Circulating blood volume measured by pulse dye-densitometry - Comparison with I-131-HSA analysis

Background: Pulse dye-densitometry (PDD) is a newly developed technique for monitoring the arterial concentration of indocyanine green. Using this met hod, circulating blood volume (CBV) can be calculated without using radiois otopes. In this study, the CBV value obtained by PDD was validated by compa rison using the human serum albumin (I-131-HSA) dilution method, Methods: Eleven healthy volunteers underwent placement of cannulae into the radial artery and antecubital vein for withdrawal of blood samples and inj ection of indicator. Probes for PDD were attached to the right nostril and the right index finger. Indocyanine green (20 mg), dissolved in 4 ml water, and 25 mu Ci I-131-HSA in 1 mi distilled water mere injected simultaneousl y into the left antecubital vein, Blood samples were withdrawn 3, 6, to, 20 , 30, and 45 min after injection, then processed for spectrophotometric mea surement of indocyanine green and scintillation counting. Results: The blood dye concentration correlated web with the values obtaine d by PDD (r = 0.986, imprecision 0.04 +/- 0.11 mg/l, 10.0 +/- 31%. The impr ecision of the CBV value obtained by PDD (nose probe) and by the I-131-HSA dilution method was 3.99 +/- 10.54%, 0.259 +/- 0.593 1. The imprecision of the CBV obtained by irt vitro spectrophotometry compared with PDD was 2.47 +/- 9.00%, 0.100 +/- 0.4461. Conclusions: This newly developed, less invasive method can measure CBV wit h an imprecision of 3.99 +/- 10.54%, 0.259 +/- 0.593 I(nose probe), and thu s is also as accurate as the conventional radioisotope method.