Combined evaluation of total and functional liver plasma flows and intrahepatic shunting.

A diagnostic protocol was studied, designed to evaluate the main parameters of liver circulation in man. A water solution of D-sorbitol (S) and indocyanine green (ICG) was infused intravenously in six controls and nine cirrhotics. Steady-state renal and hepatic S clearances as well as hepatic ICG clearance were calculated. In controls the values (mean +/- SD) of the independent measurements of S and ICG hepatic clearance were 978 +/- 107 and 519 +/- 142 ml/min, respectively, while in cirrhotic patients they were 554 +/- 238 and 231 +/- 90 ml/min. Owing to the kinetic properties of S, its hepatic clearance may be regarded as a measure of functional liver plasma flow (FLPF). The total liver plasma flow (TLPF) values (mean +/- SD), calculated according to Fick's principle, were 1091 +/- 157 ml/min (S method) and 1033 +/- 153 ml/min (ICG method) in controls, and 1251 +/- 554 and 1284 +/- 677 ml/min in cirrhotics. In controls, FLPF was found to be very close to TLPF. In cirrhotic patients the difference between TLPF and FLPF (ranging from 169 to 2093 ml/min when measured by S method) was considered as an approximate estimate of intrahepatic shunting. The procedure is safe and simple and may add a new dimension to the investigation of hepatic circulation.

Application of artificial intelligence techniques to a well defined clinical problem: jaundice diagnosis.

Jaundice is a very common medical condition, in which pathophysiological knowledge has been quite well assessed and clinical features are usually well known. However, incorrect conclusions are sometimes reached in medical practice which can lead to serious implications. Thus, jaundice diagnosis appears as one of the medical situations which might be substantially improved by computer assistance. The present study is aimed at describing and discussing in what way a computer program supporting medical decision making in jaundiced patients can be developed on the basis of advanced Artificial Intelligence methods. To this extent methodological problems concerned with the organization and the formalization of medical knowledge have been outlined with some detail. The resulting expert system is expected to become a well assessed and potentially useful tool for both medical decision making and medical education.

D-sorbitol plasma disappearance rate: an index to evaluate changes in liver circulation.

The hepatic clearance of D-sorbitol was proven to be a reliable parameter for evaluating the functional liver plasma flow. Twenty-five normal subjects and 50 cirrhotic patients were studied in order to assess if the measure of the plasma disappearance rate of sorbitol can be used as a simpler procedure to evaluate changes in liver perfusion and to predict modifications of drug bioavailability due to circulatory events. The plasma disappearance rate was calculated between 10 and 20 min after intravenous administration of a 2-g dose because in this time interval plasma levels were in the optimum range for the chemical assay, and the plasma concentration/time curve fitted a decreasing exponential function. Plasma disappearance rate values were found to correlate significantly (r = 0.666, p less than 0.001) with sorbitol hepatic clearance, as calculated after the 2-h test. The test had a good day-to-day reproducibility both in normal subjects and cirrhotic patients. In 5 patients submitted to surgical side-to-side portacaval shunt, decreases of plasma disappearance rate and sorbitol hepatic clearance showed no significant difference. Mean values (+/- SD) of D-sorbitol plasma disappearance rate were 0.048 +/- 0.014 min-1 in cirrhotic patients, and 0.081 +/- 0.014 min-1 in normal subjects (p less than 0.001).