Severe sepsis can be defined as a condition that arises when the body's response to an infection injures its own tissues and organs, sometimes progressing to septic shock. Multiple organ (lung, liver, and kidney) dysfunction is possible, which may result in death. Severe sepsis is characterized by organ dysfunction, hypoperfusion, and/or hypotension.*
The U.S. Centers for Medicare and Medicaid Services (CMS) in its core measure for sepsis, Severe Sepsis/Septic Shock Early Management Bundle (SEP-1) defines severe sepsis as "having a suspected source of clinical infection and two or more manifestations of systemic infection (SIRS criteria) plus one or more variable of organ dysfunction". SIRS criteria include:
- A body temperature >38°C (100.4°F) or <36°C (96.8°F)
- A heart rate >90 beats/minute
- Respiratory rate >20 breaths/minute
- An alteration in the white blood cell (WBC) picture, such as a count >12.0 x 109/L or <4.0 x 109/L or >10% immature neutrophils
According to SEP-1, variables of organ dysfunction, leading to a diagnosis of severe sepsis include any one of the following:
- Lactate >2mmol/L
- INR >1.5 or aPTT >60 seconds
- Platelet count <100,000
- Bilirubin >2mg/dL
- Creatinine >2, or urine output <0.5mL/kg/hr for 2 hours
- Systolic blood pressure (SBP) <90mmHg, or mean arterial pressure <65mmHg, or decrease in SBP >40mmHg from last previously recorded "normal" for that patient
*
NOTE: Some clinicians (particularly in countries outside the U.S.) have stopped using the term, "severe sepsis," and simply refer to the condition as "sepsis."
