In the May 2008 issue of Emergency Medicine Practice, , Dr. Ethan Booker provides an excellent review of the management of severe sepsis and septic shock. He brings up the value of ScvO2 to diagnose tissue hypoperfusion., even in the face of a good blood pressure and adequate CVP. The ScvO2 can be obtained by drawing a blood gas from the distal port of your neck central line; make sure to draw up 3-5 ml of blood and discard, before drawing the gas. ScvO2 can detect occult shock in other conditions besides sepsis, though the literature is not as robust. A low ScvO2 (<70) should make you wary that the tissues might not be receiving enough oxygen.
The author points out that the value of CVP as a marker of inadequate fluid resuscitation is debatable. The study he cites showed very little utility to using CVP for this purpose. However, the population in the study were ICU patients already past their resuscitative phase. The ED population is very different; often, we will get a CVP when the patient is still under-resuscitated. I often obtain CVPs of 1-2 mm HG on patients with severe sepsis and septic shock at the beginning of their treatment. These values almost always indicate the need for fluid resuscitation. Resuscitating from these low levels to the 8-12 recommended in the sepsis guidelines will rarely lead to too much fluid and in fact may under-estimate the volume needs of your patient.Until better measures come to the ED, CVP is essential to treat these patients, even if the set-up of the monitoring equipment is sometimes a hurdle.
