Sepsis without SIRS is still sepsis

The host response to infection is pivotal to the clinical features observed in a patient with sepsis. Indeed, Sir William Osler noted that “Except on few occasions, the patient appears to die from the body’s response to infection rather than from it”. Importantly, evidence of the host response, in the form of the systemic inflammatory response syndrome (SIRS), during a documented or suspected infection is required criteria for sepsis diagnosis. Currently, the consensus for sepsis diagnosis, based on expert opinion, requires evidence of SIRS based on two or more of the following signs, abnormalities in white blood cell count, fever or hypothermia, tachycardia or elevated respiratory rate. Unfortunately, these criteria have never been validated and therefore the diagnosis of sepsis may include a heterogeneous population of patients, potentially with various pathophysiology and different outcomes, who may also benefit from distinct therapeutics. However, the mechanisms of sepsis remain uncertain. Given the need to standardize sepsis diagnostics, the SIRS plus infection criteria was embraced by the clinical and research community.