Cardiopulmonary Bypass Inflammatory Response Index (CPB-IRI) Calculator

Cardiopulmonary Bypass Inflammatory Response Index (CPB-IRI): Explanation and Clinical Context The CPB-IRI is based upon the concept of the systemic immune/inflammation index (SII) — calculated as platelet count multiplied by neutrophil count and divided by lymphocyte count. It serves as a surrogate marker of the inflammatory response initiated during cardiopulmonary bypass (CPB). CPB activates complement, neutrophils, monocytes, endothelial cells, and cytokine cascades and may culminate in systemic inflammatory response syndrome (SIRS) or organ dysfunction.

Pre-operative elevation of SII has been shown to independently predict in-hospital mortality in on-pump cardiac surgery patients. Although an absolute “normal” threshold for CPB-IRI is not fully validated in large cohorts, higher values suggest greater immune activation and possibly worse postoperative outcomes. This tool can aid clinicians in stratifying risk and potentially guiding perioperative anti-inflammatory or ultrafiltration strategies.