Intrathoracic blood volume measurement: comparison of transpulmonary lithium indicator dilution with indocyanine green indicator dilution

Intrathoracic blood volume (ITBV) is thought to be a superior measure of cardiac preload compared with intravascular pressure [1]. Transpulmonary indocyanine green (ICG) indicator dilution is regarded as the most reliable method of ITBV measurement but is no longer commercially available. Our previous work suggests lithium indicator dilution could be used to measure the ITBV [2].