Similarity of blood flows using indocyanine prepared in saline or distilled water

Directly measured blood flow pumped through a mixer circuit was compared to estimates of flow from indicator dilution curves derived from bolus injections of indocyanine green dye prepared in 0.9% saline (saline dye) and in triple-distilled water (3 D dye). At flows whose mean appearance time was 1.6 s, the mean error of estimate +/-SD of 2.3 +/- 5.1% using 3 D dye was significantly different (P less than 0.05) from that of 5.6 +/- 7.0% using saline dye. Essentially, there was no difference in estimates of blood flow with each dye solution when mean appearance time was increased to 3.8 s. Thus, the error, which was perhaps due to electrolyte in the concentrated indocyanine green dye (saline dye) and subsequent slowed rate of optical stabilization after dilution in plasma, is small and does not explain the overestimation by indocyanine dilution curves of blood flow in intact dogs.

A simplified method for quantitating left-to-right shunts from arterial dilution curves

This report presents a new, simple and reliable method of quantitating left-to-right shunts from arterial dilution surves. When indicatior (e,g., indocyanine green) is injected centrally (right venticle or pulmonary artery) and blood is withdrawn rapidly from either the aorta or other central systemic artery, in the presence of a left-to-right shunt to recorded indicator-dilution curve usually shows two discrete peaks: p-1 of the magnitude of the shunt expressed as percent of pulmonary blood flow, Experimental and clinical data demonstrate that this method is accurate in quantitating shunts from such curves.

A new method for calibrating indicator dilution curves

A technique is proposed and experiments carried out to validate an in vivo method of calibrating ascorbate dilution curves. Cardiac output measured by the proposed method (COi) was compared to cardiac output measured by electromagnetic flowmeter (COe). COe averaged 1,281 mg/min and COi averaged 1,284 ml/min (P greater than 0.90). Correlation between the two methods was 0.92. It is concluded that the proposed method measures CO with reasonable accuracy and provides a number of advantages over the usual method of measuring blood flow by means of indicators.

Cardiac output measurement with a simplified thermodilution technique. Comparison with the Fick method

A simplified thermodilution technique for cardiac output measurement is compared with the Fick method in dogs, over a wide range of cardiac output values. The reproducibility of the method is satisfactory (differences less than 10 per cent for 95 per cent of the measurements). The overall correlation factor (r = 0.97) is highly significant for cardiac outputs ranging from 750 to 7,500 ml.mn(-1). The influence of hematocrit (when lower than 30%) and of the injection site of indicator are discussed. Present experiments confirm that the use of pre-set factors allow for the thermal loss inside the catheter does not obviate the accuracy of thermodilution method for cardiac output measurements. The slope of the regression line is very close to 1. Lack of fit to linearity is tested and is found not significant throughout the explored range. This technique should therefore have extensive clinical applications.