Biological research for nursing
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Accurate temperature measurement is critical to the assessment and management of temperature fluctuation in the acutely ill adult. Unfortunately, an accurate, noninvasive method to measure core temperature has yet to be established, and current instruments produce a wide range of temperatures for any given patient. This article provides an integrative review of studies comparing selected invasive and noninvasive temperature measurement methods in acutely ill, hospitalized adult patients. ⋯ The only study evaluating the use of temporal artery thermometry in the adult population found the instrument to be unreliable. Results also indicate that high-quality evidence supporting the accuracy of tympanic thermometry, the preferred instrument for noninvasive core temperature measurement in many acute care settings, is lacking, and in fact, the most recent high-quality studies evaluating the accuracy of this instrument fail to show support for its use. Evidence does, however, support the use of oral thermometry as an accurate means of temperature assessment in the adult, acutely ill population.
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Cardiac variability can be assessed from two perspectives: beat-to-beat performance and continuous performance during the cardiac cycle. Linear analysis techniques assess cardiac variability by measuring the physical attributes of a signal, whereas nonlinear techniques evaluate signal dynamics. This study sought to determine if recurrence quantification analysis (RQA), a nonlinear technique, could detect pharmacologically induced autonomic changes in the continuous left ventricular pressure (LVP) and electrographic (EC) signals from an isolated rat heart-a model that theoretically contains no inherent variability. ⋯ These results suggest that when either the sympathetic or parasympathetic division of the autonomic nervous system overwhelms the other, the dynamics underlying cardiac variability become stationary. This study also shows that information concerning inherent variability in the isolated rat heart can be gained via RQA of the continuous cardiac signal. Although speculative, RQA may be a tool for detecting alterations in cardiac variability and evaluating signal dynamics as a nonlinear indicator of cardiac pathology.