Two optimizing procedures for the solution of complex systems of equations: a powerful tool for modelling and simulation of metabolism

Introduction Standard calculations for the evaluation of indirect calorimetry (IC) are based on two-dimensional nonlinear systems of equations. For a more sophisticated evaluation metabolic models can be used, which are described by complex systems of equations. Since the solutions are multidimensional, a concrete result must be selected by means of constraints, using optimizing procedures. These multidimensional optimizations are critical concerning processing time and reproducibility of minimum detection. Methods In order to simulate the status of metabolism of ICU patients on the basis of IC data, a complex model of metabolism was developed. The model was described by a system of equatio…

Messung des zirkulierenden Blutvolumens

Simulation of Metabolism for The Calculation of Enzyme Activities in Stress Metabolism

Abstract Using data of indirect calorimetry, total energy turnover as well as the rate of combustion of carbohydrates, fat and amino acids can be calculated. For the evaluation, simple standard procedures (4) are used. These procedures presume, that several assumptions are satisfied, e.g. a complete degradation of the energy delivering substrates and undisturbed enzyme activities. To be able to interprete also measurements, which are performed in the post-traumatic state as well as for estimation of the extent and consequences of reduced enzyme activities, a new method for the simulation of metabolism was developed. Hie underlying model considers a reduced activity of key enzymes and a swit…

Single Preoperative Oral Application of Ascorbic Acid Does Not Affect Postoperative Plasma Levels of Ascorbic Acid

<i>Background and Aims:</i> A decrease in ascorbic acid (AA) plasma concentration is well known during the postoperative period and postulated to be caused by increased radical scavenging activity in response to surgical trauma. This often affects postoperative patients and is associated with multiple organ failure. Therefore, substitution of AA could potentially decrease the risk of postoperative complications. This study examines the effect of preoperative oral administration of 1,000 mg AA on the postoperative AA plasma concentration. <i>Methods:</i> 54 patients were randomly split into two groups; patients in group 1 received no AA preoperatively while group 2 re…

Nahtoderfahrungen

Menschen, die lebensbedrohliche Situationen uberlebt haben, berichten gelegentlich uber optische und akustische Wahrnehmungen, die als Nahtoderlebnis (Near-Death Experience, NDE) bezeichnet werden. In fruheren Jahrhunderten nur in Einzelfallen erwahnt, gewinnt dieses Phanomen mit den Entwicklungen von Reanimatologie, Notfall- und Intensivmedizin zunehmend an Bedeutung. Die vorliegende Arbeit zeigt, dass die seit etwa 4 Jahrzehnten stattfindende intensive wissenschaftliche Beschaftigung mit diesem Thema zwar eine Systematik in die Phanomenologie von Nahtoderlebnissen bringen konnte, plausible wissenschaftliche Erklarungen jedoch weiterhin ausstehen. Die diskutierten Erklarungsansatze umfasse…

Investigation of Inspiratory Pressure-Volume Curves on Mechanically Ventilated Patients Using Least Square Polynomial Fit

Abstract An on-line method for the registration of pressure volume 1 oops TrT mechanically ventilated patients was developed using a personal computer with analog/digital interface. A third order polynomial function was fitted to the measured inspiratory pressure volume pairs. The significance of the fitting procedure was calculated using regression ANOVA. The inflection point of the pressure-volume curve was determinated by calculating the root of the second derivative of the polynomial. The method was teseted on 20 patients without major pulmonary dysfunction and on 6 patients with severe ARDS.