Hepatic lymphatic mapping: a pilot study for porta hepatis lymph node identification

The status of the porta hepatis lymph nodes in patients with hepatic metastases from colorectal cancer affects their prognosis and management. Lymphatic mapping with isosulfan blue dye is well established in breast cancer and melanoma. An animal model consisting of three dogs receiving general anesthesia was utilized. Each dog underwent a laparotomy and increasing doses of isosulfan blue dye were injected into the right medial segment of the liver. Intraoperatively, the presence of blue dye in the porta hepatis region was determined and the lymph node identified. Continuous physiological monitoring was performed. Serum determination of liver function tests, amylase levels, and white blood cell count were performed preoperatively and on postoperative days 1, 2, 4, and 7. The animals were sacrificed on day 7. A portal lymph node was identified in each case and there was no perioperative morbidity or mortality. There were no significant alterations in blood pressure or heart rate in the animals. There was a dose-responsive decrease in the O2 saturation as measured by transcutaneous monitoring, but arterial blood gas analysis showed that pO2 levels remained stable. There were no significant changes in the liver function tests, amylase levels, or white blood cell counts. There was a small increase in alkaline phosphatase, which normalized by postoperative day 7. Hepatic injection of isosulfan blue dye appears to be safe and effective in identifying porta hepatis lymph nodes in the animal model and sets the basis for further study in human subjects.