Category: Uncategorized

Lactate is Dead! Long Live Lactate?

Our use of serum lactates as targets for resuscitation in sepsis is more than a little flawed. Once upon a time, we resuscitated using central venous oxygenation as part of the Rivers’ trial. Whether those targets were actually a valid part of the multi-pronged bundle remains an excellent and open question. Of course, CVO2 requires invasive monitoring – and serum lactate became our less-invasive surrogate. And, yes, patients with high lactates do poorly – but that doesn’t specifically address the assumption lactate-guided resuscitation is tied to outcomes, or the optimal resuscitation strategy.

This multi-center trial out of Latin America looks at another marker of perfusion status, capillary refill time, that is likewise observationally associated with mortality in sepsis. In a randomized, open-label trial, the first eight hours of resuscitation was guided either by lactate levels or capillary refill time. Resuscitation in both arms used a specific protocol of fluids, fluid-responsiveness assessments, vasopressors, and inodilators.

Without unpacking these specifics in too great of detail, as will be done by many other critical care physicians, the results are quite interesting: of 424 patients randomized, they observed 34.9% mortality in the CRT-guided cohort compared with 43.4% in the lactate-guided cohort. Other secondary outcomes, including lactates at 48 and 72 hours, SOFA scores at 72 hours, generally favored the CRT cohort.

Is this the end of lacate? Certainly, in a resource austere setting, it would generally indicate there’s no rush to adopt lactate use in the context of a just-as-good, zero-cost means of assessment. The accompanying editorial wonders aloud: why not use both? While this seems like a reasonable idea, it probably doesn’t go far enough – why not use all the data for an individual patient to determine their optimal treatment, rather than our current one-size-fits-all nuclear option? Reliance on any single approach to resuscitation – perhaps mandated by “quality” measures – is almost certain to be short-sighted. While I do not advocate a return to the wild west of late recognition and neglect, these data should add further fuel to a reassessment of our golden idols and targets in the treatment of sepsis.

“Perfusion Status vs Serum Lactate Levels on 28-Day Mortality Among Patients With Septic Shock: The ANDROMEDA-SHOCK Randomized Clinical Trial”

https://jamanetwork.com/journals/jama/fullarticle/2724361

Pediatric Lactate & Sepsis

Some syndicated media has “Shark Week”. We have Sepsis Week!

The current generation of sepsis care is defined not just by our quixotic quest for simplified early warning tools, but also, more than anything, by lactate levels. In someways, lactate is our friend – no more central catheter placement solely for measurement of central venous oxygenation. However, the ease of use of checking a lactate level also means we apply it indiscriminately. The lactate has become the D-dimer of infection – increasingly weakly predictive, the more we rely upon it.

This is a snapshot of the performance of lactate levels in pediatric sepsis. This is an observational registry of patients evaluated in the Emergency Department of a pediatric hospital, consisting of 1,299 patients in whom clinically suspected sepsis resulted in a lactate order. These authors hypothesized that, as in adults, a lactate level of 36mg/dL (4mmol/L) would portend increased mortality.

And, naturally, they were correct. However, its predictive value was virtually nil. There were 103 patients with lactate elevated above their cut-off and 1,196 below. Only 5 of the 103 patients elevated lactate suffered 30-day mortality. Then, of the 1,196 below the cut-off, 20 suffered 30-day mortality. A mortality of 4.8% is higher than 1.7%, but the sensitivity is only 20% – and the specificity of 92.3% with such a low prevalence of the primary outcome means over 95% of elevated lactate levels are “false positives”.

There are some limitations here, however, that could have a substantial effects on the outcomes. There is a selection bias inherent to eligibility in which lactates were likely ordered only on the most ill-appearing patients. The effect of this would be to improve the apparent performance characteristics of the test in the study population. However, then, it is likely the patients with elevated lactate levels received more aggressive treatment than if the treating clinicians were blinded to the result. The effect of this would be a mortality benefit in the population with elevated lactate, worsening the apparent test characteristics.

