Estimation of hepatic blood flow by hydrogen gas clearance.

The hydrogen gas clearance technique was evaluated to estimate regional hepatic blood flow. Initially, the H2 gas method was compared to the indocyanine green clearance in mini pigs. The blood flow measured by the H2 gas method (0.49 +/- 0.03 ml/min/gm) was only 39% of the calculated blood flow by the indocyanine green method (1.26 +/- 0.14 ml/min/gm). The blood flow determined by H2 gas decreased to 0.06 +/- 0.04 ml/min/gm after ligation of the hepatic artery. No difference in blood flow was found by simultaneous measurements on the left (0.89 +/- 0.1 ml/min/gm) and right (0.96 +/- 0.13 ml/min/gm) liver lobes in rats. After ligation of the left hepatic artery in the rats, a delayed response to H2 application was present and the determined blood flow (0.14 +/- 0.02 ml/min/gm) was significantly reduced (p less than 0.001) compared with the right liver lobe H2 determined blood flow as a control. No current was generated after ligation of the left hepatic artery and the portal vein indicating that there was no blood flow measured by the gas H2 method. The results indicate that the H2 gas clearance technique may be a method that assesses hepatic arterial liver perfusion rather than estimates total hepatic blood flow. The safety and simplicity of the H2 gas clearance technique may make it suitable for clinical application in serial measurement of hepatic arterial blood flow in man.