Review Of: van Beest P, Mulder P, Oetmo S, et al. Measurement of lactate in a prehospital setting is related to outcome. Eur J Emerg Med. 2009;16(6):318–322.
This study from the Netherlands evaluated the relationship between measuring serum lactate levels in the prehospital setting and patient outcomes. The investigators conducted chart reviews on patients who had lactate levels measured prospectively, categorizing them into two groups: non-shock (lactate levels less than 4 mmol/L), and shock (lactate levels at least 4 mmol/L).
A total of 216 charts were reviewed. One hundred and thirty-five patients were categorized to the shock group, and 81 to the non-shock group. The researchers analyzed several variables, including demographics, vital signs, length of stay and in-hospital mortality. The most staggering statistic was in-hospital mortality: the shock group had a 26.7% mortality rate compared with1.2% for the non-shock group. The authors conclude that obtaining lactate measurements in the field is feasible and may have clinical relevance.
Doc Wesley: I congratulate these authors for bringing attention to the vital role serum plays in lactate measurements. We’ve treated shock from a tight set of vital sign parameters or subjective interpretation of mental status for too long. Elevated serum lactate levels have long been identified with increased mortality from sepsis and other systemic conditions. It’s a physiologic marker of poor tissue perfusion. In the emergency department, "early goal directed therapy" for sepsis is based on serum lactate levels and the patient’s response to fluid resuscitation. Strong evidence exists that shows the sooner fluid resuscitation occurs the more likely the patient is to survive.
So why isn't this used in American EMS? Simple. Point-of-care testing using only FDA-approved devices is expensive. This study used the Accutrend Lactate monitor, which isn’t FDA cleared. It’s a device athletic trainers and athletes use to measure a workout’s level of strenuousness. In an athlete’s case, elevated lactate levels indicate that they pushed their body into anaerobic metabolism, which is their goal.
This condition isn’t beneficial for the septic patient because they’re using anaerobic metabolism as a result of poor perfusion. Several states prohibit the use of such devices without Clinical Laboratory Improvement Amendments waivers or licenses that assure they’re accurate. This is the case with glucose monitors. Although I don't personally agree with this stance, that's the federal government for you. We use pulse oximeters and other monitoring devices without any federal oversight and successfully treat our patients with them.
However, in many states, the medical director is responsible for approving devices and authorizing their use. These devices are safe and accurate, and I, for one, plan to implement them in my paramedic service. Serum lactate levels are the best bio-marker we have for identifying septic patients and elevated levels in normotensive patients that require fluid resuscitation in order to improve tissue perfusion.
Medic Marshall: I’m with the Doc on this one; I really like this study. It’s simple and conducted well and seems to strengthen what we already know: A relationship between elevated lactate and mortality exists. Essentially, a patient with elevated lactate levels has a greater risk of death. So what does this mean for us field providers?
We know that elevated lactate is an excellent indicator for systemic shock (e.g. sepsis) and vital signs may not be as sensitive in the beginning stages (because the body does a phenomenal job compensating) of physiological changes, which causes problems for field providers because they lack “point-of-care” testing abilities. These patients are some of the hardest to recognize as being “sick” because often a low grade fever is all we have to go on.
But if we had the ability to identify early the signs of shock, then we could initiate early and aggressive fluid resuscitation. I’m happy to see the Doc is going to implement this device in our service. Like him, I see tremendous value in this small device, and more specifically, the benefits of expanding “point-of-care” testing in the field.