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K J Fischer

Publications and source records attributed to K J Fischer.

23 records · Page 2Linked to original sources
PubMed1978

[Tracheal wall/load during prolonged intubation. Experimental investigations on a model trachea (author's transl)].

Prolonged endotracheal intubation may be complicated by tracheal wall lesions caused by the blocking cuff of the tube. This happens when the tracheal wall load exceeds the capillary perfusion pressure. It is therefore important to control this load. As direct measurement presents difficult methodological problems, there have been many attempts to approximate the pressure load using different formulae. In a model trachea we showed the significance of the tracheal wall pressure as approximated by an indirect measurement principle. Our investigations demonstrate that the examined indirect method provides a sufficient approximation of the tracheal wall load only if it is used with the new low pressure high volume cuffs. It fails if it is used with the customary high pressure low volume balloons.

Humans↗
PubMed1976

[Myocardial contractility during limited haemodilution (author's transl)].

The direct cardiac effects of limited isovolaemic haemodilution by low molecular dextran was investigated in the cat heart-lung preparation. This type of preparation does not allow evaluation of the significance of nervous or humoral influences. All haemodynamic and contractile parameters remain unchanged as does myocardial adaptability to acute changes in pressure or volume load. However, cardiac function curves and the estimation of contractility by means of force-velocity-relations reveal a slight increase of the inotropic state.

Animals↗
PubMedDate not supplied

Observations of convergence and uniqueness of node-based bone remodeling simulations.

Some investigators have indicated that mathematical theories and computational models of bone adaptation may not converge and that the density solutions from such simulations are dependent on the initial density distribution. In this study, two-dimensional finite element models were used to investigate the effect of initial density distribution on the final density distribution produced using a node-based bone remodeling simulation. The first model was a generic long bone, and the second was a proximal femur, For each model, we conducted time-dependent, node-based, linear rate-law bone remodeling simulations. Five initial density conditions were used with the generic long bone and three with the proximal femur. Remodeling simulations were performed, and the largest average nodal density differences at the end of the simulations were 0.000010 g/cm3 and 0.000006 g/cm3 for the generic long bone and proximal femur models, respectively. Results illustrate that, for a given set of loads and a given finite element model, the node-based bone adaptation algorithm can yield a unique density distribution. In conjunction with previous studies, this finding suggests that uniqueness of the density solution is dependent on both the mathematical theory and the computational implementation.

Algorithms↗