Hettrick D A, Battocletti J H, Ackmann J J, Linehan J H, Warltier D C
Department of Anesthesiology, Medical College of Wisconsin, Milwaukee 53226, USA.
Ann Biomed Eng. 1996 Nov-Dec;24(6):675-84. doi: 10.1007/BF02684180.
This investigation examined the feasibility of applying the conductance catheter technique for measurement of absolute aortic segmental volume. Aortic segment volume was estimated simultaneously in vitro by using the conductance catheter technique and sonomicrometer crystals. Experiments were performed in five isolated canine aortas. Vessel diameter and pressure were altered, as were the conductive properties of the surrounding medium. In addition, a three-dimensional finite-element model of the vessel and apparatus was developed to examine the electric field and parallel conductance volume under different experimental conditions. The results indicated that in the absence of parallel conductance volume, the conductance catheter technique predicted absolute changes in segmental volumes and segmental pressure-volume relationships that agreed closely with those determined by sonomicrometry. The introduction of parallel conductance volume added a significant offset error to measurements of volume made with the conductance catheter that were nonlinearly related to the conductive properties of the surrounding medium. The finite-element model was able to predict measured resistance and parallel conductance volume, which correlated strongly with those measured in vitro. The results imply that absolute segmental volume and distensibility may be determined only if the parallel conductance volume is known. If the offset volume is not known precisely, the conductance catheter technique may still be applied to measure absolute changes in aortic segmental volume and compliance.
本研究探讨了应用电导导管技术测量主动脉绝对节段容积的可行性。通过使用电导导管技术和超声微测晶体，在体外同时估计主动脉节段容积。在五条离体犬主动脉上进行了实验。改变血管直径和压力以及周围介质的导电特性。此外，建立了血管和仪器的三维有限元模型，以研究不同实验条件下的电场和平行电导容积。结果表明，在不存在平行电导容积的情况下，电导导管技术预测的节段容积绝对变化和节段压力-容积关系与超声微测法测定的结果密切相符。平行电导容积的引入给电导导管测量的容积带来了显著的偏移误差，该误差与周围介质的导电特性呈非线性关系。有限元模型能够预测测得的电阻和平行电导容积，其与体外测量结果高度相关。结果表明，只有在已知平行电导容积的情况下，才能确定绝对节段容积和扩张性。如果偏移容积不能精确得知，电导导管技术仍可用于测量主动脉节段容积和顺应性的绝对变化。
