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While some additional tests might make sense and help patients in the back of an ambulance, I’m not convinced that serum lactate is one of them, unless you’re just aiming to deliver the results to the ED.

One of the abstracts at the 2008 International Conference on Emergency Medicine (sorry, no link to the abstract available) tries to make an argument for EMS lactate testing (in fact, that’s a paraphrase of the subtitle to their article) in potentially septic patients to look for “cryptic shock,” or elevated lactate levels with normal BPs.  The thought, apparently, is to “promote early diagnosis and management [of sepsis] by EMS personnel.”  So, let’s have a look at the guidelines for management of sepsis:

• Begin resuscitation immediately in patients with hypotension or elevated serum lactate.

Sounds reasonable enough; any ALS unit has enough IV supplies to give patients some saline, and should be doing so to the hypotensive patients.  And as for the non-hypotensive patients?  Well, those goals are:

• Central venous pressure 8-12mmHg
• Urine output >0.5 mL/kg/hr
• Central venous or mixed venous O2 saturation >70%

Of these, only urine output is even conceivably possible (with accuracy, anyhow; I’m not basing someone’s treatment on my secret Cardiology CVP estimation trick), but I don’t personally know of a single ambulance stocked with Foley catheters.  However, the recommendations get even less EMS-friendly:

• If saturation and CVP parameters above aren’t met, transfuse packed RBCs (which you can’t carry in the back of an ambulance) and/or administer dobutamine (possible, but how are you going to measure those numbers accurately?).
• Begin IV antibiotics (which paramedics aren’t allowed to do in any state that I know of).
• Source control (that means cutting out or draining infected tissue–not exactly part of any EMS training).

I have no problem with showing up in the ED with a reading if it’s going to help the patient, but I think it’s a bit of a stretch to see lactate levels changing EMS practice in the field, any more than cardiac enzymes would.

Filed under: EMS Research