause of acute food poisoning in humans. Despite the recent development of different detection methods, new effective control measures and better diagnostic tools are required for quick and reliable detection of pathogenic micro-organisms. Thus, the objective of this study was to determine a simple method for rapid identification of enterotoxic Bacillus strains. Here, a special attention is given to an electrochemical biosensor since it meets the requirements of minimal size, lower costs and decreased power consumption. RESULTS: A bead-based sandwich hybridization system was employed in conjugation with electric chips for detection of vegetative cells and spores of Bacillus strains based on their toxin-encoding genes. The system consists of a silicon chip based potentiometric cell, and utilizes paramagnetic beads as solid carriers of the DNA probes. The specific signals from 20 amol of bacterial cell or spore DNA were achieved in less than 4 h. The method was also successful when applied directly to unpurified spore and cell extract samples. The assay for the haemolytic enterotoxin genes resulted in reproducible signals from B. cereus and B. thuringiensis while haemolysin-negative B. subtilis strain did not yield any signal. CONCLUSIONS: The sensitivity, convenience and specificity of the system have shown its potential. In this respect an electrochemical detection on a chip enabling a fast characterization and monitoring of pathogens in food is of interest. This system can offer a contribution in the rapid identification of bacteria based on the presence of specific genes without preceding nucleic acid amplification.

Electrical biochip technology--a tool for microarrays and continuous monitoring.

Based on electrical biochips made in Si-technology cost effective portable devices have been constructed for field applications and point of care diagnosis. These miniaturized amperometric biosensor devices enable the evaluation of biomolecular interactions by measuring the redox recycling of ELISA products, as well as the electrical monitoring of metabolites. The highly sensitive redox recycling is facilitated by interdigitated ultramicroelectrodes of high spatial resolution. The application of these electrical biochips as DNA microarrays for the molecular diagnosis of viral infections demonstrates the measurement procedure. Self-assembling of capture oligonucleotides via thiol-gold coupling has been used to construct the DNA interface on-chip. Another application for this electrical detection principle is continuous measuring with bead-based biosensors. Here, paramagnetic nanoparticles are used as carriers of the bioanalytical interface in ELISA format. A Si-micromachined glucose sensor for continuous monitoring in interstitial fluid ex vivo shows the flexibility of the electrical platform. Here the novel approach is a pore membrane in micrometer-dimensions acting as a diffusion barrier. The electrochemical detection takes place in a cavity containing glucose oxidase and a Pt-electrode surface. The common hydrogen peroxide detection, together with Si technology, enable precise differential measurements using a second cavity.