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R Giniger

Publications and source records attributed to R Giniger.

9 recordsLinked to original sources
PubMed1988

Comparison between measured and fick-derived values of hemodynamic and oxymetric variables in patients with acute myocardial infarction.

PURPOSE: Previous studies have compared the relationship between directly measured values for cardiac output, systemic oxygen consumption (VO2), and arteriovenous oxygen difference (D(A-v)O2) with those calculated by the Fick principle. However, the validity of Fick's principle in critically ill patients undergoing physiologic changes and pharmacologic interventions is unknown. The purpose of our study was to compare directly measured values for hemodynamic and oxymetric variables with those calculated by the Fick equation in patients with acute myocardial infarction, at baseline and after the hemodynamic changes produced by pharmacologic interventions. PATIENTS AND METHODS: Cardiac output, (VO2), and (D(A-v)O2) were measured in 33 patients with acute myocardial infarction, at baseline (50 +/- 30 hours after the onset of symptoms) and after pharmacologic intervention to relieve pulmonary congestion. These values were then compared with indirect values derived from the Fick equation. RESULTS: High and significant correlations were found between thermodilution and Fick-derived cardiac output at baseline (r = 0.91, p less than 0.001) and post-intervention (r = 0.92, p less than 0.001). Similarly, VO2 values measured by expired gas analysis showed a significant correlation with VO2 calculated by the Fick principle, at baseline (r = 0.85, p less than 0.001) and post-intervention (r = 0.84, p less than 0.001). Lastly, when D(A-v)O2 of arterial and mixed venous samples was measured by spectrophotometry and compared with calculated values, there was a significant correlation at baseline (r = 0.85, p less than 0.001) and after intervention (r = 0.85, p less than 0.001). Analysis of variance revealed no difference between measured and calculated values for the three variables under those two conditions. CONCLUSION: In patients with acute myocardial infarction, cardiac output, VO2, and D(A-v)O2 indirectly calculated by the Fick principle are equivalent to directly measured values, despite the various degrees of hemodynamic dysfunction and the currently used therapeutic interventions.

Aged↗
PubMed1987

Gentamicin dosage regimen based on serum creatinine concentration.

In order to avoid gentamicin toxicity trough serum concentrations when drug monitoring is not available, a correction factor for serum creatinine was calculated and evaluated. In a first group of 35 patients under aminoglycoside treatment with variable serum creatinine (SCr) values, the regression plot of SCr concentrations versus half-life (T1/2) values was established: log T1/2 = log 2.28 + 1.45 log SCr, r = 0.90, p less than 0.01. A second group of 18 patients was treated with doses of 1.0 mg/kg of gentamicin. Dose intervals equivalent to 3 T1/2 were daily adjusted. The T1/2 was calculated from SCr according to the relationship established for the patients of the first group. All the patients studied maintained trough levels within the therapeutic range.

Adult↗
PubMed1983

Kinetic analysis of the protonation of a surface group of a macromolecule.

The dynamics of proton transfer between a surface-attached acidic moiety and the bulk of the solution was measured using the laser-induced proton pulse technique. [Gutman, M., Huppert, D. and Pines, E. (1981) J. Am. Chem. Soc. 103, 3709-3713]. The model system for this study consists of pH indicators (either neutral red or bromcresol green) adsorbed on Brij 58 micelles, as defined targets for protonation and a non-adsorbed proton emitter (2-naphthol-3,6-disulfonate) for generation of protons in bulk. The reaction was measured with 50-ns time resolution over a time period of about 200 microseconds. The results were analyzed by a numerical solution of the coupled nonlinear differential equation corresponding with the reaction system. [Gutman, M., et al. (1983) J. Am. Chem. Soc. 105, 2210-2216]. Quantitative analysis reveals two independent reactions which govern the observed dynamics: (a) a diffusion-controlled reaction between the proton and the surface targets; (b) translocation of the protonated target between the hydration layer of the interface and a more hydrophobic one. The contribution of the translocation reaction to the dynamics of surface protonation is more pronounced for compounds like carboxylates or phenolates which increase their hydrophobicity upon protonation. Amines and azoaromatic structures are more hydrophilic in their protonated states, the dynamics of their protonation is less affected by post-protonation distribution within the microenvironments of the interface. The interrelation between the partial rate constants and the macroscopic time constants and equilibrium parameters is analyzed.

Bromcresol Green↗