PIRO: The Key to Success?

Sepsis continues to represent a major problem in intensive care units worldwide. Diagnosis and management are often complex due in part to the remarkably diverse nature of the septic patient. Indeed, sepsis can range in severity from mild systemic inflammation of little clinical importance through to a widespread severe inflammatory response with multiple organ failure and a mortality rate in excess of 50%. Sepsis can affect individuals of any age group, with no or multiple co-morbidities, and with many different ongoing diagnoses. It can occur as the result of infection by one or more of a multitude of microbial pathogens impacting on any of numerous different sites within the body. Given the huge complexity of sepsis and the diverse populations of patients it affects, simple definitions are of relatively little use and a more detailed framework which can be used to better characterize patients with sepsis has been proposed, much as the TNM classification (tumor size, nodal spread, metastases) has been successfully used in clinical oncology. In this chapter, we discuss the development of this PIRO system, and suggest how it may be used in the future to aid diagnosis, guide therapy, and improve prognostication.