Descending Aortic Flow Contribution to Intrathoracic Impedance—Development and Preliminary Testing of a Dual Impedance Model

• Published in: Journal of clinical monitoring and computing Vol. 22; no. 1; pp. 11 - 22
• Main Authors: Baker, A. Barry, McLeod, Chris N., Roxburgh, Alastair J., Bannister, Paul
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 2008; Springer; Springer Nature B.V
• Subjects: Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Anesthesiology; Aorta, Thoracic - physiology; Biological and medical sciences; Cardiac Output - physiology; Cardiography, Impedance - methods; Critical Care Medicine; Electric Impedance; Electrodes; Emergency and intensive cardiocirculatory care. Cardiogenic shock. Coronary intensive care; Health Sciences; Humans; Intensive; Intensive care medicine; Medical sciences; Medicine; Medicine & Public Health; Models, Cardiovascular; Monitoring, Physiologic - methods; Regional Blood Flow - physiology; Statistics for Life Sciences; Stroke Volume - physiology; itrathoracic impedance; aortic flow; model; Intensive care; Blood vessel; Aorta; Circulatory system; Impedance; Artery; Resuscitation
• ISSN: 1387-1307; 1573-2614
• DOI: 10.1007/s10877-007-9102-z

Objective Impedance measurement of cardiac output has struggled to become established partly because there have been only a few attempts to establish a sound theoretical basis for this measurement. Our objective is to demonstrate that there is valuable aortic flow information available from an intrathoracic impedance signal which may eventually be useful in the measurement of cardiac output by impedance technology. Methods A model, using dual impedance measurement electrodes and the change in impedance when blood flows, has been developed based on an intrathoracic impedance model of the descending aorta and esophagus. Using this model as the basis for measurement by an esophageal probe, we provide solutions to the velocity of blood flow in the descending aorta. Results Five patients were studied. Only three patients had suitable signals for analysis but the aortic flow profiles from these three patients were consistent and realistic. Conclusion Aortic blood flow information may be obtained from the intrathoracic impedance signal using this dual impedance method.