Changes in hepatic flow induced by continuous positive pressure ventilation in critically ill patients

To quantify the influence of continuous positive pressure ventilation (CPPV) on hepatic plasma flow (HPF) in 8 critically ill patients submitted to controlled ventilation, we measured simultaneously HPF by the indocyanine green dye (IGD) clearance and cardiac output (CO) by the thermodilution technique, while increasing PEEP from 0--20 cm H2O. CPPV induced a significant decrease in HPF which was related to the level of PEEP. A linear correlation was documented between HPF and CO; HPF remained a constant fraction of CO during CPPV. These results suggest that the decrease in CO is the most likely mechanism of the fall in HPF during CPPV.