Florence Nightingale.
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History, Modern 1601-↗
Biomedical subjects
S Everett
Publications and source records attributed to S Everett.
Characterization of natural and total artificial heart acceleration.
The pulsatile nature of an implanted total artificial heart (TAH) may have several deleterious effects. To define the level of TAH impact, acceleration was measured and compared with that of the natural heart in a series of in vivo and in vitro experiments. In TAH implantations in calves, miniature accelerometers were incorporated onto the housing of a Utah-100 left ventricle. Identical accelerometers were glued to felt pledgets to obtain measurement of radial cardiac acceleration when sewn to the epicardial surface of the natural heart. Measurement of natural and artificial heart acceleration was made both intraoperatively and postoperatively in several animals. Many pumping conditions were also investigated with a similarly instrumented UVAD 85 left ventricle during in vitro testing. The peak natural heart acceleration measured was nearly 2 g both intraoperatively and at rest. Treadmill exercise or epinephrine infusion produced twice the resting peak acceleration value of the natural heart. Artificial heart peak acceleration as great as +/- 100 g was found intraoperatively and postoperatively. Peak TAH acceleration could be reduced by allowing the ventricle to fill fully prior to the start of the next systole, by allowing the ventricle to fully eject prior to the next diastole, or by using a ventricular pressurization waveform that has a smooth contour with a sinusoidal-like profile. The ability to lower TAH acceleration may lead to a reduction in undesirable consequences of TAH implantation.
Animals↗
Systemic effects of mydriatics in low weight infants.
Two-and-a-half percent phenylephrine eye drops were used in combination with 0.5% tropicamide for routine pupillary dilation in 10 low weight infants. Significant systolic blood pressure elevation was noted in eight of 10 infants. A matched control group dilated with cycloplegics alone did not show a significant rise in systolic blood pressure. The mean change in pupillary dilation in the study group was 3.9 mm compared with 3.1 mm in the control group. This difference is not statistically significant. We therefore recommend that cycloplegic agents alone be used for pupillary dilation in these high risk infants.
Blood Pressure↗
Factors influencing the accuracy of the cardiac output monitoring and diagnostic unit for pneumatic artificial hearts.
The Cardiac Output Monitor and Diagnostic Unit (COMDU) has been the most widely used method to noninvasively determine cardiac output in pneumatic ventricles for the past 10 years. Clinical observation has suggested a discrepancy between the COMDU and expected cardiac outputs. In vivo tests verified and quantified this error. The error sources were examined using in vitro test conditions, with both the inflow and outflow, as well as COMDU flow readings, being analyzed. Transducer and calibration error sources were also identified, and the accuracy of the method for determining cardiac output for the in vitro test conditions was quantified. With a more accurate calibration scheme, the in vitro average error was reduced from -16.2% (range of 0.1% to -41.1%) to 0.1% (range 4.8% to -3.65). The major error sources were identified as missed inflow, transducer calibration and drift, and system variance.
Animals↗