Background Echocardiography is regarded as a gold standard for measuring hemodynamic values. The ultrasonic cardiac output monitor （USCOM） is a new method for measuring hemodynamics and could provide non-invasive po...Background Echocardiography is regarded as a gold standard for measuring hemodynamic values. The ultrasonic cardiac output monitor （USCOM） is a new method for measuring hemodynamics and could provide non-invasive point of care guidance. So far, there are no published USCOM reference values for neonates, nor has USCOM＇s accuracy been established in this population. We aimed to determine the accuracy and clinical utility of the USCOM in healthy neonates relative to published echocardiographic data, to establish normal hemodynamic parameters that it measures, and to assess the possible role of USCOM as an alternative to echocardiography as a trend monitor. Methods Right and left heart hemodynamics of 90 normal neonates were measured during circulatory adaptation over the first three days of life using the USCOM and automated oscillotonometry. Results Heart rate showed a significant decline from days one to three, from 126 to 120 （P〈0.001）. Systolic, diastolic and mean arterial pressures all increased significantly from 66 to 71 mmHg, 33 to 38 mmHg and 44 to 49 mmHg, respectively （P 〈0.001 in each case）. Right ventricular cardiac index （RV-CI） showed no change with a mean of 5.07 L.minl.m2. Left ventricular cardiac index （LV-CI） declined from 3.43 to 3.00 L.minl.m2 （P 〈0.001）. RV-CI exceeded LV-CI on all three days by a mean of 61%. The systemic vascular resistance index （SVRI）, based on LV-CI, increased significantly over the three days from 1083 to 1403 dyne.sec.cm5.m2 （P 〈0.001）. Conclusions Normal neonatal hemodynamic values, as indicated by USCOM, were established. LV-CI measurement showed excellent agreement with published echocardiographic studies. RV-CI was constant and exceeded LV-CI for all three days of this study. It may be falsely high due to flow velocity measurement errors arising from the pulmonary branch arteries, and may represent a limitation of the USCOM method. The progressive rise of arterial pressure and SVRI despite a declining LV-CI may indicate funct展开更多
Two models are defined for predicting the trajectory of a foam jet originating from a fire monitor(hydrant)and the related intensity drop point.An experimental framework is also defined and used accordingly to compare...Two models are defined for predicting the trajectory of a foam jet originating from a fire monitor(hydrant)and the related intensity drop point.An experimental framework is also defined and used accordingly to compare real-time data with the predictions of such models.This mixed theoretical-experimental approach is proven to be effective for the determination of otherwise unknown coefficients which take into account several important factors such as the operation pressure,the elevation angle and the nozzle diameter.It is shown that the mean absolute error is smaller than 20%.展开更多
文摘Background Echocardiography is regarded as a gold standard for measuring hemodynamic values. The ultrasonic cardiac output monitor （USCOM） is a new method for measuring hemodynamics and could provide non-invasive point of care guidance. So far, there are no published USCOM reference values for neonates, nor has USCOM＇s accuracy been established in this population. We aimed to determine the accuracy and clinical utility of the USCOM in healthy neonates relative to published echocardiographic data, to establish normal hemodynamic parameters that it measures, and to assess the possible role of USCOM as an alternative to echocardiography as a trend monitor. Methods Right and left heart hemodynamics of 90 normal neonates were measured during circulatory adaptation over the first three days of life using the USCOM and automated oscillotonometry. Results Heart rate showed a significant decline from days one to three, from 126 to 120 （P〈0.001）. Systolic, diastolic and mean arterial pressures all increased significantly from 66 to 71 mmHg, 33 to 38 mmHg and 44 to 49 mmHg, respectively （P 〈0.001 in each case）. Right ventricular cardiac index （RV-CI） showed no change with a mean of 5.07 L.minl.m2. Left ventricular cardiac index （LV-CI） declined from 3.43 to 3.00 L.minl.m2 （P 〈0.001）. RV-CI exceeded LV-CI on all three days by a mean of 61%. The systemic vascular resistance index （SVRI）, based on LV-CI, increased significantly over the three days from 1083 to 1403 dyne.sec.cm5.m2 （P 〈0.001）. Conclusions Normal neonatal hemodynamic values, as indicated by USCOM, were established. LV-CI measurement showed excellent agreement with published echocardiographic studies. RV-CI was constant and exceeded LV-CI for all three days of this study. It may be falsely high due to flow velocity measurement errors arising from the pulmonary branch arteries, and may represent a limitation of the USCOM method. The progressive rise of arterial pressure and SVRI despite a declining LV-CI may indicate funct
基金the National Key Research and Development Plan(Grant No.2016YFC0801300).
文摘Two models are defined for predicting the trajectory of a foam jet originating from a fire monitor(hydrant)and the related intensity drop point.An experimental framework is also defined and used accordingly to compare real-time data with the predictions of such models.This mixed theoretical-experimental approach is proven to be effective for the determination of otherwise unknown coefficients which take into account several important factors such as the operation pressure,the elevation angle and the nozzle diameter.It is shown that the mean absolute error is smaller than 20%.
