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Alterations in circulating vasoactive substances in the critically ill —a comparison between survivors and non-survivors (1995)

Boldt, J. ; Menges, T. ; Kuhn, D. ; [et al.]

Springer

Intensive care medicine 21 (1995), S. 218-225

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ISSN: 1432-1238

Keywords: Critical illness ; Hemodynamics ; Circulation ; Vasoactive substances ; Endothelin ; Catecholamines ; Atrial natriuretic peptide ; Outcome

Source: Springer Online Journal Archives 1860-2000

Topics: Medicine

Notes: Abstract Objective Regulation of circulatory homeostasis is based on several factors including various circulating vasoactive substances. Whether these regulators differ between survivors and non-survivors was investigated in critically ill patients. Design Prospective study. Setting Clinical investigation on a surgical intensive care unit of an university hospital. Patients 60 consecutive patients suffering from trauma (n=21) or postoperative complications (n=39) were studied prospectively. The patients were divided into survivors (n=27) and non-survivors (n=33). Therapy was adjusted to the standards of modern intensive care management by physicians who were not involved in the study. Measurements and results Endothelin-1, atrial natriuretic peptide (ANP), vasopressin, renin, and catecholamine (epinephrine, norepinephrine) plasma levels were measured from arterial blood samples using radioimmunoassay (RIA) or high-pressure liquid chromatography (HPLC) technique on the day of admission to ICU and during the following 5 days. Various hemodynamic parameters were also monitored during that period. The non-survivors showed elevated pulmonary artery pressure (PAP: 34.1±5.4 mmHg) and pulmonary capillary wedge pressure (PCWP: 20.3±7.3 mmHg) already at the beginning of the study. Cardiac index (CI) did not differ among the groups, whereas right ventricular ejection fraction (RVEF) decreased in the non-survivors. PaO2/FIO2 decreased only in the non-survivors, whereas VO2 increased in the survivors (from 246±48 to 331±43 ml/min). Plasma levels of renin (from 206±40 to 595±81 pg/ml) and vasopressin (from 5.78±0.82 to 7.97±0.69 pg/ml) increased significantly in the non-survivors. Epinephrine and norepinephrine plasma concentrations were elevated in the non-survivors already at baseline and tremendously increased in these patients during the following days. ANP plasma levels significantly increased also only in the non-survivors (from 188±63 to 339±55 pg/ml) (p〈0.05). Endothelin-1 decreased in the survivors, whereas it significantly increased in the non-survivors (from 3.62±0.68 to 9.37±0.94 pg/ml) during the study period (p〈0.05). Analyses of co-variance revealed overall no significant correlation between circulating vasoactive substances and hemodynamics. Conclusions Systemic and regional regulators of the circulation were markedly changed by critical illness. In survivors, these regulators almost normalized within the study period of 5 days, whereas in non-survivors these alterations were even aggravated. It can only be speculated whether these regulator systems were influenced by activation of various mediator systems or whether they themselves influenced the negative outcome in the non-survivors.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01701475

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Transient three-dimensional flow in an enclosure with a hot spot on a vertical wall (1988)

Kuhn, D. ; Oosthuizen, P. H.

Chichester : Wiley-Blackwell

International Journal for Numerical Methods in Fluids 8 (1988), S. 369-385

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ISSN: 0271-2091

Keywords: 3D flow ; Vector potential vorticity vector ; Finite difference method ; Engineering ; Engineering General

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Notes: A numerical method for the solution of the vector potential/vorticity vector formulation of the transient, fully three-dimensional Navier-Stokes energy and continuity equations has been applied to simulate the development of natural convective flow within a ‘box’ after a sudden temperature change on a vertical portion of the wall. Only one cavity size has been considered, this having a vertical height of three times its width and a horizontal length of six times its width. A single heated rectangular hot spot or ‘element’ on an otherwise adiabatic wall is centred between the vertical end walls. The opposite vertical wall is held at the intial fluid temperature, and all other walls are assumed to be adiabatic. Fluid properties have been assumed constant except for the density change with temperature that gives rise to the buoyancy force. The numerical method is an underrelaxation Gauss-Seidel method using finite differencing at each time step. Solutions have been obtained for a Prandtl number of 0.71, for Rayleigh numbers, based on the width, of between 0 and 100000 and for a number of heated element locations and sizes.

Additional Material: 13 Ill.