Mitchell M M, Newbower R S
Am J Physiol. 1979 Mar;236(3):R168-74. doi: 10.1152/ajpregu.1979.236.3.R168.
The sensing of intrathoracic electrical impedance from an esophageal probe may allow relatively noninvasive monitoring of cardiac and respiratory functions of particular interest in anesthesia and intensive care. We have obtained a partial solution of the intrathoracic current-field problem for impedance measurements made from a four-terminal linear array of electrodes located in the esophagus. It allows prediction that aortic root motion will exceed aortic distension as a major determinant of the cardiac intrathoracic esophageal impedance signal. This prediction was confirmed for a specific carefully selected and placed electrode array in anesthetized dogs. In general, motions of organs will be more important than volume changes in affecting the esophageal impedance signal. Thus, timing information (preejection period and left ventricular ejection time) is available from electrodes on an esophageal probe, but cardiac output information appears to be inaccessible for fundamental reasons.
通过食管探头感测胸内电阻抗，可能实现对麻醉和重症监护中特别关注的心脏和呼吸功能进行相对无创的监测。我们已经得到了一个针对食管内四端线性电极阵列进行阻抗测量的胸内电流场问题的部分解决方案。它可以预测，作为心脏胸内食管阻抗信号的主要决定因素，主动脉根部运动将超过主动脉扩张。在麻醉犬中，对于精心选择并放置的特定电极阵列，这一预测得到了证实。一般来说，在影响食管阻抗信号方面，器官的运动比体积变化更为重要。因此，食管探头上的电极可获取定时信息（射血前期和左心室射血时间），但由于根本原因，心输出量信息似乎无法获取。
