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The current status and future directions of impedance cardiography in ICU (1989)

Fuller, H. ; Raskob, G. ; Keurs, H. ; [et al.]

Springer

Annals of biomedical engineering 17 (1989), S. 483-494

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ISSN: 1573-9686

Keywords: Impedance cardiography ; Stroke volume ; Ejection fraction ; End-diastolic volume ; End-systolic volume ; Intensive care unit ; Review

Source: Springer Online Journal Archives 1860-2000

Topics: Medicine , Technology

Notes: Abstract Impedance cardiography has not achieved popularity in the Intensive Care Unit (ICU) to date probably because of the limitations in technique and interpretation associated with the altered physiology of critically ill patients, and also because of interference from other machinery in the ICU. The current climate of questioning the existing technology for bedside cardiovascular assessment however spurs the need to evaluate impedance cardiography as a noninvasive alternative. Validation in noncritically ill patients is good when compared to other technologies (e.g., thermodilution, Fick, dye dilution (r〉0.9)). Reliability is good with a coefficient of variation in an ICU population of 8.9%, (compared to 18.6% for thermodilution). It has also shown promise in detecting the clinically significant changes of central intravascular volume. Impedance cardiography appears to be useful for measurement of stroke volume (SV) and ejection fraction (EF). From these, left ventricular end-diastolic volume (VED) can be calculated, probably a more reliable estimate of left ventricular filling than pulmonary capillary wedge pressure (PW), measured by pulmonary artery (PA) catheter. In addition, VES can be calculated and with the knowledge of left ventricular end-systolic pressure (PES) (from invasive arterial monitoring), an end-systolic pressure-volume (ES-PV) (relationship can be derived. This is thought to be a measure of contractility that is independent of preload and afterload. The ultimate test in the ICU for impedance cardiography is whether clinical outcome of critically ill patients is altered by the use of this technology. Such outcome testing is essential before the true value of impedance cardiography in the management of critically ill patients can be determined.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02368068

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Applications of focused ion beams in microelectronics production, design and development (1995)

Stevie, F. A. ; Shane, T. C. ; Kahora, P. M. ; [et al.]

Chichester [u.a.] : Wiley-Blackwell

Surface and Interface Analysis 23 (1995), S. 61-68

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ISSN: 0142-2421

Keywords: Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Physics

Notes: Focused ion beam (FIB) systems using gallium liquid metal ion sources can remove material with a lateral resolution below 50 nm and can produce metal deposition at a similar resolution with ion beam-enhanced chemical vapour deposition. These capabilities have resulted in many valuable applications for the microelectronics industry. Circuit modifications are possible because existing connections can be severed and reconnected to different locations. Testing of circuitry can be enhanced by isolation of specific circuits, removal of overlayers and by creation of probe pads where desired. Grain sizes can be determined from secondary electron images by the delineation of individual grains due to orientation-dependent channeling of the ion beam. Secondary ion mass spectrometry analyses of small areas can provide ion images, elemental identification of small areas and endpoint detection with depth profiles. Scanning electron microscopy and transmission electron microscopy sections are prepared routinely using the FIB. These FIB-prepared sections are notable because specific features, such as defects, can be exposed and a range of materials including silicon, indium phosphide, gallium arsenide and even metal layers can be cut without distortion. Transmission electron micrographs of superior quality have been obtained with a large area of very uniform thickness that permits identification of features such as areas under stress.

Additional Material: 7 Ill.