Comparison of cardiac output determined by bioimpedance and bioreactance methods at rest and during exercise

DG Jakovljevic, S Moore, K Hallsworth, G Fattakhova, C Thoma, MI Trenell

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

Bioreactance is a novel non-invasive method for cardiac output measurement that involves the analysis of blood flow-dependent changes in the phase shifts of electrical currents applied across the chest. The present study (1) compared resting and exercise cardiac outputs determined by bioreactance and bioimpedance methods and those estimated from measured oxygen consumption, (2) determined the relationship between cardiac output and oxygen consumption, and (3) assessed the agreement between the bioreactance and bioimpedance methods. Twelve healthy subjects (aged 30 ± 4 years) performed graded cardiopulmonary exercise test on a recumbent cycle ergometer on two occasions, 1 week apart. Cardiac output was monitored at rest, at 30, 50, 70, 90, 150 W and at peak exercise intensity by bioreactance and bioimpedance and expired gases collected. Resting cardiac output was not significantly different between the bioreactance and bioimpedance methods (6.2 ± 1.4 vs. 6.5 ± 1.4 l min−1, P = 0.42). During exercise cardiac outputs were correlated with oxygen uptake for both bioreactance (r = 0.84, P < 0.01) and bioimpedance techniques (r = 0.82, P < 0.01). At peak exercise bioimpedance estimated significantly lower cardiac outputs than both bioreactance and theoretically calculated cardiac output (14.3 ± 2.6 vs. 17.5 ± 5.2 vs. 16.9 ± 4.9 l min−1, P < 0.05). Bland–Altman analyses including data from rest and exercise demonstrated that the bioimpedance method reported ~1.5 l min−1 lower cardiac output than bioreactance with lower and upper limits of agreement of −2.98 to 5.98 l min−1. Bioimpedance and bioreactance methods provide different cardiac output estimates, particularly at high exercise intensity, and therefore the two methods cannot be used interchangeably. In contrast with bioimpedance, bioreactance cardiac outputs are similar to those estimated from measured oxygen consumption.
Original languageEnglish
Pages (from-to) pages63–68(
Number of pages6
JournalJournal of Clinical Monitoring and Computing
Volume26
Early online date11 Jan 2012
DOIs
Publication statusPublished - Apr 2012
Externally publishedYes

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