Using SOFA Scores to Identify Sepsis-3 Patients Post-Cardiopulmonary Bypass: A Retrospective Chart Review to Aanalyze Pre- and Peri- Operative Patient Predictors For Sepsis-3 Development

Abstract

Cardiopulmonary Bypass (CPB) allows a cardiothoracic surgeon to operate on a bloodless and still heart, vastly increasing the number of surgical interventions possible to treat various heart diseases. Development of Sepsis-3 after CPB occurs in only a small proportion of the patient population, but this group is characterized by a significantly more complicated post operative course, including a mortality rate above 40%. Sepsis-3 development in this population is due to several reasons, including contact of the blood to the foreign surfaces of the bypass circuit, shear stress from the action of blood being pumped by the circuit, and the general trauma of cardiothoracic surgery. Almost all patients who undergo CPB will experience some level of transient organ dysfunction. However, it is not entirely clear why some patients experience more permanent organ dysfunction and Sepsis-3. The Sequential Organ Failure Assessment (SOFA) score has been used across intensive care units (ICUs) to quickly quantify Sepsis-3 development in patients. Tracking SOFA scores, patients with increase greater than or equal to 2 are diagnosed as Sepsis-3 patients. This retrospective chart review evaluated 102 patients who underwent CPB at Banner University Medical Center - Tucson in 2022, analyzed their pre-operative history, perioperative values, and post-operative outcomes. SOFA scores were measured at baseline, and then daily post operatively for three days. We found that a higher threshold of increase in SOFA score greater or equal to 4 versus the traditional increase of 2 is required in post CPB patients to accurately discriminate between transient organ dysfunction and actual Sepsis-3 patients. With this new threshold for increase in SOFA score, 13 patients were identified as having Sepsis-3 with suspected or proven infection. Five of them had proven infection with a positive blood, sputum, or urine culture post operatively. The Sepsis-3 group had significantly worse post operative outcomes. This study found that several pre-operative conditions were significantly higher in the Sepsis group; Diabetes, Body Surface Area (BSA), Body Mass Index (BMI), and tobacco use. Of the chemical values typically recorded prior to cardiac surgery, only baseline lactate levels were higher in the Sepsis-3 group when compared to the Non sepsis group. Patients who develop Sepsis-3 post CPB had longer CPB and Cross-Clamp times. These patients required greater 5 pharmacological and mechanical support post-operatively and had significantly worse morbidities and mortalities. Lactate levels were found to be correlated with a Sepsis-3 development, as well as significantly higher baseline and higher change in lactate levels. Therefore, caution should be used when implementing SOFA scores on CPB patients. Lactate levels could be a biomarker useful for identifying higher risk patients. This can allow physicians to implement prophylactic measures to try and reduce the development of Sepsis-3 post-operatively