Multi-channel electrical bioimpedance: A new noninvasive method to simultaneously measure cardiac and peripheral blood flow

Objectives: We sought to assess the ability of a new multi-channel electrical bioimpedance (MEB) methodology to accurately measure both cardiac blood flow and peripheral limb blood flow. Background: Cardiac output is the primary determinant of peripheral blood flow; however, optimal regional tissue perfusion is ultimately dependent on the patency of the arterial conduits that transport that flow. A complete understanding of regional tissue perfusion requires knowledge of both cardiac and peripheral blood flow. Existing noninvasive devices do not simultaneously assess the cardiac and peripheral circulations. Methods: Cardiac blood flow (cardiac output) was measured by MEB in 30 healthy volunteers and was compared to a 2D-Echo Doppler cardiac output. Peripheral blood flow (regional ankle and arm flow) was measured by MEB in 15 healthy volunteers. The MEB ankle/arm flow ratio (AAI index) was then compared to a conventional ankle/brachial pressure ratio (ABI index). Results: There was good correlation between the mean cardiac index by MEB (3.08 l/min/m2) and by Echo Doppler (3.13 l/min/m2) and bias and precision was 0.051 (1.6%) and ±0.52 l/min/m2 (±17%), respectively. The close correlation was maintained for each measurement over a wide range of cardiac indices. There was good correlation between AAI and ABI measurements (p < 0.05) with a sensitivity of 100% and specificity of 100%. Conclusions: MEB methodology can precisely measure cardiac outputand peripheral limb flow in healthy volunteers. © Springer Science+Business Media B.V. 2007.