Circulating Blood Volume Measured by Pulse Dye-Densitometry: Comparison with131 I-HSA Analysis

Background: Pulse dye-densitometry (PDD) is a newly developed technique for monitoring the arterial concentration of indocyanine green. Using this method, circulating blood volume (CBV) can be calculated without using radioisotopes. In this study, the CBV value obtained by PDD was validated by comparison using the human serum albumin (131) I-HSA) dilution method.

Methods: Eleven healthy volunteers underwent placement of cannulae into the radial artery and antecubital vein for withdrawal of blood samples and injection 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 [micro sign]Ci131 I-HSA in 1 ml distilled water were injected simultaneously into the left antecubital vein. Blood samples were withdrawn 3, 6, 10, 20, 30, and 45 min after injection, then processed for spectrophotometric measurement of indocyanine green and scintillation counting.

Results: The blood dye concentration correlated well with the values obtained by PDD (r = 0.986, imprecision 0.04 +/- 0.11 mg/l, 10.0 +/- 31%. The imprecision of the CBV value obtained by PDD (nose probe) and by the131 I-HSA dilution method was 3.99 +/- 10.54%, 0.259 +/- 0.593 l. The imprecision of the CBV obtained by in vitro spectrophotometry compared with PDD was 2.47 +/- 9.00%, 0.100 +/- 0.446 l.