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Flow Waveform (flow + waveform)
Selected AbstractsExtracting arterial flow waveforms from pulse oximeter waveformsANAESTHESIA, Issue 6 2001apparatus A method is described which allows an approximation to the arterial flow waveform to be derived from a pulse oximeter waveform. The observed pulse oximeter waveform is the sum of arterial inflow and venous outflow. These components are separated mathematically. Subtraction of the venous outflow reveals the underlying arterial flow waveform. The assumptions on which the method is based are stated explicitly and discussed. [source] Perfusate Lactate Dehydrogenase Level and Intrarenal Resistance Could Not Be Adequate Markers of Perfusion Quality During Isolated Kidney PerfusionARTIFICIAL ORGANS, Issue 11 2000Berta Herrera Abstract: The main goal of this work was to study the influence of perfusion pressure and flow waveform during kidney perfusion, and the relationship between renal vascular resistance (RVR) and lactate dehydrogenase (LDH) concentration in the perfusate. Simultaneous constant pressure kidney perfusions were performed with either pulsatile or continuous flow at either 30 or 80 mm Hg of constant perfusion pressure. Mean flow, pressure, and RVR were displayed online during perfusion. Perfusate samples for LDH, creatine phosphatase kinase (CPK), and alkaline phosphatase (AP) determinations were taken. At the end of the perfusion, 2 ml of Evans blue was injected into the circuit to obtain images of perfusate distribution, and the kidneys were weighed. Also, hematoxylin/eosine studies were performed, showing more Bowman's space and tubular dilation in kidneys perfused with high pressure. We did not find differences in RVR between kidneys perfused at 30 and 80 mm Hg; nevertheless, perfusate distribution was better in the 80 mm Hg perfusions. We did not find any correlation between enzyme release and RVR in kidneys perfused with different mean pressures. These findings suggest that vascular resistance and LDH concentration cannot be independently considered as adequate markers of perfusate distribution. [source] Extracting arterial flow waveforms from pulse oximeter waveformsANAESTHESIA, Issue 6 2001apparatus A method is described which allows an approximation to the arterial flow waveform to be derived from a pulse oximeter waveform. The observed pulse oximeter waveform is the sum of arterial inflow and venous outflow. These components are separated mathematically. Subtraction of the venous outflow reveals the underlying arterial flow waveform. The assumptions on which the method is based are stated explicitly and discussed. [source] Optimizing the Circuit of a Pulsatile Extracorporeal Life Support System in Terms of Energy Equivalent Pressure and Surplus Hemodynamic EnergyARTIFICIAL ORGANS, Issue 11 2009Choon Hak Lim Abstract:, The nonpulsatile blood flow obtained using standard cardiopulmonary bypass (CPB) circuits is still generally considered an acceptable, nonphysiologic compromise with few disadvantages. However, numerous reports have concluded that pulsatile perfusion during CPB achieves better multiorgan response postoperatively. Furthermore, pulsatile flow during CPB has been consistently recommended in pediatric and high-risk patients. However, most (80%) of the total hemodynamic energy generated by a pulsatile pump is absorbed by the components of the extracorporeal circuit and only a small portion of the pulsatile energy is delivered to the patient. Therefore, we considered that optimizations of CPB unit and extracorporeal life support (ECLS) system circuit components were needed to deliver sufficient pulsatile flow. In addition, energy equivalent pressure, surplus hemodynamic energy, and total hemodynamic energy, calculated using pressure and flow waveforms, were used to evaluate the pulsatilities of pulsatile CPB and ECLS systems. [source] | ||||||||||