Interleukin 8 in postoperative delirium - preliminary findings from two studies

OBJECTIVE: Studies have suggested that inflammation contributes to the pathogenesis of postoperative delirium, but previous results on the proinflammatory cytokine IL-8 in plasma are contradictory. Additionally, a significant fraction of IL-8 is bound to erythrocytes, but the relevance of whole blood IL-8 in delirium has not been studied. In this work, we analyzed the association of postoperative delirium with levels of unbound IL-8 in plasma and levels of IL-8 in whole blood in patients from two studies which were conducted in our department and have not been presented previously. We assessed the prognostic value of whole blood IL-8. METHODS: Plasma/whole blood IL-8 was measured at least once in N ​= ​504 patients preoperatively, on day one (d1) and/or three months after surgery in the BioCog observational study. Whole blood IL-8 was measured in N ​= ​64 patients from the PHYDELIO trial preoperatively, on d1 and d7 after surgery. For the determination of whole blood IL-8, EDTA-preserved blood samples underwent lysis by adding Triton-X100 surfactant. Plasma and whole blood IL-8 levels were assessed with two different immunoassay kits. Delirium was appraised systematically for seven postoperative days according to DSM criteria using two comparable protocols consisting of validated screening tools. RESULTS: Delirium occurred in 25% of BioCog and 14% of PHYDELIO patients. In BioCog, IL-8 was elevated on d1 and in delirious patients. A steeper postoperative increase in delirium was confounded by surgery-related factors. A crescendo-decrescendo pattern of whole blood IL-8 levels was observed in non-delirious patients with a peak on d1. This pattern was more distinct in delirious BioCog patients, but inverted in delirious PHYDELIO patients. Preoperative whole blood IL-8>318.4 ​pg/mL (reference <150 ​pg/mL) had adequate sensitivity (0.79/0.78) and specificity (0.53/0.67) for delirium in both samples. CONCLUSION: Our results contribute to an inflammatory hypothesis of postoperative delirium

Dam-Break Waves’ Hydrodynamics on Composite Bathymetry

Among others, dam-break waves are a common representation for tsunami waves near- or on-shore as well as for large storm waves riding on top of storm surge water levels at coasts. These extreme hydrodynamic events are a frequent cause of destruction and losses along coastlines worldwide. Within this study, dam-break waves are propagated over a composite bathymetry, consisting of a linear slope and an adjacent horizontal plane. The wave propagation on the slope as well as its subsequent inundation of the horizontal hinterland is investigated, by varying an extensive set of parameters, for the first time. To that end, a numerical multi-phase computational fluid dynamics model is calibrated against large-scale physical flume tests. The model is used to systematically alter the parameters governing the hydrodynamics and to link them with the physical processes observed. The parameters governing the flow are the slope length, the height of the horizontal plane with respect to the ocean bottom elevation, and the initial impoundment depth of the dam-break. It is found that the overland flow features are governed by the non-dimensional height of the horizontal plane. Empirical equations are presented to predict the features of the overland flow, such as flow depth and velocities along the horizontal plane, as a function of the aforementioned parameters. In addition, analytical considerations concerning these dam-break flow features are presented, highlighting the changing hydrodynamics over space and time and rising attention to this phenomenon to be considered in future experimental tests