Comparison of the effects of sevoflurane, isoflurane and halothane on indocyanine green clearance.

We have examined the effects of inhalation anaesthetics on indocyanine green (ICG) clearance, as an index of hepatic function, in patients undergoing elective surgery. Recently, a new method has been developed to measure in real-time the disappearance rate of ICG from plasma. This method eliminates the multiple sampling and delay of the conventional ICG test. ICG clearance is displayed as two indices: K (ICG disappearance rate) and R15 (ICG retention rate 15 min after injection of ICG 0.5 mg kg-1). This measurement was performed in patients before and after 1 MAC of sevoflurane (n = 6), 2 MAC of sevoflurane (n = 6), 1 MAC of isoflurane (n = 6), 2 MAC of isoflurane (n = 6), 1 MAC of halothane (n = 6) or 2 MAC of halothane (n = 6) without surgical stress. Although mean arterial pressure decreased significantly at 1 and 2 MAC of sevoflurane, 2 MAC of halothane, and 1 and 2 MAC of isoflurane, ICG clearance was maintained at awake levels, except at 2 MAC of halothane (K = mean-33 (sem 3)%, R15 = +90 (3)% from awake values). We conclude that sevoflurane and isoflurane have a more favourable effect on liver circulation than halothane.