But, hairs split aside, these pediatric results are grossly similar to those in adults. An elevated lactate is a warning signal, but should hardly be relied upon.

“Association Between Early Lactate Levels and 30-Day Mortality in Clinically Suspected Sepsis in Children”
https://www.ncbi.nlm.nih.gov/pubmed/28068437

@emlitofnote at #ACEP16

Off to Las Vegas!

Come say “Hello” anywhere you see me, or at:

FOAMBar, Monday October 17th, 1-2:30pm at the Annals of Emergency Medicine Kiosk

#ACEP16 Social Media Meet-Up, Monday October 17th, 6pm at the Border Grill at Mandalay Bay

Annals of Emergency Medicine Podcast, with Rory Spiegel, Tuesday October 18th, 12-1:00pm at the recording booth in the ACEP16 Exhibit Hall

See you soon!

Stumbling Around Risks and Benefits

Practicing clinicians contain multitudes: the vastness of critical medical knowledge applicable to the nearly infinite permutaions of individual patients.  However, lost in the shuffle is apparently a grasp of the basic fundamentals necessary for shared decision-making: the risks, benefits, and harms of many common treatments.

This simple research letter describes a survey distributed to a convenience sample of residents and attending physicians at two academic medical centers. Physicians were asked to estimate the incidence of a variety of effects from common treatments, both positive and negative. A sample question and result:

treatment effect estimates
The green responses are those which fell into the correct range for the question. As you can see, in these two questions, hardly any physician surveyed guessed correctly.  This same pattern is repeated for the remaining questions – involving peptic ulcer prevention, cancer screening, and bleeding complications on aspirin and anticoagulants.

Obviously, only a quarter of participants were attending physicians – though no gross differences in performance were observed between various levels of experience. Then, some of the ranges are narrow with small magnitudes of effect between the “correct” and “incorrect” answers. Regardless, however, the general conclusion of this survey – that we’re not well-equipped to communicate many of the most common treatment effects – is probably valid.

“Physician Understanding and Ability to Communicate Harms and Benefits of Common Medical Treatments”
http://www.ncbi.nlm.nih.gov/pubmed/27571226

The Febrile Infant Step-by-Step

You’ve heard of the Philadelphia Criteria. You’ve heard of the Rochester Criteria. But – Step-by-Step?

This is an algorithm developed by European emergency physicians to identify low-risk infants who could be safely managed without lumbar puncture nor empiric antibiotic treatment. After retrospectively validating their algorithm on 1,123 patients, this is their prospective validation in 2,185 – looking for IBI or “Invasive Bacterial Infection” as their primary outcome.

The easiest way to summarize their algorithm and results is by this figure:

Step by Step

Sensitivity and specificity, respectively, were as follows:

  • Rochester – 81.6% and 44.5%
  • Lab-score – 59.8% and 84.0%
  • Step-by-Step – 92.0% and 46.9%

The authors attribute 6 of the 7 missed by Step-by-Step to evaluation early in the disease process – presentation within 2 hours of onset of fever.

Their algorithm is reasonable at face validity, and could be incorporated into a protocol with close follow-up to re-evaluate those early in their disease process. We still have, however, a long way to go regarding specificity.

“Validation of the “Step-by-Step” Approach in the Management of Young Febrile Infants”
http://www.ncbi.nlm.nih.gov/pubmed/27382134

Santa “Danger” Claus

If you’re like me – and have drawn the Christmas Holiday straw this year – perhaps you’re lamenting your choice of profession as you drive into work.

Of course, you could have Santa’s job.

Night-time flying, a sleigh-landing hazards, mental health stressors, cardiovascular risks … it’s a wonder Santa survives and returns year after year!

“The occupational health of Santa Claus”
http://www.occup-med.com/content/10/1/44 (free fulltext)