Validation of impedance cardiography in pulmonary arterial hypertension.
BACKGROUND
Non-invasive methods of measuring cardiac output are highly desirable in pulmonary arterial hypertension (PAH). We therefore sought to validate impedance cardiography (ICG) against thermodilution (TD) and cardiac magnetic resonance (CMR) in the measurement of cardiac output in patients under investigation for PAH.


METHODS
A prospective, cross-sectional study was performed to compare single-point measurements of cardiac output obtained by impedance cardiography (COICG) technology (PhysioFlow®) with (i) contemporaneous TD measurements (COTD) at rest and steady-state exercise during right heart catheterization and (ii) CMR measurements (COCMR) at rest obtained within 72 h.


RESULTS
Paired COICGand COTDmeasurements were obtained in 25 subjects at rest and 16 subjects at exercise. COCMRmeasurements were obtained in 16 subjects at rest. There was unsatisfactory correlation and agreement between COICGand COTDat rest (r = 0·42, P = 0·035; bias: 1·21 l min-1, 95% CI: -2·33 to 4·75 l min-1) and exercise (r = .65, P = .007; bias: 1·41 l min-1; 95% CI: -3·99 to 6·81 l min-1) and in the change in COICGand COTDfrom rest to exercise (r = 0·53, P = 0·033; bias: 0·76 l min-1, 95% CI: -3·74 to 5·26 l min-1). There was also a lack of correlation and unsatisfactory agreement between resting COICGand COCMR(r = 0·38, P = 0·1; bias: 1·40 l min-1, 95% CI: -2·48 to 5·28 l min-1). In contrast, there was close correlation and agreement between resting COTDand COCMR(r = 0·87, P<0·001; bias: -0·16 l min-1, 95% CI: -1·97 to 1·65).


CONCLUSIONS
In a representative population of patients under investigation for PAH, ICG showed insufficient qualitative and quantitative value in the measurement of resting and exercise cardiac output when compared with TD and CMR.
Scottish Pulmonary Vascular Unit, Golden Jubilee National Hospital, Glasgow, UK.
Marios
M
Panagiotou
Faculty of Physical Education and Sports Sciences, National and Kapodistrian University of Athens, Athens, Greece.|Faculty of Health and Life Sciences, Department of Sport, Exercise and Rehabilitation, Northumbria University, Newcastle UponTyne, UK.
Ioannis
I
Vogiatzis
Scottish Pulmonary Vascular Unit, Golden Jubilee National Hospital, Glasgow, UK.
Geeshath
G
Jayasekera
Faculty of Physical Education and Sports Sciences, National and Kapodistrian University of Athens, Athens, Greece.|Faculty of Kinesiology and Rehabilitation Sciences, Department of Rehabilitation Sciences KU Leuven, Division of Respiratory Rehabilitation, University Hospitals Leuven, Belgium.
Zafeiris
Z
Louvaris
Scottish Pulmonary Vascular Unit, Golden Jubilee National Hospital, Glasgow, UK.
Alison
A
Mackenzie
Scottish Pulmonary Vascular Unit, Golden Jubilee National Hospital, Glasgow, UK.
Neil
N
Mcglinchey
Institute of Clinical Exercise and Health Science, University of the West of Scotland, Hamilton, UK.
Julien S
JS
Baker
Scottish Pulmonary Vascular Unit, Golden Jubilee National Hospital, Glasgow, UK.
Alistair C
AC
Church
Scottish Pulmonary Vascular Unit, Golden Jubilee National Hospital, Glasgow, UK.
Andrew J
AJ
Peacock
Scottish Pulmonary Vascular Unit, Golden Jubilee National Hospital, Glasgow, UK.
Martin K
MK
Johnson
D000368:Aged; D006328:Cardiac Catheterization; D002302:Cardiac Output; D002307:Cardiography, Impedance; D003430:Cross-Sectional Studies; D005080:Exercise Test; D005260:Female; D006801:Humans; D006976:Hypertension, Pulmonary / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000503:physiopathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015203:Reproducibility of Results; D013815:Thermodilution
cardiac magnetic resonance; cardiac output; thermodilution