Diagnostic uses for thoracic electrical bioimpedance in the emergency department: clinical case series

Rl, Summers; Jc, Kolb; Lh, Woodward; Rl, Galli

doi:10.1097/00063110-199909000-00004

Cited by 8 publications

(9 citation statements)

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“…Guidance in the correct choice of therapy in patients with shock 43 The early differentiation of causes of acute shortness of breath 72,95,98 Real time feedback to allow correct titration of therapy 98 …”

Section: Resultsmentioning

confidence: 99%

Transthoracic electrical bioimpedance: A means of filling the void?

Thom

Taylor

2005

Emerg Medicine Australasia

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Section: Resultsmentioning

confidence: 99%

Transthoracic electrical bioimpedance: A means of filling the void?

Thom

Taylor

2005

Emerg Medicine Australasia

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“…This technology can be used in the acute setting as a diagnostic adjunct when the primary hemodynamic state is uncertain and information obtained from ICG can be critical to the determination of the patient's underlying pathophysiologic condition. 12 Distinguishing high from low flow states is important in the differentiation of such conditions as sepsis, dehydration, and cardiogenic shock. ICG often provides the missing piece of the hemodynamic puzzle and has been found to aid in the differentiation of conditions that mimic acute heart failure.…”

Section: Hemodynamics Of Heart Failure and Icgmentioning

confidence: 99%

“…19,20 It has long been expected that some noninvasive measure of cardiac output will emerge as a vital sign in much the same way that pulse oximetry measurements of oxygen saturation did within the past decade. 12 There are several limitations to the ICG technology that have been noted. Anything that creates noise within the system will affect the stroke volume and other parameter measurements.…”

Section: Limitations and Conclusionmentioning

confidence: 99%

Emerging Diagnostics

Summers

2005

Critical Pathways in Cardiology: A Journal of Evidence-Based Medicine

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A cute heart failure is a physiologic state in which the circulation is unable to meet the needs of the body tissues because of a decompensation in the complex interactions between the heart and the peripheral vasculature. Adequate assessment of the central circulation in acute decompensated heart failure requires knowledge of the hemodynamics beyond that offered by the traditional vital signs. In fact, an accurate and complete analysis of circulatory function often cannot be made based upon the vital signs of blood pressure and heart rate alone. 1 Although systemic pressures and rates of cardiac contraction are indicators of cardiovascular integrity, what we really want to know is blood flow. It is this flow (in the form of cardiac output) that is the measure of how well the circulation is delivering oxygen and nutrients to the vital organs and that is the focus of all resuscitation efforts.In the past, the determination of cardiac output required the insertion of a catheter directly into the heart. As it becomes increasingly evident that these conventional invasive cardiac output monitoring methods may result in a greater patient morbidity and mortality, noninvasive techniques are commonly being considered as an acceptable alternative. 2 Perhaps the most intriguing of the new noninvasive technologies is based on information generated as measured waveforms from the thoracic electrical bioimpedance (TEB). The study of the waveforms derived from TEB is collectively known as the field of impedance cardiography (ICG). 3,4 The method is based on the idea that the human thorax is electrically a nonhomogeneous, bulk conductor. 5,6 A high-frequency measurement current injected across the thorax produces a waveform signature of voltage changes produced by varying resistances sensed by 2 pairs of electrodes placed at the edges of the chest (Fig. 1). The changes (⌬Z) are produced by fluid shifts within the thorax consisting of baseline changes of fluid levels in the intra-alveolar and interstitial thoracic compartments (a result of edema) and volumetric (cardiac output) and velocity (contractility) changes of aortic blood produced by the heart's pumping.Although the ECG depicts the electrical events of the heart, the TEB waveform (Fig. 2) is a depiction of the mechanical events of cardiac contraction. When used in conjunction with the timing landmarks on the ECG, the dZ/dt signals afford measurement of the systolic time intervals. These include the ventricular ejection time (VET) and the pre-ejection period (PEP) and can provide an analysis of other electromechanical activities. This constellation of measurement functions in combination with the technical aspects of ease of use and continuous monitoring capabilities suggests that ICG could potentially be a valuable tool for the emerging evaluation and management of patients with suspected or confirmed acute decompensated heart failure.In the past there have been some questions about the accuracy of the cardiac output measurements obtained from ICG when compared with the "g...

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“…Studies conducted within the emergency setting have demonstrated the usefulness of ICG as a diagnostic adjunct in these challenging clinical situations. 10,21,22 A more complex analysis of the underlying circulatory mechanisms involved may be especially helpful when the pathophysiologic derangements are due to some toxicologic agent or unusual medical condition (e.g., thyrotoxicosis, heart transplant rejection, pacemaker malfunction). 23,24 In general, the ICG measurement can be used to put the findings of the traditional vital signs into a more complete systems-analysis perspective.…”

Section: Clinical Applications In Emergency Medicinementioning

confidence: 99%

“…While the typical ''vital signs'' offer some insight into delineating the circulatory pathophysiology, it is often impossible to determine the true clinical state from an analysis of blood pressure and heart rate alone. 2,22 Recently, oxygen saturation by pulse oximetry has emerged as a fifth vital sign that has helped in determining the severity of the patient's condition. 38 Cardiac output is the hallmark of the circulation's ability to deliver oxygen and nutrients to the vital organs and often is considered the ''unknown vital sign.''…”

Section: Future Of Impedance Cardiography In Emergency Medicine: the mentioning

confidence: 99%

Bench to Bedside: Electrophysiologic and Clinical Principles of Noninvasive Hemodynamic Monitoring Using Impedance Cardiography

Summers

Shoemaker

Peacock

et al. 2003

Academic Emergency Medicine

115

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The evaluation of the hemodynamic state of the severely ill patient is a common problem in emergency medicine. While conventional vital signs offer some insight into delineating the circulatory pathophysiology, it is often impossible to determine the true clinical state from an analysis of blood pressure and heart rate alone. Cardiac output measurements by thermodilution have been the criterion standard for the evaluation of hemodynamics. However, this technology is invasive, expensive, time-consuming, and impractical for most emergency department environments. Impedance cardiography (ICG) is a noninvasive method of obtaining continuous measurements of hemodynamic data such as cardiac output that requires little technical expertise. ICG technology was first developed by NASA in the 1960s and is based on the idea that the human thorax is electrically a nonhomogeneous, bulk conductor. Variation in the impedance to flow of a high-frequency, low-magnitude alternating current across the thorax results in the generation of a measured waveform from which stroke volume can be calculated by a modification of the pulse contour method. To adequately judge the possible role of this technology in the practice of emergency medicine, it is important to have a sufficient understanding of the basic scientific principles involved as well as the clinical validity and limitations of the technique.

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Diagnostic uses for thoracic electrical bioimpedance in the emergency department: clinical case series

Cited by 8 publications

References 0 publications

Transthoracic electrical bioimpedance: A means of filling the void?

Transthoracic electrical bioimpedance: A means of filling the void?

Emerging Diagnostics

Bench to Bedside: Electrophysiologic and Clinical Principles of Noninvasive Hemodynamic Monitoring Using Impedance Cardiography

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