The precise recognition of feature points of impedance cardiogram (ICG) is the precondition of calculating hemodynamic parameters based on thoracic bioimpedance. To improve the accuracy of detecting feature points of ICG signals, a new method was proposed to de-noise ICG signal based on the adaptive ensemble empirical mode decomposition and wavelet threshold firstly, and then on the basis of adaptive ensemble empirical mode decomposition, we combined difference and adaptive segmentation to detect the feature points, A, B, C and X, in ICG signal. We selected randomly 30 ICG signals in different forms from diverse cardiac patients to examine the accuracy of the proposed approach and the accuracy rate of the proposed algorithm is 99.72%. The improved accuracy rate of feature detection can help to get more accurate cardiac hemodynamic parameters on the basis of thoracic bioimpedance.

Objective To investigate physiological changes in peri extracorporeal circulation period of patients who underwent cardiac valve replacement surgeries with crystalloid solution mixed with colloidal solutions and pure crystal solution as extracorporeal circulation priming solution, and explore the clinical value and practicability of crystalloid solution as the sole extracorporeal circulation priming solution.Methods A retrospective analysis was performed in 130 patients who underwent cardiac valve replacement surgeries.Pure lactated Ringer's solution liquid and Lactated Ringer's solution mixed with Voluven as the extracorporeal circulation priming solution were used.We respectively compared hematocrit at different time points, postoperative blood routine, liver and kidney function, blood coagulation index, duration of intensive care and trachea cannula in two groups.Results There were no significant differences in ages, preoperative blood routine, kidney function, blood coagulation function, duration of operation, clamping time, bypass time, intensive care, postoperative blood routine, kidney function, blood coagulation function and hematocrit at different time points in two groups (P ＞0.05).However, the hospital day of group which used crystalloid solution as extracorporeal circulation priming solution was significant shorter compared to group which used lactated Ringer's solution mixed with Voluven (P ＜ 0.05).Alanine aminotransferase of group which used crystalloid solution as extracorporeal circulation priming solution was significant higher compared to group which used lactated Ringer's solution mixed with Voluven (P ＜0.01).Conclusions Crystalloid solution as extracorporeal circulation priming solution is safe and economy in cardiopulmonary bypass.Pure crystalloid solution as the sole extracorporeal circulation priming solution can be safely used on patients (New York Heart Association class Ⅱ-Ⅲ) who have normal liver and kidney function before the operation of adult heart valve replacement with cardiopulmonary bypass.