Accuracy of the Impedance Cardiogram in the Measurement of Cardiac Output in the Elderly

Abstract

The cardiac output has been determined by radionuclide angiocardiography and by impedance cardiography in 93 elderly patients. The agreement between the two methods was excellent in patients in sinus rhythm, without regurgitant valvular lesions, and without severe airways obstruction or right bundle branch block. In atrial fibrillation the lack of correlation may be due to differences in heart rate during the two measurements, in regurgitant valvular lesions to the fact that impedance cardiography measures stroke output, whether forward or backward, in airways obstruction to high values for the basal thoracic impedance, and in right bundle branch block perhaps to the abnormal impedance wave-form often present.

Stroke volume response to cycle ergometry in trained and untrained older men

“…The equivocality of the SV response during the early phase of aerobic exercise has been attributed primarily to the limitations of SV assessment techniques that require subjects to be exercising at steady-state. In contrast to rebreathing and echocardiography techniques, impedance cardiography permits the assessment of SV, on a beat-by-beat basis, during non-steady-state exercise (Ebert et al 1984;Williams and Caird 1985).…”

“…Specialized software that utilizes ensemble averaging was used to process the impedance cardiogram (COP, Microtronics, Chapel Hill, N.C., USA). Impedance cardiography has been shown to be a valid and reliable method for assessing the SV of young subjects during exercise (Sheps et al 1982;Teo et al 1985), and of older subjects at rest (Ebert et al 1984;Williams and Caird 1985). In our laboratory, CO values determined using impedance cardiography were validated by comparing them with CO 2 -rebreathing values (Sensor Medics, 2900 NICO).…”

Bioimpedance analysis as a tool for hemodynamic monitoring: overview, methods and challenges

“…Kubicek's method has been widely analysed and compared with existing methods. For most of the initial studies, the correlation values ranged between 0.7 and 0.93 on comparison with the Fick method (Hetherington et al 1985, Miles et al 1988, Fuller 1992), 0.87-0.95 with carbon dioxide rebreathing method (Qu et al 1986, Du Quesnay et al 1987, Niizeki et al 1989, 0.65-0.9 with ventriculography (Ebert et al 1984, Williams and Caird 1985, Wilson et al 1989, Fuller 1992) and 0.63-0.96 with thermodilution. The consensus points towards overestimation of low COs during exercise for young, healthy individuals and an underestimation of high COs for pregnant and obese individuals, from this method.…”

“…The consensus points towards overestimation of low COs during exercise for young, healthy individuals and an underestimation of high COs for pregnant and obese individuals, from this method. Some studies have also pointed towards its inaccuracies with cardiac shunts, atrial fibrillation and valvular disease (Kubicek 1968, Kubicek et al 1974, Ebert et al 1984, Williams and Caird 1985.…”

“…For the Sramek-Bernstein equation, initial studies showed disparity from the thermodilution and other reference methods for conditions of higher HRs, irregular heartbeats and hyperdynamic sepsis (Bernstein 1986a, 1986b, Introna et al 1988, Spinale et al 1988, Spinale et al 1989, Castor et al 1990, Wong et al 1990, O'connell et al 1991. Sramek-Bernstein equation led to a non-invasive computer cardiac output monitor (NCCOM) 3 device (BoMed Medical, Irvine, CA, USA) which underwent several revisions in the first few years to address its initial flaws (Williams andCaird 1985, Mickell et al 1990). NCCOM3 revisions 6 and 7 showed good correlation with other reference methods (Masaki et al 1989, Jiveg\aard et al 1990, Clancy et al 1991.…”