Towards a transferable design of solid-state embedding models on the example of a rutile TiO2 (110) surface.

In this work, we present general and robust transferable principles for the construction of quantum-mechanically treated clusters in a solid-state embedding (SSE) approach, beyond the still prevalent trial and error approach. Thereby, we probe the quality of different cluster shapes on the accuracy of chemisorption energies of small molecules and small polaron formation energies at the rutile TiO2 (110) surface as test cases. Our analyses show that at least the binding energies and electronic structures in the form of the density of states tend to be quite robust already for small, nonoptimal cluster shapes. In contrast to that, the description of polaron formation can be dramatically influenced by the employed cluster geometry possibly leading to an erroneous energetic ordering or even to a wrong prediction of the polaronic states themselves. Our findings show that this is mainly caused by an inaccurate description of the Hartree potential at boundary and surrounding atoms, which are insufficiently compensated by the embedding environment. This stresses the importance of the cluster size and shape for the accuracy of general-purpose SSE models that do not have to be refitted for each new chemical question. Based on these observations, we derive some general design criteria for solid state embedded clusters.

[Operation planning of secondary interventions after polytrauma]. / Operationsplanung von sekundären Eingriffen nach Polytrauma.

A prospective study of 135 secondary operations (> 24 h after trauma) in patients with multiple injuries (ISS 40.6 pts) was performed to determine specific and unspecific indicators of the inflammatory response that may indicate the degree of risk of postoperative organ failure in these patients. On the morning of the operation each patients' data were recorded and blood samples were collected. Patients were divided in those in whom respiratory, renal and/or hepatic failure developed or preexisting organ failure worsened by more than 20% from baseline within 2 days after the operation and those who had no complications. In 29 patients who were operated upon between 24 and 72 h after trauma only the pO2/FiO2 ratio allowed discrimination between the two groups. The overall accuracy of this parameter as a predictor of postoperative organ failure was 83%, with a sensitivity of 78% and a specificity of 85%. In 106 patients with secondary operations later than 72 h after trauma, neutrophil elastase, C-reactive protein and platelet count revealed the highest predictive accuracy, with cut-off values of 250 ng/ml, 11 mg/dl and 180 x 10(6)/ml, respectively. The combined accuracy of these three parameters in prediction of postoperative organ failure was 79% (sensitivity 73%, specificity 83%). In this group of patients the pO2/FiO2 ratio was of less value and blood pressure, heart rate, renal function parameters, lactate and coagulation parameters were of no value.(ABSTRACT TRUNCATED AT 250 WORDS)

Posttraumatic inflammatory response, secondary operations, and late multiple organ failure.

The objective of this study was to determine the role of surgical procedures as secondary inflammatory insults in the development of late multiple organ dysfunction syndrome in patients with multiple trauma and to evaluate both specific and nonspecific indicators of the inflammatory response in their ability to indicate the risk of severely injured patients to develop organ failure after secondary operations. In a prospective study of 106 severely injured patients (ISS 40.6) who underwent secondary operations (> 3 days after trauma), we compared the level of preoperative inflammation with the sequelae of surgical trauma. The interventions included facial reconstructions; osteosynthesis of the pelvic girdle, long bones, and spine; and others. Group 1 consisted of 40 patients (38%) who developed respiratory, renal, or hepatic failure, or combinations thereof, within 2 days after the operation or whose preexisting organ dysfunction worsened by more than 20% from baseline. The remaining 66 patients (62%) with an uneventful recovery formed group 2. The preoperative levels of neutrophil elastase (92.2 vs. 61.3 ng/dL), C-reactive protein (12.4 vs. 7.6 mg/dL), and platelet count (118,000 vs. 236,000/microL) were significantly more abnormal in the patients of group 1. PO2/FiO2 ratio was also somewhat lower in group 1 patients (305.5 vs. 351), whereas other parameters (e.g., blood pressure, heart rate, bilirubin, creatinine, urinary output, lactate, pH, and coagulation) did not allow preoperative differentiation between groups 1 and 2. An increased state of inflammation (neutrophil elastase > 85 ng/mL, C-reactive protein > 11 mg/dL, platelet count < 180,000/microL) predicted postoperative organ failure with an accuracy of 79% (sensitivity, 73%; specificity, 83%). We conclude that secondary operations may act as a second insult and may precipitate late multiple organ dysfunction syndrome if they are performed in patients with multiple trauma while they still have an increased level of posttraumatic inflammation. However, future investigations have to show whether postponing surgery until inflammation has subsided or the use of less invasive surgical techniques will decrease the rate of postoperative organ failure in the trauma patient.

[Operative injury in spinal surgery in the management of polytrauma patients]. / Operationstrauma Wirbelsäule in der Versorgung polytraumatisierter Patienten.

The release of indicators and mediators of the posttraumatic inflammatory response following spine surgery was measured in patients with multiple injuries. Eight of a group of 113 patients (mean injury severity score 36) who underwent delayed operative stabilization of vertebral fractures (> 24 h after trauma) were studied. The following significant postoperative changes of blood levels (median values, Wilcoxon signed-rank test) compared with the preoperative starting point were found: polymorphonuclear granulocyte elastase rose from 220 to 337 ng/ml, cathepsin B from 84.5 to 135.5 mU/l, C-reactive protein from 9.1 to 11.6 mg/dl, lactate from 9.6 to 15.2 mg/dl and neopterin from 6.9 to 15.2 nmol/l, while antithrombin III fell from 107.5% to 84%, platelet count from 102 to 88 x 10(9)/l and pO2/FiO2-ratio from 361 to 260. The alterations in the blood levels of these parameters following spine surgery showed a pattern similar, albeit of lesser magnitude, to that which can be observed after severe accidental trauma. We conclude that the additional activation of the inflammatory response following surgery for vertebral lesions should be taken into account when planning these operations in patients with multiple injuries.

[Postoperative homeostatic imbalance after trauma surgical interventions of various degrees in polytrauma]. / Postoperative Homöostasestörung nach unterschiedlich grossen unfallchirurgischen Eingriffen beim Polytrauma.

The objective of this study was to evaluate and compare the derangement of body homeostatis and the inflammatory response after different types of traumatological operations in patients with multiple injuries. These were determined in a total of 60 operations. The procedures comprised osteosynthesis of the femur (n = 28), the pelvic girdle (n = 11) the spine (n = 8), and facial and basal skull reconstructions (n = 13). Specific and unspecific parameters of the inflammatory response were determined on the morning of the operation, immediately after the procedure, every 6 h on the 1st day and 48 h after the end of surgery. After all types of operations (pelvis, femur, spine, face/basal skull) significant alterations were observed for neutrophil elastase, C-reactive protein, interleukin 6, interleukin 8, antithrombin III, partial thromboplastin time and other parameters. The degree of postoperative changes differed significantly (Kruskal-Wallis test, P < 0.05) among the four types of operations for lactate, heart rate, PO2/FiO2 ratio and nitrogen excretion and showed a strong discriminating tendency for neutrophil elastase and C-reactive protein. The changes were most pronounced after operations on the pelvic girdle, followed by procedures in the femoral, spinal, and facial/basal skull regions. We conclude that a considerable inflammatory response and pronounced disturbance of body homeostasis follow traumatological operative procedures, varying in severity with the type of surgery. Several parameters allow quantitation of the surgical trauma and differentiation between different operations/regions. Further research should focus on the interrelationship between pre-existing preoperative inflammation and the additional trauma inflicted by surgery in patients with severe injuries.(ABSTRACT TRUNCATED AT 250 WORDS)