Background: Cardiac surgery is one of the most frequently performed major surgical procedures. Following surgery, haemodynamic instability and prevention of organ dysfunction may be treated in the intensive care unit (ICU) with intravenous fluid, inotropes and vasopressors. In other surgical groups, liberal intravenous fluid administration and a positive fluid balance have been associated with adverse outcomes and increased risk of morbidity and mortality. There is a paucity of evidence to guide intravenous fluid administration in cardiac surgery patients. We have previously shown that a protocol-guided strategy avoiding unnecessary fluid administration significantly reduces fluid loading.
Objective: To present the design and statistical analysis plan for a randomised controlled trial comparing a conservative fluid management strategy to usual care in patients after cardiac surgery.
Methods: We designed a prospective, multicentre, parallel-group, randomised controlled trial - the FAB (Fluids After Bypass) study. A total of 700 patients undergoing cardiac surgery using cardiopulmonary bypass who have a European System for Cardiac Operative Risk Evaluation (EuroSCORE) II ≥ 0.9 will be enrolled in this study and randomly allocated to a protocol-guided strategy using stroke volume variation to guide administration of bolus fluid or to usual care fluid administration in a 1:1 ratio, stratified by centre. Study treatment will be administered from post-operative admission to the ICU until de-sedation or for a 24-hour period (whichever is shorter). The primary outcome is ICU length of stay. Secondary endpoints include quality of life and disability-free survival at 3 and 6 months after surgery, and process-of-care, physiological and safety measures.
Conclusion: This trial aims to determine whether a protocol-guided strategy that avoids unnecessary fluid administration reduces ICU length of stay and improves outcomes in higher-risk adults undergoing cardiac surgery.