Trick of the Trade: Serial lactate measurements in sepsis?

Does your Emergency Department have computerized spectrophotometric catheters to measure continuous central venous oxygen saturation (ScvO2) in early goal directed therapy (EGDT) for severe sepsis? That's what was used in the original Rivers' EGDT study.

I've never even seen one before.

Many emergency physicians are getting around not having the specialized equipment issue by obtaining intermittent venous blood gas measurements off of a central venous line.

But what if you had a 30 y/o woman with early pyelonephritis/urosepsis who has severe sepsis by definition? She's got 10 peripheral lines (I'm exaggerating, of course), a normalized blood pressure with early IV fluids, and appears non-toxic. Her lactate, however, is 9! Do you really need a central line? My gut says no, but the EGDT protocol says yes -- for the purpose of CVP and ScvO2 measurements.

Trick of the Trade: 
Use a less-invasive approach where bedside ultrasound and serial venous lactate levels replace central venous lines and ScvO2 measurements, respectively.

Last year, JAMA published a landmark study showing that lactate clearance of ≥10% over the first 2 hours is "not a worse measurement" than ScvO2≥70%. This double-negative statistical speak came about because it was a non-inferiority study.

So how does this affect the original Rivers protocol? To review, here's the original protocol, which I posted about earlier:

(click to view larger image)

In the less invasive model:

• Fluid resuscitate through peripheral IV access instead of a central line. 
• Follow volume status either with a bedside ultrasound or urine output.
• Follow venous lactate levels at time 0 and 2 hours. If the lactate clearance is ≥10% over these 2 hours, you should follow the algorithm as if the ScvO2≥70%. That means no need for immediate transfusion or vasopressor agents.

How do you know when you have adequately volume-resuscitated a patient using bedside ultrasound? Measure the IVC diameter about 1-2 cm from the right atrium junction.

• If the IVC diameter ≤1.5 cm and has ≥50% collapse with inspiration, the patient has a very low CVP.
• If the IVC diameter is at least 1.5 cm and has minimal collapse with inspiration, the patient is euvolemic. Move to the next step -- assessing the MAP.

Pearl: 
This doesn't mean that all EGDT patient should have ONLY peripheral lines. Persistent hypotension, a non-clearing lactate level, and/or clinical toxicity warrant more invasive monitoring and management.

Scott Weingart has an in-depth, 21-minute podcast about the JAMA article and noninvasive approach to sepsis: Podcast link. Scott also briefly interviews Dr. Alan Jones (Carolinas Medical Center), the first author of the study, in the podcast.

Reference
Jones AE, et al; Emergency Medicine Shock Research Network (EMShockNet) Investigators. Lactate clearance vs central venous oxygen saturation as goals of early sepsis therapy: a randomized clinical trial. JAMA : the journal of the American Medical Association. 2010, 303(8), 739-46. PMID: 20179283
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