Stroke volume equation for impedance cardiography

The study's goal was to determine if cardiac output (CO), obtained by impedance cardiography (ICG), would be improved by a new equation N, implementing a square root transformation for dZ/dtmax/Z0, and a variable magnitude, mass-based volume conductor Vc. Pulmonary artery catheterisation was performed on 106 cardiac surgery patients pre-operatively. Post-operatively, thermodilution cardiac output (TDCO) was simultaneously compared with ICG CO. dZ/dtmax/Z0 and Z0 were obtained from a proprietary bioimpedance device. The impedance variables, in addition to left ventricular ejection time TLVE and patient height and weight, were input using four stroke volume (SV) equations: Kubicek (K), Sramek (S), Sramek-Bernstein (SB), and a new equation N. CO was calculated as SV × heart rate. Data are presented as mean ± SD. One way repeated measures of ANOVA followed by the Tukey test were used for inter-group comparisons. Bland-Altman methods were used to assess bias, precision and limits of agreement. P<0.05 was considered statistically significant. CO implementing N (6.06±1.48 l min−1) was not different from TDCO (5.97±1.41 l min−1). By contrast, CO calculated using K (3.70±1.53 l min−1), S (4.16±1.83 l min−1) and SB (4.37±1.82 l min−1) was significantly less than TDCO. Bland-Altman analysis showed poor agreement between TDCO and K, S and SB, but not between TDCO and N. Compared with TDCO, equation N, using a square-root transformation for dZ/dtmax/Z0, and a mass-based VC was superior to existing transthoracic impedance techniques for SV and CO determination.

[1]  S Furman,et al.  Impedance Cardiography for Cardiac Output Estimation in Pacemaker Patients: Review of the Literature , 1993, Pacing and clinical electrophysiology : PACE.

[2]  D P Bernstein,et al.  A new stroke volume equation for thoracic electrical bioimpedance: Theory and rationale , 1986, Critical care medicine.

[3]  Thomas W. Kamarck,et al.  Stability of cardiac impedance measures: Aortic opening (B-point) detection and scoring , 1993, Biological Psychology.

[4]  R. Patterson,et al.  Development and evaluation of an impedance cardiac output system. , 1966, Aerospace medicine.

[5]  K. Visser,et al.  Electric properties of flowing blood and impedance cardiography , 2006, Annals of Biomedical Engineering.

[6]  B. Wikström,et al.  Gender and age differences in transthoracic bioimpedance. , 1997, Acta physiologica Scandinavica.

[7]  B V Howard,et al.  Relations of Stroke Volume and Cardiac Output to Body Composition: The Strong Heart Study , 2001, Circulation.

[8]  H. G. Goovaerts,et al.  A meta-analysis of three decades of validating thoracic impedance cardiography. , 1999, Critical care medicine.

[9]  J. Nyboer,et al.  Electrical Impedance Plethysmography: A Physical and Physiologic Approach to Peripheral Vascular Study , 1950, Circulation.

[10]  L. Critchley,et al.  A Meta-Analysis of Studies Using Bias and Precision Statistics to Compare Cardiac Output Measurement Techniques , 1999, Journal of Clinical Monitoring and Computing.

[11]  S. White,et al.  Thoracic resistivity for stroke volume calculation in impedance cardiography. , 1981, Journal of applied physiology: respiratory, environmental and exercise physiology.

[12]  R. Barker Bausell,et al.  Power Analysis for Experimental Research: A Practical Guide for the Biological, Medical and Social Sciences , 2002 .

[13]  H L Paz,et al.  Measuring cardiac output in critically Ill patients: disagreement between thermodilution-, calculated-, expired gas-, and oxygen consumption-based methods. , 1997, Cardiology.

[14]  Sujoy K. Guha,et al.  Quantitative electrical-impedance plethysmography for pulmonary oedema , 1977, Medical and Biological Engineering and Computing.

[15]  J. A. Bushman,et al.  Medical & biological engineering & computing , 2006, Medical and Biological Engineering and Computing.

[16]  Hiroshi Kanai,et al.  Electrical Characteristics of Flowing Blood , 1979, IEEE Transactions on Biomedical Engineering.

[17]  C R Thompson,et al.  Comparison of transesophageal echocardiographic, fick, and thermodilution cardiac output in critically ill patients. , 1996, Journal of critical care.

[18]  Peter Baylor,et al.  Lack of Agreement Between Thermodilution and Fick Methods in the Measurement of Cardiac Output , 2006, Journal of intensive care medicine.

[19]  Tomoyuki Yambe,et al.  Beat-to-beat evaluation of systolic time intervals during bicycle exercise using impedance cardiography. , 2004, The Tohoku journal of experimental medicine.

[20]  J. P. Holt,et al.  Ventricular volumes and body weight in mammals. , 1968, The American journal of physiology.

[21]  J M Levett,et al.  Thermodilution cardiac output: a critical analysis and review of the literature. , 1979, The Journal of surgical research.

[22]  K. Visser,et al.  Investigation of the parallel conductor model of impedance cardiography by means of exchange transfusion with stroma free haemoglobin solution in the dog. , 1987, Cardiovascular research.

[23]  W. Cleveland.  Robust Locally Weighted Regression and Smoothing Scatterplots , 1979 .

