While sepsis defies simple definition, it's generally understood to be a clinical syndrome caused by infection that may have profound adverse physiologic consequences.1 Although its precise incidence is unknown, sepsis is believed to be a leading cause of critical illness and hospital mortality, accounting for more than one-third of all deaths in U.S. hospitals.2-4 For patients with sepsis, early identification and rapid intervention are crucial to the restoration of tissue perfusion. The Centers for Disease Control and Prevention recently partnered with clinical professional organizations and patient advocacy groups to launch a comprehensive campaign focused on prevention and rapid recognition of sepsis as critical components of patient safety programs.5 Definitions of sepsis and septic shock are used to help clinicians identify patients with this complex clinical syndrome, to guide nursing and collaborative interventions, and to support research efforts. This article discusses the ways in which our understanding of sepsis and septic shock have changed over the years, the origin of the Surviving Sepsis Campaign (SSC), the latest revised SSC treatment guidelines, changes in the sepsis bundle interventions, and the new definitions and predictive tools introduced by the Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3).
CHANGING DEFINITIONS OF SEPSIS AND SEPTIC SHOCK
The first working definition of sepsis was developed in 1991 to guide research and practice.6 Bone and colleagues introduced a broad definition of sepsis and the concept of systemic inflammatory response syndrome (SIRS), which is characterized by a cluster of symptoms triggered by an inflammatory response that may or may not be due to an infectious process. SIRS was said to be characterized by, though not limited to, more than one of the following clinical symptoms6:
- abnormally high or low temperature
- abnormally high or low white blood cell count
- elevated heart rate
- elevated respiratory rate
In the presence of infection and at least two clinical symptoms of SIRS, the systemic response was identified as sepsis.6 While clinical treatment of sepsis and sepsis research continued to evolve, resulting in several practice guideline updates, SIRS remained part of the continuum of the sepsis syndrome.7-10
The SSC was launched in 2002 by the Society of Critical Care Medicine (SCCM) and the European Society of Intensive Care Medicine (ESICM), with the goal of reducing mortality from sepsis by increasing awareness, improving diagnosis and treatment, educating health care providers, developing management guidelines, implementing a performance improvement plan, and improving post-ICU care (see www.survivingsepsis.org). A major goal of the campaign has been to encourage clinicians to recognize symptoms along the continuum from SIRS to sepsis and septic shock in order to facilitate early identification and aggressive treatment of sepsis, thereby improving patient outcomes. The SSC released its first management guidelines in 2004, and these have been updated every four years, with the most recent update completed in 2016.
The Sepsis-3 task force, convened in 2014 by the SCCM and the ESICM, introduced new definitions for sepsis and septic shock based on advances in the scientific understanding of this complex syndrome.1, 11, 12 A principal change in the new definitions was the requirement that sepsis be triggered by infection.1 This pathobiological understanding removes SIRS from the definition of sepsis, as numerous conditions other than infection may cause SIRS.
The Sepsis-3 definitions focus on the understanding that sepsis is a multifaceted patient response to infection and results in organ dysfunction.1, 11 The new definitions thus focus on organ dysfunction and hypoperfusion in the presence of infection, rather than on inflammation (specifically SIRS). Furthermore, the term severe sepsis is no longer recommended, as it is hard to identify clinically and is not helpful in guiding clinical treatment interventions.1, 11 Septic shock is now defined as a subset of sepsis in which the patient has profound hypoperfusion. Four years following publication of the SSC 2012 guidelines, Sepsis-3 published its new and refined definitions.1 (For a comparison of the guidelines, see Table 1.1, 9, 13) Although there is some debate about the Sepsis-3 definitions, the changes were proposed to aid clinicians in rapidly identifying and treating patients with sepsis, with the goal of reducing morbidity and mortality.
