Sau khi 20, 25, và 30 phút của ICG truyền, động mạch và các mẫu máu tĩnh mạch gan được lấy cùng một lúc. Mức plasma ICG được đo bằng quang phổ và được xác định bằng cách sử dụng một đường cong dập thu được bằng cách pha loãng một số lượng ICG | Splanchnic Blood Flow 207 infusion of 12 mg a continuous infusion of 1 mg min is administered for 30 min. After 20 25 and 30 min of ICG infusion arterial and hepatic venous blood samples are taken simultaneously. The plasma ICG levels are measured by spectrophotometry and determined using a stamping curve obtained by dilution of a known ICG quantity in a control serum. According to Uusaro et al 12 the measurement of hepatosplanchnic blood flow by this technique has a variation coefficient of 7 1 . According to the Fick principle the hepatosplanchnic blood flow HBF can then be calculated as HBF ml min ICG administration rate mg min Ca - Chv x 1 - Hct where Ca and Chv are the systemic arterial and suprahepatic venous ICG blood concentration mg ml respectively and Hct the hematocrit of the blood sample. An alternative approach to this method for the estimation of hepatosplanchnic blood flow is the bolus ICG dye clearance technique 13 . Nevertheless when compared to the former it should be noted that the bolus technique seems to yield less valid results 12 . Hepatic venous catheterization is mandatory for both techniques first the hepatic ICG extraction may vary widely in individualpatients since hepatic ICG extractions between 15 and 95 have been reported in disease states 12 second ICG extraction is influenced by therapeutic interventions such as infusion of dobutamine or other vasoactive compounds resulting in changes of up to 50 in either direction 12 finally ICG extraction must always exceed the limit of 10 which is necessary for the valid application of this method 12 . For clinical reasons due to its easier applicability ICG clearance without hepatic venous catheterization can be used as a bedside parameter of hepatic function and perfusion. In principle after a bolus injection arterial ICG concentrations will fall in a monoexponential manner. By logarithmic transformation of the typical indicator dilution curve the decay of concentration is characterized by a .
