ObjectiveTo develop a liver-specific biosensor system/catheter assembly that can be used to localize and cannulate the hepatic venous system without the need for fluoroscopic imaging. This would permit the bedside placement of a hepatic venous catheter for monitoring purposes without radiographic guidance.DesignExperimental, in vitro.Study SettingExperimental laboratory at a university center.SubjectThis was a simulation study to evaluate the ability of a cardiovascular monitoring catheter mounted with a liver-specific biosensor to anatomically identify a side arm tributary. The experimental system used for this study mimics the hepatic vein draining into the inferior vena cava and allows its localization without the need for assisted imaging. The biosensor design and catheter/sensor assembly function were studied in this in vitro model.InterventionsA liver-specific biosensor was developed by housing a homogeneous affinity fluorescence assay system sensitive to galactose in a microdialysis hollow fiber receptacle. A polyvinyl chloride tube containing a side arm was constructed to mimic the confluence of a venous tributary (i.e., the hepatic vein) with a major vascular channel (i.e., the vena cava). In this simulation, the side arm was continuously perfused with a liver-sensitive analyte (galactose) and the main channel was perfused with galactose-free buffer. A cardiovascular catheter containing a fiberoptic waveguide mounted with a galactose-sensitive fluorescent probe was advanced along the main conduit to assess its ability to identify the location of the galactose side arm infusion site.Measurements and Main ResultsThe response of the fiberoptic sensor to different galactose concentrations was assessed and found to be almost linear over the concentration range of 0 to 2 mM, which encompasses the expected utilization range of this system. The variability in identifying the galactose infusion point (simulated hepatic vein) in a 15-cm conduit was 1.7 to 2.8 mm, or 1.1% to 1.9%.ConclusionsThe construction of a catheter/sensor system with the ability to provide accurate spatial/anatomical localization data for the hepatic venous system is feasible. This assembly will eliminate the need for ancillary imaging systems for catheter/sensor delivery to an individual organ system and potentially can be positioned at the bedside in a fashion similar to the pulmonary artery flotation catheter. (Crit Care Med 1999; 27:1598-1602)