SummaryThe aim of this study was to compare the accuracy of pulse dye densitometry with that of bolus thermodilution cardiac output measurement in patients before and after elective coronary artery bypass grafting. Twenty-eight patients were studied. Agreement between mean thermodilution and pulse dye densitometry cardiac output values was assessed by Bland-Altman analysis. [2.0-7.2] l.min )1 for pulse dye densitometry using indocyanine green 20 mg. Mean bias was + 0.566 l.min )1 , the limits of agreement were ± 2.51 l.min )1 and mean error was 60.9%. Postoperative cardiac output data were not analysed because pulse dye densitometry signals were low or absent in > 50% of the patients. We conclude that pulse dye densitometry using indocyanine green 5 mg or 20 mg is inaccurate in anaesthetised patients before coronary artery bypass surgery and cannot be used after surgery because of a high incidence of low pulse dye densitometry signal amplitudes. Pulse dye densitometry is based on the principle of indocyanine green dye dilution, whereby indocyanine green is injected through a central [7] or peripheral [8] venous line and the changes in dye concentration over time are detected by pulse spectrophotometry using a finger probe [7,9] or a nose probe [10,11]. Only a few investigators [7,[12][13][14] have compared pulse dye densitometry with standard methods of cardiac output determination, and the accuracy of pulse dye densitometry is therefore in dispute.Our primary aim was to validate pulse dye densitometry in patients before and after elective coronary artery bypass graft surgery (CABG). Our secondary aim was to investigate whether different concentrations of indocyanine green would affect the accuracy of pulse dye densitometry. The accuracy of cardiac output determination by pulmonary thermodilution has been assessed and confirmed at our institution [15].
MethodsWith the approval of the Local Research Ethics Committee and written, informed consent, 28 patients who were scheduled for elective CABG were enrolled in the study. Exclusion criteria comprised: allergy to iodine, presence of an aortic counterpulsation device, severe renal disease or liver dysfunction and intake of drugs with a Anaesthesia, 2005, 60, pages 968-973