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Methods: Dogs (n = 8) were fitted with instruments for long-term measurement of LV and aortic blood pressure, aortic blood flow, and subendocardial segment length and received dexmedetomidine (1.25, 2.5, and 5 [micro sign]g/kg) in a cumulative manner before and after 19 +/- 3 (mean +/- SEM) days of rapid LV pacing. LV afterload was measured with aortic input impedance [Zin ([Greek small letter omega]) and quantified with a three-element Windkessel model. Hemodynamics and Zin ([Greek small letter omega]) were assessed under control conditions and 5 and 60 min after administration of each dose.
Results: Dexmedetomidine caused early and late decreases in heart rate, the maximum rate of increase of LV pressure, mean aortic blood flow, and stroke volume in dogs before and after pacing. Dexmedetomidine caused similar early increases in total arterial resistance and decreases in total arterial compliance in dogs before and after pacing. Early dexmedetomidine-induced increases in resistance and decreases in compliance caused similar reductions in mean aortic blood flow in cardiomyopathic compared with healthy dogs. Resistance and compliance returned to control values, and characteristic aortic impedance decreased late after dexmedetomidine in healthy dogs. In contrast, resistance remained elevated late after dexmedetomidine in dogs with dilated cardiomyopathy. 相似文献
Design: Qualitative field research.
Population, Sample, Setting: Populations were critical care nurses and critically ill adult patients in the 10-bed medical critical care unit of a 900-bed teaching hospital. A convenience-purposive sample of 27 nurses and 31 patients was studied in 1985.
Methods: Six months of participant observation, unstructured interviews, and the constant comparison method of grounded theory.
Findings: Markedly different patterns were found in expert and nonexpert practice. The substantive theory of conversion helped explain how the majority of nonexpert nurses advanced their practice. The metaphor of catalyzed conversion captures how a unit-based expert nurse serves as a catalyst to advance the practice of nonexperts. Presence, defined as the way of being within a given clinical context, differentiated nurses.
Conclusions: (a) Expert and nonexpert practices are substantively different, (b) Expert and nonexpert practice results in different patient outcomes, (c) Conversion helps explain changes in nonexpert practice.
Clinical Implications: A unit-based expert nurse can increase patient-focused care. 相似文献