Indocyanine Green: Observations

Indocyanine green 1 (ICG) is a tricarbocyanine dye (Figure 1) which has been used in the indicator dilution technique for measuring cardiac output (1, 2). Animal studies (3) and preliminary observations of human subjects (4, 5) have suggested that this dye may have characteristics that could make its uptake, storage, and excretion by the liver helpful indices of hepatic function. The present investigations were carried out to determine whether indocyanine green has properties that may render it suitable for assessing liver function and hepatic blood flow in man.