Blood Cultures Save Lives and Other Pearls of Wisdom

It’s been sixteen years since the introduction of Early Goal-Directed Therapy in the Emergency Department. For the past decade and a half, our lives have been turned upside-down by quality measures tied to the elements of this bundle. Remember when every patient with sepsis was mandated to receive a central line? How great were the costs – in real, in time, and in actual harms from these well-intentioned yet erroneous directives based off a single trial?

Regardless, thanks to the various follow-ups testing strict protocolization against the spectrum of timely recognition and aggressive intervention, we’ve come a long way. However, there are still mandates incorporating the vestiges of such elements of care –such as those introduced by the New York State Department of Health. Patients diagnosed with severe sepsis or septic shock are required to complete protocols consisting of 3-hour and 6-hour bundles including blood cultures, antibiotics, and intravenous fluids, among others.

This article, from the New England Journal, looks retrospectively at the mortality rates associated with completion of these various elements. Stratified by time-to-completion following initiation of the 3-hour bundle within 6 hours of arrival to the Emergency Department, these authors looked at the mortality associations of the bundle elements.

Winners: obtaining blood cultures, administering antibiotics, and measuring serum lactate
Losers: time to completion of a bolus of intravenous fluids

Of course, since blood cultures are obtained prior to antibiotic administration, these outcomes are co-linear – and they don’t actually save lives, as facetiously suggested in the post heading. But, antibiotic administration was associated with a fraction of a percent of increased mortality per hour delay over the first 12 hours after initiation of the bundle. Intravenous fluid administration, however, showed no apparent association with mortality.

These data are fraught with issues, of course, relating to their retrospective nature and the limitations of the underlying data collection. Their adjusted model accounts for a handful of features, but there are still potential confounders influencing mortality of those who received their bundle completion within 3 hours as compared to those who did not.  The differences in mortality, while a hard and important endpoint, are quite small.  Earlier is probably better, but the individual magnitude of benefit will be unevenly distributed around the average benefit, and while a delay of several hours might matter, minutes probably do not.  The authors are appropriately reserved with their conclusions, however, only stating these observational data support associations between mortality and antibiotic administration, and do not extend to any causal inferences.

The lack of an association between intravenous fluids and mortality, however, raises significant questions requiring further prospective investigation. Could it be, after these years wandering in the wilderness with such aggressive protocols, the only universally key feature is the initiation of appropriate antibiotics? Do our intravenous fluids, given without regard to individual patient factors, simply harm as many as they help, resulting in no net benefit?

These questions will need to be addressed in randomized controlled trials before the next level of evolution in our approach to sepsis, but the equipoise for such trials may now exist – to complete our journey from Early Goal-Directed to Source Control and Patient-Centered.  The difficulty will be, again, in pushing back against well-meaning but ill-conceived quality measures whose net effect on Emergency Department resource utilization may be harm, with only small benefits to a subset of critically ill patients with sepsis.

“Time to Treatment and Mortality during Mandated Emergency Care for Sepsis”

http://www.nejm.org/doi/full/10.1056/NEJMoa1703058