Rapid determination of functional liver plasma flow in ICU patients by a modified hepatic D-sorbitol plasma clearance method.

Changes in liver perfusion may have a substantial influence on the pharmacokinetics of drugs with flow-controlled metabolism. This may have important implications for drug dosage in patients in an intensive care unit (ICU). The hepatic D-sorbitol plasma clearance has been suggested as a non-invasive test for evaluating functional liver plasma flow, which is in reasonable agreement with the direct blood measurement. However, its determination requires D-sorbitol infusion for 3 h or administration of a D-sorbitol bolus and withdrawal of blood specimens every 3-5 min. Since both variants are impractical in the ICU setting, a bolus/infusion technique was tested. A combined technique applying a bolus (0.85 mg/kg) and steady-state infusion (0.0014 mg/kg/min) of D-sorbitol was tested in 10 ICU patients without hepatic disease (group 1) and in 10 ICU patients with liver disease (group 2). Steady-state plasma levels (+/- 9%, P < 0.05) could be achieved within 60 min in all patients. The modified D-sorbitol clearance method requires a bolus and an infusion of D-sorbitol and withdrawal of a single blood specimen after 60 min. The lowest values of functional liver plasma flow were determined in patients with decompensated liver cirrhosis, acute fatty degeneration of the liver or Budd-Chiari syndrome. The method for routine determination of functional hepatic plasma perfusion proved to be rapid, safe and non-invasive in ICU patients. Hepatic D-sorbitol clearance may be especially useful for assessing the functional aspect of liver perfusion.