The bromsulphalein method of estimating liver blood flow in man first introduced by Bradley, Ingelfinger, Bradley, and Curry (1) has proved to be a very useful tool in the hands of various workers. Though there is not complete agreement as to the question of extrahepatic dye loss and the problem of a single hepatic vein sample not being entirely representative of all the blood leaving the liver, a considerable amount of information has been gathered by studying the state of liver circulation in normal and diseased subjects and its alterations produced by exercise, posture, anesthesia, and various drugs. However, the technic employed is by no means a simple one and requires the team work of several highly trained people.Very recently, an entirely different method has been applied to the study of hepatic circulation. It is based on the assumption that the phagocytes of liver and spleen are highly efficient in removing colloid particulate matter from the blood stream in a single passage. If this assumption holds true, then the disappearance rate of this colloid from the circulation would essentially be a parameter of liver blood flow. Since the liver and spleen are in series with each other and since the bone marrow takes up only minimal amounts of this colloid, it was felt by Sheppard, Jordan, and Hahn (2) that it should be possible to calculate liver blood flow from the disappearance rate constant as the fraction of blood volume perfusing the liver per unit time. This idea has been put into practice by Dobson, Warner, Finney, and Johnston (3) who used chromic phosphate labeled with radiophosphorus as the particulate matter. However, this method again appears not to be as simple as one would want it to be for a routine diagnostic procedure. The preparation of a chromic phosphate colloid of suitable particle size is quite a laborious procedure, and the determination of the disappearance rate itself involves the withdrawal of serial blood samples which, to the patient, results in the loss of a considerable amount of blood.A further simplification of the estimation of liver blood flow in man would, therefore, be afforded by using a colloid readily at hand, and by labeling it with a Remitting isotope which would permit external determination of the disappearance rate without the need for withdrawing blood samples. The present paper reports some results obtained with colloidal radioactive gold (Au198) used as the particulate matter, the measurements being carried out by means of a counter placed between the calves of the subject. Various factors which might influence the reliability and accuracy of this method as well as some of the questions which have to be answered before the transformation of colloid disappearance rates into terms of liver blood flow could be considered to be justified, will be discussed. Some preliminary results have been published elsewhere (4). METHODSColloidal radioactive gold. Colloidal Au' was obtained from A.E.R.E., Harwell, England, as a 0.5 per cent (W/V) solution with a specific activity ...

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In a previous paper (1) we have described a method of following the disappearance of intravenously injected colloidal radioactive gold from the circulation in man and have discussed the possibilities of calculating liver blood flow from the disappearance rate constant as the fraction of blood volume perfusing the liver per unit time.If liver blood flow values estimated in this way could be demonstrated to be correct this method should have many advantages over other methods currently in use: it does not require hepatic vein catheterization; with only one blood sample withdrawn for determination of hematocrit and plasma volume, it does not involve any undue blood loss to the patient; being exceedingly simple and mechanized to a considerable extent by the use of counting rate meters and recorders, it can be carried out by a single technician; it can be repeated several times without exposing the patient to any risk thereby enabling observation of changes in hepatic circulation over any period of time.Hepatic blood flow values estimated by this method in 25 normal subjects (18 males and 7 females) were found to average 1310 ml. per min.(1) and thus to be somewhat lower but still within the range of normal values reported by other groups who used the bromsulphalein or other methods. However, even this difference might not have been a real one. In this laboratory the observed venous hematocrit is corrected for trapped plasma and for the uneven distribution of cells and plasma within the whole body circulation. with the average normal radiogold results, appear to have used any correction of the hematocrit. It might, therefore, well be that the difference between average hepatic blood flows estimated by these two methods in different groups of normal subjects has been caused by the difference in the methods of calculating blood volume.However, a few experiments designed to investigate the efficiency of the liver phagocytes to remove the colloid particles from the blood passing through the liver, indicated that the radiogold method underestimates the true hepatic blood flow by almost 20 per cent (1). If this is true a direct comparison of BSP and radiogold results should reveal a real difference in the calculated flow values. Simultaneous estimations of hepatic blood flow by these two methods were, therefore, performed in 15 subjects the results of which are presented in this paper. METHODSMaterial. The subj ects studied were hospitalized patients in whom for diagnostic purposes a heart or hepatic vein catheterization was warranted. Therefore, none of the subjects could be considered to be "normal."Catheterization.