Background: The indocyanine green (ICG) clearance test has been used to estimate liver functional reserve before hepatectomy. However, changes in ICG clearance after hepatectomy have not been investigated, and their extent remains unknown.
Patients and methods: The ICG(K) value, signifying the ICG elimination rate constant, was measured with pulse-dye densitometry before operation and 1, 2, 3, 5, and 7 days postoperatively in 22 patients who underwent liver resection of various extent. CT volumetry was used to calculate the residual liver volume ratio. The relationship between the pre- and postoperative ICG(K) value and the residual liver volume ratio was examined statistically.
Results: There was a significant drop in ICG(K) value, from 0.193 +/- 0.011 before operation to 0.160 +/- 0.013 on Postoperative Day 1, and then it remained significantly low at the postoperative examination times. The residual liver volume ratio was 70.2 +/- 5.4%. The estimated ICG(K) value, calculated by the preoperative ICG(K) value and the residual liver volume ratio, showed a significant correlation with the actual postoperative value (r = 0.859 on Postoperative Day 1, P < 0.0001). In five patients with prolonged jaundice, the estimated ICG(K) value was significantly lower than in those without it (0.077 +/- 0.028 versus 0.153 +/- 0.012, P = 0.0136).
Conclusions: The perioperative ICG(K) value measured by pulse-dye densitometry revealed a significant decrease in ICG(K) after operation depending on the reduction in liver volume, and the estimated ICG(K) based on the residual liver volume was useful in predicting postoperative morbidity.