Discrepancy between inferior vena cava and right atrial oxygen saturations as a sign of ischemia in the mesenteric circulation.

We describe the case of a 72-year-old patient admitted to intensive care following abdominal surgery. Venous oxygen saturations from the right atrium and superior vena cava (SVC) showed large variation due to ongoing ischemia in the mesentric circulation. If trends in venous oxygen saturation are to be followed, serial samples must be taken from the same central venous catheter (CVC) port.