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Numerous liver function tests have been devised and most investigators agree that some disturbance in liver function occurs during the toxemias of pregnancy. These changes are of relatively small magnitude and the clinical use of these tests in pregnancy is not widespread. The technique of venous catheterization with resultant sampling of blood directly leaving the liver offers further opportunities for study of liver function. METHODSA method of estimating hepatic blood flow in man based on the "Fick" principle has been described by Bradley and coworkers (1). In their article they point out that "The 'Fick' principle may be applied to any organ provided three facts are known: (1) the concentration of some substance, X, in the blood entering the organ, (2) the concentration of X in the mixed venous blood leaving the organ, and (3) the total amount of X removed from the blood by the organ each minute. Given these data, the blood flow through the organ per minute may be calculated by dividing the total removal rate of X by the amount of X removed from each milliliter of blood as it traverses the organ."The removal rate of X by the liver cannot be measured directly, but an indirect method is available if X can be given at such a rate that its blood level remains constant. Under these conditions, the infusion rate equals the hepatic removal rate, provided that the extraction of X depends entirely upon hepatic activity. Bromsulfalein (BSP) was used as the test substance since it apparently satisfied these conditions. The calculation of hepatic blood flow then can be determined by the following formula: R1 EHEF = 0.01 (P - Tables I, II, and III these peripheral vein hematocrits are starred (*). If the concentration of BSP in the peripheral blood is changing, hepatic blood flow may also be estimated if the plasma volume is determined. In this case, R (the removal rate of BSP by the liver) = I (the infusion rate mgm. per minute) plus or minus AP X V where AP = the rate of change in concentration of BSP in the peripheral blood in mgm. per ml. per minute and V = plasma volume in ml. Plus or minus depends on whether the concentration of BSP in the peripheral blood is rising or falling. If the peripheral concentration is rising, R = I -(AP x V) since less dye is being removed than is administered.If the peripheral concentration is falling, R = I + (AP X V) for the converse reason.Samples of hepatic vein blood are obtained with more or less ease by catheterization of the right hepatic vein with a 100-cm. No. 8 ureteral catheter with a slightly curved through-and-through tip with one eye. The catheter, through which an isotonic saline infusion is running, is inserted in the median basilic vein under local anesthesia. With the patient in the supine position on a fluoroscope table, the catheter is then passed into the subclavian vein, the superior vena cava, the right atrium, the inferior vena cava, and the right hepatic vein. The patient experiences no discomfort during this procedure. The most difficult part of the procedure...

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