Redefining the systemic inflammatory response to Cardiopulmonary bypass

Investigators:

¹ R. Clive Landis, ² Filip de Somer, ³ Yves Durandy

1 Chronic Disease Research Centre, Tropical Medicine Research Institute, The University of the West Indies, Bridgetown, Barbados 2 Heart Center, University Hospital Gent, Gent, Belgium 3 Pediatric Cardiac Surgery, CCML, Le Plessis‐Robinson, France

Start Date:

Aug 2014

End Date:

2015

Rationale:

The "systemic inflammatory response" has never been defined from a cardio‐thoracic surgery perspective but borrowed its definition from the critical care field at a landmark 1992 definition conference on sepsis. It is unclear why the diagnostic criteria for SIRS were adopted in isolation, ignoring other potentially more useful definitions for Severe Septic Shock or Secondary Multiple Organ Dysfunction Syndrome. The 1992 SIRS definition for sepsis has since been updated at a conference in 2001 and the need for a similar update for heart surgery is obvious since the current definition of SIRS is widely seen as too non‐specific: when used as described, Klaus Werdan and colleagues have shown it would occur in > 60% of all adult patients undergoing CPB and work from project collaborator Yves Durandy that it occurs in 100% of pediatric patients.

Methods:

The precedent of the sepsis update for SIRS suggests the following steps will be required to redefine the systemic inflammatory response to heart surgery: 1). Obtain buy‐in from the leading societies for cardiothoracic surgery, anesthesia, and perfusion on the need for a redefinition conference; 2). Formally abandon the existing SIRS definition. 3). Assign relative risk scores to different premorbid exposures, operative insults, and host response factors on clinical outcome to develop a new risk model; 4). Validate risk model in a prospective cohort; 5). Develop algorithms or ‘apps’ to facilitate rapid diagnosis and staging of care at bedside.

Main Results:

In the most recent evidence based review on the systemic inflammatory response in heart surgery, a dwindling proportion (14%) of articles even mentioned SIRS and 0% monitored all four SIRS criteria. The Consensus Statement authors have agreed on the need to re‐define (or indeed to define for the first time) the systemic inflammatory response, including Stephen Westaby who first described it in 1993. The first step is to scrap an effete definition that is not used in the field and is too non‐specific: Two papers are under preparation with a twofold purpose to: A. to scrap the SIRS definition from heart surgery and B. examine continuous perfusion parameters as a possible replacement.

Expected Impact:

The stated purpose of the 1992 SIRS definition in sepsis was "to facilitate bedside diagnosis for the rapid clinical staging of critically ill patients, and, second, to provide simple entry criteria for clinical trials". However, SIRS fails on both criteria in the field of heart surgery. It is therefore imperative that the field takes intellectual control over the definition, beginning with repeal of the existing SIRS definition.

Next Steps / Future Plans:

The first step is to formally repeal the SIRS definition. The next step will be to seek consensus among the major societies for a redefinition conference. The Outcomes 2010 Consensus Statement panel will serve as the nexus of a new consensus panel and have voiced their support of ongoing and future efforts.