Behavior of the portal vein system in man after laparotomy

At the end of an abdominal operation, a Teflon catheter was inserted into the portal vein, where it remained for nine days. Thus, blood samples could be withdrawn for analyses, and pressures could be recorded. The investigations were carried out in 41 patients who had a gastric or intestinal operation and had an uncomplicated postoperative course. The pressures in the portal vein and the arterioportal oxygen content difference were constant with 7 to 8 millimeters of mercury and by 2 volume per cent, respectively, during the period of all nine postoperative days. The pressure gradient between portal and central veins was about 6 millimeters of mercury. By infusing 350 to 500 milliliters of dextran 60 on day one or two postoperatively, the cardiac output was elevated about one-third, the central venous pressure increased from 0.9 to 4.9 millimeters of mercury and the portal venous pressure increased from 7.8 to 9.7 millimeters of mercury. This means that the pressure difference between the portal and central veins diminished. Simultaneously, the oxygen content difference between the systemic and pulmonary artery decreased from 4.7 to 3.3 volume per cent and between the systemic artery and portal vein, from 1.8 to 1.3 volume per cent. By assuming a constancy of the oxygen consumption in the region of the mesenteric circulation during infusion, it can be calculated from the behavior of the arterioportal oxygen content difference that the flow increase in the portal vein nearly equals that of cardiac output. The physical transhepatic resistance decreased about 50 per cent.