[24]  S. Lindstedt,et al.  Use of allometry in predicting anatomical and physiological parameters of mammals , 2002, Laboratory animals.

[25]  P. M. J. M. Vries,et al.  Impedance cardiography , 1996, Intensive Care Medicine.

[26]  Robert Patterson,et al.  Contributions to the impedance cardiogram waveform , 2006, Annals of Biomedical Engineering.

[27]  H G Goovaerts,et al.  The influence of extravascular lung water on cardiac output measurements using thoracic impedance cardiography. , 1998, Physiological measurement.

[28]  A. Beckett,et al.  AKUFO AND IBARAPA. , 1965, Lancet.

[29]  R. Patterson,et al.  The Minnesota impedance cardiograph- theory and applications. , 1974, Biomedical engineering.

[30]  D. G. Newman,et al.  The non-invasive assessment of stroke volume and cardiac output by impedance cardiography: a review. , 1999, Aviation, space, and environmental medicine.

[31]  J. D. Young,et al.  Comparison of thoracic electrical bioimpedance and thermodilution for the measurement of cardiac index in patients with severe sepsis. , 1993, British journal of anaesthesia.

[32]  S. Mohapatra,et al.  Non Invasive Cardiovascular Monitoring by Electrical Impedance Technique , 1988 .

[33]  R. Malacrida,et al.  Determination of cardiac output during mechanical ventilation by electrical bioimpedance or thermodilution in patients with acute lung injury: effects of positive end-expiratory pressure. , 1998, Critical care medicine.

[34]  R M Lang,et al.  Doppler and electromagnetic comparisons of instantaneous aortic flow characteristics in primates. , 1991, Circulation research.

[35]  K. Visser,et al.  Investigation of the origin of the impedance cardiogram by means of exchange transfusion with stroma free haemoglobin solution in the dog. , 1990, Cardiovascular research.

[36]  H Belzberg,et al.  Outcome prediction of emergency patients by noninvasive hemodynamic monitoring. , 2001, Chest.

[37]  H. Brock,et al.  Monitoring intravascular volumes for postoperative volume therapy. , 2002, European journal of anaesthesiology.

[38]  R. Barker Bausell,et al.  One-way repeated measures analysis of variance , 2002 .

[39]  B J Rubal,et al.  Correlation between maximum dZ/dt and parameters of left ventricular performance. , 1980, Medical & biological engineering & computing.

[40]  H. Sato,et al.  Assessment of left ventricular performance in man with impedance cardiography. , 1978, Japanese circulation journal.

[41]  J. Gardin,et al.  Evaluation of blood flow velocity in the ascending aorta and main pulmonary artery of normal subjects by Doppler echocardiography. , 1984, American heart journal.

[42]  J M Bland,et al.  Statistical methods for assessing agreement between two methods of clinical measurement , 1986 .

[43]  Dean R Chittock,et al.  Lack of agreement between thermodilution and fick cardiac output in critically ill patients. , 2002, Chest.

[44]  J A Reitan,et al.  Determinants and Genesis of Canine Pneumocardiogram , 1978, Anesthesia and analgesia.

[45]  P. Vries,et al.  The technique of impedance cardiography. , 1997, European heart journal.

[46]  J. Jansen,et al.  The thermodilution method for the clinical assessment of cardiac output , 1995, Intensive Care Medicine.

[47]  A Zollinger,et al.  Changes in intrathoracic blood volume associated with pneumoperitoneum and positioning , 2002, Acta anaesthesiologica Scandinavica.

[48]  S Dohi,et al.  Errors in the measurement of cardiac output by thermodilution , 1993, Canadian journal of anaesthesia = Journal canadien d'anesthesie.

[49]  O Gödje,et al.  Central venous pressure, pulmonary capillary wedge pressure and intrathoracic blood volumes as preload indicators in cardiac surgery patients. , 1998, European journal of cardio-thoracic surgery : official journal of the European Association for Cardio-thoracic Surgery.

[50]  W S Seitz,et al.  Interpretation of the HJ interval of the normal ballistocardiogram based on the principle of conservation of momentum and aortic ultrasonic Doppler velocity measurements during left ventricular ejection. , 1988, Cardiovascular research.

[51]  L. Critchley,et al.  The effect of lung injury and excessive lung fluid, on impedance cardiac output measurements, in the critically ill , 2000, Intensive Care Medicine.

[52]  B. C. Penney,et al.  Theory and cardiac applications of electrical impedance measurements. , 1986, Critical reviews in biomedical engineering.

[53]  W. Laskey,et al.  Effects of exercise and nitroprusside on left ventricular ejection dynamics in idiopathic dilated cardiomyopathy. , 1987, The American journal of cardiology.

[54]  R. Vogel,et al.  Impedance cardiography: the next vital sign technology? , 2003, Chest.

[55]  Ken-ichi Yamakoshi,et al.  Evaluation of the theory of cardiac-output computation from transthoracic impedance plethysmogram , 1977, Medical and Biological Engineering and Computing.

[56]  J Feldschuh,et al.  Prediction of the Normal Blood Volume: Relation of Blood Volume to Body Habitus , 1977, Circulation.

[57]  W. G. Kubicek,et al.  On the source of peak first time derivative (dZ/dt) during impedance cardiography , 2006, Annals of Biomedical Engineering.