The use of bio-electrical impedance analysis (BIA) to guide fluid management, resuscitation and deresuscitation in critically ill patients : a bench-to-bedside review

The impact of a positive fluid balance on morbidity and mortality has been well established. However, little is known about how to monitor fluid status and fluid overload. This narrative review summarises the recent literature and discusses the different parameters related to bio-electrical impedance analysis (BIA) and how they might be used to guide fluid management in critically ill patients. Definitions are listed for the different parameters that can be obtained with BIA; these include among others total body water (TBW), intracellular water (ICW), extracellular water (ECW), ECW/ICW ratio and volume excess (VE). BIA allows calculation of body composition and volumes by means of a current going through the body considered as a cylinder. Reproducible measurements can be obtained with tetrapolar electrodes with two current and two detection electrodes placed on hands and feet. Modern devices also apply multiple frequencies, further improving the accuracy and reproducibility of the results. Some pitfalls and conditions are discussed that need to be taken into account for correct BIA interpretation. Although BIA is a simple, noninvasive, rapid, portable, reproducible, and convenient method of measuring body composition and fluid distribution with fewer physical demands than other techniques, it is still unclear whether it is sufficiently accurate for clinical use in critically ill patients. However, the potential clinical applications are numerous. An overview regarding the use of BIA parameters in critically ill patients is given, based on the available literature. BIA seems a promising tool if performed correctly. It is non-invasive and relatively inexpensive and can be performed at bedside, and it does not expose to ionising radiation. Modern devices have very limited between-observer variations, but BIA parameters are population-specific and one must be aware of clinical situations that may interfere with the measurement such as visible oedema, nutritional status, or fluid and salt administration. BIA can help guide fluid management, resuscitation and de-resuscitation. The latter is especially important in patients not progressing spontaneously from the Ebb to the Flow phase of shock. More research is needed in critically ill patients before widespread use of BIA can be suggested in this patient population.The impact of a positive fluid balance on morbidity and mortality has been well established. However, little is known about how to monitor fluid status and fluid overload. This narrative review summarises the recent literature and discusses the different parameters related to bio-electrical impedance analysis (BIA) and how they might be used to guide fluid management in critically ill patients. Definitions are listed for the different parameters that can be obtained with BIA; these include among others total body water (TBW), intracellular water (ICW), extracellular water (ECW), ECW/ICW ratio and volume excess (VE). BIA allows calculation of body composition and volumes by means of a current going through the body considered as a cylinder. Reproducible measurements can be obtained with tetrapolar electrodes with two current and two detection electrodes placed on hands and feet. Modern devices also apply multiple frequencies, further improving the accuracy and reproducibility of the results. Some pitfalls and conditions are discussed that need to be taken into account for correct BIA interpretation. Although BIA is a simple, noninvasive, rapid, portable, reproducible, and convenient method of measuring body composition and fluid distribution with fewer physical demands than other techniques, it is still unclear whether it is sufficiently accurate for clinical use in critically ill patients. However, the potential clinical applications are numerous. An overview regarding the use of BIA parameters in critically ill patients is given, based on the available literature. BIA seems a promising tool if performed correctly. It is non-invasive and relatively inexpensive and can be performed at bedside, and it does not expose to ionising radiation. Modern devices have very limited between-observer variations, but BIA parameters are population-specific and one must be aware of clinical situations that may interfere with the measurement such as visible oedema, nutritional status, or fluid and salt administration. BIA can help guide fluid management, resuscitation and de-resuscitation. The latter is especially important in patients not progressing spontaneously from the Ebb to the Flow phase of shock. More research is needed in critically ill patients before widespread use of BIA can be suggested in this patient population

A new age model and chemostratigraphic framework for the Maastrichtian type area (southeastern Netherlands, northeastern Belgium)

The youngest time interval of the Cretaceous Period is known as the Maastrichtian, in reference to the shallow-marine strata outcropping in the area surrounding the city of Maastricht, in the Netherlands-Belgium border region. While the type-Maastrichtian strata have yielded a wealth of paleontological data, comparatively little geochemical work has so far been carried out on this succession. To date, age assessment of the type-Maastrichtian, and stratigraphic correlation with sections elsewhere, have largely been based on biostratigraphy and preliminary attempts at cyclostratigraphy. However, these techniques are hampered by bio-provincialism and the presence of stratigraphic gaps in the succession, respectively. In recent years, stable carbon isotope stratigraphy has proven to be a powerful tool for correlating Upper Cretaceous strata on a global scale. When integrated with biostratigraphy, carbon isotope stratigraphy can be used to test the synchroneity of biological and climatic events across the globe and to reconcile inter-regional biostratigraphic schemes. Therefore, we have generated the first high-resolution bulk stable carbon isotope stratigraphy for the type-Maastrichtian, using an extensive sample set acquired within the context of the Maastrichtian Geoheritage Project spanning approximately 100 meters of stratigraphy at the Hallembaye and former ENCI quarries. In combination with bulk major and trace element data generated using µXRF, this record presents the first high-resolution chemostratigraphic survey for the type-Maastrichtian. The µXRF-based element profiles through the type-Maastrichtian succession reveal variable fluxes of terrigenous input into this carbonate system over time, marking three distinct stratigraphic sequences, separated by sequence boundaries at the Froidmont, Lichtenberg and Vroenhoven horizons. In addition, the carbon isotope profile records the Campanian–Maastrichtian Boundary Event (CMBE) and the Mid-Maastrichtian Event (MME) in the Maastrichtian type area for the first time. Our refined age model allows for global correlation between the type-Maastrichtian sequence and Maastrichtian successions worldwide and places the abundant paleontological records from the type-Maastrichtian in a global context