“…4 Intraoperative measurement of portal pressure alone can be unreliable because of the effects of anesthesia, administration of inotropes, position of catheters, position of abdominal viscera, phase of respiration, and manipulations of the portal vein. 13 However, limitations associated with measurement of surface oxygen tension include the need to have a relatively long period in which to obtain a steady-state recording, variability among operators, maintenance of consistent contact between sensors and tissues, and peristaltic movements of intestines. 9 Portal hypertension is defined as a persistent increase in portal vascular pressure caused by an increase in portal venous blood flow or by an increase in resistance to portal venous blood flow.…”