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Pulse dye densitometry using indigo carmine is useful for cardiac output measurement, but not for circulating blood
1Kawasaki Medical School, Departments of Anesthesiology and ICM, Japan. fujitay@med.kawasaki-m.ac.jp
Insights
A new indigo carmine densitometer accurately measures cardiac output but overestimates blood volume. This method shows promise for cardiovascular monitoring, though further research is needed for precise volume assessment.
Area of Science:
- Cardiovascular Physiology
- Medical Instrumentation
- Diagnostic Techniques
Background:
- Cardiac output and circulating blood volume are critical hemodynamic parameters.
- Accurate measurement is essential for patient management and research.
- Existing methods have limitations, necessitating novel approaches.
Purpose of the Study:
- To evaluate the validity of a novel pulse dye densitometer using indigo carmine.
- To assess its accuracy in measuring cardiac output and circulating blood volume.
- To compare its performance against established techniques.
Main Methods:
- Cardiac output and blood volume were measured in dogs using the indigo carmine densitometer.
- Measurements were taken during varying volemic states (normovolaemia, hypovolaemia, hypervolaemia).
- Validation involved comparison with thermodilution (cardiac output) and 51Cr-labelled red blood cells (blood volume).
Main Results:
- The indigo carmine densitometer showed good agreement with thermodilution for cardiac output (r = 0.885).
- Circulating blood volume measurements by the densitometer were higher and showed weaker agreement (r = 0.587) compared to the 51Cr method.
- Indigo carmine demonstrated significant passage into the extravascular space, indicated by a sieving coefficient of 0.34 during haemofiltration.
Conclusions:
- Indigo carmine densitometry is a reliable method for determining cardiac output.
- The method tends to overestimate circulating blood volume.
- Extravascular distribution of indigo carmine likely accounts for the overestimation of blood volume.
Background And Objective:
We evaluated the validity of a newly developed pulse dye densitometer for indigo carmine for measuring cardiac output and circulating blood volume.
Methods:
Measurements of cardiac output and circulating blood volume were performed with the indigo carmine densitometer during normovolaemia, hypovolaemia and hypervolaemia in nine mongrel dogs under general anaesthesia. The validity was evaluated by comparison of the values of cardiac output and circulating blood volume obtained by the thermodilution technique and the 51Cr-labelled red blood cell method, respectively. We also examined indigo carmine removal by continuous veno-venous haemofiltration after indigo carmine injection.
Results:
There was good agreement between dye densitometer- and thermodilution-derived cardiac output (r = 0.885, P < 0.001). The bias and limits of agreement of these values were 0.09 and+/-1.07 L min(-1) (2 SD, n 22), respectively. The dye-densitometer-derived circulating blood volume was greater than that of the 51Cr-labelled red blood cell method, and both values showed weak agreement (r = 0.587, P < 0.027). The sieving coefficient of indigo carmine through continuous veno-venous haemofiltration was 0.34+/-0.06.
Conclusions:
These data indicate that indigo carmine densitometry is a reliable method for cardiac output determination, but it overestimates circulating blood volume, probably due to the transition of indigo carmine into the extravascular space in the systemic circulation.
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