I. How to Use

When to Use

  • Patients that present with two or more SIRS criteria and a suspected or confirmed infection should be screened for Severe Sepsis.

  • Currently many institutions encourage or even mandate obtaining a lactic acid level on these patients. A lactate ≥ 2 mmol/L is considered elevated and the initiation of standard sepsis care is warranted if the patient meets other diagnostic criteria for sepsis.

  • Patients who meet the above criteria but are persistently hypotensive despite the initiation of intravenous fluid resuscitation are in septic shock and aggressive resuscitation measures should be initiated immediately.

Pearls / Pitfalls

  • SIRS, sepsis, severe sepsis, and septic shock criteria were chosen by a panel of experts and not prospectively or retrospectively derived from large-scale population studies (SCCM 2021 guidelines).

  • There remains controversy over the sensitivity and specificity of these criteria, even though they have been largely adopted for the purpose of research and in clinical practice.

  • Clinical judgment remains important since a significant number of patients presenting to emergency departments will meet criteria for Sepsis but do not require further screening or management.

For example, a 21 year old healthy male with a viral illness can present with a fever and tachycardia. While this patient meets the definition of Sepsis, one can easily argue further investigation and aggressive interventions are likely unnecessary if the patient is well appearing.

Why Use

  • Early initiation of broad spectrum antibiotics and aggressive resuscitative measures have been shown to decrease mortality in patients with severe sepsis and septic shock. The early recognition of these conditions is therefore of the utmost importance.

  • SIRS criteria are mostly used as a screening tool to identify patients that may need further workup for sepsis and severe sepsis.

  • Severe sepsis and septic shock are universally accepted as indications to initiate standard sepsis management protocols.

Having clearly defined criteria for SIRS, Sepsis, Severe Sepsis, and Septic Shock is also important in order to standardize clinical research, as well as institutional protocols for the management of these conditions.

II. Next Steps

Management

  • When a patient presents with two or more SIRS criteria but with hemodynamic stability (i.e. blood pressure at baseline), a clinical assessment must be made to determine the possibility of an infectious etiology.

  • If an infection is suspected or confirmed, the patient is diagnosed with sepsis and a lactate level is obtained to determine the degree of hypoperfusion and inflammation. A lactate level ≥ 2 mmol/L is considered elevated and may warrant further investigation. Aggressive management with broad spectrum antibiotics, intravenous fluids, and vasopressors should be initiated, especially in patients with lactate >4 mmol/L.

  • Patients that present with a suspected or confirmed infection AND hemodynamic instability should immediately be treated for septic shock. While SIRS criteria will likely be present in these patients, aggressive management should not be delayed while waiting for laboratory values such as the WBC or lactate.

  • Early recognition of sepsis, severe sepsis, and septic shock, and early administration of broad spectrum and organism specific antibiotics are the most critical actions.

  • There remains controversy in the type of fluids that should be used, their quantity, and the timing of vasopressors and/or inotropes.

Critical Actions

  • Assess all patients presenting with two or more SIRS criteria for the possibility of an infectious etiology.

  • Screen for severe sepsis by obtaining a lactate level on patients with sepsis, that are elderly, immunocompromised, or ill appearing.

  • Some experts recommend obtaining a lactate level on all patients in whom blood cultures are sent. This is institution dependent however and not mandated in any guidelines.

  • When severe sepsis or septic shock are identified, initiate broad spectrum antibiotics immediately. These antibiotics should be organism specific and therefore institutional antibiograms should be used.

The Surviving Sepsis Campaign Guidelines recommend initiation of antimicrobials within one hour from the time of recognition of Severe Sepsis or Septic Shock, or within three hours of the patient’s arrival to the hospital.

III. Evidence

Evidence Appraisal

  • This paper was released after the first consensus conference in 1991. The goal of this conference was to standardize the use of terms such as “SIRS”, “sepsis”, “severe sepsis”, and “septic shock” to facilitate enrollment of patients in clinical trials.

  • In 2001, the International Sepsis Definitions Conference expanded on these definitions by adding additional elements such as laboratory data. See here.

  • The Third Consensus Conference is the most recent iteration of this guidance.

Formula
SIRS Criteria Points
Temp >38°C (100.4°F) or < 36°C (96.8°F) Y/N
Heart Rate > 90 Y/N
Respiratory Rate > 20 or PaCO2 < 32 mm Hg Y/N
WBC > 12,000/mm>3, < 4,000/mm>3, or > 10% bands Y/N
Sepsis Criteria (SIRS + Source of Infection)
Suspected or Present Source of Infection Y/N
Severe Sepsis Criteria (Organ Dysfunction, Hypotension, or Hypoperfusion)
Severe Sepsis with Hypotension, despite adequate fluid resuscitation Y/N
Multiple Organ Dysfunction Syndrome Criteria
Evidence of ≥ 2 Organs Failing Y/N

Facts & Figures

  • SIRS - 2 YES answers meets criteria.

  • Sepsis Criteria - 2 YES of SIRS + Suspected Source of Infection.

  • Severe Sepsis Criteria - 2 YES of SIRS + Lactic Acidosis, SBP.

  • Multiple Organ Dysfunction Syndrome - 2 YES of SIRS + Evidence of ≥ 2 Organs Failing.

Check with your own hospital for its sepsis guidelines, sepsis ‘bundle’, or sepsis algorithm

Literature

Original/Primary Reference

International Guidelines for Management of Severe Sepsis and Septic Shock: 2012

Bone RC, Balk RA, Cerra FB, Dellinger RP, Fein AM, Knaus WA, Schein RM, Sibbald WJ. Definitions for sepsis and organ failure and guidelines for the use of innovative therapies in sepsis. The ACCP/SCCM Consensus Conference Committee. American College of Chest Physicians/Society of Critical Care Medicine.Chest. 1992 Jun;101(6):1644-55.

Evans L, Rhodes A, Alhazzani W, et al. Surviving sepsis campaign: international guidelines for management of sepsis and septic shock 2021. Intensive Care Med. 2021;47(11):1181-1247.

Clinical Practice Guidelines

Surviving Sepsis Campaign: International Guidelines for Management of Sepsis and Septic Shock: Critical Care Medicine

Other References

Levy MM, Fink MP, Marshall JC, et al. 2001 SCCM/ESICM/ACCP/ATS/SIS International Sepsis Definitions Conference. Crit Care Med. 2003;31(4):1250–1256.

Singer M, Deutschman CS, Seymour CW, et al. The third international consensus definitions for sepsis and septic shock(Sepsis-3). JAMA. 2016;315(8):801-810.