Background and Purpose: Hemodilution in the acute phase of ischemic stroke is still controversial. Multicenter studies have failed to demonstrate any benefit. The present study focuses attention on analysis of circulation in stroke and on individual restabilization of circulation.Methods: The Amsterdam Stroke Study is a prospective, single-center, randomized clinical trial (n=300). Normovolemic hemodilution is accomplished in a customized procedure by administration of 20% albumin plus crystalloids under hemodynamic and rheological monitoring in the acute phase of stroke. All patients receive general intensive care treatment and monitoring with a pulmonary artery catheter. This custom-tailored fluid therapy is guided on the basis of a target pulmonary capillary wedge pressure (12 ±3 mm Hg) and hematocrit (0.32 ±0.02). The control group receives only customized rehydration by infusion of crystalloids.Results: We obtained significant (p<0.05) reduction in mortality at 3 months (from 27% to 16%) and an increase in independence at home (from 35% to 48%) after viscosity reduction by means of hemodilution with albumin in the subgroup with a hematocrit <0.45 (n=201) (specific viscosity effect). We also obtained a significant (p<0.005) reduction in mortality at 3 months (from 27% to 8%) and an increase in independence (from 35% to 59%) after only rehydration with crystalloids in the subgroup with overt dehydration (hematocrit >0.45; «=51) as compared with the normal-hematocrit group without signs of dehydration (hematocrit <0.45; «=103) (specific rehydration effect).Conclusions: This study may provide an explanation for the failures in former hemodilution trials and may re-establish proper hemodilution and rehydration as a valuable therapy in the acute phase of stroke, thus reducing mortality and improving independence after 3 months. (Stroke 1992;23:181-188)
Mean-arterial pressure (MAP), heart period (HP) and the level of physical activity were measured in conscious rabbits and averaged over one-hour periods during 14 consecutive days. Serial autocorrelation coefficients and serial crosscorrelation coefficients were computed, to analyse periodicity. Measurements were started immediately after implantation of the cannula (group A, n = 11) or 10-46 days after implantation of the cannula (group B, n = 6). In the course of 14 days, in group A, MAP decreased 9 mmHg and HP increased 21 ms (P less than 0.05). In group B, MAP decreased and HP increased in a similar way. Percentage activity did not show a trend. Significant diurnal rhythms were found. MAP and percentage activity reached the lowest values at noon, and the highest late in the evening. HP reached the highest values at noon and the lowest late in the evening. MAP and HP fluctuated exactly in antiphase. This suggests a common origin for both rhythms. During physical activity MAP was 10-15 mmHg higher and HP was 35-40 ms shorter than during rest. These differences did not show a trend or a diurnal variation. In individual animals MAP and HP varied greatly from hour to hour. These biological variations in MAP and HP as well as the influence of activity should be taken into account when conclusions are drawn from short-term measurements.
A measuring system is described for the long-term continuous beat-to-beat measurement of mean aortic pressure and heart period (interval between beats) in the conscious unrestrained rabbit. Pressures and heart periods were collected in hourly histograms. The histograms were summed into day (0800-2000 h), night (2000-0800 h) and 24-hour histograms. Separate histograms were formed for resting and active periods. From each histogram the mean value, standard deviation, fifth percentile, 50th percentile and 95th percentile were calculated and stored on a floppy disc together with the histograms. Off-line, histograms and their descriptive parameters were plotted and sent to a HP1000 computer for bulk storage and further analysis. The measuring system is capable of handling up to eight animals simultaneously for an indefinite period. The design functioned properly in the long-term measurement (more than 4 weeks) of mean level and variability of arterial pressure and heart period. The measuring system is useful in the study of arterial blood pressure behaviour after sino-aortic denervation and in the evaluation of drug effects in conscious animals.
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