Calc Function

    • Calcs that help predict probability of a diseaseDiagnosis
    • Subcategory of 'Diagnosis' designed to be very sensitiveRule Out
    • Disease is diagnosed: prognosticate to guide treatmentPrognosis
    • Numerical inputs and outputsFormula
    • Med treatment and moreTreatment
    • Suggested protocolsAlgorithm





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    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


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    • 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 ≥ 4 mmol/L is considered diagnostic for Severe Sepsis, and aggressive management with broad spectrum antibiotics, intravenous fluids, and vasopressors should be initiated (aka EGDT).
    • 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.
    • The management of Severe Sepsis and Septic Shock is the topic of intense research and scrutiny.
    • While Early Goal Directed Therapy has been advocated in the Surviving Sepsis Guidelines, there remains controversy as to which of the bundled interventions are necessary.
    • Recent studies have showed EGDT not to be better than “usual care”, and called for significant amendments to currently used sepsis protocols.
    • To date, most experts agree that early recognition of Sepsis, Severe Sepsis, and Septic Shock, and early administration of broad spectrum and organism specific antibiotic 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.
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