Definitions¹¹

Through the years attempts have been made to define sepsis and sepsis-related terms to help understand the syndrome and accurately diagnose patients. However, efforts have not always been met with universal support.¹² In 1991 the American College of Chest Physicians (ACCP) and the Society of Critical Care Medicine (SCCM) met with the goal of agreeing on sepsis definitions.¹³ In 2001 ACCP, SCCM, the European Society of Intensive Care Medicine (ESICM), the American Thoracic Society (ATS), and the Surgical Infection Society (SIS) revisited the 1991 definitions and found that they still had merit and should remain as described 10 years prior. The following list contains definitions of common terms used in the diagnosis and classification of sepsis¹³:

Figure 21-1 shows the interrelationships among SIRS, sepsis, and infection.

Fig. 21-1 Interrelationships among systemic inflammatory response syndrome (SIRS), sepsis, and infection.

(From American College of Chest Physicians & Society of Critical Care Medicine Consensus Conference Committee. [1992]. American College of Chest Physicians/Society of Critical Care Medicine Consensus Conference: Definitions for sepsis and organ failure and guidelines for the use of innovative therapies in sepsis. Critical Care Medicine, 20[6], 864–874.)

Identifying SIRS or Sepsis

The pathophysiology of sepsis is a complex set of events that involves innate immune response, inflammatory cascades, procoagulant and antifibrinolytic pathways, alterations in cellular metabolism and signaling, and acquired immune dysfunction.¹⁴

SIRS is a dynamic state that starts when a major insult to the body (Fig. 21-1) progresses to an overwhelming systemic inflammation. When infection is the cause of that insult, the systemic inflammatory response can quickly transition into severe sepsis or septic shock. Prompt identification of the patient with potential sepsis is crucial in the ED setting. While nearly 30% of all patients diagnosed with sepsis enter the hospital through the ED, it is also known that these patients may not fit neatly into the definitions described in the literature.¹¹

General assessment of the patient during triage, coupled with a thorough history and physical assessment is crucial in identifying sepsis. Patients with sepsis may present with fever, chills, shortness of breath or tachypnea, tachycardia, rash, or confusion. These symptoms can mimic other disease processes making it difficult to diagnose sepsis in the early stages.¹⁵ In the triage process it is important to consider the age and history of the patient. The elderly, children, and infants have a higher incidence of sepsis than young adults.⁵ It is also essential to determine whether the patient is immune-compromised or if he or she has had any recent surgery, urinary tract infections, respiratory infections, skin infections, or invasive medical procedures. Medical history, such as diabetes, should also be factored into triage decisions.

Patients with a suspected infection should be immediately assessed for signs and symptoms of SIRS. Treatments and medications taken by the patient should be considered when analyzing SIRS criteria; for instance, a patient who is taking prescribed beta-blockers may not have an elevated heart rate. Further laboratory testing can also provide more information about the patient’s condition.

If the patient history is suspicious for a new infection and if any two of the following signs or symptoms of infection are present and new for the patient, there is a high index of suspicion for sepsis:

If there is suspicion of infection and any of the following signs of new-onset organ dysfunction are present, the patient meets criteria for severe sepsis:

If the patient meets the criteria for severe shock and is hypotensive with a SBP less than 90 mm Hg, which has not been reversed with fluid resuscitation, the patient meets the criteria for septic shock.

The Surviving Sepsis Campaign and the Institute for Healthcare Improvement recommend that facilities consider evaluating high-risk patients for sepsis or severe sepsis.^16,17 These groups have developed a tool that can be implemented in the ED setting and provides an algorithm for decision making using SIRS criteria. This screening tool is shown in Figure 21-2.

Fig. 21-2 Sample screening tool for severe sepsis.

(From Surviving Sepsis Campaign. [2005]. Individual chart measurement tool. Retrieved from http://ssc.sccm.org/files/Tools/individualchartmeasurementtool.pdf. Reproduced with permission. Copyright 2005. European Society of Intensive Care Medicine, International Sepsis Forum, and Society of Critical Care Medicine.)

According to the Surviving Sepsis Campaign, patients with SIRS and an identified source of infection are considered to have sepsis.¹⁶ If a patient presents with two or more of the SIRS criteria and new-onset organ dysfunction, the patient meets criteria for severe sepsis. Patients in septic shock present with severe sepsis along with hypoperfusion, which is recognized by a MAP of less than 65 mm Hg or a measured lactate level of greater than 4 mmoL/L.² In septic shock, hypoperfusion will continue despite fluid resuscitation. The patient’s SBP will remain less than 90 mm Hg or the patient’s SBP will drop more than 40 mm Hg.¹⁸

The PIRO model of sepsis identification uses predisposition, infection or insult, response, and organ dysfunction to stage sepsis and predict mortality (Table 21-1).¹⁹ A PIRO score can be calculated within each category:

TABLE 21-1 PIRO SCORE

Another method of identifying potential sepsis patients is the Mortality in Emergency Department Sepsis (MEDS) score (Table 21-2). It takes into account some of the variables of PIRO. This score combines such variables as the patient’s age, mental status, tachypnea or hypoxemia, and platelet count along with risk factors such as being a nursing home resident or having a lower respiratory infection or terminal illness. There is evidence that this is a reliable means of risk stratification in SIRS or sepsis patients in the ED.^21,22

TABLE 21-2 MEDS SCORING AND PREDICTED MORTALITY