I hope that by now you are very aware of the new sepsis definitions as brought forth by a task force from the Society of Critical Care Medicine and the European Society of Intensive Care Medicine. The work of this group is distinct from the Surviving Sepsis Campaign, although the same two organizations are the stimuli behind each.
The new definitions attempt to advance the field. The previous definitions were based purely on the Delphi approach, without the input of any data analysis and review. I am certain that data were involved, since experts in the field were most certainly aware of the data that existed at that time. The new definitions essentially redefine and thus reclassify conditions that previously existed. For example, infections still exist and can include systemic signs of inflammation, but they do not meet the definition of sepsis until there is organ dysfunction. Sepsis with organ dysfunction used to be thought of as severe sepsis. The new definition eliminates the term severe sepsis and simply recognizes that sepsis is severe! It is also important to note that the new definition clarifies that there is not a continuum that starts with sepsis and progresses to septic shock; some patients start with septic shock.
The previous definition was a highly sensitive one. That may indeed have been good at some level because we all want high sensitivity in a screening tool. However, very high sensitivity without specificity can lead to misuse of tests or medications. Too many noninfectious etiologies are captured by the previous diagnosis, including pancreatitis and even routine surgery with its inherent surgical stress response sometimes referred to as surgical systemic inflammatory response syndrome. So the new definition continues to allow infection, with or without a systemic inflammatory response, to exist and to be an extremely important healthcare and public health entity. In fact, I believe it opens up the opportunity to investigate and better understand what exactly the diagnostic and therapeutic steps are in infected conditions that are associated with significantly lower mortality.
Sepsis-Related Organ Failure Assessment (SOFA) may be useful in helping identify the degree of organ dysfunction that is associated with high mortality and thus sepsis. It should be noted that SOFA and quick SOFA (qSOFA) are not part of the definition, but are potential clinical tools. SOFA was identified as a potential tool by the task force without data analysis. This was done in the interest of trying to help clinicians at the bedside with possible clinical criteria. Additional studies are indeed warranted.
The qSOFA is a new tool that was derived from analysis of large datasets; it can be used for screening in someone with suspected infection. Of course, despite the use of multiple databases to assess this tool, it is important to note that retrospective data analysis can only answer so much. Stated otherwise, retrospective data is useful from an evidence-based approach in that it is the best data presently available. Of course, it raises the question about the need for prospective trials. In addition, others with significant data repositories are welcome to test this tool against their datasets. Such work is sorely needed in our field and thus is encouraged by the authors and by the societies that established the joint task force.
Septic shock is now clarified as well. From a practical standpoint, the definition is almost the same as the previous definition. Septic shock is a subset of sepsis in which underlying circulatory and cellular/metabolic abnormalities are profound enough to increase mortality. From a clinical perspective, septic shock is sepsis plus persistent hypotension requiring vasopressors to maintain mean arterial pressure greater than 65 mm Hg and lactate level greater than 2 mmol/L despite adequate volume resuscitation. This definition was reached after evaluating seven different possible blood pressure associations as well as differing lactate thresholds.
I feel that these new definitions represent advances in the field. I believe they open the door to studies and improvement in the care of patients with infections who do not have organ dysfunction and thus a lower predicted mortality. I believe they open the door for academic debate and investigation, and these debates will themselves also help advance the field. I also believe that these definitions help draw a distinction between disease states that do not require dedicated and present critical care expertise, such as infection, and disease states that do require dedicated and present critical care expertise, such as sepsis and septic shock.
Finally, I know that it may be confusing for some to have different definitions being used by different data collection entities that range from quality improvement organizations to regulators. I strongly recommend the Critical Care Medicine article “Application of a Framework to Assess the Usefulness of Alternative Sepsis Criteria” (Crit Care Med. 2016 Mar;44(3):e122-e130) and especially focusing on Table 2. In addition to the superb explanation provided, I would like to point out that our job on the academic side is to advance the science. As we move to a more nimble system that could adjust guidelines and recommendations in a more continuous fashion, those who collect data and who use this data, such as those in quality improvement and in the regulatory world, will need to become nimble as well.