Vishal Garg, MS

Fulminant colitis/ Toxic megacolon This has arbitrarily been defined as having three or more of the following criteria present:  1)tachycardia greater than 100,  2)leukocytosis greater than 12,000/dL3,  3)hypoalbuminemia less than 3 g/dL3,  4)a temperature greater than 38°C, or  5)a diameter of the transverse colon on a plain abdominal radiograph greater than 5 cm.  Three or more of these criteria meet the definition of toxic megacolon;  note that a “megacolon” does not need to be present in order to meet this definition. Thus, the definition of toxic megacolon merely refers to a patient who is septic due to very severe colitis. Toxic megacolon can be present not only from severe UC but also due to severe Crohn colitis or severe infectious or ischemic colitis. Truelove and Witts is a popular classification scheme ( Severity of Ulcerative Colitis ) that characterizes patients by the severity of their diarrhea, the presence of blood in stool, the presence of fever, tachycardia, anemia,

MIXED VENOUS OXYGEN SATURATION The percentage saturation of oxygen returning to the heart from the body is a measure of the oxygen delivery and extraction by the tissues.  Accurate measurement is via analy­sis of blood drawn from a long central line placed in the right atrium.  Estimations can be made from blood drawn from lines in the superior vena cava, but these values will be slightly higher than those of a mixed venous sample (as there is rela­ tively more oxygen extraction from the lower half of the body).  Normal mixed venous oxygen saturation levels are 50–70%.  Levels below 50% indicate inadequate oxygen delivery and increased oxygen extraction by the cells. This is consistent with hypovolaemic or cardiogenic shock. High mixed venous saturations (>70%) are seen in sepsis and some other forms of distributive shock.