You have just finished seeing a 76-year-old man with your resident. He presented with fever, urinary symptoms, and altered mental status. He has a heart rate of 115 bpm, a blood pressure of 101/64 mm Hg, and a white blood cell count of 16. You drew cultures, provided empiric antibiotics, and started fluid resuscitation. You decide to review SIRS, sepsis, and septic shock with your resident, but you are confronted by a strange look. “SIRS is so 2015. Haven't you heard of SOFA and the new sepsis definitions?”
It's true; new definitions for sepsis have been published. A worldwide taskforce composed of 19 brilliant infectious disease and critical care experts came up with the Third International Consensus Definitions for Sepsis and Septic Shock. (JAMA 2016;315:801.)
Sepsis is now defined as “life-threatening organ dysfunction caused by a dysregulated host response to infection.” Identifying organ dysfunction is now done through the sequential organ failure assessment (SOFA) score, which includes a number of laboratory and clinical parameters and is best looked up in your favorite medical calculator. An acute change of two or more points on SOFA, thought to be caused by infection, can now be called sepsis. Using this definition, sepsis is associated with a 10 percent in-hospital mortality.
The qSOFA, or quick SOFA score, really has nothing in common with SOFA, but is offered as a quicker screening tool that can be easily used at the bedside. It consists of three components: systolic blood pressure less than 100 mm Hg, altered mental status (GCS ≤ 13), and tachypnea (≥ 22). This score is considered positive if your patient has two or more of these criteria.
Severe sepsis no longer exists under the new guidelines, and septic shock is redefined as “sepsis in which underlying circulatory and cellular metabolism abnormalities are profound enough to substantially increase mortality.” Clinically, this means sepsis with persisting hypotension requiring vasopressors to maintain a MAP greater than or equal to 65 mm Hg plus a serum lactate level greater than 2 mmol/L (18 mg/dL) despite adequate volume resuscitation. This septic shock definition is associated with in-hospital mortality rates greater than 40 percent.
This is a valuable publication with great intent, but you probably don't need to commit these new definitions to memory just yet because they are being hotly debated. Valuable for research and epidemiology, these definitions are not meant for immediate emergency department implementation. They are discussed as epidemiologic and diagnostic tools to be used “once initial assessment and immediate management are completed,” according to the JAMA study. They are not designed for emergency department resuscitation.
Why Redefine Sepsis?
Our understanding of the pathophysiology of sepsis has improved significantly since the current definitions were developed. We now understand rather than simply being a systemic inflammatory response to infection, sepsis involves a dysregulated host response with resultant organ dysfunction. The new definitions more accurately represent the underlying pathophysiology of sepsis. As practicing physicians, however, pathophysiology is less important than terminology that is practical and useful. Einstein's relativity, with its bends in space-time, provides a more accurate description of gravity, but if you want to build a bridge, the older, simpler Newtonian definitions are more useful.
Practically speaking, the new definitions are really about getting rid of systemic inflammatory response syndrome (SIRS). This task force dislikes SIRS so much that they said, “The current use of two or more SIRS criteria to identify sepsis was unanimously considered by the task force to be unhelpful.” (JAMA 2016;315:801.) I admit SIRS has its problems. Every emergency physician knows that. It under- and overcalls sepsis if used without judgment. But considering the massive improvements we have seen in sepsis management over the past few decades, all guided by our current definitions based on SIRS, could SIRS really be completely unhelpful?
The authors suggest that SOFA should replace SIRS. They present data from a large retrospective, database study, published in full as a separate paper, that indicates SOFA might be better than SIRS (but not necessarily better than clinician judgment) in ICU patients. (JAMA 2016;315:762.) Outside of the ICU, however, SOFA and SIRS perform identically (with an area under the curve of 0.79; 95% CI, 0.78-0.80 vs. 0.76; 95% CI, 0.75-0.77). So for our emergency department patients, the score we already know and is easier to use performs just as well as the proposed, more complex replacement.
Don't get me wrong. I would be very happy to see SIRS disappear. I develop SIRS criteria every time I walk up a flight of stairs. SIRS is a straw man, however. We don't use SIRS by itself. We use clinical judgment at the bedside, which includes SIRS, but is clearly better than SIRS alone. To really know if the SOFA score (or qSOFA) will be valuable to practicing physicians, we need to see it prospectively compared with the current standard: physician judgment.
qSOFA seems appealing because it is purely clinical and could easily be applied at triage and in resource limited settings. The authors admit, though, that qSOFA is not ready for prime time because it lacks prospective validation and presents an algorithm in which a positive qSOFA must be followed by a full SOFA calculation. The value of the purely clinical qSOFA is lost. Furthermore, with very similar predictive values, it is not clear that using qSOFA and SOFA in a series is a valid approach. The biggest issue with qSOFA may ultimately be its inability to add value above physician judgment. How often are you missing sepsis in hypotensive patients with altered mental status?
It is worth noting these definitions have not been endorsed by any of the major emergency medicine societies, and several groups have expressed opposition. (Chest 2016 March 26; http://bit.ly/1M8eKYZ.) Endorsements are probably more political than scientific, but they represent an important context to consider when proposals to change sepsis management start appearing in your emergency department.
Universally accepted and consistent definitions of sepsis are clearly beneficial. It is just as important to consider the potential harms of the new definitions, too. The SOFA score requires a measurement of the PaO2 and therefore arterial blood gases. Depending on implementation, this could lead to a substantial increase in a time-intensive and painful investigation with known complications.
Without prospective validation, we don't actually know SOFA outperforms current practice, and it could actually be worse. Most importantly, millions of dollars have been spent developing and implementing sepsis protocols at hospitals around the world. Spending millions more to redesign those protocols without clear evidence of benefit would be irresponsible.
These definitions might be a significant improvement. They are more precise than the multitude of similar but conflicting definitions used now. They more accurately represent current understandings of sepsis pathophysiology. They will help researchers and epidemiologists. Someday, they may even help in clinical practice after they have been prospectively validated and compared with physician judgment.
For now, we should not rush to change practice. The authors remind us that “neither qSOFA nor SOFA is intended to be a stand-alone definition for sepsis.” Bedside assessment and physician judgment are essential. Emergency department management should continue to focus on what we already do well: early identification of sepsis using all available clinical information, early antibiotics, and fluid resuscitation.
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