Indocyanine green densitometry in flowing blood compensated for background dye

Abstract

Blood is nonhomogeneous; hence, the relationship between light transmission and increasing concentration of dye in whole blood is never the perfect exponential curve predicted by Beer's law. Instead, as the concentration of indocyanine green is increased to high levels (40 mg/liter) the light transmission decreases exponentially toward an asymptote at 6–8% transmission for nearly monochromatic densitometers (half-band width: 13–20 mμ), but at 30–40% for densitometers using light of wide-band width. Consequently, following recording of a dilution curve, circulating background dye reduces the change in transmission per unit increase in dye concentration in subsequent curves. This decrease in sensitivity cannot be compensated for by a simple increase in the sensitivity of the densitometer or in the intensity of its light source. Compensation can be attained, however, if increasing densitometer sensitivity is associated with the automatic scale expansion provided when a suppressed zero point is used. At correct zero suppression, the deflection for zero output of the densitometer coincides with the asymptotic transmission value mentioned above. indicator-dilution in circulation; blood flow measurement; blood optical density; dye dilution technic; cardiac output measurement Submitted on April 15, 1963

Transcoronary intravascular transport functions obtained via a stable deconvolution technique

“…Calibrations were done by using a control of undyed blood and four different dye concentrations in blood three times during each animal experiment: at the beginning, in the middle, and at the end. These were done on both arterial and venous blood to avoid errors due to differences in oxygen saturation or to differences in hematocrit during the experiment, as was shown to be necessary for precise quantitation (Edwards et al, 1963). The calibration data were analyzed essentially as described previously (Bassingthwaighte et al, 1964) for these densitometers, which provide a Beer's law relationship between detector output and dye concentration over the range 0 to 20 mg per liter.…”

“…The calibration data were analyzed essentially as described previously (Bassingthwaighte et al, 1964) for these densitometers, which provide a Beer's law relationship between detector output and dye concentration over the range 0 to 20 mg per liter. The densitometers were set up carefully so that their calibrations were independent of the level of background dye in the blood (Edwards et al, 1963).…”

Optical Artifacts in Whole Blood Densitometry: A Review of Undesirable Optical Signals, Nonspecific Effects, Encountered during Measurements of Oxygen Saturation and Dye Dilution Curves by Light Transmission

“…EDWARDS [5] and NILSSON [19] found that the calibration curve of a monochromatic densitometer utilizing an interference filter with a narrow pass band (half band width of approximately 13 millimicrons) deviates approximately 3 % from Beers Law 7. A greater deviation from Beers Law results when a filter is used with a wider wave band ( fig.…”

“…The magnitude of the deviation varies with the width of the wave band of incident light. It has also been shown that there will be deviation from Beers Law in the calibration curve of a densitometer due to the presence of red blood cells [5]. where I is the transmitted light, I, the incident light, E is a constant for the test substance (dye in this case) at a particular wavelength, c is the concentration of a test substance (dye) and d is the logrithmic relationship between concentration of the dye and the transmitted light.…”

Atrial Contribution to Stroke Volume in Dogs with Chronic Heart Block

“…6 In addition, the right atrial catheter could be connected interchangeably to a saline manometer via a two-way stopcock so that mean right atrial pressures could be read at frequent intervals throughout the experiment. The zero reference level for all pressures was taken at the middorsal-ventral level of the thorax.…”