EARLY RECOGNITION OF SEPSIS: SOFA AND QSOFA
The emphasis in the Sepsis-3 definitions on organ dysfunction caused by infection requires clinicians to take a more concentrated, objective approach to the assessment of organ function. The Sepsis-3 recommendation is to use an organ dysfunction assessment tool to identify patients with sepsis. The Sequential Organ Failure Assessment (SOFA), most commonly used in ICUs, is effective in quantifying the severity of organ dysfunction and morbidity and estimating mortality risk.14, 15
The SOFA evaluates the following physiologic functions: respiration, coagulation, hepatic, cardiovascular, central nervous system, and renal.15 In order to calculate a patient's SOFA score, it is necessary to obtain the following laboratory values: bilirubin, creatinine, coagulation studies, and arterial blood gases. However, while these can reveal organ dysfunction, they may not accurately reflect the patient's perfusion status. The higher the SOFA score, the greater the patient's risk of morbidity and mortality.16 (See The Sequential Organ Failure Assessment (SOFA) Score.15)
The quick SOFA (qSOFA), an abbreviated organ dysfunction assessment, was introduced in Sepsis-3.1 The qSOFA relies on only three variables: systolic blood pressure, respiratory rate, and mentation.1 In non-ICU patients, the qSOFA score predicts elevated risk of death and extended ICU stay, but it is not designed to stand alone as an early warning of sepsis or to identify which patients should be transferred to the ICU.17, 18 (See The Quick Sequential Organ Failure Assessment (qSOFA) Score.1)
The information imparted by serum lactate levels can also play an important role in guiding clinical decision making. A serum lactate level greater than 2 mmol/L suggests hypoperfusion, with higher lactate levels indicating more severe hypoperfusion. Normalization of lactate in patients with elevated lactate levels remains a recommendation in the current SSC guidelines.13 That said, adding serum lactate levels to the parameters used to determine the qSOFA score has been found to do little to improve its predictive validity for mortality.11
The advantages of the qSOFA are that it is easy to use and enables clinicians to identify at-risk patients in the absence of laboratory values. The qSOFA score is not a component of the new sepsis definition; rather, it should alert clinicians to patients in need of further assessment for organ dysfunction, which may escalate care for those with previously unrecognized infection or possible sepsis.19 Patients presenting with even modest organ dysfunction associated with infection can deteriorate rapidly; this underscores the importance of early recognition and intervention.13, 20, 21 Recent commentaries21, 22 and recommendations from the SSC23 provide examples of how to integrate the SOFA and qSOFA into the assessment of patients at risk for sepsis. For a composite clinical example from our practice, see Assessing Risk of Organ Failure in Patients with Infection.
SEPSIS BUNDLE CHANGES
In 2017, the new SSC guidelines were published, containing major changes to the sepsis bundles.13, 24 The new SSC guidelines briefly discuss the Sepsis-3 definitions, but acknowledge that the research informing the guidelines incorporated the earlier definitions of sepsis and septic shock that included SIRS.13 Furthermore, the new SSC guidelines do not include qSOFA or SOFA as clinical requirements for assessing patients with suspected sepsis or septic shock, as some studies suggest additional research is needed to evaluate the benefits of including these organ assessment tools in the efforts to identify and treat patients with sepsis as early as possible.16, 25
The elements of the new SSC guidelines that most affect nursing practice focus on the following actions:
- early identification of patients with possible infection and sepsis
- rapid and aggressive fluid resuscitation (at least 30 mL/kg within three hours of sepsis-induced hypoperfusion)
- frequent hemodynamic reassessment of patient response to fluids
- administration of iv antibiotics within one hour of suspected sepsis or septic shock
Readers are encouraged to review the new guidelines—Surviving Sepsis Campaign: International Guidelines for Management of Sepsis and Septic Shock: 201613 —as well as the three- and six-hour SSC bundles. All are available for download on the SSC website, along with supplemental educational materials and related editorials (see www.survivingsepsis.org/Guidelines/Pages/default.aspx).
LIMITATIONS OF THE SEPSIS-3 DEFINITIONS
The new Sepsis-3 definitions are not without controversy. There is debate about whether the exclusion of SIRS and the inclusion of the new sepsis definitions will expedite identification of patients with sepsis.20, 26, 27 Bear in mind that the qSOFA score is a predictor of mortality risk and not a defining characteristic of sepsis. It should be used to identify patients who require further assessment for organ failure.11, 13, 17, 20, 21 Clinical deterioration in patients with a positive qSOFA score may be due to causes other than sepsis. On the other hand, in the study used to develop the new Sepsis-3 definitions, more than 75% of the patients with a suspected infection who scored 2 or higher on the qSOFA also had a positive SOFA score, indicating the presence of organ dysfunction and suspected sepsis.11
IMPLICATIONS FOR NURSING PRACTICE
Although the changes in the definitions of sepsis and septic shock may have little effect on the way nurses provide care to patients, one argument in their favor is that the simplification of terms used to describe suspected sepsis syndrome will expedite intervention. Encouraging nurses to “think sepsis” when subtle changes occur in patients with possible infection is key to early intervention and improved patient outcomes. While the value of the qSOFA in predicting risk of sepsis has not yet been well studied, it is a simple tool that can point to the need for additional focused assessment and intervention.
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24. Dellinger RP, et al A users’ guide to the 2016 Surviving Sepsis guidelines Crit Care Med 2017 45 3 381–5
25. Fullerton JN, et al New sepsis definition changes incidence of sepsis in the intensive care unit Crit Care Resusc 2017 19 1 9–13
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27. Verdonk F, et al The new sepsis definition: limitations and contribution to research and diagnosis of sepsis Curr Opin Anaesthesiol 2017 30 2 200–4
For seven additional continuing nursing education activities on the topic of sepsis, go to www.nursingcenter.com/ce.