Introduction
Coronary artery bypass grafting (CABG) surgery for coronary artery disease (CAD) remains the most common cardiac surgery performed in the USA and Canada4. The increased age of patients along with risk factors for CAD (i.e., hypertension (HTN), diabetes mellitus (DM), obesity and chronic kidney disease (CKD) increase the perioperative risk for acute kidney injury (AKI) and subsequent fluid overloaded (FO) states. The incidence of post operative AKI after cardiac surgery has been reviewed and reported as high as 40%.5 Understandably, the two most common chronic risk factors for heart disease (i.e., HTN and DM) are also the leading causes for chronic kidney disease in the USA6. Pre, intra and post operative factors for AKI include but are not limited to baseline preoperative heart failure states, baseline renal function, intraoperative intravenous fluid over or under hydration, and or decreased renal excretion7-9. Other perioperative risk factors for AKI include dye contrast from cardiac angiography and the systemic inflammatory response syndrome (SIRS) due to surgery. More concerning, is the relatively high failure to rescue (FTR) rate reported for post cardiac surgery AKI3. Although the STS mortality risk score is the most common indicator used to differentiate low, medium, and high-risk cardiac surgical patients, it fails to predict and capture other well-known high mortality risk factors including uncontrolled DM (i.e., HgbA1c level)10, nutritional status (i.e., albumin level) and decompensated heart failure (i.e., BNP levels). According to the most recent 2019 STS results, the average in-hospital and 30-day mortality rates for CABG are 1.8% and 2.2%, respectively7. Excess fluid overload in the perioperative phase of care has also been associated with increase morbidity and mortality6. Modified Ultrafiltration (MUF) techniques have been used for decades in the operating room to remove fluid but the use of simplified UF in the post operative cardiac surgery period has not been fully investigated. Enhanced Recovery after Surgery (ERAS) recommends using goal directed therapy (GDT) to avoid excess perioperative salt and water intravenous infusions and maintenance of euvolemia11, 12. Simplified ultrafiltration therapy with its low extracorporeal volume can be used to accomplish this task safely by removing isotonic plasma water in the post-operative period.
The current data evaluates a simplified UF technology for the removal of isotonic plasma water in high-risk post operative cardiac surgery patients. No randomized controlled trial data has yet been published on this subject. Results presented in this paper show safety and applicability of this technology in post cardiac surgery care.