[Non-invasive versus invasive cardiovascular monitoring. Determination of stroke volume and pulmonary hydration using a new bioimpedance monitor]

Abstract

Measurement of hemodynamic parameters by noninvasive techniques is gaining more and more popularity in the face of severe complications associated with invasive methods. Thoracic electrical bioimpedance is a noninvasive means of estimating cardiac output (CO) and pulmonary edema formation. The validity of this method, however, has been controversial. In the present study a new bioimpedance monitoring system (NCCOM 3) was used in 10 intensive care patients undergoing mechanical hemofiltration (group I) and in 20 cardiac surgery patients undergoing either aortic valve replacement (AVR, group IIa, n = 10) or aorto-coronary bypass grafting (CABG, group IIb, n = 10). In cardiac surgery patients the measurements were performed before as well as after extracorporeal circulation (ECC). CO measured by the impedance monitor was compared to the standard thermodilution method; pulmonary fluids were estimated by a thermo-dye technique and by measurement of total electrical impedance (base impedance), expressed as the thoracic fluid index (TFI). The principal finding of the study was that CO as measured by the two techniques differed significantly in all groups with regard to absolute values. The relative changes in CO, however, were comparable in both intensive care patients and CABG patients. In patients with special thoracic blood flow conditions (regurgitation in aortic insufficiency patients), no corresponding course of CO could be found.(ABSTRACT TRUNCATED AT 250 WORDS)