Cardiovascular Monitoring by Pulse Dye Densitometry or Arterial Indocyanine Green Dilution

Noninvasive cardiac output (CO) monitoring is possible by indocyanine green (ICG) dilution measured by pulse dye densitometry (PDD). To validate the precision of this method, we compared hemodynamic variables derived from PDD (DDG-2001, Nihon Kohden, Japan) with those derived from simultaneously taken arterial blood ICG concentrations. In 20 patients (6 M/14 F), ASA I or II, 36 sessions were performed (n = 24 with the PDD-finger probe, n = 10 with the PDD-nose probe). After IV administration of 10 mg ICG, 34 arterial blood samples were taken during each session, with 20 samples taken during the first 2 min. CO, central blood volume (CBV), and total blood volume (TBV) were calculated independently from ICG and PDD and the results compared between methods using Bland-Altman analysis. The results are reported as mean difference (bias) and limits of agreement (LOA = +/- 2 sd). PDD using the finger probe underestimated CO (LOA) by 5% (-56% and 47%); overestimated CBV by 21% (-54% and 96%) and underestimated TBV by -15% (-38% and 8%). PDD using the nose probe overestimated CO (LOA) by 30% (-67% and 127%); CBV by 48% (-98% and 193%) and underestimated TBV by -10% (-47% and 27%). Despite the permissible bias, the wide LOA of the PDD-derived hemodynamic variables CO and CBV, compared with those simultaneously obtained by invasive arterial ICG measurements, suggest that PDD is unsuitable for evaluation of cardiovascular variables in the individual patient. Hence, the reliability and clinical use of this method seem limited.