Critical care medicine
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Critical care medicine · Jan 1996
Factors affecting the performance of the models in the Mortality Probability Model II system and strategies of customization: a simulation study.
To examine the impact of hospital mortality and intensive care unit (ICU) size on the performance of the Mortality Probability Model II system for use in quality assessment, and to examine the ability of model customization to produce accurate estimates of hospital mortality to characterize patients by severity of illness for clinical trials. ⋯ Mortality Probability Model II models can be used to assess quality of care in ICUs, but the size of the sample should be considered when assessing calibration and discrimination.
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Critical care medicine · Jan 1996
Cerebral blood flow and carbon dioxide reactivity in neonates during venoarterial extracorporeal life support.
a) To determine if cerebral blood flow is symmetric after internal carotid artery and ipsilateral internal jugular vein ligation in infants during venoarterial extracorporeal life support. b) To determine the cerebral CO2 reactivity (delta cerebral blood flow/delta torr CO2) of neonates during venoarterial extracorporeal life support and its correlation to neurodevelopmental outcome. ⋯ Hemispheric cerebral blood flow was symmetric in infants during early and late venoarterial extracorporeal life support. Some subgroups showed a trend toward decreased right hemispheric cerebral blood flow, but the small number of patients limited interpretation of this finding. CO2 reactivity and cerebral blood flow were highly variable in this population, and were not predictive of short-term neurodevelopmental outcome. Stressed neonates with extremely low cerebral blood flow rates may have relatively normal short-term neurodevelopmental outcome after venoarterial extracorporeal life support.
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Critical care medicine · Jan 1996
Nitric oxide synthase inhibition during experimental sepsis improves renal excretory function in the presence of chronically increased atrial natriuretic peptide.
To test whether renal excretory function decreases after nitric oxide synthase inhibition during experimental hyperdynamic sepsis. ⋯ In this ovine model of experimental hyperdynamic sepsis, renal excretory function decreases in the presence of chronically increased concentrations of atrial natriuretic peptide. Administration of the nitric oxide synthase inhibitor, N omega-nitro-L-arginine methyl ester, reverses the vasodilatory state, thereby improving fluid balance and glomerular filtration.
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Critical care medicine · Jan 1996
Single breath CO2 analysis: description and validation of a method.
To evaluate the performance of a newly developed single breath CO2 analysis station in measuring the airway deadspace in a lung model (study 1), and then to quantify the bias and precision of the physiologic deadspace measurement in a surfactant-depleted animal model (study 2). ⋯ Our initial experience with the single breath CO2 analysis station indicates that this device can reliably provide on-line evaluation of the single-breath CO2 waveform. In particular, estimation of the airway and physiologic deadspace under a variety of testing conditions was consistently within 5% of actual values. We feel that with further application and refinement of the technique, single breath CO2 analysis may provide a noninvasive, on-line monitor of changes in pulmonary blood flow.
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Critical care medicine · Jan 1996
Comparative StudyOxygen consumption calculated from the Fick equation has limited utility.
To determine if oxygen consumption (VO2) calculated using the Fick relationship (calculated VO2) determines total body VO2 accurately and precisely enough to employ this method during clinical assessment of oxygen transport. ⋯ Even in a tightly controlled, clinical simulation in the laboratory, calculated VO2 from the Fick relationship systematically underestimated VO2 measured with a water-sealed spirometer. If true VO2 changes, the magnitude and direction of change will be reflected by calculated VO2 but with approximately 20% error in the absolute value. Heart failure, acute lung injury, and their combination did not affect the accuracy of calculated VO2. Therefore, calculating VO2 using the Fick relationship is too inaccurate to be used for research purposes. Because assessment of the directional change of VO2 may be clinically useful, calculated VO2 can be employed with discretion during clinical oxygen transport evaluation, bearing in mind the calculation's inherent imprecision.