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    Patent Pending

    SIRS, Sepsis, and Septic Shock Criteria

    Defines the severity of sepsis and septic shock.


    Note: sepsis definitions are evolving and difficult to finalize without a gold standard. These criteria are what is reported and the literature is listed, but note that nuances exist for all sepsis definitions and can differ locally, regionally, nationally, and internationally, as well as in clinical vs administrative vs research settings. Sepsis-3 Consensus Definitions are frequently cited as one paradigm.

    For patients under 18, please use the Pediatric SIRS, Sepsis, and Septic Shock Criteria.

    When to Use
    Why 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 ≥ 4 mmol/L is considered the cutoff value for the diagnosis of severe sepsis and the initiation of Early Goal Directed Therapy (EGDT).
    • 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.
    • 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.
    • 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.
    • SIRS is commonly used as a screening tool in the emergency department to identify patients at risk for Severe Sepsis. These criteria have not been validated in this setting however.
    • 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.
    • 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. In the emergency department it is a triage tool that helps determine patient acuity and identify patients that are potentially septic and in need of further screening.
    • Severe Sepsis and Septic Shock are universally accepted as indications to initiate sepsis management protocols such as Early Goal Directed Therapy.
    • 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.
    SIRS Criteria (≥ 2 meets SIRS definition)
    Sepsis Criteria (SIRS + Source of Infection)
    Severe Sepsis Criteria (Organ Dysfunction, Hypotension, or Hypoperfusion)
    Septic Shock Criteria
    Multiple Organ Dysfunction Syndrome Criteria
    Confirmed positive
    Confirmed negative


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    Next Steps
    Creator Insights
    Dr. Robert A. Balk

    From the Creator

    Why did you issue the consensus statement on the SIRS Criteria and Septic protocol? Was there a clinical experience that inspired you to update these guidelines for clinicians?
    The American College of Chest Physicians and the Society of Critical Care Medicine convened the first sepsis definitions conference in 1991 to help researchers define a population of severe septic patients who would be suitable for enrollment in clinical trials of new investigational agents that were thought to be able to block the proinflammatory cascade, and thus improve survival of patients with severe sepsis and septic shock. To accomplish this goal, the conference participants aimed to use readily available clinical signs, symptoms and basic laboratory studies that would then support a rapid diagnosis. The trade-off for such a sensitive group of parameters that would alert physicians to the early manifestations of severe sepsis and septic shock was a group of criteria that lacked a great deal of specificity. It was also recognized that the same clinical signs, symptoms and laboratory data seen in patients with severe sepsis and septic shock were also present in other populations of critically ill patients with other proinflammatory conditions, such as trauma, burns, pancreatitis, etc. It was therefore decided to define the patients with a documented or highly suspicious infection that results in a systemic inflammatory response as having sepsis. In the ICU, sepsis patients would typically manifest organ dysfunction (severe sepsis) or septic shock, with or without multiple organ dysfunction syndrome.
    The second goal of the consensus conference was to facilitate better communication in the literature and scientific communication (including on rounds) which will enhance future comparative efforts among clinical trials and facilitate outcome comparisons of septic populations.
    What pearls, pitfalls and/or tips do you have for users of the SIRS Criteria? Are there cases in which they have been applied, interpreted, or used inappropriately?
    Users of the SIRS - Sepsis criteria need to understand that they are overly sensitive to identify potential patients as early as possible, but the criteria lack specificity. The 2001 international sepsis definition conference attempted to enhance the utility and specificity of the definition by including additional signs, symptoms, laboratory data, biomarkers and physiologic parameters. Unfortunately, we are still awaiting the perfect clinical definition that has both high sensitivity and specificity for severe sepsis and septic shock.
    For example, if you believe the patient has an infection AND meets the SIRS criteria, then the patient may be septic. Infection is likely its most useful application. The score is designed to be sensitive, but not specific. It's meant to help with early diagnosis. SIRS was not designed to be algorithmic, such as: if you have a score of X, you must do Y. Rather, it's a table of points to see whether or not the patient has any of these criteria. You then apply that result to the specific clinical scenario.
    What recommendations do you have for health care providers once they have applied the SIRS Criteria? Are there any adjustments or updates you would make to the criteria given recent changes in medicine?
    Investigators are continuing to refine the SIRS - Sepsis criteria and make them more clinically useful. The current approach has involved the use of various biomarkers to facilitate the identification of patients with a high likelihood of bacterial infection and/or high risk for morbidity and mortality. Some of the current biomarkers under evaluation include procalcitonin, C-reactive protein, proadrenalmodulin, N-terminal BNP and lactate.
    Other comments? Any new research or papers on this topic in the pipeline?
    The future will likely include significant refinements in the SIRS criteria using biomarkers and PCR or nanotechnology to improve the specificity of the diagnosis and provide the information in a more rapid fashion.

    About the Creator

    Robert A. Balk, MD, is a professor and practicing physician in pulmonology, internal medicine and critical care at Rush University Medical Center. His research interests include septic shock, acute lung injury, acute respiratory distress syndrome and ventilator-associated pneumonia.

    To view Dr. Robert A. Balk's publications, visit PubMed

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    MDCalc loves calculator creators – researchers who, through intelligent and often complex methods, discover tools that describe scientific facts that can then be applied in practice. These are real scientific discoveries about the nature of the human body, which can be invaluable to physicians taking care of patients.
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